On the descending branch of the pushover curve for multistory buildings |
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| Authors: | John F Hall |
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| Affiliation: | Department of Mechanical and Civil Engineering, California Institute of Technology, Pasadena, CA, USA |
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| Abstract: | The paper discusses nonlinear pushover curves for multistory moment‐frame buildings. Attention is brought to the steepening effect that elastic unloading has on the slope of the descending branch of the pushover curve, with the possibility of snapback. Displacement control is shown to be effective for the entire range of pushover analysis, including the descending branch. The method is enhanced by controlling the difference in displacement of 2 floors in the vicinity of the collapse mechanism rather than, say, controlling the roof displacement. An automated drift control version is described and tested. Analysis of a 20‐story building demonstrates that variable strength of plastic hinges and inclusion of the strength and stiffness of the gravity frames in the model affect the pushover curve significantly, especially the descending branch. The concept of dynamic pushover is described, and results are compared with the static version. |
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| Keywords: | collapse mechanism descending branch moment‐frame buildings nonlinear pushover curve |
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