HIPAVE User Manual

H I PAV E 5 .0 User Manual MINCAD Systems Pty. Ltd. P.O. Box 2114, Richmond South, Vic., 3121 Australia Tel.:(03) 9427 1085 Intl. +613 9427 1085 Fax:(03) 9428 1197 Intl. +613 9428 1197 Email: [email protected] Web: http://www.mincad.com.au April 2009 © MINCAD Systems Pty. Ltd. i Contents Summary HIPAVE End User Licence Agreement Introduction 5 7 9 Background ....................................................................................................................................9 Realistic Modelling with HIPAVE..................................................................................................11 Material Modelling..............................................................................................................12 Modelling of Multiple Wheels and Axle Groups .................................................................14 Nature of Damage Pulses..................................................................................................14 Overview 15 How HIPAVE handles Traffic Distributions ..................................................................................15 Cumulative Damage Concept ......................................................................................................16 Lateral Vehicle Wander................................................................................................................18 Material Performance ...................................................................................................................18 Traffic and Loading.......................................................................................................................19 How Vehicle characteristics are defined ......................................................................................19 Standard Vehicle Library....................................................................................................19 Unequal Axle Loads...........................................................................................................20 Equal Axle Loads ...............................................................................................................21 Coordinate System for Vehicles.........................................................................................22 Methods for handling Damage Pulses .........................................................................................24 Dynamic Load Factors .................................................................................................................25 Container Weight Distributions.....................................................................................................26 Automatic Thickness Design........................................................................................................26 Cross-anisotropy and Isotropy in Pavement Materials ................................................................27 Cost Calculation ...........................................................................................................................28 Automatic Parametric Analysis ....................................................................................................29 Overview of User Interface 31 Introduction...................................................................................................................................31 Creating, Opening and Saving Files ............................................................................................32 Creating and Editing Input Data ...................................................................................................32 Database Approach ...........................................................................................................33 Running the Analysis and Plotting Results ..................................................................................33 Run Analysis ......................................................................................................................33 Plot Results ........................................................................................................................33 Options .........................................................................................................................................34 How to Start Using HIPAVE 35 Opening and Running an Existing Job.........................................................................................36 ii Contents Global Coordinate System ...........................................................................................................42 Alternative Calculation Options 45 Overview ......................................................................................................................................45 Damage Calculation Details.........................................................................................................45 Thickness Design Capability ........................................................................................................47 Calculating Selected Results at User-defined Z-values (depths) ................................................48 How to Use Advanced Features 51 Cost Calculation ...........................................................................................................................51 Calculation of Total Cost....................................................................................................51 Material Costs ....................................................................................................................52 Automatic Parametric Analysis ....................................................................................................53 Example—Cost Optimization .......................................................................................................54 How to Modify the Databases 61 Introduction...................................................................................................................................61 Units ...................................................................................................................................61 Sign Convention.................................................................................................................62 Overview of Database Approach .......................................................................................63 The "Layered System" and "Materials" Databases ......................................................................64 Overview of Layered System and Material Properties ......................................................64 Cross-anisotropy and isotropy in road pavement materials ..............................................65 Creating a new Layered System........................................................................................66 Defining the Layer properties.............................................................................................67 Duplicating a Layered System ...........................................................................................68 Adding a new Elastic Material............................................................................................69 Adding a new Performance Criterion.................................................................................71 Example: Asphalt tensile strain relationship ........................................................... 71 Example: Log-linear performance relationship ....................................................... 73 Adding a new Material Type ..............................................................................................75 The "Loads" and "Traffic Spectrum" Databases ..........................................................................76 Introduction ........................................................................................................................76 Vehicle Specifications ........................................................................................................76 Automatic Updates for the Standard Vehicle Library ............................................. 77 Adding Custom Vehicle Specifications ................................................................... 77 Traffic Spectrums...............................................................................................................82 Creating a new Traffic Spectrum ............................................................................ 82 Characterizing Payload Distributions...................................................................... 84 Using a Standard Payload Distribution................................................................... 84 Defining a Custom Payload Distribution ................................................................. 85 Duplicating a Traffic Spectrum ............................................................................... 87 Standard Payload Distributions..........................................................................................88 Introduction ............................................................................................................. 88 Creating a new Standard Payload Distribution....................................................... 89 Dynamic Load Factors .......................................................................................................92 Wander Options .................................................................................................................93 Coordinates for Results................................................................................................................95 Appendices 97 References ...................................................................................................................................99 Contents iii Coordinate System for Loads.................................................................................................... 100 such as forklifts. horizontal. Increased wander reduces pavement damage by different amounts that depend upon the pavement thickness.5 Summary HIPAVE (Heavy Industrial PAVEment design) is for the mechanistic analysis and design of flexible pavements subjected to the extremely heavy wheel loads associated with freight handling vehicles in industrial facilities. HIPAVE has many other powerful features. fully continuous (rough) or fully frictionless (smooth) layer interfaces. in particular. gantry cranes and side loaders. A Parametric Analysis feature can loop through a range of thicknesses for one or two layers. straddle carriers. This feature will optimise up to three layers. a comprehensive range of load types. HIPAVE is an outgrowth of CIRCLY and APSDS (Airport Pavement Structural Design System). ability to define and store container weight distributions. HIPAVE can handle the variety of mobile equipment used in container facilities. non-uniform surface contact stress distributions. It is designed to conveniently model each combination of vehicle type and container load and to combine the damage using the Cumulative Damage Factor concept. etc. and automatic sub-layering of unbound granular materials. allows for fine-tuning of layer thicknesses to minimize construction and maintenance costs. Vehicle wander is the statistical variation of the paths taken by successive vehicle movements relative to lane centrelines. including vertical.. . intermodal container terminals. and automatic calculation of axle loads from vehicle geometry and container weight. torsional. CIRCLY was first released in 1977 and APSDS in 1995. HIPAVE takes account of vehicle wander at a more fundamental level than earlier methods.that can be automatically updated from our webserver. while simultaneously designing the thickness of another layer. including selection of– cross-anisotropic and isotropic material properties. Combining this with a Cost Analysis feature. HIPAVE has unique features to expedite pavement design projects— a standard vehicle library . . are excluded. However. (b) HIPAVE is supplied with certain operating instructions and a failure to follow these instructions carefully could result in erroneous data being produced by HIPAVE. 