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Pushover Analysis for RFEM 6 / RSTAB 9
Analysis of Deformation Capacity of Nonlinear Systems
Earthquakes may have a significant impact on the deformation behavior of buildings. A pushover analysis allows you to analyze the deformation behavior of buildings and compare them with seismic actions. Using the Pushover add-on, you can analyze the seismic actions on a particular building and thus assess whether the building can withstand the earthquake. The pushover analysis allows you to identify deformations and damage to a building.
For this purpose, the program determines a capacity curve, taking into account the nonlinear structural properties of the building. To calculate this curve, a horizontal load distributed over the height is applied to the entire structure and gradually increased until reaching the specified limit criterion.
After the capacity curve has been determined, it can then be compared to an action. For the seismic action, you can access the full scope of the libraries contained in the Response Spectrum Analysis add-on. The comparison is made using the procedure specified in Eurocode 8 (the N2 method) for determining the target displacement. This is processed in the program by means of graphical and tabular results for the evaluation. Furthermore, you can visualize and evaluate the acceptance criteria graphically.
- Consideration of nonlinear component behavior using plastic standard hinges for steel (FEMA 356, EN 1998‑3) and nonlinear material behavior (masonry, steel - bilinear, user-defined working curves)
- Direct import of masses from load cases or combinations for the application of constant vertical loads
- User-defined specifications for the consideration of horizontal loads (standardized to a mode shape or uniformly distributed over the height of the masses)
- Determination of a pushover curve with selectable limit criterion of the calculation (a collapse or limit deformation)
- Transformation of the pushover curve into the capacity spectrum (ADRS format, single degree of freedom system)
- Bilinearization of the capacity spectrum according to EN 1998‑1:2010 + A1:2013
- Transformation of the applied response spectrum into the required spectrum (ADRS format)
- Determination of target displacement according to EC 8 (the N2 method according to Fajfar 2000)
- Graphical comparison of the capacity and required spectrum
- Graphical evaluation of the acceptance criteria of predefined plastic hinges
- Result display of the values used in the iterative calculation of the target displacement
- Access to all results of the structural analysis in the individual load levels
The pushover analysis is managed by a newly introduced analysis type in the load combinations. Here, you have an access to the selection of the horizontal load distribution and direction, the selection of a constant load, the selection of the desired response spectrum for the determination of the target displacement, and the pushover analysis settings tailored to the pushover analysis.
In the pushover analysis settings, you can modify the increment of the increasing horizontal load and specify the stopping condition for the analysis. Furthermore, it is possible to easily adjust the precision for the iterative determination of the target displacement.
Calculation and Results
During the calculation, the selected horizontal load is increased in load steps. A static nonlinear analysis is carried out for each load step until reaching the specified limit condition.
The results of the pushover analysis are extensive. On the one hand, the structure is analyzed for its deformation behavior. This can be represented by a force-deformation line of the system (a capacity curve). On the other hand, the response spectrum effect can be displayed in the ADRS display (Acceleration-Displacement Response Spectrum). The target displacement is automatically determined in the program based on these two results. The process can be evaluated graphically and in tables.
The individual acceptance criteria can then be graphically evaluated and assessed (for the next load step of the target displacement, but also for all other load steps). The results of the static analysis are also available for the individual load steps.
- Consideration of the real load-bearing behavior in a seismic analysis, thus efficient design
- User-friendly, clear input
- Consideration of all nonlinearities
- Utiliyation of user-defined response spectra as well as response spectra from the library
- Estimation of structural capacities in the nonlinear range
- Evaluation using diagrams for better understanding
Manual of Dynamic Analysis for RFEM 6 / RSTAB 9
This article will show you how to define plastic hinges with bilinear properties.
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