What is Difference Between Time History Analysis and Response s

What is difference between time history analysis and response spectrum analysis?- ResearchGate or Search for publications, researchers, or questions Discover by subject area Join for free Página 1 de 22 Log in Sohaib Nazar King Khalid University What is difference between time history analysis and response spectrum analysis? On what basis we can evaluate structure performance based on these methods? What is limitations of these methods. Topics Structural Design Structural Analysis Spectrum Analysis Feb 19, 2015 Share 1 /1 Popular Answers Mohammad Sadeq Eskandarjuy · Shiraz University of Technology A full time history will give the response of a structure over time during and after the application of a load. To find the full time history of a structure's response, you must solve the structure's equation of motion. Response-spectrum analysis (RSA) is a linear-dynamic statistical analysis method which measures the contribution from each natural mode of vibration to indicate the likely maximum seismic response of an essentially elastic structure. Response-spectrum provides insightfor scientists and researchers. ResearchGate is theanalysis professional network into dynamic behavior by measuring pseudo-spectral acceleration, https://www.researchgate.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 What is difference between time history analysis and response spectrum analysis? - ResearchGate velocity, or displacement as a function of structural period for a given time Question followers (34) Página 2 de 22 See all history and level of damping. It is practical to envelope response spectra such that a smooth curve represents the peak response for each realization of structural period. Response-spectrum analysis is useful for design decision-making because it relates structural type-selection to dynamic performance. Structures of shorter period experience greater acceleration, whereas those of longer period experience greater displacement. Structural performance objectives should be taken into account during preliminary design and response-spectrum analysis. Views 20535 Followers 34 Answers 12 Feb 20, 2015 All Answers (12) C. Rainieri · Università degli Studi del Molise In time history analyses the structural response is computed at a number of subsequent time instants. In other words, time histories of the structural response to a given input are obtained ad a result. In response spectrum analyses the time evolution of response cannot be computed. Only the maximum response is estimated. No information is available also about the time when the maximum response occurs. I hope this can help Feb 19, 2015 Claes Richard Fredö · Qring Technology Intl. AB Hi In addtion to the above answer, perhaps it is useful to know that a time history, convolved with the transfer function of s single degree of freedom the professional for scientists and researchers. (sdof) system is what producesResearchGate the responseisspectrum. More innetwork detail, the https://www.researchgate.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 The procedure is used for shocks. there is a difference between shock response spectrum (SRS) and response spectrum analysis where the latter refers to sdof base-mass relative motion and the former referes to (absolute) fixed frame motion of the sdof mass.ResearchGate Página 3 de 22 frequency axis of the response spectrum is not ordinary frequency but rather the natural frequency of the sdof system. Sincerely Claes Feb 19. seismic analysis. is an instrument comprised of stems of varying lengths with varying natural frequency were in the days of old used both to determine frequency and vibration amplitude (from logging reed tip motion). The foundations of the method can be hard to comprehend.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . at least I had trouble understanding where it all came from. but is stated in old version of the Shock and Vibration Handbook by Harris. 2015 ResearchGate is the professional network for scientists and researchers. The procedure simplifies downstream estimation of maximum response and allows combination of multiple time histories.What is difference between time history analysis and response spectrum analysis? .researchgate. the multiplication of the modal reponse by the response spectrum amplitude at the  natural frequency of the computed modes. Mohammad Sadeq Eskandarjuy · Shiraz University of Technology https://www. Also. The reed (see picture below). In essence. The response spectrum basically is what a reed instrument would have recorded. packaging design and many other analyses where simple answers are hard found. what is needed is simple modal analysis. Structural performance objectives should be taken into account during preliminary design and response-spectrum analysis. Whereas it is possible to include material or geometrical nonlinearities in time domain analysis. whereas those of longer period experience greater displacement. Structures of shorter period experience greater acceleration. 2015 Dominik Stengel · Bundesanstalt für Materialforschung und -prüfung Response spectrum analysis are limited to linear assumptions on the system's response. 