A New Lateral Load Pattern Study Based on a Different Limit States

Abstract

The main objective of this study is to overview the effect of different type lateral load patterns on the moment-resisting steel frames (MRSF) by pushover analysis. In this study, a number of different load patterns (k = 0.5, k = 0, k = 0.5, k = 1 and k = 1.5) were used since this characteristic has a major influence on the ensuing analysis in order to determine the capacity demands of the structure. Seismic analyses on models designed (2-, 4- and 6- storeys MRSF) based on Eurocode 8 with different lateral load patterns are carried out using SAP2000 software. Maximum base shear force and drift (%) that based on Vision 2000 and FEMA-356 are determined to evaluate the seismic performance of the MRSF. From the result, for every lateral load pattern, the maximum base shear force has a significant decrement in higher number of storeys MRSF with a uniform cross-section beams and columns due to larger structural weight. Performance is very close for uniform distribution (k = 0) and parabolic distribution (k = 0.5). Similarly inverted triangle distribution (k = 1.0) and another type of inverse parabolic distribution (k = 1.5) performance appears to be same. As a comparison of drift from the analysis with limit states that stated on Vision-2000 and FEMA-356, using FEMA-356 to evaluate the performance level is more suitable is has higher drift limit value for every stage and every lateral load pattern. In the graphs according to FEMA-356, it can be noticed that all the collapse points are located near the point which has maximum base shear value for all the lateral load pattern cases. In order to get more accurate results, further studies need to be done by using different material constructed the frames, using irregular shape of frames, or higher proposed storeys.