21. such term shall be deemed to be included in this Agreement. in whole or part. failure or omission of Mincad. Customer warrants that it has not relied on any representation made by Mincad or upon any descriptions or illustrations or specifications contained in any document including any catalogues or publicity material produced by Mincad.7 HIPAVE End User Licence Agreement HIPAVE © Mincad Systems Pty Ltd ABN 27 006 782 832. translated or reduced to any electronic medium or machine readable form.1 To the maximum extent permitted by law all warranties whether express. . photocopied. Mincad shall not be under any liability (contractual. This documentation is licensed and sold pursuant to the terms and conditions of the HIPAVE End User Licence Agreement. to any one or more of the following: if the breach related to goods: the replacement of the goods or the supply of equivalent goods. implied. or the payment of the cost of having the goods repaired. reproduced. 20. Acknowledgement 21.1Customer acknowledges and agrees that: (a) pavement design and engineering is a complex area and the HIPAVE is not designed as a substitute in any way for professional advice. or the payment of the cost of having the services supplied again.2 To the maximum extent permitted by law and subject only subject only to the warranties and remedies set out in Clause 12 and Sub-clause 21. tortious or otherwise) to Customer in respect of any loss or damage (including. the repair of such goods. which appears under the HIPAVE "About" dialogue box which provides (in part). All rights Reserved Copyright This manual is copyright and may not be copied. without the prior written consent of Mincad. consequential loss or damage) howsoever caused. the liability of Mincad for any breach of such term shall be limited.1. at the option of Mincad. Where legislation implies in this Agreement any condition or warranty and that legislation avoids or prohibits provisions in a contract excluding or modifying the application of or the exercise of or liability under such term. the payment of the cost of replacing the goods or of acquiring equivalent goods. 20. without limitation. which may be suffered or incurred or which may arise directly or indirectly in respect to the supply of goods or services pursuant to this Agreement or the act. relating in any way to the subject matter of this Agreement or to this Agreement generally. statutory or otherwise.Exclusions and Limitation of Liability 20. and if the breach relates to services the supplying of the services again. 21.2 HIPAVE is licensed on the basis set out in this Agreement on the understanding that to the extent permitted by law Mincad is not responsible for the results of any actions taken. . expenses. and (e) They shall obtain professional advice in relation to all results provided by HIPAVE. without limitation: (i) the applicable Pavement engineering standards. HIPAVE is designed to be used by persons who have a detailed knowledge of. Indemnity Customer warrants that any materials supplied to Mincad by Customer do not infringe Intellectual Property Right of any person. against any loss. including. (b) a breach of this agreement by Customer. employees and agents. costs. taxes or liability whether direct or indirect arising out of: (a) use of HIPAVE. its officers. Customer shall fully indemnify and keep indemnified Mincad. unlawful or negligent act or omission of Customer. (d) They shall manually check all results provided by HIPAVE for any anomalies. 22. or (c) any wilful. To the extent permitted by law.8 HIPAVE User Manual (c) Whilst HIPAVE may be used by persons without a detailed knowledge of computers. and (ii) All appropriate legislation and other relevant instruments. without limitation the relevant industry recognised engineering design guides. either by Customer or a third party relying on figures supplied or not supplied by HIPAVE. demands. The variety of vehicle types and traffic levels were approximated by "Equivalent" wheel loads and "wheel proximity factors". HIPAVE can handle the variety of mobile equipment used in container facilities. Databases are used for material properties and loadings. in particular. HIPAVE takes account of vehicle wander at a more fundamental level than earlier methods of treating wander. intermodal container terminals. 1996) were developed prior to personal computers being commonplace. These simplifying approximations are no longer justified now that personal computers are commonly available. It is designed to conveniently model each combination of vehicle type and container load and to combine the damage using the Cumulative Damage Factor concept.that can be automatically updated from our webserver. such as forklifts. ability to define and store container weight distributions. Previous methods for structural design of container terminal pavements such as the British Ports Association guide (3rd edition. gantry cranes and side loaders. Therefore simplifying assumptions were necessary for manual calculation. straddle carriers. . For example the "equivalent thickness" concept was used to accommodate materials and properties not covered by the design charts. Results can be obtained in tabular form or as report-quality plots on any printer or plotter supported by Microsoft Windows. HIPAVE has unique features to expedite pavement design projects— a standard vehicle library . HIPAVE is targetted at structural design of flexible pavements subjected to the extremely heavy wheel loads associated with freight handling vehicles in industrial facilities. Increased wander reduces pavement damage by different amounts that depend upon pavement thickness. Vehicle wander is the statistical variation of the paths taken by successive vehicle movements relative to lane centrelines.9 CHAPTER 1 Introduction Background HIPAVE (Heavy Industrial PAVEment design) is an outgrowth of CIRCLY and APSDS (Airport Pavement Structural Design System). HIPAVE has a user-friendly menu-driven interface that runs under Microsoft Windows. thus eliminating the need to constantly re-key information. Results can be easily exported to other application packages such as spreadsheets for further processing. and automatic calculation of axle loads from vehicle geometry and container weight. The wander algorithm that is used in HIPAVE was first released in APSDS 3. CIRCLY. The program allows all of these load types to be simulated for a circular loaded shape. 2007). CIRCLY was first released in 1977 and handled polynomial type radial variations in contact stress and multiple loads which provide a much closer representation of the actual loading conditions (Wardle 1977). John Lancaster (VicRoads. The program on which it is based. Canada). has been in regular use in Australia and worldwide for more than two decades. CIRCLY 3. CIRCLY 4. HIPAVE is based on integral transform techniques and offers significant advantages over other linear elastic analysis techniques. CIRCLY 5. such as the finite element method. MINCAD Systems. HIPAVE has been designed to conveniently handle comprehensive details of the freight handling vehicles and the characteristics of the payload distribution for each vehicle. Australia). In 2007 Mincad Systems and Pioneer Road Services released the Heavy Duty Industrial Pavement Design Guide (Mincad Systems and Pioneer Road Services. The interfaces between the layers can be either fully continuous (rough) or fully frictionless (smooth). University of Waterloo. unwieldy data input makes it very difficult to model more than one or two payloads per vehicle. Commencing in 2004. Australia) and Dr. HIPAVE incorporates all the features of CIRCLY 5. MINCAD Systems has released a number of trial versions of HIPAVE. For most problems the program uses less computer time than a finite element program. torsional wheel loads due to cornering. including a major re-write of the integration algorithms and automatic sub-layer generation for granular materials. 1998). Leigh Wardle of Mincad Systems. horizontal wheel loads due to traction and braking. cross-anisotropic material properties can also be considered. loads may be applied to soil or rock pavement layers in the form of vertical wheel loads. While CIRCLY and APSDS have been used very successfully for heavy duty industrial pavements. The Guide has been developed to assist users of the HIPAVE software. .0. A cross-anisotropic material is assumed to have a vertical axis of symmetry. Civil Engineering.0 in 1995 (Wardle and Rodway. Input data for the program is much simpler than that required for most finite element programs.0 was released in early 2004.4) was made in early 1996. The Guide is a collaborative effort currently involving Dr. proving its worth in thousands of design applications.10 HIPAVE User Manual As well as the usual isotropic properties. and the "gripping" load developed by pneumatic tyres on pavements. This Australian designed system has been developed by the Melbourne company.0 was commercially released in September 2005. Melbourne.0 was released in early 1999 and extended the software to include an automatic thickness design capability.0 was released in late 1996 and included many improvements. Anisotropies of this type have been observed in soil and rock deposits due to processes involved in their formation. HIPAVE 5. HIPAVE can also model non-uniform contact stress distributions. In practice. CIRCLY was commercialised in 1988 by MINCAD Systems. Susan Tighe (Dept. or a combination of both types. Ian Rickards (Pioneer Road Services Pty Ltd. A limited release of the first Windows version (Version 2. Otherwise so many assumptions must be made about the uncertain parameters that the model predictions will be meaningless.Chapter 1 Introduction 11 The Guide presents the author’s attempts to reflect best practice in the design of new construction and rehabilitation of industrial pavements. that will influence the reliability of design predictions made using HIPAVE. For further details see http://www.mincad. The following Sections summarize the "state of the art" with respect to modelling of heavy loads such as container handling equipment and the behaviour of pavement materials. including the accuracy of input material properties and the constraints of the layered elastic model. Realistic Modelling with HIPAVE You should be aware of a number of factors.au/hdipdg/. . The Guide steers the designer through all necessary design considerations and suggests external sources for research updates.com. For further details see http://www. More detailed advice is given in the Heavy Duty Industrial Pavement Design Guide (Mincad Systems and Pioneer Road Services.au/hdipdg/. or for that matter. Care must be taken to ensure that the sophistication of the analysis method is consistent with the quality of the input data. The Guide is a ‘living document’ that will be regularly updated to reflect advances in pavement technology and made freely available via the Internet at no charge. 2007). any alternative design software.mincad. Although HIPAVE can produce what appear to be very accurate solutions to problems. The design values chosen for material properties are likely to be gross simplifications of the complex and variable properties of the pavement and subgrade materials.com. the predictions cannot be any more reliable than indicated by the degree of scatter given by the back-analysis of the full-scale field tests against which HIPAVE has been 'calibrated'. Much of this knowledge has been derived from airport pavement research. A preferred subgrade performance relationship for heavy duty pavements was developed by Wardle et al. (2001). The subgrade strains are converted to damage using a performance relationship of the form: ⎡k ⎤ N=⎢ ⎥ ⎣ε ⎦ b . the empirical connection between the test data and the new design is broken. But research has shown that highway pavement design methods such as Austroads (1992.. Because each failure criterion is derived in the context of its own detailed design procedure. 