The Endurance Time Method For Seismic Response Analysis Of Steel-concrete Hybrid Structures

Steel-concrete hybrid structure system combines the beneficial qualities of both steel and concrete, namely, convenience of construction,high strength, excellent ductility, multiplex arrangement,higher stiffness and low cost. The steel-concrete hybrid structure is a kind of high-rise building structure form that matches the state of our country. However, the research on the seismic performance of this kind of structures at home and abroad is not sufficient and there are a lot of questions and doubts. In this paper, the endurance time(ET) method is used to analyze steel-concrete hybrid structure system, which helps to understand its seismic performance correctly and evaluate the ET method. The main research works are as follows:(1) The background and the recent development of the ET method is introduced, the basic concept of the ET method is symbolically depicted by a hypothetical shaking table test, and the generating method of ET accelerograms is explained in detail. To four ET accelerograms whose duration is 30 s as an example, their acceleration response spectra and the design response spectra are analyzed in error to verify the accuracy of ET accelerograms. Given the generating efficiency, this paper analyzes the different periodic spacing effects on ET accelerograms.(2) A brief introduction of module functions and structure component simulation of Perform-3D software is given. The basic principles of incremental dynamic analysis(IDA) method are established and defined, including steps of implementation and selection of ground motion records. In this paper, the applicability of the ET method in the nonlinear seismic analysis of steel concrete hybrid structures is verified by a 12-story steel-concrete hybrid structure which is the prototype of a shaking table test and whose finite element model is set up by Perform-3D software. The results obtained by the ET method are compared with the results of shake table test, conventional time history analysis(THA) method and the IDA method. Meanwhile, the uncertainty of ET accelerograms and its influence on seismic performance of steel-concrete hybrid structures are also discussed.(3) According to the definition of seismic fragility,the ET method-based seismic fragility analysis method of hybrid structure is proposed. Structural seismic fragility analysis process is illustrated by using a 20-story steel-concrete hybrid structure. The ET-based seismic fragility curve and its transition method are obtained.(4) Endurance time analyses are carried out for steel- concrete hybrid structure when ET accelerograms are input in one, two or three directions. According to the results, the influence of the seismic waves dimension on single endurance time curves, structural response and base shear force-roof displacement curves were discussed.