Analysis and Design of Prestressed Concrete Box Girder Bridge

March 25, 2018 | Author: Natarajan Nalanth | Category: Prestressed Concrete, Civil Engineering, Strength Of Materials, Concrete, Bending
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11/3/13Analysis and design of prestressed concrete box girder bridge Analysis and design of prestressed concrete box girder bridge Posted in Prestress Engineering, Project Reports, Research Papers | Email This Post | By Miss.P.R. Bhivgade Abstract:- Bridge construction today has achieved a worldwide level of importance. Bridges are the key elements in any road network Use of box girder is gaining popularity in bridge engineering fraternity because of its better stability, serviceability, economy, aesthetic appearance and structural efficiency. The structural behavior of box girder is complicated, which is difficult to analyze in its actual conditions by conventional methods. In present study a two lane simply supported Box Girder Bridge made up of prestressed concrete which is analysis for moving loads as per Indian Road Congress (IRC:6) recommendations, Prestressed Code (IS: 1343) and also as per IRC: 18 specifications. The analyzed of box girder using SAP 2000 14 Bridge Wizard and prestressed with parabolic tendons in which utilize full section. The various span/ depth ratio considered to get the proportioning depth at which stresses criteria and deflection criteria get satisfied. Keywords: Concrete Box Girder Bridge, Prestress Force, Eccentricity, Prestress Losses, Reinforcement, Flexure strength, shear strength, SAP Model. I. INTRODUCTION Prestress concrete is ideally suited for the construction of medium and long span bridges. Ever since the development of prestressed concrete by Freyssinet in the early 1930s, the material has found extensive application in the construction of long-span bridges, gradually replacing steel which needs costly maintenance due to the inherent disadvantage of corrosion under aggressive environment conditions. One of the most commonly used forms of superstructure in concrete bridges is precast girders with cast-in-situ slab. This type of superstructure is generally used for spans between 20 to 40 m. T or I-girder bridges are the most common example under this category and are very popular because of their simple geometry, low fabrication cost, easy erection or casting and smaller dead loads. In this paper study the India Road Loading considered for design of bridges, also factor which are important to decide the preliminary sizes of concrete box girders. Also considered the IRC:18-2000 for “Prestressed Concrete Road Bridges” and “Code of Practice for Prestressed Concrete ” Indian Standard. Analyze the Concrete Box Girder Road Bridges for various spans, various depth and check the proportioning depth. II. FORMULATION A. Loading on Box Girder Bridge The various type of loads, forces and stresses to be considered in the analysis and design of the various components of the bridge are given in IRC 6:2000(Section II. But the common forces are considered to design the model are as follows: Dead Load(DL): The dead load carried by the girder or the member consists of its own weight and the portions of the weight of the superstructure and any fixed loads supported by the member. The dead load can be estimated fairly accurately during design and can be controlled during construction and service. Superimposed Dead Load (SIDL): The weight of superimposed dead load includes footpaths, earth-fills, wearing course, stay-in -place forms, ballast, waterproofing, signs, architectural ornamentation, pipes, conduits, cables and any other immovable