1998). There are a number of differences to the Austroads pavement model: Basecourse. The relationship was developed using a range of different aircraft with masses varying from 40 tonnes to 397 tonnes and subgrade strengths varying from CBR = 3% to CBR = 15%. sub-base and subgrade are assumed to be isotropic (Austroads assumes anisotropic). the vital empirical link between the design and the original performance data used to calibrate the criterion is broken. 2003). This performance relationship was established by calibrating pavement designs using APSDS against designs based on the US Army Corps of Engineers CBR method (Method S77-1. 2004) are not applicable to the higher loadings typically applied to heavy duty pavements used at ports and container terminals (Wardle et al. it will only produce sensible pavement designs when used as part of that same procedure. The process of establishing a performance relationship entails assigning moduli values to unbound basecourse and sub-base materials in accordance with a particular system of sublayering. If a failure criterion is used in conjunction with a different design procedure. Unless this is done. Pereira 1977). The material performance characteristics recommended for use in HIPAVE are based on calibrations developed from airport pavement research. This issue is discussed in more detail by Wardle et al. A different methodology (Barker and Brabston. using the Austroads design method for container handling equipment where the loads can be 20 tonnes per wheel has been shown to lead to grossly underdesigned pavements (Rodway and Wardle.12 HIPAVE User Manual Material Modelling HIPAVE is an open system that will accommodate material properties and transfer functions for any pavement design methodology. (2003). Care should be taken to ensure that the sub-layering system used to establish the performance relationship is also used when analysing or designing pavement structures. 1975) is used to sublayer the basecourse and sub-base. For example. 64 10-09 E3 .0274 E +9.Chapter 1 Introduction 13 where N is the predicted life (repetitions of ε) k b is a material constant is the damage exponent of the material ε is the load-induced strain (unitless strain) The parameters k and b vary with subgrade modulus (E) in units of MPa as given by the following: k = 1.12 10-07 E3 +8.4.18 10-05 E + 0.38 10-4 E2 -0.31 10-07 E2 + 2.57 .00289 b = -2. Results from these studies show that the successful calibration of simplified design models against the full-scale test data does not create a capability to confidently extrapolate beyond the limits of the test data. Care needs to be taken to select which wheels to include in the model. Given the above comments. for deep subgrades. There is significant uncertainty in the design of thick pavements because data must be extrapolated from thinner test pavements which have narrower pulses than those expected for the deeper subgrades. These 'WES' tests were essentially conducted using single gear assemblies. Wardle and Rodway 1998. This methodology was derived from full-scale aircraft pavement tests conducted by the US Army Corps of Engineers at their Waterways Experiment Station (WES). a two-axled gear produces two strain pulses per pass for shallow subgrades and one strain pulse. Three different performance models. APSDS has been used to study multiple gear interaction effects for a Boeing 747 and 777 aircraft using a range of alternative damage models (Rodway 1995a. as a general rule only groups of wheels that are within 2 metres of each other should be modelled as a single load case.5 m or more) the models predict a single combined pulse resulting from the entire gear. For example. the most appropriate way of modelling a Fork Lift is described in Coordinate System for Vehicles (on page 22). Rodway. The differences between the alternative predictions increased with increasing depth to subgrade. There is still no experimental data to show to what extent pavement damage depends on the transverse and longitudinal widths of the load pulse. No tests were carried out to investigate the increased damage that might result due to interaction effects of adjacent gear assemblies. Considerable uncertainty exists with respect to prediction of damage for aircraft that have main gears in close proximity. Pulse counts and pulse shapes both change with pavement thickness. The recommended model for base/sub-base materials and subgrade performance relationship recommended for heavy duty loads was described above. Extensive research gives us guidance on choosing the "right" combination of wheels to include in the model. For deep pavements (say 1. gave greatly different predictions of the damage caused by the interactions of the sixteen main wheels. Nature of Damage Pulses The WES tests were performed on relatively thin pavements. HIPAVE uses strain repetitions as the basis for damage predictions. Wardle and Wickham 1999). In most of the test sections the elastic models predict a distinct strain pulse at subgrade level for each axle of a two-axled gear. In other words. . of significantly different shape.14 HIPAVE User Manual Modelling of Multiple Wheels and Axle Groups HIPAVE lets you use the actual wheel layouts of the vehicles that operate on the pavement. Using more wheels can lead to inaccurate model predictions. each of which gave a similar 'goodness of fit' to the full-scale test data. The studies showed that simple damage models give unrealistic predictions for the damage caused by all sixteen main wheels of the aircraft when compared to that computed for a single isolated 4wheel gear. not passes or coverages. Payload Distribution Count 8000 7000 6000 5000 4000 3000 2000 1000 0 2.5 17.Payload Distribution Count 8000 7000 6000 5000 4000 3000 2000 1000 0 2.5 22.5 27. Vehicle Model A Vehicle Model A . You also define a payload distribution for each vehicle model.5 27.5 12.5 17.5 Payload (tonnes) Vehicle Model B Vehicle Model B .5 22.5 12. You define the anticipated repetitions over the design period for each vehicle model. How HIPAVE handles Traffic Distributions HIPAVE lets you define your vehicle loadings and traffic in detail. The following example illustrates the concepts. Here there are two vehicle models. A and B.15 CHAPTER 2 Overview HIPAVE has many features to facilitate pavement analysis and design.5 Payload (tonnes) .5 4 6 8. Each vehicle model is assigned a payload distribution.5 4 6 8. The procedure takes account of— the design repetitions of each vehicle model/payload combination. It is not necessary to approximate passes of different vehicles or axles to passes of an ‘equivalent’ standard load or "design vehicle". k The system is presumed to have reached its design life when the cumulative damage reaches 1.16 HIPAVE User Manual Cumulative Damage Concept The system accumulates the contribution from each loading in the traffic spectrum at each analysis point by using Miner's hypothesis. If the cumulative damage is less than 1. The damage factor for any given loading is defined as the number of repetitions (n) of a given response parameter divided by the ‘allowable’ repetitions (N) of the response parameter that would cause failure: CDF = n N The Cumulative Damage Factor (CDF) for the parameter is given by summing the damage factors over all the loadings in the traffic spectrum: CDFtotal = ∑ ∑ CDFkj k =1 j =1 M Nk where: k is summed over M vehicle models Nk is the number of different payloads for vehicle model no.0 the system has excess capacity and the cumulative damage represents the proportion of life consumed. If the cumulative damage is greater than 1.0 the system is predicted to ‘fail’ before all of the design traffic has been applied. and the material performance properties used in the design model. .0. This approach allows analyses to be conducted by directly using a mix of vehicle models. HIPAVE can also generate graphs that show the variation of the damage factor across the pavement. as shown below: .Chapter 2 Overview 17 HIPAVE does a full spectral analysis of pavement damage by using the cumulative damage concept to sum the damage from multiple vehicle models and payload cases for one set of layered system material properties. The figure below is a sample cumulative damage plot produced by HIPAVE: Note that there is a data point for each combination of vehicle model and payload. vertical deflection. . Material Performance Generally most performance models may be represented graphically by a plot of tolerable strain versus load repetitions (generally by a straight line of 'best fit' on a log-log plot). HIPAVE usually represents models in the form: ⎡k ⎤ N=⎢ ⎥ ⎣ε ⎦ where N k b ε b is the predicted life (repetitions) is a material constant is the damage exponent of the material is the induced strain (dimensionless strain) Log-log relationships can be readily converted to the above form. etc. You can use your own performance equations by specifying values for ‘k’ and ‘b’ and the particular component to be used. bypasses the simplified concepts of “coverage” and “pass-tocoverage ratio” (PCR) that have been traditionally used for aircraft pavement design. You nominate a standard deviation of vehicle wander about the centreline that is appropriate to the particular vehicle and pavement. The sophisticated method of handling wander. for example vertical strain. HIPAVE is supplied with a comprehensive range of published performance models.18 HIPAVE User Manual Lateral Vehicle Wander The analysis optionally includes the effect of the lateral distribution of successive vehicle passes along the pavement. maximum tensile strain. HIPAVE can also handle models of the form: log10 ( N) = k − b ε This log-linear relationship is used by European designers for cement-treated materials. and equal loads on each axle. In designing HIPAVE account has been taken of a number of important issues relating to the definition of vehicle loading characteristics. We encourage all users to send us vehicle specifications for inclusion in the standard vehicle library.a benefit of of the Standard Vehicle Library is that it takes the worry out of selecting which wheels to model. and axle mass characteristics. . you can define your own vehicle models directly in HIPAVE. HIPAVE uses the following vehicle data— wheel locations and numbers. You will also save time by not having to seek vehicle specifications from manufacturers or facility operators.Chapter 2 Overview 19 Traffic and Loading You define the anticipated repetitions over the design period for each vehicle or axle group and the payload mix — that is the repetitions for each payload that is modelled. You can obtain updates (new vehicles) automatically by clicking the "Import" icon on the toolbar. Most importantly. a critical issue is choosing the optimum number of wheels to use in the model . Container handling equipment can be broadly sub-divided into two categories according to the load transfer characteristics: unequal loads on each axle. The master version is maintained on our webserver. How Vehicle characteristics are defined Standard Vehicle Library In designing HIPAVE we have introduced the concept of a Standard Vehicle Library. Of course. For example this could be the Unladen case together with one specific Container Weight. This screendump shows some sample data: . The graph below illustrates the concept. In this case. Axle loads for other container weights are obtained automatically by linear interpolation.20 HIPAVE User Manual Unequal Axle Loads Examples of these vehicles are Fork Lifts and Reach Stackers. the vehicle loading characteristics are specified in terms of two load cases that express the axle loads as a function of Container Weight. you will see more details for