Modal Pushover Analysis Method Research Articles

Spectrum-based pushover analysis for estimating seismic demand of tall buildings

A quick and accurate estimate of the seismic demand of tall buildings is one of the important issues in the seismic evaluation of buildings. Nonlinear response time history analysis method (NLRHA) is considered as the most accurate and rigorous method, but the computation requirement of NLRHA for tall buildings can be complex and very time-consuming. Whereas the conventional pushover procedure is not capable of reasonably estimating seismic demand of mid and high rise-buildings, due to the oversimplification of conventional pushover approaches and the complexity of seismic performance of buildings. In this paper, a quick, yet effective, method of analysis, named as a spectrum-based pushover analysis (SPA) method, is proposed to estimate the seismic demand of tall buildings. In the SPA procedure, the very complex and complicated dynamic coupling effect of modes of the nonlinear seismic performance of a building is simplified, and the consecutive pushover technique is adopted to consider the simplified coupling effect. Comparison of the results obtained from NLRHA, the modal pushover analysis method, the consecutive modal pushover analysis method and the proposed SPA method is made. It is seen that the SPA method predicted the seismic demand of buildings well, including the inter-storey drift ratio and hinge plastic rotation, which are very close to those of NLRHA. Owing to its accuracy, effectiveness, and spectrum-based calculation procedure, the proposed SPA procedure is considered to be a very promising tool for predicting the seismic demand of tall buildings.

Seismic Analysis of Continuous Rigid Frame Bridge with Energy-Based Modal Pushover Method

Energy-based modal pushover analysis method has been proved to be an appropriate approach to perform seismic analysis for structures whose high mode effect is not negligible. It directly establishes the capacity spectrum based on energy increments, which corrects the deficiency of conventional modal pushover method that the capacity curve would not be unique or even be retorted while the base shear-top displacement curve is established with respect to different reference nodes of the structure. In this paper, a continuous rigid frame bridge with tall piers in seismic zone is analyzed with EMPA method. The results showed that EMPA is more adaptable than conventional methods, and the seismic performance of the bridge can satisfy the demand of the design code.

Evaluation of modal incremental dynamic analysis, using input energy intensity and modified bilinear curve

AbstractIn this paper, a technique for the study of nonlinear performance of structures in different levels of earthquakes is developed. In this method, the Incremental Dynamic Analysis (IDA) curves are not achieved from nonlinear dynamic analysis of multi‐degree‐of‐freedom (MDF) structure. However, the procedure of constructing these curves is based on modelling of the entire structure with several single‐degrees‐of‐freedom (SDF) structures and evaluating them through the modal pushover analysis method. An innovative idea for approximating pushover curves that is based on error distribution is introduced in this investigation. Furthermore, the total input energy applied towards the SDF oscillator, which gets converted into MDF structure, is used as intensity measure to impose the different levels of scaled earthquakes.This technique possesses all the advantages of the IDA method in studying the performance of structures in different levels of earthquake. In addition, it benefits from easy usage, high solving speed and less computational CPU time and in attendance with the modified bilinear curves. In this paper, six earthquake records have been applied over four different 4, 8, 12 and 16‐storey structures. The structural responses derived by this method, in the format of multi‐modal incremental curves, containing maximum displacement, drift, hinge rotation and hysteretic energy at the end of the earthquake, have been compared with the IDA method. Comparison of the results is found to have acceptable precision and reveals good agreement between two methods. Copyright © 2008 John Wiley & Sons, Ltd.