appurtenances installed on the structure. Live Load(LL): Live loads are those caused by vehicles which pass over the bridge and are transient in nature. These loads cannot be estimated precisely, and the designer has very little control over them once the bridge is opened to traffic. However, hypothetical loadings which are reasonably realistic need to be evolved and specified to serve as design criteria. There are four types of standard loadings for which road bridges are designed. i. IRC Class 70R loading ii. IRC Class AA loading iii. IRC Class A loading iv. IRC Class B loading The model is design by considering IRC Class A loading, which is normally adopted on all roads on which permanent bridges and culverts are constructed. Total load is 554, the Fig.1 show the complete details of Class A. www.engineeringcivil.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge.html#more-4815 1/13 C. www. D. the thickness of such flange shall not be less than 150 mm plus diameter of duct hole.9dbAs Fp Where. b = the width of rectangular section or web of beam fck= characteristics strength of concrete G. the effect of the tensile stresses developed by the untensioned reinforcement due to shrinkage and creep shall be considered. E. As = the area of high tensile steel Fp = the ultimate tensile strength for steel without definite yield point or yield stress or stress at 4 per centelongation whichever is higher for steel with a definite yield point. Calculation of Section un.207.176 bdb2 fck Where. In computing the losses in prestress when untensioned reinforcement is present. Thickness of Bottom Flange The thickness of the bottom flange of box girder shall be not less than 1/20th of the clear web spacing at the junction with bottom flange or 200 mm whichever is more.html#more-4815 2/13 . under these two alternative conditions of failure shall be calculated by the following formulae and the smaller of the two values shall be taken as the ultimate moment of resistance for design: i. due regard shall be paid to all losses and variations in stress resulting from creep of concrete.engineeringcivil. Thickness of Top Flange The minimum thickness of the deck slab including that at cantilever tips be 200 mm. Calculation of Ultimate Strength Ultimate moment resistance of sections. For top and bottom flange having prestressing cables.11/3/13 Analysis and design of prestressed concrete box girder bridge Other information regarding Live load combination as per IRC:6 2000 Clause No. Thickness of Web The thickness of the web shall not be less than d/36 plus twice the clear cover to the reinforcement plus diameter of the duct hole where‘d’ is the overall depth of the box girder measured from the top of the deck slab to the bottom of the soffit or 200 mm plus the diameter of duct holes. F. the shortening (elastic deformation) of concrete at transfer. Losses in Prestress While assessing the stresses in concrete and steel during tensioning operations and later in service.cracked in flexure b = width in the case of rectangular member and width of the rib in the case of T. I and L beams d = overall depth of the member fcp = compressive stress at centroidal axis due to prestress taken as positive. and friction and slip of anchorage. Failure by crushing concrete M ult = 0. shrinkage of concrete.1 Note No.4 B. db = the depth of the beam from the maximum compression edge to the centre of gravity of the steel tendons. Failure by yield of steel (under-reinforced section) M ult = 0.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge. whichever is greater. relaxation of steel. ii. fci = 0. fct = 0.9 Case5 L/d= 15. 