2015 Taha Ibrahim · Benha University A response spectrum is simply a plot of the peak or steady-state response (displacement.ResearchGate Página 4 de 22 A full time history will give the response of a structure over time during and after the application of a load. or displacement as a function of structural period for a given time history and level of damping.researchgate. velocity or acceleration) of a series of oscillators of varying ResearchGate is the professional network for scientists and researchers. that are forced into motion by the same base vibration or shock. The resulting plot can then be used to pick off the response of https://www. velocity. you must solve the structure's equation of motion. To find the full time history of a structure's response. Response-spectrum analysis (RSA) is a linear-dynamic statistical analysis method which measures the contribution from each natural mode of vibration to indicate the likely maximum seismic response of an essentially elastic structure. It is practical to envelope response spectra such that a smooth curve represents the peak response for each realization of structural period. natural frequency. Feb 20. Feb 24. Response-spectrum analysis is useful for design decision-making because it relates structural type-selection to dynamic performance.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . Response-spectrum analysis provides insight into dynamic behavior by measuring pseudo-spectral acceleration.What is difference between time history analysis and response spectrum analysis? . researchgate.ResearchGate Página 5 de 22 any linear system. the peak response is reported. A typical combination method is the square root of the sum of the squares (SRSS) if the modal frequencies are not close. or else the response will be infinite. since phase information is lost in the process of generating the response spectrum. The equation takesisonthe theprofessional form A(t) = network Ao*sin for scientists and researchers. Response spectra can also be used in assessing the response of linear systems with multiple modes of oscillation (multi-degree of freedom systems). although attempts have been made to develop non-linear seismic design spectra with wider structural application. If the input used in calculating a response spectrum is steady-state periodic. One such use is in assessing the peak response of buildings to earthquakes. but a value will be obtained even with no damping. Harmonic Forcing Function The harmonic forcing function varies in a sinusoidal fashion and requires ResearchGate Ao and ω to be specified. For transient input (such as seismic ground motion). Response spectra can be generated for nonlinear systems. The results of this cannot be directly combined for multi-mode response. then the steady-state result is recorded. The science of strong ground motion may use some values from the ground response spectrum (calculated from recordings of surface ground motion from seismographs) for correlation with seismic damage. although they are only accurate for low levels of damping. The result is typically different from that which would be calculated directly from an input. These peak responses are then combined to estimate a total response. given its natural frequency of oscillation. (ω*t) and A(t) multiplies all static loads placed in the time history load https://www. but are only applicable to systems with the same nonlinearity.What is difference between time history analysis and response spectrum analysis? . The main limitation of response spectra is that they are only universally applicable for linear systems. Damping must be present. Some level of damping is generally assumed. Modal analysis is performed to identify the modes. and the response in that mode can be picked from the response spectrum.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . Note the text "Force" on the first line.05 1. Load Amplitude loads are commonly used to model wind loads.0 0.researchgate.1 1. A(t) multiplies the static loads applied to the structure in the time history load case at various times.0 9.What is difference between time history analysis and response spectrum analysis? . (I. The base displacement is exactly as it sounds. Y.0 As with the harmonic function. X and Y directions respectively. Force 0. Harmonically varying loads are probably most common when analyzing the effects of machinery on a structure.0 0. the Base Displacement uses a text file for input. the structure is forced through some varying ground displacement over time.ResearchGate Página 6 de 22 case at various times.) Units for the text file are always assumed https://www. and possibly blast loadings. These displacements can act independently in the global X.1001 0.