the currently selected Vehicle Model: Equal Axle Loads Vehicles such as straddle carriers are assumed to have equal loads on each axle. In this case the vehicle loading characteristics are specified in terms of the unladen weight of the vehicle. The screendump below shows some sample data: . the number of axles seen from one side of the vehicle).e. the total number of wheels on the vehicle and the tyre pressure.Chapter 2 Overview 21 If you now click on the Load Components and Locations tab. the number of axle rows (i. . To ensure consistency between results for different vehicle types it is recommended that X = 0 to the lane centreline.22 HIPAVE User Manual If you now click on the Load Components and Locations tab. you will see more details for the currently selected Vehicle Model: Coordinate System for Vehicles The X axis is taken as the direction transverse to the lane. Usually all vehicles are assumed to have their centrelines at X=0. This example is for a Hyster Fork Lift -Model H40. . there is no interaction between axle loads. Modelling the two axles as separate components means that the two axles are modelled as two separate load cases. HIPAVE will normally model the two axle loadings as separate components.e. with the front axle (assumed to be on Y=0) as component 1 and the rear axle as component 2.00-16CH. Usually it is only necessary to model the wheels on one side (X ≥ 0) of the vehicle. i.Chapter 2 Overview 23 The Figure below illustrates the convention used to define the wheel locations. for large depths relative to the axle spacing the maximum strain will generally occur under the centroid of the gear. was implemented in a prototype version of this software to overcome this problem and to ensure a smooth transition between the two extremes. HIPAVE then computes the damage pulse beneath the centroid of the gear due to the strain contributions for all wheels of the vehicle. for large depths. for shallow depths. then multiplies the computed damage by the number of axle rows (i. . as used in bridge design to handle complex loadings. The two extremes of behaviour are— multiple distinct pulses resulting from each axle. For shallow pavement depths compared to axle spacing one ‘pulse per axle’ is selected. But this method is not currently available. HIPAVE lets you specify the method to be used to calculate the damage. and a single pulse that reflects the overall loading on the axle group. Recently the ‘reservoir’ method. HIPAVE then computes the damage beneath that axle due to the strain contributions for all wheels of the vehicle. HIPAVE relies on you specifying one set of axles at Y=0 [see Convention used to define wheel locations (on page 23)]. and ignores the number of axles in the group.24 HIPAVE User Manual Methods for handling Damage Pulses The problems associated with damage pulses were introduced in the Overview section under Nature of damage pulses (on page 14). the number of axles seen from one side of the vehicle). The damage that a given point in the pavement will experience during the passage of a multiple axle primarily depends on the depth below surface. Between these two extremes the pulses resulting from each axle overlap making the calculation of damage problematic. In this case you specify 'combined pulse for gear' and HIPAVE will automatically shift the load coordinates so that the origin is at the centroid of the gear as shown on Automatic shift of Y-coordinates for 'combined pulse for gear' case (on page 25). However.e. . These are simple multipliers that are applied to the design loads and can vary with each axle. Dynamic Load Factors So-called Dynamic Load Factors are used in the British Ports Association Design Guide (British Ports Association. accelerating.Chapter 2 Overview 25 Figure 1: Automatic shift of Y-coordinates for ‘combined pulse for gear’ case It is your decision whether the pavement is relatively deep or shallow compared the axle spacing. whether HIPAVE or other analysis methods are used. HIPAVE lets you use your own values for the factors. Computation of damage at intermediate depths involves judgement based on knowledge of the strain pattern. braking and surface uneveness. HIPAVE automatically shifts the position of the load coordinates if you specify 'combined pulse for gear'. 1996) to account for the effects of dynamic loading induced by cornering. Container weight distribution for 40 foot containers based on data provided by UK ports (British Ports Association 1996). HIPAVE includes the "Standard" distributions provided by British Ports Association (1996). .26 HIPAVE User Manual Container Weight Distributions HIPAVE lets you specify detailed container weight distributions. The "Custom" distribution is used for just one traffic spectrum / vehicle model combination. The "Standard" distribution feature lets you re-use a particular distribution across a range of vehicle models and projects. The following graph shows the container weight distribution for 40 foot containers. Automatic Thickness Design You can automatically determine the optimum thickness of a given layer. For example. For further details see Thickness Design Capability. The container weight distributions are categorized as being "Standard" or "Custom". the British Ports Association Guide (1996) includes frequency data based on data provided by UK ports. In general. The stress-strain relations for a cross-anisotropic material in a particular layer are: εxx = εyy = εzz = εxy = εxz = εyz = (1/Eh) (σxx .e.νh σxx + σyy . In the Austroads pavement design method (1992 and 2004) cross-anisotropic properties are used for subgrade materials and unbound granular aggregates and isotropic properties are used for bound materials such as asphalt and cemented materials. A cross-anisotropic material has an axis of symmetry of rotation.5 > ν > -1.νhv σzz) (1/Eh) (. which is assumed to be vertical..νh σyy . whereas isotropic materials have the same elastic properties in both the vertical and horizontal directions.νhv σzz) (1/Ev) (.νvh σxx .Chapter 2 Overview 27 Cross-anisotropy and Isotropy in Pavement Materials The elastic material in each layer of the pavement structure is assumed to be homogeneous and of cross-anisotropic or isotropic symmetry. the elastic properties are equivalent in all directions perpendicular to the axis of symmetry (in horizontal.νvh σyy + σzz) ((1+νh)/Eh) σxy (1/f) σxz (1/f) σyz The moduli and Poisson's ratios are related by the following equation: νvh/Ev = νhv/Eh The condition that the strain energy must be positive imposes restrictions on the values of the elastic constants: Eh > 0 1 > νh > -1 Ev > 0 f>0 1-νh-2νhvνvh > 0 For isotropic materials the restrictions become: E>0 0. radial directions).0 . these properties are different from those in the direction parallel to the axis. i. 5 Ev νvh = νh = ν f = Ev/(1+ν) In this case. subgrade stabilization and the like. . only the Elastic modulus and Poisson’s ratio need to be entered.28 HIPAVE User Manual To be able to model a cross-anisotropic material you need to specify five constants: the vertical Elastic modulus (Ev). the material is defined simply by the vertical Elastic modulus. The areal component can also be used in circumstances where the relationship between total layer cost and thickness has a non-zero component for zero thickness. and a single Poisson's ratio. Ev. such as surface treatments. Data values for all five constants are rarely available. the Poisson’s ratio (νvh). the horizontal Elastic modulus (Eh). Cost Calculation The unit costs for the materials laid and constructed in the layers can be specified using a combination of both a volumetric (or weight) component and an areal component. as they are assumed to be the same in all directions. the Poisson’s ratio (νh) and the Shear modulus (f). ν. The Austroads Pavement Design Guide uses the following simplifications to model subgrade and unbound granular materials: Eh = 0. The areal component lets you take account of costs that are primarily a function of area. For isotropic materials. By combining Automatic Parametric Analysis with the Cost Analysis feature you can finetune layer thicknesses to optimise construction cost. Additionally. Layer 3 Thickness . for each combination of those layer thicknesses. Automatically generated plot: Total Cost vs. you can automatically design the thickness of another layer. For example. you can have Layer 3 vary from 800 mm to 1000 mm in steps of 10 mm.Chapter 2 Overview 29 Automatic Parametric Analysis Automatic Parametric Analysis lets you automatically loop through a range of thicknesses for one or two nominated layers. . 31 CHAPTER 3 Overview of User Interface Introduction HIPAVE has a standard format Microsoft Windows menu. but most commands can be accessed directly from the toolbar as shown below: . ) HIPAVE32 cumulative damage results file (for plotting) HIPAVE32 results summary file (damage factors and critical strains) All of these files are text files that can be opened by standard text editors. Opening and Saving Files You supply a 'Jobname' to use as the basis for naming all of the files associated with a 'job' or analysis. strains. then opens an existing job.clo Jobname.dam Jobname. etc. Icon Description Closes the current job. then clicking Save As.32 HIPAVE User Manual Creating. open and save job files. If the job name is Jobname the following files are used– Jobname.cli Jobname. Updates the current job file. prompting you to save any changes.dmx HIPAVE32 input data file HIPAVE32 'printable' results file HIPAVE32 raw results file (i. Three icons on the toolbar allow you to create. then creates a new job. Creating and Editing Input Data The following eight icons allow you to create and modify your input data.. Each icon corresponds to one of the main groups of data necessary to fully define a Job.cls HIPAVE data file— this is used to save the details of your job. All the other files are generated automatically by the system: Jobname.e. Closes the current job.prn Jobname. prompting you to save any changes. . You can also save your job under a different name by clicking on the File Menu. You can tailor each of the databases to contain specific sets of regularly used data. For example.Chapter 3 Overview of User Interface 33 Database Approach Some of the input data items are entered using very simple input forms. Running the Analysis and Plotting Results Run Analysis This invokes the analysis. Plot Results Usually. During a long analysis you can switch to another application (HIPAVE will continue to run at a lower priority using Microsoft Windows multi-tasking). .. The relational database approach gives maximum flexibility in data preparation. as an option you can produce a graph of a selected displacement. this command will produce a graph of the damage contribution from each vehicle type and the overall total (damage contribution from all the traffic). Most of the input data is handled using a relational database approach. stress or strain component. X=0 corresponds the centrelines of the vehicles). vertical distances/depths below the surface of the pavement) and results can be plotted for a selected displacement. This graph option shows the variation of the CDF as a function of X. all Layered systems that use that material and subsequently all Jobs that use those layered systems will automatically access the modified material properties. This is designed to eliminate re-entry of data for design loads and material properties. the distance from the centreline of the pavement (i. Alternatively.e. stress or strain component at your chosen Z-values (i. If this data is subsequently modified.e. the data for a commonly used material need only be entered into the system once. Optionally you can graph the maximum CDF as a function of Payload. 34 HIPAVE User Manual Options The Options screen allows specification of the following folder: location for all data files (Defaults to the sub-folder. "data". in the folder in which HIPAVE has been installed.) . run the analysis and then graph the results.35 CHAPTER 4 How to Start Using HIPAVE The easiest way of trying HIPAVE out is to open one of the sample jobs. . as shown below. Select the job "Example 1". 