4. d=2. ftw = 0 As per IS:1343-1980 Ec = 5700fck1/2 = 40.5 m Overhang from face of girder = 1. ANALYSIS AND DESIGN OF POST-TENSIONED DECK TYPE BOX-GIRDER BRIDGE A post. E = 2×105 Mpa www. As per IRC:18-2000 fck= 50 Mpa.6 Case 2 L/d =18.2.3 m The tendon profile is considered as parabolic in nature.85.7 Case3 L/d = 17.33fck = 16. d = 1.engineeringcivil.2 m Girder thickness = 0.8fck = 40 Mpa.8 Case4 L/d= 16.11/3/13 Analysis and design of prestressed concrete box girder bridge III.0 Preliminary data Clear span = 30m Width of roadway = 7. d = 1.2m Deck thickness = 0.0 Mpa.30 kN/m2 fp = 1862 Mpa.5 Mpa ft = 1/10fct = 2. Assume Live Load as per IRC: 6-2000 vehicle is passing over deck given in chapter 4 and table no. d = 1.5m.html#more-4815 3/13 . The Bridge analysis for different L/d ratio starting from 15 to 20 and different L/d ratio considered are as follows: Case 1 L/d= 19.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge. fcw = 0.tensioned deck type Box – Girder Bridges of clear span 30m and width of roadway is 7.5fci = 20 Mpa. d= 1.2 m Bottom slab thickness = 0. n = 0. 04 124.46 95.2 Bending Moment(t.1L 0.0L (m) 0. live load and superimposed load.85 587.63 494.5L www. Same as deflection calculated.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge.36 mm 30. This results are the Case:1.1 Deflection Load Case Deflection (at midspan) DL + SIDL Live Prestressing Load Force -14.4L 0.8 mm 25.2 mm Table.50 0.2L 0.4L 0.11/3/13 Analysis and design of prestressed concrete box girder bridge Validation of Resuts The bending moment.23 1443.3L 0.00 625.0L 0.56 148.00 218.76 381.1L 0.00 353.82 0.5L 0. The bending moment and shear force are calculated by considering different loading condition such as dead load.45 Table.78 1105.3 Shear Force (t) Span 0. Table.00 53.m) Span (m) DL LL SIDL Total 0.html#more-4815 4/13 .56 628.56 824. shear force and deflection result obtained by SAP 2000.3L 0.10 564.2L 0.98 942.engineeringcivil.84 982.12 0.74 142.26 1718.82 1650. 80 15.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge.6 143.7 Table.84 11.0 SIDL 19.0 0.4 26.88 7.27 7.0 0.95 ^S ^C ^E ^A ^F ^R Total n 90 182.5 Calculation of Eccentricity Eccentricity Prestressing The eccentricity (mm) Force (kN) which give minimum prestressing force (e) = 731mm 440 21617.92 23.92 Total 183.3 0.7 78.6 Calculation of Prestress Losses (As per IS:1343-1980) Span (m) 0.0 LL 32.html#more-4815 5/13 .0 2.06 16489.9 www.8 0.15 Table.0 0.6 2.0 0.6 0.4 Calculation of Prestress Force Table.engineeringcivil.7 67.9 104.57 52.1L 0.96 548 650 731 19380.11/3/13 Analysis and design of prestressed concrete box girder bridge DL 130.0L 0.90 32.9 104.62 3.7 90 90 0.0 0.42 2.69 17655.29 14.3 78 9. 91 2.2L 0.16 0.4L 0. effective Prestressing Force (P) = P (1-Losses) = 14011.3 90 169.367 < 0.2L 0.24 6.3L 0.44 At Service Load Top fibre 4.1L 0.46 Bottom Fibre 4.8 0.8 Calculation of Ultimate Flexure Strength Failure by Failure by Ultimate Moment Span yielding of crushing of Mu = (1.11/3/13 Analysis and design of prestressed concrete box girder bridge 0.9 9.42 0.5DL +2.5 20 54.66 < 0.91 2.4 39 22 90 155.37 7.6 2.0 0.7 2.979 < 3mpa (As per IS:1343 – 1980) Working Stage = No tensile stress 2.m) (kN.00 0.00 0.7 0.5 mpa Tensile stress at Initial Stage = 2.1 8.5L Compressive Stress at Transfer = 6.00 6.5 fcj = 20 mpa Service = 8.html#more-4815 6/13 .6 2.48 6.00 0.3 16 171 90 294.00 Table.engineeringcivil.98 1.67 6.0L 0.m) www.16 6.m) (kN.51 kN 8E05 2.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge.24 3.85 Table.29 6.91 2.0 0.16 5.5 (m) steel concrete LL) (kN.33 fck = 16.4 26 36.35 8.7 Calculation of Stresses at top and bottom fibre At Transfer Span (m) Top Fibre 4.88 6.3L 0.4L 0.5L Where.7 90 157.112 Bottom fibre 4.00 0. ^S = Shrinkage ^C= Creep ^E = Shortening of concrete ^A = Slip in anchorage ^F = Friction ^R = Relaxation n= Efficiency After Losses.16 2. 