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . Note that the units on ω are such that ω*t has angle units of radians. If you wanted to model an event at a 45 degree angle to the X and Y directions you could specify the necessary components in the ResearchGate is the professional network for scientists and researchers.0 0.0 0. When this text file is read into VisualAnalysis the first line indicates the type of data. and Z directions. time (t) and A(t) which is the amplification factor. The text file requires two columns. Base Displacement Like the Load Amplitude loading type. Factored Forcing Functions (Load Amplitude) The Load Amplitude time history option essentially uses a text file to specify the fraction of the load at specific times. The displacements can be any combination of all or some of these directions. impact loads. Often unbalanced rotating machinery or parts are most applicable.0 0. Shown below is a sample of what would appear in the text file along with a plot of the data.e. In the example the uy(t) and uz(t) columns are included but have no effect.0 0. The text file requires at least two columns and can have up to four (refer to the Text File Notes section below for more information).0 1. the Base Acceleration loading type uses a text file for input.0 1. and z directions and again they can be any combination of all or some of these directions. űx(t).5" would be 50% of G).0 https://www.0 0. Logically.5 ft if your current project units were lb-ft. y. "0.0 -5. Note below the text file is shown in a space delimited format.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 .0 0.0 0.0 3.0 2. The base acceleration is very similar to the base displacement and represents putting the structure through some varying ground acceleration over time.0 0. t.e.0 0. These columns would be the time.0 ResearchGate is the professional network for scientists and researchers. and uz(t).0 5. These columns would be time (t). the accelerations can act in the x. and űz(t) where the accelerations are specified as a decimal fraction of G (I.What is difference between time history analysis and response spectrum analysis? . űy(t).0 Note that the line is extrapolated linearly between the t = 2. if one of the displacement values was 6 in it would be read in as 0. Base Acceleration Again. For example.0 0. Note also that if you are working in a plane structure the uz(t) column will always be ignored.0 0.0s and t = 3.0 0.0 0. After the file is read in the data will be converted to the current unit system. ux(t). You must be working in a space frame structure to have z displacements. 1.0 0. Similarly.0 0.0 0.ResearchGate Página 7 de 22 to be seconds and inches.0 5.5 seconds. Acceleration 0.0s values but our time increments limit the displacement to 2. uy(t). Displacement 0.researchgate. the base acceleration is just the second derivatives of the base displacements.0 0. The text file requires at least two columns and can have up to four (refer to the Text File Notes section below for more information). vap) and the connection to the data file is not maintained.researchgate. Text File Notes Some general notes about the input text files. you would need to edit the Time History load case to re-load the data from the file. or tab delimited.0 3.ResearchGate Página 8 de 22 2. https://www.0 2. the static loads applied within the time history case are varied dynamically according to what is specified.0 Base Displacement and Base Acceleration Notes With the base displacement and base acceleration analysis types static loads only have an inertial effect on the structure.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 .0 0.0 0. ResearchGate is the professional network for scientists and researchers.What is difference between time history analysis and response spectrum analysis? . Any statically applied loads that do not act in the gravity direction (positive or negative Y) and any moments are simply ignored by VisualAnalysis and will have no effect on the displacement or acceleration analysis results. the data is stored in your project file (*. It then has an inertial effect on the results similar to adding lumped mass to nodes. If you edit or modify your data file. Once the data file is opened and read successfully. the number of columns in the data file will change based on the structure type.0 0. For the displacement and acceleration types. VisualAnalysis converts any statically applied load in the time history load case acting in the positive or negative Y direction to a mass.0 0. or Acceleration "headings" on the first line are not essential for the file to work but it is recommended. Storing the data file in the project file allows the project to be sent to a colleague or opened at some future time when the text file is not available or may have a different location. With the harmonic and amplitude analysis types. The Force. Displacement. The text files can be comma.01 0.0 0. space. The table below summarizes the data required for the various structure types.0 0. As noted above.0 0.0 0. 