1 Open the Job Click on the button. This invokes the analysis.36 HIPAVE User Manual Opening and Running an Existing Job In the interests of providing instant hands-on experience. run the analsis and inspect the results. . When the analysis is complete the results for the damage factor (CDF) will be transferred to the top table on the screen. 2 Run the Analysis Click on the button. When the analysis starts you will see a blue "progress bar" at the bottom left corner of the screen. for this example you simply open an existing job. Chapter 4 How to Start Using HIPAVE 37 . Plot the Results Click on the button. the distance from the centreline of the pavement (i. Click on the Plot Type combo box then click on CDF vs. Optionally you can graph the maximum CDF as a function of Payload. . X=0 corresponds the centrelines of the vehicles).e. Payload. This will generate a graph of the results: This graph option shows the variation of the CDF for the Subgrade as a function of X. Note that the results for the different payloads have been aggregated.38 HIPAVE User Manual 3. Chapter 4 How to Start Using HIPAVE 39 This graph option shows the maximum CDF for each Vehicle Model and Payload. . You can print a copy of the chart by clicking on the Print icon on the toolbar. You do this via the context-sensitive graph menu that drops down when you right click with the mouse pointer anywhere on the graph as shown below: .40 HIPAVE User Manual As can be seen from the graph there is one result point for each combination of vehicle model and payload. The two graphs give results for the subgrade layer. You can switch to the CDF for the asphalt layer by clicking on the combo box in the top left-hand corner. You can also copy the graph to the clipboard and then paste into another application such as Microsoft Word or Powerpoint. The 'Export Dialog' lets you export to a variety of formats. but for most purposes select 'Metafile' to ensure that the graphics are scalable.Chapter 4 How to Start Using HIPAVE 41 Then click on 'Export Dialog'. . the layered system geometry and the points below the road surface at which results are required. Two alternative formats are available for specifying the points to be used for results calculation: An array of equally spaced points along a line parallel to the X-axis. The X-axis is usually taken as the direction transverse to the direction of vehicle travel.42 HIPAVE User Manual Global Coordinate System A global coordinate system is used to define load locations. Figure 2: Global Coordinate System The Z-axis is vertically downwards with Z = 0 on the pavement surface. The global coordinate system is also used to describe the resultant displacements and stress and strain tensors. A grid of points with uniform spacing in both the X-direction and the Y-direction. The Y-axis is then parallel to the direction of vehicle travel. . Chapter 4 How to Start Using HIPAVE 43 Y Direction of Travel 0 X Xmin Xdel Xmax Results points Figure 3: Coordinates for results defined by a line of equally spaced points Ymax Y Ydel Ymin X 0 Xmin Xdel Xmax Direction of Travel Results points Figure 4: Coordinates for results defined by a uniform grid of points . . stress or strain component at selected Z-values (depths below the pavement surface). Damage Calculation Details Typically. Alternatively. This will bring up the following screen: 1 2 3 . Click on the button. cementstabilised layer and subgrade) will have performance criteria associated with them. between one layer (the subgrade) and three layers (asphalt surfacing. you can calculate results for any given displacement. you will calculate the damage factors (CDF) for your pavement.45 CHAPTER 5 Alternative Calculation Options Overview HIPAVE offers a number of calculation options. Normally. You can automatically determine the optimum thickness of a given layer. the key features on the screen (the numbers refer to the screenshot above) are: This table is a summary of the layered system including material titles and current thicknesses. The multipliers are simply used to increase the ESA count (in the 'Movements' field) that is specified in the Traffic Spectrum screen. This table is a summary of the properties for those layers that have a performance criterion. Here the Traffic Multipliers are multipliers that are used in Equivalent Single Axle (ESA) calculations (as described in the Austroads Pavement Design Guide. 2 3 .46 HIPAVE User Manual 1 Two alternative calculation options are available: Calculate damage factors (CDF). These multipliers are necessary to take account of the material type and the actual traffic mix. When operating in 'calculate damage factors' mode. 1992.5). Section 7. or Calculate selected results at user-defined Z-values (see Calculate Selected Results at User-defined Z-Values (see "Calculating Selected Results at User-defined Z-values (depths)" on page 48)). Also the current Cumulative Damage Factors (CDFs) will be shown if the problem has been run previously. Traffic Multipliers are a consequence of the Equivalent Standard Axle approach and would not generally be used for heavy duty pavements. The current thickness of any layer can be changed from this screen. the design will use the maximum damage factor (CDFmax) from all the layers that have a performance criterion. 1 The thickness design capability is invoked by clicking on the checkbox that is labelled 'Design thickness of layer highlighted below'. The tick-box can be toggled on and off by clicking on it. The layer selected will be highlighted in blue. In some circumstances. it may be necessary to ignore one or more layers when calculating the maximum damage factor. 2 3 By default. Here a tick ( ) denotes that the layer will be included in the maximum damage factor calculation. This procedure is very fast. The design involves bringing the maximum damage factor to 1. 1 2 3 . typically taking 4-5 times the usual analysis time.0 by varying the thickness of the highlighted layer. You select the layer you wish to design by moving the mouse pointer to the appropriate layer and clicking the mouse button once.Chapter 5 Alternative Calculation Options 47 Thickness Design Capability You can automatically determine the optimum thickness of a given layer. Calculating Selected Results at User-defined Z-values (depths) In some circumstances. Click on the button. you may need to calculate selected results (displacements. stress or strain component. or these fields can be left blank.0. When you use this option.48 HIPAVE User Manual Minimum and maximum thicknesses can be specified for each layer. stresses and strains) at selected Z-values (depths). If a specified maximum or minimum thickness limit prevents attainment of a CDF of 1. so that no constraints are applied. This will bring up the following screen: 1 2 3 4 5 6 . Specify first convenient Z-values and then plot results for a selected displacement. the CDF for the thickness limit will be computed. damage factors are not calculated. g. This will invoke this drop down list: 1 2 Click on the component type that you wish to use.e. You can choose the component that is to be plotted by first clicking on the 'Component type' tab. 5 . above the interface. You can then define the component type (e. you can specify which side of the interface is to be used (i. displacement. strain etc. A drop down list of alternatives will appear: 3 Click on the Component that you wish to use.) by clicking on the down arrow on the right hand side of the 'component type' combo box. When a Z-value coincides with the interface between two layers. The actual component (e.g.) is specified by clicking on the down arrow on the right hand side of the 'Component' combo box.. vertical. Each Z-value is added by clicking the New button 6. or below the interface).Chapter 5 Alternative Calculation Options 49 This option is invoked by clicking the button that is labelled 'Calculate selected results at user-defined Z-values'. etc. 4 Now you can define the Z-values. You can delete any entry by clicking on it and then clicking the Delete button. . This will bring up the following screen: Total Cost 1 1 Click on the Calculate Cost checkbox .51 CHAPTER 6 How to Use Advanced Features Cost Calculation Calculation of Total Cost HIPAVE can automatically calculate Total Cost for a pavement from the unit costs of materials in each layer. Click on the button. 52 HIPAVE User Manual Material Costs The unit costs for the layers can be specified using a combination of both a volumetric (or weight) component and an areal component. i) ($/m2) = Unit Volumetric Cost (layer no. i) (mm) + Unit Areal Cost (layer no. etc. or Cost/Weight and the density of the material (Weight/Volume). The areal component can also be used in circumstances where the relationship between total layer cost and thickness has a non-zero component for zero thickness. i) ($/m3) x Thickness (layer no. i) ($/m2) The Unit Volumetric Cost can be defined in terms of: 1 2 Cost/Volume. Unit Material Costs The Total Cost for a given layer is calculated as follows: Total Cost (layer no. . The areal component lets you take account of costs that are primarily a function of area such as surface treatments. subgrade stabilization. the number of Layers for which you are varying the thickness): 1. Additionally.e. One Independent Variable. Click on the button. 3 This lets you choose which layer (thickness) is to be used as the first Independent Variable. This will bring up the following form: 1 This combo box lets you specify the number of Independent Variables (i. For example. This will bring up the following screen: 1 1 Click to switch on Parametric Analysis. . you can automatically design the thickness of another layer. 4 Here you specify the range of thicknesses to be used for that layer: The thickness will range from T1minimum to T1maximum in steps of T1step. you can have Layer 2 vary from 100 mm to 200 mm in steps of 10 mm. 2 This section gives the details of the first Independent Variable. Combining this with the Cost Analysis feature lets you fine-tune layer thicknesses to optimize construction cost. for each combination of those layer thicknesses. Two Independent Variables.Chapter 6 How to Use Advanced Features 53 Automatic Parametric Analysis Automatic Parametric Analysis lets you automatically loop through a range of thicknesses for one or two nominated layers. or 2. . you will get HIPAVE to automatically design the thickness of Layer 2. For each Layer 3 thickness.54 HIPAVE User Manual To use two Independent Variables. 2 This section gives the additional details for the second Independent Variable 3 Here you specify which layer (thickness) is to be used as the second Independent Variable 4 Here you specify the range of thicknesses to be used for that layer: The thickness will range from T2minimum to T2maximum in steps of T2step. Example—Cost Optimization In this example you will use the Automatic Parametric Analysis feature to automatically loop through a range of thicknesses for one layer (Layer 3) and to determine which thickness has the minimum Total Cost. Open the sample file "Example for Cost Optimization". click the combo box ( 1 on the screenshot below). Step 1. One Independent Variable. the number of Layers for which you are varying the thickness). 2 Click the Parametric Analysis check-box. 1 Make sure the Calculate Cost check-box is ticked. For this example you will use the default. the thickness of Layer 3. 4 Here you specify the range of thicknesses to be used for Layer 3: For this example. This will bring up the following form: 1 This combo box lets you specify the number of Independent Variables (i. 2 This section gives the details of the Independent Variable.e. 3 This lets you choose which layer (thickness) is to be used as the first Independent Variable.Chapter 6 How to Use Advanced Features 55 Step 2. (as you are varying the thickness of Layer 3). . you will let Layer 3 vary in thickness from 700 mm to 1200 mm in steps of 100 mm. For this example change this to "3". 