Multi-Dimensional Seismic Response Analysis Of The Reinforced Concrete Frame-Bent Structure Considered Lateral-Torsional Coupled

In the R.C industrial structures such as electric power, metallurgy and mine, because of the demand of production technology, the multilayer deoxidized bay joined with bunker bay and large-span monolayer steam-turbine-house, which is a big spatial system comprised of multilayer structures and monolayer structures in a whole workshop. This is the R.C fame-bent structure system which is comprised of multilayer frame and monolayer bent. Because heavy equipments offset one-side of workshop, the center of stiffness departures the centroid of the system, which becomes into being a spatial asymmetric structure. The spatial torsional performance of the biaxial eccentric structure should be considered on the longitudinal vibration itercoupled with transverse vibration. So, we should make a coupled vibration analysis of horizontal deformation and torsional vibration under two horizontal components of ground motion. To this kind of structure, the former seismic analysis method of eathquake effect on transverse or longitudinal unilateral ground motion in not correct, which was used as a common workshop. This paper made the prototype with large-scale thermal power plants principal workshop of 600MW power per unit, which had has been constructed and put into production. The sub-space model of three-bay, eight-span frame-bent R.C structure comprised of steam-turbine-house, deoxidized bay and bunker bay was adopted to analyze the spatial seismic response. This study is to research the mechanical behavior and the influence factors on lateral torsional coupled reaction of the structure excited by two horizontal components of ground motion.1 From making use of the UPFs of ANSYS program to have the second development, and the elastic-plastic model of concrete was modified through FORTRAN program. Establishing spatial computational model of integral structure, the elastoplastic time-history analysis of lateral torsional coupled seismic response was adopted from using APDL language. And the result was compared with the time-history analysis of plane model, the spatial performance of integral structure was discussed too.Modal analysis of plane model and spatial model of structure were studied, and the natural vibration characteristics of integral structure were analysis too, which was provided for seismic analysis. Excited by different earthquake from transverse and longitudinal direction of the integral structure in the same time, the most displacement, the most interstory displacement angle, the most torsional angle, the most interstory shear force and the time-history curve of seismic response in the spread of time were studied, including the seismic response of the integral structure in different work-stage, especially the torsional performance. Based on characteristics of the soft, the yield surface model method was adopted to analyze the nonlinear performance of structure. The calculation program was compiled to simulate the plastic hinge forming, the failure progress of integral structure and the coordinated working performance of frame and bent, which based on the distribted steel of structural members in practice. Afterward, aiming at the result of plane modal was used in practial engineering design, adjusting coefficients of space properties were pointed out.2 The spatial seismic response and torsional performance under unidirectional earthquake action contrasted with bidirectional earthquake action during the elastic and elastoplastic time-history analysis, and the calculation formula of critical angle was deduced.The most seismic response of unidirectional and bidirectional earthquake action analyzed by contrasted, and the torsional influence of bidirectional earthquake action on structure analyzed too, at the same time, the position of weak layers were pointed out, which should be attached importance to. The unidirectional and bidirectional earthquake action were excited on oblique incidence, the most value of seismic response in the time-history were point out, afterward the most seismic response of different operation direction were received. From contrasting the most seismic response of unidirectional earthquake action with bidirectional earthquake action, proportion values were received by statistical method, and the combination formula of bidirectional earthquake response in seismic code was revised by coefficients. At last, the critical angle of structure was analyzed, and the influence of seismic response by the relativity of two horizontal component of ground motion was researched.3 The irregularity of spatial frame-bent structure was analyzed, including the influence on structure of different factor. To this structure, the torsional controlling measures were suggested.The torsional deflection index was pointed out to analysis the irregularity of frame-bent structure excited by two-directional horizontal earthquake. The influence of factors which affect the coupled response were analyzed such as static eccentric, strength eccentric, the frequency ration of lateral to torsional, and so on. Aiming at the point of the structure such as vertical discontinuous, local retractile floor, the torsional controlling measures were pointed out to avoid torional failure.4 The mode-superposition response spectrum method on seismic response of spatial frame-bent structure excited by two-directional horizontal earthquake was built up. Different modal combination method leads to different results and the number of combined modes was suggested.Making use of the mode-superposition response spectrum method to analyze seismic response of structure excited by severe earthquake. The number of combined modes satisfied with the computing precision was pointed out, and the different of seismic response of different modal combination method were discussed. At last, the influence degree of high modes on seismic response of structure was analyzed. Aiming at the modal combination method in the seismic code, the suitable combination method was pointed out to frame-bent structure, and the lateral torsional coupled response of different mode was discussed.5 The pseudo-dynamic test and quasi-static test of spatial model were operated to provide the experimental data for R.C frame-bent structures. The result of theoretical analysis and test was contrasted.According to the prototype of workshop, a sub-space model of three-bay, three-span frame-bent R.C structure was operated on pseudo-dynamic test. The chiefly content were studied as follows: the mechanism behavior of the structure under two-directional horizontal earthquake, including the characteristics of seismic force, the deformed performance, yielding sequence, energy dissipation capacity, the performance of column of ground floor, and so on. The result of tests was consistent with theoretical study.From the analysis of spatial seismic response of the biaxial eccentric and irregular structure excited by different intensity earthquake, the seismic behavior of the system, the influence of different direction of earthquake input and the irregularity on structure was analyzed. Aiming at this kind of system, calculation method of initial force and the revise of correlative list in seismic code were pointed out. Combined with the result of pseudo-dynamic test, the research can be used as reference to establish the relative codes.