01 sec entry the program would simply have continued to interpolate a straight line between the acceleration of 1 at t = 1 sec and zero at t = 2. Z Space Frame 4 T. therefore. Y Plane Frame 3 T. The parameters of the Newmark method are described in what follows. [3]. For example. it is essential that one select a numerical integration method that is unconditional for all time steps. the values in the text files are always linearly interpolated until you set a new value. Y. Wilson in [3] recommends ∆t ≤ 1/ (ωMAX*√(γ/2 .L. Amplitude. For a further discussion ResearchGate refer to [1].What is difference between time history analysis and response spectrum analysis? . If we had not added the t = 2. X.0 sec and continuing on past 2.researchgate. To accomplish this we specified an acceleration of zero at t = 2. in the sample acceleration data we wanted the acceleration to be zero at a time of 2 seconds and beyond. E. Delta t – This is the time increment for each step. Y. Acceleration. X. Y Space Truss 4 T. and Displacement Input In time history analysis procedures there are a number of ways to numerically integrate the fundamental equation of motion.ResearchGate Página 9 de 22 Structure Type Columns Per Line Data In Columns Plane Truss 3 T. Z Lastly.β)). The time step increment can be very important as well. VisualAnalysis uses the Newmark method of numerical integration which is considered a generalization of the linear acceleration method. Number of Steps – This is the number of time steps over which you wish to analyze.isand the[4].0 sec and also at t = 2. X.0 seconds. X. For large multi degree of freedom structural systems there is a different limit.01 sec. professional network for scientists and researchers. https://www.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . Many of these are discussed in text books including the referenced texts included in this document. This due to computer models of large real structures normally containing a large number of periods which are smaller than the integration time step. https://www. This is discussed for mode shapes and response spectra and applies to time history analysis too. as derived by the Wilson-theta method.L. Time History Dialog To perform a time history analysis. You can also refer to the Time History tutorial where members are split to improve the analysis accuracy. This is done on the Load menu in VisualAnalysis.researchgate. Using other values. connections. These default values make the Newmark method unconditionally stable and provide satisfactory accuracy. which is the natural log of the ratio of any two successive peak amplitudes in free vibration. note that it is usually more accurate to split the members of your model to get a better mass distribution and a better solution. Gamma and Beta replaced the 1/2 and 1/6 coefficients on the incremental acceleration terms of the equation for incremental displacement. E. etc. Relating to mass. This is the effect of internal damping due to materials. Many text books on the subject also describe these parameters. Most dynamics texts discuss damping including those referenced below. Note that VisualAnalysis uses viscous damping. Wilson presents a good discussion in [3] regarding the beta and gamma parameters for Newmark's method. and adding mass to the structure.ResearchGate Página 10 de 22 Gamma and Beta – The Newmark method is basically considered a generalization of the linear acceleration method (Wilson-Theta).net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . For a harmonically varying forcing function simply select Harmonic from the drop down list. The default values of gamma = 1/2 and beta = 1/4 may be used unless you are sure otherwise. The other loading types require a for scientists and researchers. The second page of the dialog is where you specify the type of loading you would like applied to the structure. The dialog will require a name for the time history case and the parameters discussed above must be entered.What is difference between time history analysis and response spectrum analysis? . then specify AoResearchGate and ω. particularly gamma greater than 1/2 can lead to "numerical damping" and "period elongation". Delta – Delta defines the amount of damping and is usually defined as the logarithmic decrement. is the professional network text file input so "From file" would be selected from the drop down list. you must first create a new time history case. while in a Result View you can right click a node in your time history case and select "Graph Node Results" from the context menu.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . using an envelope would quickly allow you to see the overall maximum and minimum extremes for just the time history case or for multiple load cases. Results section for more information. beta. and delta values. displacement. you can view member internal forces at any of the time increments during the analysis. or acceleration information. The unique characteristic of time history cases is you can view results for every time step. The Time History Cases item includes a number of items with the most common ones being the number of time steps. forces. and Forcing Function Summary. and moments over time for the selected node. A very useful way to look at results is to use the graph feature. Refer the Enveloped ResearchGate is thetoprofessional network for scientists and researchers.researchgate. Also. Time History Reports There are three main report items available for time history load cases: Time History Cases. After creating a time history case and applying any necessary loads to the structure within this case. the use of enveloped results becomes very useful for processing time history results.ResearchGate