| It is indicated by research and experience that the structure is in intricate stress state under seismic excitation, however, the previous study was base on plane analytical model. The thesis of Luo Wenjin showed that the values of beam-column graded coefficients are partial small for the spatial frames in Intensity 8 (0.2g) , which's designed according to the code for seismic design of buildings (GB50011-2001), and then gave the reasonable values for frames in Intensity 8 under bilateral seismic excitation. What's more, the thesis of Wan Jianhui showed that the values of beam-column graded coefficients are partial small for the spatial frames in Intensity 7, which's designed according to the code for seismic design of buildings (GB50011-2001), but without giving the reasonable values. For the sake of solving the problems above, the author would carry out the following systemic study.In this paper, the author firstly accomplished the design of two special reinforced concrete frames according to the code for concrete structure design (GB50010-2002) and the code for seismic design of buildings (GB50011-2010) in Intensity Region 7 with accelerations 0.1g and 0.15g. Moreover, the author achieved the computation of internal forces in SAP2000 and the design of reinforcement with self-made program, as well as the nonlinear analysis for the structure under rare seismic ground motion (with large component input in Direction X and Direction Y). Additionally, finishing the analysis of structure's global response law (topmost lateral displacement, inner-story displacement ration and the base shear) and local response law (reinforced fibre strain, concrete fibre strain, end rational angle, hinge ration, ductility etc.). Basing on such response laws, the author modulated the graded coefficients for the base of bottom column and the ends of upper column of the frame, and obtained another five typical frames (Frame A1,A3~A6 and B1,B3~B6) of different column reinforcement either in Region 0.1g or Region 0.15g. The more rational factors were presented through the analysis of the response evaluation of the frames under rare earthquake. Finally, this paper also checked the super intense response of the spatial frames of A1 and B1, which were designed according to the code for seismic design of buildings (GB50011-2001), in Intensity Region 7 under Wenchuan seismic wave, Above all, several conclusions of this paper are as following:①The Frame A2, which is strictly designed according to the code for seismic design of buildings (GB50011-2010) in Intensity Region 7 (0.1g) would maintain favorable seismic behavior under a majority of seismic waves while emerging"Layer lateral shift phenomenon"under some waves. Comparing the seismic capacity of such frames with six combination coefficients, the author discovers the seismic efficiency of Frame A6 (the column moment capacity amplification factor for the base of bottom column is 1.5 and the factor for the upper column is 1.6.) is the best.②The Frame B2, which is strictly designed according to the code for seismic design of buildings (GB50011-2010) in Intensity Region 7 (0.15g) would exceed the elastic-plastic limitvalue of inner-story displacement ratio in frame structures under most of seismic waves and emerge"Layer lateral shift phenomenon". Comparing the seismic capacity of such frames with six combination coefficients, the author discovers the seismic efficiency of Frame B5 (the column moment capacity amplification factor for the base of bottom column is 1.5 and the factor for the upper column is 1.8.) is the best.③Making a comprehensive survey of the seismic response laws for Frame A1 in Region 0.1g and Frame B1 in Region 0.15g, can the author find that the change of the column moment capacity amplification factor would do no influence to the maximum topmost displacement of the structure.④Frame A1 in Intensity Region 7 (0.1g) and Frame B1 in Intensity Region 7 (0.15g), which are designed according to the code for seismic design of buildings (GB50011-2010), would form"Column hinges energy dissipation mechanism"under rare seismic excitation , within major plastic hinges at the column ends and a few at the beam ends.⑤Concluding from the nonlinear response of the spatial frames in Intensity 7 under the Wenchuan seismic ground motion, Frame A1 in Intensity 7 (0.1g) shows the max nonlinear response, which means the failure of the frame. The nonlinear response of Frame B1 in Intensity 7 (0.15g) is relative large showed that the frame is under danger. The amount of beam hinges for Frame A1 and Frame B1 suffering the super intense effect of Wenchuan seismic wave is scare small and the main energy dissipation comes from the column hinges, which is consistent with the seismic investigation summing-up of the Wenchuan Earthquake. |
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