2L 0.35 419.4L 0.85 2720.1L 0.90 0.4 < 250 mm Main Reinforcement Ast = 3192.53 5970560 Table. Ast = 1254 mm/2 Providing 24 bars of 12 mm dia.5 LL) (kN.95 0.43 2391.3L 0.88 340578.m) 0.38 1713.2L 0.1L 0. located concentrically at centre.51 kN.05 x 1350 x 300/100 = 202.0L 0.85 26598.34 24.45 31654.85 0.3ML + 0.html#more-4815 7/13 .3L 0. ypo /y0 = 75/150 = 0.5 . Side Face Reinforcement As per clause 18.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge.00 11574.56 517.3 of IS:1343-1980 Ast = 0.50 432.5 mm/2 Provide 6 – 12 mm dia on each face of web Design of Deck Slab Using M30 grade concrete and Fe415 Total moment due to DL+SIDL+LL = 1427.96 1089. As per IRC:18-2000.5L 0.5DL (kN) +2.6.753 kN Using 12 mm diameter links.97 1971. bw = 200 mm Assume 150 mm wide and 150 mm deep distribution plate.5L 3084.4L 0.00 492. From table value of Fbst/ Pk = 0.engineeringcivil.11/3/13 Analysis and design of prestressed concrete box girder bridge 0. area of steel links are.9 Calculation of Ultimate Shear strength Span (m) Ultimate Shear Balance Spacing Moment capacity Shear (mm) Vu = Vcw (kN) (1.6824 mm/2 Providing 16mmØ bars dia 100 mm c/c Design of Transverse Reinforcement M = 0.54 1280.27 363.00 619. 750mm also bar of 12 mm dia @ 110 mm c/c horizontally to form mesh.2(MDL + MSIDL) www. d = 1350 mm.28 30402.0L 0.m Depth required = 150.0 kN.17 and Fbst = 452.3.90 470.00 55 75 100 200 300 0 Design of Reinforcement in Box Girder Bridge P =14011.43 20394. engineeringcivil.m Ast = 724. Table.html#more-4815 8/13 .com/analysis-and-design-of-prestressed-concrete-box-girder-bridge.74 mm/2 Providing 12 mm dia bars @ 160 mm c/c IV. deflection and stresses values are obtained for various span/depth ratio ( table no.10 Comparison of Deflection for various span/depth ratio. COMPARSION OF RESULT FOR VARIOUS SPAN/ DEPTH RATIO The comparison of prestress force. 10 & 11) for box girder bridge. The values are calculated as per IS:1343-1980. Deflection Prestress Eccentricity DL +LL Span/Depth Force DL(mm) – (kN) Prestress Prestress Force Force www.11/3/13 Analysis and design of prestressed concrete box girder bridge M = 324 kN. “Precast Options for Bridge Superstructure Design” Economical and Social Linkages Session of the 2007 Annual Conference of the Transportation Association of Canada Saskatoon.6 33.20 731 777 829 886 950 3.48 731 11.7 mm 15. IS: 1343 – 1980 “ CODE OF PRACTICE FOR PRESTRESSED CONCRETE” INDIAN STANDARD. Fowler. Ferhat Akgul and Dan M.33 5.9 2.8 1.83 14. PVT.66 14.7 1.48 5. John R.2000 “STANDARD SPECIFICATIONS AND CODE OF PRACTICE FOR ROAD BRIDGES”THE ROAD CONGRESS.1 3.3 Table. 2. Bob Stofko.4 3.91 5.6 3.Eng. Saskatchewan. deflection and stress criteria satisfied the well within permissible limits. Rhomberg Fellow.11/3/13 Analysis and design of prestressed concrete box girder bridge 1. Because of prestressing the more strength of concrete is utilized and also well governs serviceability.08 Eccen Span/ Depth Prestress Tricity Force (tonne) (mm) At Transfer Top Bottom 1.6 16.9 2.4 1.8 1. “PRECAST PRESTRESSED LONG-SPAN BRIDGES” JOURNAL OF STRUCTURAL ENGINEERING © ASCE 7. Andre Picard and Bruno Massicotte. • Permissible (DL-Prestress Force) = 12 mm • Permissible (DL-LL-Prestress Force)= 85. VI.02 13. REFERENCES 1.html#more-4815 9/13 .4 9 6.0 Note: Stress at mid span at working bottom = 0 16.8 2. CONCLUSION This paper gives basic principles for portioning of concrete box girder to help designer to start with project.02 13. IRC: 18 – 2000 “ DESIGN CRITERIA FOR PRESTRESSED CONCRETE ROAD BRIDGES (POST – TENSIONED CONCRETE)” THE INDIAN ROADS CONGRESS.Eng.74 6.48 15. 