Página 11 de 22 Clicking the ellipsis button will open a new dialog where you can browse for the text file containing the amplitude. Note that many of the static reports are available at a specific time increment in a time history analysis. the forcing type. Time History Results When in a Result View. This will allow you to plot displacement. For example.What is difference between time history analysis and response spectrum analysis? . gamma. The only extra information the Forcing Function Details report gives is the data that was read in from the text file in a tabled format. Forcing Function Details. Logically. For example. the analysis is performed as usual. the time history case is selected in the status bar like any other load case in VisualAnalysis. and the forcing type. https://www. time step increment. the location of the source text file that was used (if applicable) and the number of data points. They both include the time history case name. The Forcing Function Details and Forcing Function Summary report items are very similar. although they are only accurate for low levels of damping. Response spectra can be generated for non- https://www. The main limitation of response spectra is that they are only universally applicable for linear systems. ResearchGate is the professional network for scientists and researchers. 2015 Taha Ibrahim · Benha University A response spectrum is simply a plot of the peak or steady-state response (displacement. Damping must be present. but a value will be obtained even with no damping.researchgate. A typical combination method is the square root of the sum of the squares (SRSS) if the modal frequencies are not close. given its natural frequency of oscillation. For transient input (such as seismic ground motion). Response spectra can also be used in assessing the response of linear systems with multiple modes of oscillation (multi-degree of freedom systems). The result is typically different from that which would be calculated directly from an input. The resulting plot can then be used to pick off the response of any linear system. or else the response will be infinite. velocity or acceleration) of a series of oscillators of varying natural frequency. These peak responses are then combined to estimate a total response. since phase information is lost in the process of generating the response spectrum. The science of strong ground motion may use some values from the ground response spectrum (calculated from recordings of surface ground motion from seismographs) for correlation with seismic damage.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . the peak response is reported. Some level of damping is generally assumed. Modal analysis is performed to identify the modes. that are forced into motion by the same base vibration or shock. then the steady-state result is recorded.ResearchGate Página 12 de 22 Mar 5. and the response in that mode can be picked from the response spectrum. If the input used in calculating a response spectrum is steady-state periodic.What is difference between time history analysis and response spectrum analysis? . One such use is in assessing the peak response of buildings to earthquakes. 0 9. https://www.0 0.1001 0. The equation takes on the form A(t) = Ao*sin (ω*t) and A(t) multiplies all static loads placed in the time history load case at various times. When this text file is read into VisualAnalysis the first line indicates the type of data. Load Amplitude loads are commonly used to model wind loads. although attempts have been made to develop non-linear seismic design spectra with wider structural application. Harmonic Forcing Function The harmonic forcing function varies in a sinusoidal fashion and requires Ao and ω to be specified. The results of this cannot be directly combined for multi-mode response. Note that the units on ω are such that ω*t has angle units of radians. Often unbalanced rotating machinery or parts are most applicable.05 1.researchgate.ResearchGate Página 13 de 22 linear systems. Factored Forcing Functions (Load Amplitude) The Load Amplitude time history option essentially uses a text file to specify the fraction of the load at specific times.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . Force 0. but are only applicable to systems with the same nonlinearity.1 1.0 0. and possibly blast loadings. The text file requires two columns.0 0. time (t) and A(t) which is the amplification factor. impact loads.0 0.0 0. Harmonically varying loads are probably most common when analyzing the effects of machinery on a structure. Shown below is a sample of what would appear in the text file along with a plot of the data. ResearchGate is the professional network for scientists and researchers. A(t) multiplies the static loads applied to the structure in the time history load case at various times. Note the text "Force" on the first line.0 As with the harmonic function.What is difference between time history analysis and response spectrum analysis? . Base Acceleration Again. the Base Acceleration loading type uses a text file for input.0 1. Similarly. Note also that if you are working in a plane structure the uz(t) column will always be ignored. These columns would be the time. You must be working in a space frame structure to have z displacements. y.