Research On Lateral Force And Target Displacement Of Frame

The losses which caused by the strong earthquake in recent years had made people understand the deficiency of the current seismic design thought either in the thought of seismic design or in the need of the community. In this circumstance, the performance based seismic design had been extensively discussed, and it was thought to be a main development direction in the seismic design area. As a non-linear static analysis method, push-over analysis is an important tool of the performance based seismic design. This paper study the performance of regular RC frames in different lateral load patterns through push-over analysis, besides it put forward a new equivalent non-liner single-degree-of-freedom system used for calculating the target displacement for the regular frames.First, this paper describes the background, basic assumptions, the development and the pros and cons of static elastic-plastic push-over analysis method. Based on the discussions above, this paper studies one of the most important factor—lateral load pattern which has a great effect on the precise of push-over analysis.Second, this paper analyze the five-story, nine-story and twelve-story regular frame under different later load patterns by EATBS program, then study how the factors such as load patterns, number of stories and the mode have affected the seismic capacity, story drifts and the yield mechanism of the regular frames.Besides the analysis above, this paper propose a new equivalent non-liner single-degree-of-freedom system. The main assumption of this paper is that the masses of the frame are loaded with lateral external dynamic forces so that the equivalent dynamic forces can substitute the seismic demand. Thus we can use the curve of base shear forces—top displacement diagram directly and avoid the conversion of the common equivalent method;Besides, it avoids the iteration by reduces the elastic spectrum through the strength reduction factor and calculates the target displacementaccording to the equivalent period. Finally, this method is verified by a six story regular frame system. The results show that, this method is simple and practical, and it has certain reference significances for the analysis of structure.