2 Click anywhere on the Layer 2 row. Click on the "Summary" tab (left of the "Variables" tab). Step: 100.Plot the Total Cost vs Layer 3 thickness. Click in the "Minimum Thickness" cell on this row and enter 100 (mm). When the analysis is finished. Step 3. Maximum: 1200. Now set the automatic thickness design feature to Layer 2. Step 4. . 1 Click the check-box labelled 'Design thickness of layer highlighted below'.56 HIPAVE User Manual Enter the following values: Minimum: 700. Now click on to run the analysis. click on to plot the results. Chapter 6 How to Use Advanced Features 57 This plot shows the Minimum Total Cost condition for Layer 3 thickness is 220 mm (to a resolution of 100 mm).Plot the CDF (for Layer 4. Select CDF (Select Layer =>). Step 5. Click on the Parameter combo box. Subgrade) vs. Layer 3 thickness. Click on the Layer combo box. . 1). Select CDF (Select Layer =>). Asphalt) vs. Click on the Parameter combo box.Plot the Layer 2 thickness (Design Layer) vs.3000 MPa.Plot the CDF (for Layer 1. Step 6.58 HIPAVE User Manual Select Subgrade . Select Asphalt. Layer 3 thickness. Step 7. Layer 3 thickness. VB=11% (This is Layer No. Select Thickness (Layer used for Thickness Design). 4).CBR=6 (This is Layer No. Click on the Layer combo box. . Chapter 6 How to Use Advanced Features 59 . As shown this Total Cost graph. the minimum Total Cost is given by Layer 3 thickness = 920 mm.60 HIPAVE User Manual Further refinement. at this resolution the minimum Total Cost is given by Layer 3 thickness = 900 mm. To refine this thickness we re-run the Parametric Analysis letting Layer 3 vary in thickness from 800 mm to 1000 mm in steps of 20 mm. . So far we have used Layer 3 thicknesses that are multiples of 100 mm. Pressure Weight Force Moment Strain Units mm MPa tonne N N. Displacement Elastic modulus. all data must use this system of units: Quantity Length.61 CHAPTER 7 How to Modify the Databases Introduction Units In order for HIPAVE to deliver coherent results.mm mm/mm . Displacements in negative coordinate directions are considered to be positive. Figure 5: Sign Convention . The sign conventions used in the rectangular coordinate system and cylindrical local coordinate system are illustrated below.62 HIPAVE User Manual Sign Convention Compressive direct stresses and strains are considered to be positive. Positive shear stresses are defined on the basis that both the stress and strain tensors obey the right hand rule. Hence a load causing a positive stress acts in the positive coordinate direction. all Layered Systems that use that material and subsequently all Jobs that use those Layered Systems will automatically access the modified material properties. The Figure below illustrates the relational database concept for the elastic material properties. each of the components that make up a Layered System is linked to entries in the Elastic Material Properties database via an ID (index) field of up to 20 characters. For example. Define each of the Materials and thicknesses for each of the Layers using the Layered System Components database. . Figure 6: Relationships between elements in Layered System databases A similar hierarchy applies for the Traffic database.Chapter 7 How to Modify the Databases 63 Overview of Database Approach The relational database approach is designed to eliminate re-entry of data for design loads and material properties. If this data is subsequently modified. Load Group data must be entered before the Traffic Spectrum Components data. A consequence of the relational database approach is that data should generally be prepared from the 'bottom up'. the data for a commonly used material need only be entered into the system once. these steps must be followed: 1 2 3 Create any materials that are not already in the Elastic Materials database. This means that: Elastic Materials Properties data must be entered before the Layered System Components data. To create a new layered system. Here. Each load group referenced by the Traffic Spectrum is linked to a record in the Load Group data. Create a new entry in the Layered Systems database. smooth)..e. each with differing elastic properties. 1 Layer No. and the contact can be either fully continuous (i. it is assumed to rest on a rigid base.e. or a combination of both types. Layer No. rough) or fully frictionless (i. Interfaces between the layers can be either fully continuous (rough) or fully frictionless (smooth). The layered system consists of one or more layers. 2 Layer No. The "Layered System" and "Materials" Databases Overview of Layered System and Material Properties HIPAVE models road pavements as a system of layers.64 HIPAVE User Manual Worked examples in the following sections show how you can create new data. The layer interface planes are horizontal and each layer is assumed to be of infinite extent in all horizontal directions. NL Rough rigid base Smooth rigid base Semi-infinite base ∞ .. If the bottom layer is of finite depth. The bottom layer may extend to a finite depth or to a semi-infinite depth (see the figure below). whereas isotropic materials have the same elastic properties in both the vertical and horizontal directions. In the Austroads pavement design method (1992 and 2004) cross-anisotropic properties are used for subgrade materials and unbound granular aggregates and isotropic properties are used for bound materials such as asphalt and cemented materials.νhv σzz) (1/Ev) (. i. A cross-anisotropic material has an axis of symmetry of rotation. In general.νh σyy .Chapter 7 How to Modify the Databases 65 Cross-anisotropy and isotropy in road pavement materials The elastic material in each layer of the pavement/road structure is assumed to be homogeneous and of cross-anisotropic or isotropic symmetry.νh σxx + σyy .. The stress-strain relations for a cross-anisotropic material in a particular layer are: εxx = εyy = εzz = εxy = εxz = εyz = (1/Eh) (σxx .0 . the elastic properties are equivalent in all directions perpendicular to the axis of symmetry (in horizontal. radial directions).νvh σyy + σzz) ((1+νh)/Eh) σxy (1/f) σxz (1/f) σyz The moduli and Poisson's ratios are related by the following equation: νvh/Ev = νhv/Eh The condition that the strain energy must be positive imposes restrictions on the values of the elastic constants: Eh > 0 1 > νh > -1 Ev > 0 f>0 1-νh-2νhvνvh > 0 For isotropic materials the restrictions become: E>0 0.e.5 > ν > -1. which is assumed to be vertical.νhv σzz) (1/Eh) (. these properties are different from those in the direction parallel to the axis.νvh σxx . You should now type in your ID (index) field of up to 20 characters and a descriptive title (up to 72 characters). The Austroads Pavement Design Guide uses the following simplifications to model subgrade and unbound granular materials: Eh = 0. Now you can define the details of the layers in your layered system. Data values for all five constants are rarely available. For this example you can type in 'MyLayers' as the ID and 'Example of creating a new Layered System' as the Title. A dialog box will appear as shown below. . and a single Poisson's ratio. the Poisson’s ratio (νh) and the Shear modulus (f). Click the OK button. For isotropic materials. the material is defined simply by the vertical Elastic modulus. ν.66 HIPAVE User Manual To be able to model a cross-anisotropic material you need to specify five constants: the vertical Elastic modulus (Ev). Creating a new Layered System Click on the button. as they are assumed to be the same in all directions. Click on the New button. only the Elastic modulus and Poisson’s ratio need to be entered. the Poisson’s ratio (νvh). Click on the Layered System tab.5 Ev νvh = νh = ν f = Ev/(1+ν) In this case. the horizontal Elastic modulus (Eh). Ev. or a combination of both types. You can specify any interfaces as fully frictionless. The subgrade will extend to an infinite depth if you enter the thickness as 0.. You repeat this process to add as many layers as you require. A pop-up list will appear. A list of available materials will now appear. then click on the OK button. Click on the New button.0. To select the Material Type. As explained in Overview of Layered System and Material Properties. i. 1 . as shown below.Chapter 7 How to Modify the Databases 67 Defining the Layer properties You add the layers working from the top of your pavement system. Enter the layer thickness.e. A new record will be added at the bottom of the table and the cursor will be positioned in the Thickness column. and working downwards through the pavement. Select the required material by clicking on the appropriate line. click on the appropriate line then click the OK button. You will now choose the Material Type. starting with typically asphalt or cemented material. interfaces between the layers can be either fully continuous (rough) or fully frictionless (smooth). You can then click on the down arrow at the right of the cell to select a 'Smooth' interface. all interfaces are assumed to be rough. You will then see a form that will let you define the ID and Title of the newly duplicated Layered System: . 1 Duplicating a Layered System Sometimes you may want to create a Layered System that is similar to an existing one. The Duplicate function lets you duplicate an existing Layered System. Note that for a semi-infinite subgrade both 'Rough' and 'Smooth' are equivalent.68 HIPAVE User Manual By default. You can change the condition for the interface at the bottom of a given layer by clicking in the 'Interface Type' cell. Move the blue highlight to the Layered System that you want to duplicate: Then click the Duplicate button. Then you can change the settings that need to be different. After you click the OK button you will be taken to the Layered System Components table so that you can make your changes. Click here to select Material Type Click on the New button. CBR=2. As you can see from the example below. For this example.5' for the Title. You should now type in your ID (index) field of up to 20 characters. Click on 'Subgrade (Austroads 2004)' for the Material Type.Chapter 7 How to Modify the Databases 69 The ID and Title that are provided are based on the original Layered System . Click on the material type combo box as shown below to select from the available material types. Click on the Elastic Materials tab. Click the OK button. . Adding a new Elastic Material Click on the button. A dialog box will appear.5'.make sure that you modify the Title. as shown below. you can type in 'Sub_CBR2. You now choose the material type to be used. Type in 'Subgrade. the ID is used to sort the data. 70 HIPAVE User Manual You will now be given an opportunity to select a Performance Criterion. Select 'Anisotropic' in the column headed 'Aniso?'. Click on the OK button. To select a Performance Criterion make sure the checkbox next to ‘Use performance criterion’ is checked.0 Eh = 12. A new record will be added to the table. Then type in the moduli and Poisson's ratios as follows: Ev = 25. then click on the appropriate performance criterion.5 Ev) (= ν) (= Ev/(1+ν)) The new record should be as shown below: .24 (= 0.5 νvh = νh = 0.45 f = 17. 