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 .0 0. is thederivatives professional Logically. For example. The base displacement is exactly as it sounds.0 0. and uz(t). the accelerations can act in the x. the Base Displacement uses a text file for input.0 -5.0 3. Displacement 0.0 5. After the file is read in the data will be converted to the current unit system. if one of the displacement values was 6 in it would be read in as 0.) Units for the text file are always assumed to be seconds and inches.e.0 0. The text file requires at least two columns and can have up to four (refer to the Text File Notes section below for more information).0 0. These displacements can act independently in the global X. uy(t).0 5.5 seconds. Y. (I. and z https://www.0 0. displacements. The base acceleration is very similar to the base displacement and represents putting the structure through some varying ground acceleration over time. the base accelerationResearchGate is just the second of network the base for scientists and researchers. The displacements can be any combination of all or some of these directions.What is difference between time history analysis and response spectrum analysis? . the structure is forced through some varying ground displacement over time.0 0.researchgate.0s values but our time increments limit the displacement to 2.0 2. and Z directions. In the example the uy(t) and uz(t) columns are included but have no effect.0s and t = 3.ResearchGate Página 14 de 22 Base Displacement Like the Load Amplitude loading type.0 0.0 0.5 ft if your current project units were lb-ft.0 Note that the line is extrapolated linearly between the t = 2. ux(t). If you wanted to model an event at a 45 degree angle to the X and Y directions you could specify the necessary components in the X and Y directions respectively.0 0. t. 0 0.0 0. Acceleration 0.0 0.5" would be 50% of G).ResearchGate Página 15 de 22 directions and again they can be any combination of all or some of these directions. "0. ResearchGate is the professional network your project file (*.vap) and the connection to the data file is not https://www.01 0.0 1.0 2. Any statically applied loads that do not act in the gravity direction (positive or negative Y) and any moments are simply ignored by VisualAnalysis and will have no effect on the displacement or acceleration analysis results. These columns would be time (t).0 0.0 0.0 3. the data is stored in for scientists and researchers.0 0. VisualAnalysis converts any statically applied load in the time history load case acting in the positive or negative Y direction to a mass. Note below the text file is shown in a space delimited format. Text File Notes Some general notes about the input text files.0 Base Displacement and Base Acceleration Notes With the base displacement and base acceleration analysis types static loads only have an inertial effect on the structure.0 0.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . űx(t). űy(t). or tab delimited. With the harmonic and amplitude analysis types.researchgate. The Force.What is difference between time history analysis and response spectrum analysis? .0 0.e.0 0. Displacement. and űz(t) where the accelerations are specified as a decimal fraction of G (I.0 0. For the displacement and acceleration types. space. the static loads applied within the time history case are varied dynamically according to what is specified. or Acceleration "headings" on the first line are not essential for the file to work but it is recommended. The text file requires at least two columns and can have up to four (refer to the Text File Notes section below for more information). The text files can be comma. Once the data file is opened and read successfully.0 2.0 0.0 1.0 0.0 0. It then has an inertial effect on the results similar to adding lumped mass to nodes. Z Space Frame 4 T. you would need to edit the Time History load case to re-load the data from the file. Y. the values in the text files are always linearly interpolated until you set a new value. Storing the data file in the project file allows the project to be sent to a colleague or opened at some future time when the text file is not available or may have a different location. Structure Type Columns Per Line Data In Columns Plane Truss 3 T. If we had not added the t = 2. Z Lastly. Many of these are discussed in text books including the referenced texts included in this document. the number of columns in the data file will change based on the structure type.0 sec and continuing on past 2.ResearchGate Página 16 de 22 maintained. Amplitude. To accomplish this we specified an acceleration of zero at t = 2. in the sample acceleration data we wanted the acceleration to be zero at a time of 2 seconds and beyond. https://www. If you edit or modify your data file. Y Plane Frame 3 T.What is difference between time history analysis and response spectrum analysis? . X. X. and Displacement Input In time history analysis procedures there are a number of ways to numerically integrate the fundamental equation of motion. Y.01 sec. ResearchGate is the professional network for scientists and researchers. The parameters of the Newmark method are described in what follows.