4.2 V. www.engineeringcivil.83 14.6 25. The various trail of L/d ratio are carried out for Box Girder Bridges.8 3.66 14.4 2.2 36. LTD. the prestressing force decreases and the no. James H.1 Eugene L.11 Comparison of stress for various span/depth ratio Stress at mid span (N/mm2 ) At Working Top 6. IRC: 6. Frangopol “Lifetime Performance Analysis of Existing Prestressed Concrete Bridge Superstructures” JOURNAL OF STRUCTURAL ENGINEERING © ASCE / DECEMBER 2004 6. Marquis.0 2. P. Member “SERVICEABILITY DESIGN OF PRESTRESSED CONCRETE BRIDGES” JOURNAL OF BRIDGE ENGINEERING / FEBRUARY 1999 5. Krishna Raju “DESIGN OF BRIDGES” OXFORD & IBH PUBLISHING CO.0 Note: All dimension in tonnes and mm. P.2 4. Box girder shows better resistance to the torsion of superstructure.6 30 26.6 1. 3.20 777 829 886 950 11. As the depth increases.2 Members and Edward J. Loper.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge. 8. of cables decrease.6 5.7 1.6 2. engineeringcivil. HamburgHarburg. Tushar V.. Reply Link Quote Sharma RL September 6. We are hopeful that this will be of great use to all civil engineers who are willing to understand the design of prestressed concrete box girder. 2013 at 5:19 am I got more information from the documents about bridge design.-Ing. Kindly send more information. Germany. cells connected by top flanges or cells connected both by top and bottom flanges? Why does the presence of tension reinforcement lead to increasing deflection in concrete structures? What are the functions of different reinforcement in a typical pile cap? Plate Girder In Buildings What are the limitations of grillage analysis? What is the effect of shear lag in a typical box-girder bridge? In the construction of a two-span bridge (span length = L) by using span-by-span construction. 2013 at 11:10 am I find it very interesting and knowledgeable.Excel sheets and other relevant details Thanks Sharma RL Reply Link Quote Post a comment Name Email Website Pile Testing Systems www. why is a length of about 1.25L bridge segment is constructed in the first phase of construction? Comments Hameed Ajmal Sheikh May 7. Hameed A Sheikh Reply Link Quote Yoseph Asrat July 9. Damp Patches On Your Wall Electronic Weigh Bridge Road & Pavement Profiler Post your comment Share Information Submit Content Ask An Expert What is Civil Engineering Civil Engineering Home Civil Engineering Disciplines www. See what our users say. Ugale. V. Eng. 2013 at 12:47 am It is very useful information for design engineers especially Bridge Design engineer. Yoseph Asrat.com are thankful to Er. More Entries : How do engineer determine the number of cells for concrete box girder bridges? Which type of multiple-cell box girder is better. Thanks for your cooperation.I shall be thankful if you could send me the Excel sheets for this design as I intend to use it in near future. G.11/3/13 Analysis and design of prestressed concrete box girder bridge 9. Priyanka Bhivgade for submitting her research on “Analysis and design of prestressed concrete box girder bridge” to us..If u send me more other information about bridge design or other related documents I develop my knowledge for the future. Bhavesh A.com Robust piling QA systems. Patel and H. We at engineeringcivil.html#more-4815 10/13 .piletest.com/analysis-and-design-of-prestressed-concrete-box-girder-bridge. Mojidra (2006). Rombach “Concepts for prestressed concrete bridges Segmental box girder bridges with external prestressing” Technical University. Prof. 10. 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