08) ⎤ B ⎥ N = RF ⎢ 0. and Smix= mix stiffness (Elastic modulus) in MPa. all Performance Criteria use the same Damage Relationship Type. Before you add a new Performance Criterion you need to choose the appropriate Material Type. Example: Asphalt tensile strain relationship For this example we consider the Shell asphalt fatigue criterion: ⎡ 6918(0.856 V + 1. For each Material Type.Chapter 7 How to Modify the Databases 71 Adding a new Performance Criterion HIPAVE usually represents models in the form: ⎡k ⎤ N=⎢ ⎥ ⎣ε ⎦ where N k b ε b (1) is the predicted life (repetitions) is a material constant is the damage exponent of the material is the induced strain (dimensionless strain) HIPAVE can also handle log-linear models of the form: log10 ( N) = k − b ε (2) Equation (1) is called a Standard Damage Relationship Type and Equation (2) is called a Log-Linear Damage Relationship Type. VB = percentage by volume of bitumen in the asphalt.36 µe ⎢ ⎥ Smix ⎣ ⎦ 5 where µε = maximum tensile strain (in units of microstrain). . so that the above equation simplifies to: N = [ 5889 / µε]5 To enter this data click on the Click on the Performance tab. If there are can select the component from a dropdown list by clicking on the more entries than will fit in the listbox.72 HIPAVE User Manual For this example. there will be a slider bar on the right hand side. Horizontal Tensile Strain’ (maximum horizontal tensile strain). Click the OK button.9 and Smix = 1600 MPa. The Location field defines the location (relative to a layer of this material) at which the criterion is to be applied. A record will be added to the table and you can type in the relevant data as follows: The cursor will now be in the component field. assume VB = 12.9%' for the Title. . Type in 'Asphalt1600 MPa. For this example type in 'Asph1600' for the ID. Now type in your ID (index) field of up to 10 characters and the Title (up to 72 characters). Click on the material type combo box (as shown on the first screenshot in Adding a new Elastic Material (on page 69)) to select from the available material types. The entries for the remaining two parameters define the fatigue relationship N = [5889 / µε]5. For this example select the ‘Max. You button. For this example click on 'Asphalt'. Here you specify the particular displacement. You can move down the list by clicking on the down arrow or by dragging the slider down. Vb=12. stress or strain component to be used. Click on the New button. button. Click on the button to choose between ‘Top’ and ‘Bottom’. For this example Location should be 'Bottom'. You now choose the material type to be used. Chapter 7 How to Modify the Databases 73 Note carefully that strains in HIPAVE must be specified in dimensionless units (i. Click the OK button. For this example type in 'CTB15000' for the ID. E=15000MPa' for the Title. A record will be added to the table and you can type in the relevant data as follows: .e..0. Now type in your ID (index) field of up to 20 characters and the Title (up to 72 characters). Click on the New button. Type in 'CTB. mm/mm). Click on the material type combo box (as shown below) to select Cemented (Log-Linear) from the available material types. The new record should be identical to the bottom row in the figure below: Example: Log-linear performance relationship Click on the button. length/length. the parameter µ (micro) must be replaced by 10-6 giving: N = [k / ε]b So Constant (k) will be 0. You now choose the material type to be used. Click on the Performance tab.005889 and Exponent (b) will be 5. As HIPAVE assumes that the fatigue relationship is of the form N = [k / ε]b . Horizontal Tensile Strain. length/length. Click on the button to choose Bottom. b must be adjusted appropriately. Now enter the values for k (= 10) and b (= 80000). You select the component from the drop-down list by button. The screen below shows the completed entries: .e.74 HIPAVE User Manual For this example assume that equation (2) is used with: k = 10 b = 80000 The relevant strain component that is to be used is the maximum horizontal tensile strain at the base (bottom) of the layer. Note: Equation (2) expresses the strain component as a unitless (i. If you are converting from an expression that uses microstrain. The location field defines the location (relative to a layer of this material) at which the relationship is to be applied. If there are more entries than will fit in the list box there will be a clicking on the slider bar on the right hand side. You can move down the list by clicking on the down arrow or by dragging the slider down. Select the entry Max. mm/mm) quantity. Move to the Component field by clicking on it or using the tab key. The screen should now look like this (the black highlight is on the new entry): Here you specify the particular strain or stress component to be used (in this example it will be the maximum horizontal tensile strain. click the checkbox next to ‘use sub-layering’. Click the OK button. To add a new material type. Click on the OK button. To select a SubLayering scheme. A dialog box will now appear and you can enter the ID (index) field of up to 20 characters and Title field (up to 72 characters). You will now be given an opportunity to select a Sub-Layering scheme.Chapter 7 How to Modify the Databases 75 Adding a new Material Type You can add new material types. You will now choose the Generic Material Type for your new Material Type: button. then click on the appropriate sub-layering scheme. Click on the Click on the Material Types tab. Click New to create a new entry. . Vehicle Specifications The HIPAVE vehicle library consists of so-called "Standard" vehicle specifications that are provided by Mincad Systems and "Custom" vehicles that you can define. Click on the Vehicle Models tab. Click on the button. The databases form a hierarchy: Traffic Spectrum. Load Group Components. Payload Distribution Components. Depending on whether or not the components you need already exist. then click on the Load Components and Locations tab. Traffic Spectrum Components. You can browse by clicking on the Type and Manufacturer combo boxes.76 HIPAVE User Manual The "Loads" and "Traffic Spectrum" Databases Introduction Seven inter-related databases are used for the Traffic data. Load Groups. Load Locations. . Payload Distributions. the steps required are described in the following sub-sections. To see the specifications for any listed vehicle click on that row. You can browse the vehicle specifications as follows. Adding Custom Vehicle Specifications You are encourage to send us vehicle specifications for inclusion in the Standard Vehicle Library. To do this. As soon as the Library is updated you will be able to update your Library by clicking the Import icon. The remaining details depend on the vehicle type. Fork Lift or Straddle Carrier. The status screen shows the number of Vehicle records that have been imported/updated. click on the icon. here are details on how you define your own vehicle models directly: Click on the button. Make sure you make the correct choices for the Type and Manufacturer combo boxes. But if required.Chapter 7 How to Modify the Databases 77 Automatic Updates for the Standard Vehicle Library Updates for the Standard Vehicle Library can be automatically imported from the Mincad Systems webserver. You will then see a status screen like the one below. . i. as shown below: Contact Mincad Systems for a Library Update if the combination of Type and Manufacturer that you want to use is not available.e. A dialog box will appear as shown below. For this example you can type in 'HysterHxyz' as the ID and 'Hyster Hxyz' as the Title. You should now type in your ID (index) field of up to 20 characters and a descriptive title (up to 72 characters). Now type 'Hyster Hxyz' as the Plot Label: .78 HIPAVE User Manual Vehicle with Unequal Axle Loads Click on the New button. Click the OK button. 9 MPa for all tyres. after you enter the axle load characteristics the screen will look like this: .Chapter 7 How to Modify the Databases 79 Now click on the Load Components and Locations tab. This will bring up a form that lets you specify the axle load characteristics and wheel positions. The axle load versus payload characterstics are illustrated by the following graph: Assuming the tyre pressure is 0. 80 HIPAVE User Manual Note that Component No. 1 is the Front axle. You can now add the Wheel Locations. Usually we only model one side of the vehicle. Click the New button to add each wheel. After adding the 2 wheels on the Front Axle (Component No. 1) and the one wheel on the Rear Axle (Component No. 2), the Wheel Locations table will look like this: Vehicles with Equal Axle Loads Click on the New button. A dialog box will appear as shown below. You should now type in your ID (index) field of up to 20 characters and a descriptive title (up to 72 characters). For this example you can type in 'KalmESCxyz' as the ID and 'Kalmar ESCxyz (fictitious)' as the Title. Click the OK button. Now type 'Kalmar ESCxyz' as the Plot Label: Chapter 7 How to Modify the Databases 81 Now click on the Load Components and Locations tab. This will bring up a form that lets you specify the axle load characteristics and wheel positions. Vehicles such as straddle carriers are assumed to have equal loads on each axle. In this case the vehicle loading characteristics are specified in terms of the unladen weight of the vehicle, the number of axle rows (i.e. the number of axles seen from one side of the vehicle), the total number of wheels on the vehicle and the tyre pressure. For this example, assume the following values: Number of Axle Rows (i.e. the number of axles seen from one side of the vehicle) Total Number of Wheels Tyre Pressure Unladen Weight 4 8 0.56 MPa 62 tonne After you enter these axle load characteristics the screen will look like this: You can now add the Wheel Locations. Usually we only model one axle and only one side of the axle. Click the New button to add the wheel details. After adding the one wheel, the Wheel Locations table will look like this: 82 HIPAVE User Manual Traffic Spectrums HIPAVE is designed to let you conveniently specify a Traffic Spectrum in terms of a mix of different vehicle models. For each vehicle in the spectrum you specify the number of movements and the payload distribution. For each load case the wheel loads are automatically calculated from the vehicle characteristics and the payload. For an overview of the concepts see How HIPAVE handles Traffic Distributions (on page 15). Creating a new Traffic Spectrum If the Traffic Spectrum screen is not already active, click on the Click on the Spectrum tab. Click on the New button. A dialog box will appear as shown below. You should now type in your ID (index) field of up to 20 characters and a descriptive title (up to 72 characters). For this example you can type in 'TrafficTry' as the ID and 'Example of creating a new Traffic Spectrum' as the Title. Click the OK button. button. You can move the highlight to the vehicle that you wish to use by positioning the mouse pointer on it and clicking once.Chapter 7 How to Modify the Databases 83 The Spectrum Components form will now appear. A new record will be added at the bottom of the table and the cursor will be positioned in the Movements column. Now define your Spectrum Components: Click New for each vehicle model you wish to include. choose the Hyster Forklift model H40. You can move down the list by clicking on the down arrow or by dragging the slider down. For this example. . If there are more entries than will fit in the listbox there will be a slider bar on the right.00E-16CH. This will activate a pop-up list of possible choices: You can browse by clicking on the Type and Manufacturer combo boxes. You finally select the vehicle by double clicking on it. You will now choose the Standard Payload Distribution. enter 100.000 movements. For this example. The part of the screen that relates to the choice of Payload Distribution looks like this: . The Graph Label is an optional string of up to 20 characters that is appended to the Vehicle Model Plot Label used for the Legend when plotting the results. To select the Standard Payload Distribution. A pop-up list will appear. Using a Standard Payload Distribution Click the Distribution Type combo and select Standard. for example your spectrum may include the same model twice. you can either use a "Standard" payload distribution (one that already exists in the database) or define a "Custom" distribution for the current load case.84 HIPAVE User Manual Enter the number of vehicle movements (or passages) over the desired design life. This is useful when you need to have more than one Spectrum Component that uses the same Vehicle Model. as