Ansys response spectrum analysis example

To browse Academia. Skip to main content. Log In Sign Up. VCE Co. ANSYS Tutorial: Earthquake analyses in workbench Do you want to perform earthquake analyses according to design codes or just in order to verify your structure? The current article describes in great detail two different approaches; the static response specter and the transient approach Introduction: Earthquake analyses can be performed by applying different procedures. The most popular procedure is the Response Spectrum analysis RS-analysis.

ansys response spectrum analysis example

The RS-analysis is cheap to use in terms of numerical costs as it is based on modal results. However, the spectrum solution can only show positive results, i. Another procedure is to perform a full transient analysis of the earthquake. Such analyses are computational expensive. However, they will give results based on the dynamic equation of equilibrium and hence both positive tensile and negative compressive stress results will be reported for the full length of the earthquake.

Step 1 - Modal analysis: The Modal analysis will give us the eigenfrequencies of the structure.

03 Response Spectrum - Ansys Tutorial

We are going to run a response spectrum analysis where the ground acceleration is applied in the y-direction. Figure 2: Details of the modal analysis can be found in the Solution Information Step 2: RS analysis: The RS-analysis uses the modal results obtained above as input for calculation of the earthquake response. A graphical presentation of these data can be seen in Figure 8 a. Further we decide the direction of the earthquake to be the y-direction and define the combinational method in Analysis Settings to be SRSS.

The response specter analysis can now be run. The results of the normal stress in y-direction are presented in Figure 4. Note that the results are all positive in a RS-analysis.

ansys response spectrum analysis example

Note that there are only positive results in RS analysis Step 3 — Discussion of RS results: To demonstrate how the results are obtained in a RS-analysis we will do a stepwise procedure where we manually calculate the modal contributions and combine these.

To do so we will first look at the contributions of each mode and then we will see how these results end up i. To eventually get the same result as in the RS-analysis Figure 4 we will include the contribution of the 6 first modes as was done in the RS-analysis.

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From the modal analysis we will have the following 6 normal stress results as shown 2. As a comparison we first present the normal stress results for each of the 6 modes obtained from the modal analysis see Figure 5. These are non-physical results as they are calculated from the modal displacements.

Hence, these results are used as a base for the RS-analysis.Log In. Thank you for helping keep Eng-Tips Forums free from inappropriate posts. The Eng-Tips staff will check this out and take appropriate action.

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APDL Commands Objects in ANSYS® Mechanical (Workbench) v14.5 after Response Spectrum Analysis

Students Click Here. Related Projects. Hi there, Does anyone has a simple example for response spectrum analysis in ANSYS with excitations in more than one directions? I have an idea that it will involve few load case commands but I need a reference to validate my macro.

Thanks in advance. I know this is only unidirectional response, but this falls into your "simple" request. The only difference with more than one direction is that you need to deal with cross SRSS etc. This is a big area of work to be involved in, and unfortunately the complexities don't allow a simple answer. Cheers, -- drej Red Flag This Post Please let us know here why this post is inappropriate.Log In.

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ansys response spectrum analysis example

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Response Spectrum Load Cases

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Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here. Related Projects. I'm using workbench in version 15 and I have a question about response spectrum results. Simply put, what in the world do the results mean for displacement?

Response spectrum - SRSS - negative values

The reason I ask is simple: the input required is some input frequency spectrum. Lets say for the sake of argument, I have a simply supported beam and at 10 Hz my input is 2 G's and 20 Hz my input is 1 G. That is the input spectrum. When i run it and request a displacement output, i get only one plot with displacement.

I would expect a plot for each frequency bin.

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Obviously this would be a huge file if you use more than a few frequency bins. So then the question is, well which response is it?I think you would need to set mxpand,all in the initial modal analysis. Please see Section 6. Regards, Sandeep Guidelines on the Student Community. The solution is in signif value ,we have to put minimum value as much as possible or put it zero because this value extracts only the most significant values.

Also, check the file. One other check is to look at file. Home Leaderboard Activity Badges. You must enable JavaScript to be able to use this site in full. Physics Simulation Structural Mechanics Response spectrum expanded modes in ansys apdl. Mohamed posted this 01 January - Last edited 01 January Permalink 0 0 0. Attached Files. Order By: Standard Newest Votes.