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . X. Number of Steps – This is the number of time steps over which you wish to analyze. The table below summarizes the data required for the various structure types. For example.0 seconds.0 sec and also at t = 2. VisualAnalysis uses the Newmark method of numerical integration which is considered a generalization of the linear acceleration method. Acceleration. X.researchgate.01 sec entry the program would simply have continued to interpolate a straight line between the acceleration of 1 at t = 1 sec and zero at t = 2. Y Space Truss 4 T. As noted above. E. note that it is usually more accurate to split the members of your model to get a better mass distribution and a better solution. Using other values. and [4]. This due to computer models of large real structures normally containing a large number of periods which are smaller than the integration time step. You can also refer to the Time History tutorial where members are split to improve the analysis accuracy. ResearchGate is the professional network for scientists and researchers. etc. it is essential that one select a numerical integration method that is unconditional for all time steps. E. [3]. This is discussed for mode shapes and response spectra and applies to time history analysis too.What is difference between time history analysis and response spectrum analysis? . Many text books on the subject also describe these parameters. Wilson in [3] recommends ∆t ≤ 1/ (ωMAX*√(γ/2 .researchgate. For a further discussion refer to [1].L. For large multi degree of freedom structural systems there is a different limit. The time step increment can be very important as well. Time History Dialog https://www. as derived by the Wilson-theta method. Wilson presents a good discussion in [3] regarding the beta and gamma parameters for Newmark's method. Most dynamics texts discuss damping including those referenced below. These default values make the Newmark method unconditionally stable and provide satisfactory accuracy. therefore. This is the effect of internal damping due to materials. The default values of gamma = 1/2 and beta = 1/4 may be used unless you are sure otherwise. Delta – Delta defines the amount of damping and is usually defined as the logarithmic decrement. Gamma and Beta – The Newmark method is basically considered a generalization of the linear acceleration method (Wilson-Theta).L. Gamma and Beta replaced the 1/2 and 1/6 coefficients on the incremental acceleration terms of the equation for incremental displacement. and adding mass to the structure. Note that VisualAnalysis uses viscous damping. connections.ResearchGate Página 17 de 22 Delta t – This is the time increment for each step. particularly gamma greater than 1/2 can lead to "numerical damping" and "period elongation".β)). Relating to mass.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . which is the natural log of the ratio of any two successive peak amplitudes in free vibration. A very useful way to look at results is to use the graph feature. time step increment. They both include the time history case name.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . This is done on the Load menu in VisualAnalysis.ResearchGate Página 18 de 22 To perform a time history analysis. displacement. The dialog will require a name for the time history case and the parameters discussed above must be entered. the location of the source text file that was used (if applicable) and the number of data points. Details report gives is the data that was read in from the text file in a https://www. The second page of the dialog is where you specify the type of loading you would like applied to the structure. and moments over time for the selected node. or acceleration information. Time History Reports There are three main report items available for time history load cases: Time History Cases. Forcing Function Details. beta. After creating a time history case and applying any necessary loads to the structure within this case. Time History Results When in a Result View. forces.What is difference between time history analysis and response spectrum analysis? . The Forcing Function Details and Forcing Function Summary report items are very similar. The other loading types require a text file input so "From file" would be selected from the drop down list. Clicking the ellipsis button will open a new dialog where you can browse for the text file containing the amplitude. This will allow you to plot displacement. then specify Ao and ω.researchgate. gamma. TheResearchGate only extra information the Forcing Function is the professional network for scientists and researchers. you must first create a new time history case. and the forcing type. the time history case is selected in the status bar like any other load case in VisualAnalysis. and delta values. and Forcing Function Summary. the forcing type. The Time History Cases item includes a number of items with the most common ones being the number of time steps. while in a Result View you can right click a node in your time history case and select "Graph Node Results" from the context menu. For a harmonically varying forcing function simply select Harmonic from the drop down list. For example. The unique characteristic of time history cases is you can view results for every time step. the analysis is performed as usual. Logically. Mar 5.mit.ResearchGate Página 19 de 22 tabled format.What is difference between time history analysis and response spectrum analysis? . AB Hi If you want to look at related methods and assumptions/limitations. 