shown below. once with unloaded containers and once with loaded containers. click on the appropriate line then click the OK button. Characterizing Payload Distributions As mentioned earlier. After you enter the last row of data.5 17. click the New button and enter the Payload and Count.5 Count 1000 200 300 200 100 1200 7500 1000 For each row in the table. the screen should look like this: .Chapter 7 How to Modify the Databases 85 Click the Select button if you want to choose another Standard Payload Distribution.5 12.5 22. use the following payload distribution: Payload (tonnes) 2. For this example. See Standard Payload Distributions (on page 88) for details on how to create your own standard payload distributions and how to browse the details of existing ones. Defining a Custom Payload Distribution Make sure Distribution Type is set to Custom.5 27.5 4 6 8. The following screendump shows the updated calculated columns after pressing the Enter key.0.but are updated when you press the Enter key when in the Count cell. The calculated columns are not updated while you type the data on a particular row .0) when you run a HIPAVE analysis. The absolute magnitude of the Count values is not important. scaled so that they add up to 1. The Actual Movements values are scaled so that the total matches the total number of movements (100.for example they could be based on historical data or could be simply actual movements. This gives you a lot of flexibility in how you define your Count values . as they are normalized (i.86 HIPAVE User Manual Values in the columns that are labelled Normalized Movements and Actual Movements are calculated from the values in the Count column. The Normalized Movements are given by normalizing the values of Count .so that the sum of the Normalized Movements values is 1.e.000 in this example) defined for the current Spectrum Component. . Chapter 7 How to Modify the Databases 87 Duplicating a Traffic Spectrum Sometimes you may want to create a Traffic Spectrum that is similar to an existing one. The Duplicate function lets you duplicate an existing Traffic Spectrum.make sure that you modify the Title. . Move the blue highlight to the Traffic Spectrum that you want to duplicate: Then click the Duplicate button. Then you can change the settings that need to be different. After you click the OK button you will be taken to the Traffic Spectrum Components table so that you can make your changes. You will then see a form that will let you define the ID and Title of the newly duplicated Traffic Spectrum: The ID and Title that are provided are based on the original Traffic Spectrum . Click on the button.88 HIPAVE User Manual Standard Payload Distributions Introduction The "Standard" payload distribution feature is designed to conveniently facilitate re-use of particular distributions across a range of vehicle models and projects. then click on the Distribution Details tab. Click on the Payload Distributions tab. . To see the actual distribution for any entry in the list click on that row. For this example you can type in 'TermXExport' as the ID and 'Terminal X . A dialog box will appear as shown below. You should now type in your ID (index) field of up to 20 characters and a descriptive title (up to 72 characters). . click on the Click on the Payload Distributions tab. Click the OK button.Loaded Export' as the Title. button. Click on the New button.Chapter 7 How to Modify the Databases 89 Creating a new Standard Payload Distribution If the Payload Distributions screen is not already active. use the following payload distribution: Payload (tonnes) 8. Now define your Distribution Components: For this example.0 18.90 HIPAVE User Manual The Distribution Details form will now appear. After you enter the last row of data.0 12. the screen should look like this: .0 15.0 30.0 Count 200 400 600 800 1200 5500 1000 For each row in the table.0 10. click the New button and enter the Payload and Count.0 24. The following screendump shows the updated Normalized Movements column after pressing the Enter key. The Normalized Movements are given by normalizing the values of Count .0) when you run a HIPAVE analysis. This gives you a lot of flexibility in how you define your Count values . see Creating a new Traffic Spectrum (on page 82). scaled so that they add up to 1. as they are normalized (i.so that the sum of the Normalized Movements values is 1.but are updated when you press the Enter key when in the Count cell. .e.Chapter 7 How to Modify the Databases 91 Values in the column that is labelled Normalized Movements are calculated from the values in the Count column.0. The values in the Normalized Movements column are not updated while you type the data on a particular row .for example they could be based on historical data or could be simply actual movements. The absolute magnitude of the Count values is not important. You can now use your new Standard Payload Distribution in any Traffic Spectrum. 92 HIPAVE User Manual Dynamic Load Factors So-called Dynamic Load Factors are used in the British Ports Association Design Guide (British Ports Association. you can define Dynamic Load Factors for each axle. You should now see the Load Factors form: button. For each Component. click on the Click on the Load Factors tab. These are simple multipliers that are applied to the design loads and can vary with each axle. braking and surface uneveness. accelerating. You will now see the current Traffic Spectrum Components. To use Dynamic Load Factors. 1996) to account for the effects of dynamic loading induced by cornering. Click on the Use Dynamic Load Factors checkbox. as shown below: . If the Traffic Spectrum screen is not already active. You should now see the alternative Wander options: button. click on the Click on the Wander tab. you specify the Wander in the Spectrum Components table (accessed by clicking on the Spectrum Components tab): The wander is assumed to follow the bell-shaped frequency distribution given by the Normal (or Gaussian) distribution. If the Wander varies with the Vehicle Model. Same Wander for All Vehicle Models in the Traffic Spectrum. Three alternative Wander options are available: No Wander for any Vehicle Model in the Traffic Spectrum. Normally the default values of these can be used. .Chapter 7 How to Modify the Databases 93 Wander Options If the Traffic Spectrum screen is not already active. Wander varies with Vehicle Model. The degree of wander is given by the Standard Deviation. Some additional parameters define the numerical approximation used to model the effects of Wander. 7 times the maximum Standard Deviation of wander.000 4000 3500 Standard Deviation = 1000 mm Movements in Slot 3000 2500 2000 1500 1000 500 0 00 0 80 0 -2 60 0 -2 40 0 -2 20 0 -2 00 0 -1 80 0 -1 60 0 -1 40 0 -1 20 0 -1 00 0 -8 00 -6 00 -4 00 -2 00 0 20 0 40 0 60 0 -3 -2 80 0 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 26 00 28 00 30 00 Lateral Position (mm) XWMAX (=3000 mm) . 4500 XWDEL (=100 mm) Total Movements = 100. For acceptable numerical accuracy XWMAX needs to be 2.94 HIPAVE User Manual The parameter XWDEL is used to subdivide the wander distribution. The parameter XWMAX sets the limiting value used to approximate the Normal distribution. For acceptable accuracy XWDEL must be no greater than 100 mm. or greater. Two alternative formats are available for specifying the points to be used for results calculation: An array of equally spaced points along a line parallel to the x-axis. or A grid of points with uniform spacing in both the x-direction and the y-direction.Chapter 7 How to Modify the Databases 95 Coordinates for Results Click on the button. This screen has fields for specifying the locations for which results are to be computed and the method for treating damage pulses. . . 97 CHAPTER 8 Appendices . . (Web: http://www. Miss. W. AP-17/92. 2003. Airport Technology Transfer Conference.J. US Army Corps of Engineers. B. B. (1977). Wardle. Wardle.. . (1998). Rodway. L. Illinois. T.). and Rickards. and Wickham. Conf. CSIRO Australia. British Ports Association/Interpave (1996). Federal Aviation Administration. L. Recent Developments in Flexible Aircraft Pavement Design using the Layered Elastic Method. in Advancing Airfield Pavements. Pereira. Waterways Experiment Station. Vicksburg. Report No. Cairns. Singapore. Wardle. Chicago. L. 192-201. 27-29 September.. 18 . Waterways Experiment Station. B. L. Current Issues For Mechanistic Pavement Design. L. and Naughton. Calibration of Advanced Flexible Aircraft Pavement Design Method to S77-1 Method.J. Instruction Report S-77-1.. Wardle. Youdale. I.. (1977). Layered Elastic Design of Heavy Duty and Industrial Pavements. US Army Corps of Engineers. L. Miss.J. AAPA Pavements Industry Conf. Third Int. (1995a). Australia. American Society of Civil Engineers. W..23 May. Program CIRCLY User’s Manual. Proc. J. B. Surfers Paradise. Mincad Systems and Pioneer Road Services (2007). April 1999. Rodway. 58 August 2001 (Buttlar.A.99 References Austroads (1992). 2. on Road & Pavement Technology. 2001 Airfield Pavement Specialty Conference.E.au/hdipdg/). Program CIRCLY Theory and Background Manual. B. and Wardle. pp. eds. Int. and Brabston. B. Austroads Publication No. 1995. Heavy Duty Industrial Pavement Design Guide.J. U. Australia. Procedures for development of CBR design curves.mincad. Conf. Leicester. (1998). Australia. Pavement Design . Report AP-G17/04. Interaction between wheels and wheel groups of new large aircraft.J. (1999). Beijing. Mincad Systems. Division of Applied Geomechanics. No.A Guide to the Structural Design of Road Pavements. ARRB Transport Research. Vicksburg. April 1998. in 21st ARRB and 11th REAAA Conference. The Structural Design of Heavy Duty Pavements for Ports and other Industries.J. Geomechanics Computer Program. 3rd ed. and Rodway.G. Design Of Flexible Pavements For Large Multiwheeled Aircraft. S-75-17. (2001). Austroads (2004). G. L. W. Rodway. Barker. Interpave. Development of a structural design procedure for flexible airport pavements. (2004).S. Pavement Design – A Guide to the Structural Design of Road Pavements. on Road and Airfield Pavement Technology. Wardle. Session S32. A. (1975). (2003).. Rodway. G. Wardle. Atlantic City.J. and Rodway.com. Each 'local' coordinate system may be cartesian (x. For loads that are symmetrical about their centre point the x-axis may have any orientation. You can choose the origin of the 'global' coordinate system to be any point on the upper surface of the layered system and the X and Y axes as any two mutually perpendicular axes that lie in this horizontal plane. y. which is dealt with in Wardle (2004). Z for Global coordinates and lowercase x. In terms of the 'global' coordinate system the origin of each 'local' coordinate system is specified by Xload. However. Figure 7: Global and Local Coordinate Systems . z) and has its origin at the centre of the load it describes. The Z-axis in the positive direction is taken as vertically downwards. with axes X. though. it is possible to model more complex loads induced by breaking and turning movements of vehicles. for convenience. Y. The location of the circular load is described by a ‘global’ coordinate system. The location and orientation of a load are therefore specified by Xload. Yload. y. The 'global' system is cartesian. The orientation of the load is defined by the angle (θload) between the directions of the X-axis and the x-axis. θ. Note the use of uppercase X. This load typically represents the contact of a tyre on the surface of the pavement. z) or cylindrical (r. it may be taken as parallel to the X-axis so that θload is then zero. For loads that are symmetrical about a horizontal axis this axis is taken as the x-axis. z for Local coordinates. Y.100 HIPAVE User Manual Coordinate System for Loads The most common type of load modelled in CIRCLY is a circular area over which a uniform vertical pressure is applied. Yload and θload. while 'local' coordinate systems are used to describe each of the loads. Z.