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SandeepMedikonda posted this 02 January Hi Mohamed, I think you would need to set mxpand,all in the initial modal analysis. Mohamed posted this 04 January Search in Post Topic. Popular Tags fluent ansys udf workbench cfd asc mesh fluid-dynamics error mechanical apdl cfx meshing structural-mechanics maxwell hfss static-structural general transient student Recent Activity FirasTrabelsi is a new member in the forum.Updated 16 Nov One of the main problems in time history analysis is the definition of a proper input and arranging the records for different structural analysis programs.

In the case of transient analyses, ground acceleration—time history data are used for seismic analysis. Such time histories may be derived synthetically, by either numerical simulation of the source and wave propagation mechanisms, or by considering proper stochastic models. The best way to evaluate seismic performance of structures is monitoring structural behaviour under real earthquake records. Abdurrahman Sahin Retrieved April 15, I need to the file that is the seismic analysis structure in ANSYS, just because my research, please shear it.

The system is redesigned suitable to new Peer Stong Motion Database. The velocity, dispalcement and Fourier spectrum plot functions are alsoo added into the program. I have added a paper about ANSeismic program. I have added a paper about anseismic program. I have uploaded an example file. I have detected some errors in programs, I corrected the errors now. Learn About Live Editor. Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select:.

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Toggle Main Navigation. File Exchange.I wanted to do a response spectrum analysis of a building frame. I have a RCC building. What is happening?

In a Response Spectrum analysis, the damping is included in the acceleration spectrum data, so the Modal analysis must be undamped or you would be double counting the damping. The damping is included in the acceleration data when the transient acceleration time history is converted to a Response Spectrum using a Q value in the conversion.

Home Leaderboard Activity Badges. You must enable JavaScript to be able to use this site in full. VinayN posted this 17 September Hi all. NOOB alert! I put the entire mass of building at corresponding levels as point loads. Thank You. Permalink 0 0 0. Order By: Standard Newest Votes. Hi VinayN, In a Response Spectrum analysis, the damping is included in the acceleration spectrum data, so the Modal analysis must be undamped or you would be double counting the damping.

Regards, Peter.

ansys response spectrum analysis example

Thank you, Mr. Search in Post Topic. Popular Tags fluent ansys udf workbench cfd asc mesh fluid-dynamics error mechanical apdl cfx meshing structural-mechanics maxwell hfss static-structural general transient student Recent Activity FirasTrabelsi is a new member in the forum.Enter the load cases, spectrum functions and loading directions for response spectrum analysis.

Enter the number of modes and necessary data for eigenvalue analysis in Eigenvalue Analysis Control. Define spectrum data to be applied in Response Spectrum Functions.

Set options related to response spectrum analysis in Response Spectrum Load Cases. When an analysis is completed, analyze the results using load cases or load combinations with various post-processing functions from the Results menu. Enter the name of the response spectrum analysis case. The name is used for load combinations. Refer to " Combinations ".

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Non-structural members are typically excluded in the analytical model, but rather treated as loads. Such omission can result in higher periods than actually are. This factor applies to all the natural periods calculated by eigenvalue analysis for response spectrum analysis. This functionality becomes useful when we wish to account for stiffness contribution of non-structural elements in which case we may wish to reduce the calculated periods.

Note This factor applies to all the natural periods calculated by eigenvalue analysis for response spectrum analysis. This functionality becomes useful for example when we wish to account for stiffness contribution of non-structural elements in which case we may wish to reduce the calculated periods.

Modal Combination Control. Enter the method of mode combination and specify whether to restore the signs of response spectrum analysis results. CQC method considers the probabilistic correlation between modes for a structural system with close natural frequencies, which can be found in a multi-span bridge with continuous short spans.

By applying the correlation factor in combination using close natural frequency ratios, the overestimating or underestimating problem can be resolved. ABS method renders the largest responses among different combination methods. The signs are neglected by the use of absolute values. It tends to overestimate the response results. When a specific ratio such as the rule, etc.


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