2015 Claes Richard Fredö · Qring Technology Intl. you can view member internal forces at any of the time increments during the analysis.researchgate. http://snebulos. ResearchGate is the professional network for scientists and researchers. Refer to the Enveloped Results section for more information.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . using an envelope would quickly allow you to see the overall maximum and minimum extremes for just the time history case or for multiple load cases. 2015 Ahmed Guerine · Institut National des Sciences Appliquées de Rouen Hi Response spectrum considers the spectrum of a response quantity like acceleration with respect to frequency.edu/projects/reference/NASA-Generic/NASA-HDBK7005. the use of enveloped results becomes very useful for processing time history results. For example. Note that many of the static reports are available at a specific time increment in a time history analysis. Also. This spectrum is used to generate acceleration coefficients for different masses which in turn gives the force. the Nasa Environmental Handbook is a good read. https://www.pdf Sincerely Claes Mar 5. whereas those of longer period experience greater displacement. Best regards May 25. 2015 Ahmed Guerine · Institut National des Sciences Appliquées de Rouen Hi Response-spectrum analysis  is a linear-dynamic statistical analysis method which measures the contribution from each natural mode of vibration to indicate the likely maximum seismic response of an essentially elastic structure. Structures of shorter period experience greater acceleration.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 .ResearchGate Página 20 de 22 On the other hand. Best regards May 28. Response-spectrum analysis provides insight into dynamic behavior by measuring pseudo-spectral acceleration. It is practical to envelope response spectra such that a smooth curve represents the peak response for each realization of structural period.What is difference between time history analysis and response spectrum analysis? . time history analysis uses the time history of input force or acceleration directly which is then combined to get the response. velocity.researchgate. Structural performance objectives should be taken into account during preliminary design and response-spectrum analysis. or displacement as a function of structural period for a given time history and level of damping. Response-spectrum analysis is useful for design decision-making because it relates structural type-selection to dynamic performance. system which only gives positive maximum between applied frequency range due to which it is fast but it cannot give the time step at which https://www. 2015 Nitish Shete · Indian Institute of Technology (Banaras Hindu University) Varanasi Response spectrum analysis is plot of maximum response of SDOF ResearchGate is the professional network for scientists and researchers. Time history analysis is detailed analysis in which response is calculated for each time step. time histories of the structural response to a given input are obtained ad a result.pdf Dec 16. Add your answer https://www. In other words.Brgds :DYNAMIC ANALYSIS USING RESPONSE SPECTRUM SEISMIC LOADING" DYNAMIC ANALYSIS USING RESPONSE SPECTRUM SEISMIC LOADING. 21 days ago Can you help by adding an answer? Enter your answer ResearchGate is the professional network for scientists and researchers. In response spectrum analyses the time evolution of response cannot be computed . I hope this article be helpful for you . 2015 Jaafar Mohammed · University of Duhok Hello .ResearchGate Página 21 de 22 maximum response occurs.Hello .   Jun 29.researchgate.net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 . Also.What is difference between time history analysis and response spectrum analysis? . you cannot get accurate response. It requires more time but gives good results. if applied frequency range is outside the natural frequency of system (as can happen in seismic analysis). 2015 Mohammad Sadeq Eskandarjuy · Shiraz University of Technology In time history analyses the structural response is computed at a number of subsequent time instants. net/post/What_is_difference_between_time_history_analysis_and_response_spectrum_analysis 21-07-2016 .ResearchGate © 2008-2016 researchgate. https://www.net.researchgate. All rights reserved. Página 22 de 22 About us · Contact us · Careers · Developers · News · Help Center · Privacy · Terms  |  Advertising · Recruiting ResearchGate is the professional network for scientists and researchers.What is difference between time history analysis and response spectrum analysis? .