The Control Effect And Experimental Research Of Severe Earthquake Design Method On RC Frame Structure Of Preseted Failure Mode

It is very important for the RC structure whether achieve the expected failure mode under earthquake. The designed method in our code is a capability differential adjustment measures called “Strong Column and Weak Beam” on basis of the internal force under low earthquake to ensure the “Beam Hinge” failure mode. The structure in the stage of nonlinear leads to the redistribution of force under strong earthquake, this also makes the proportions of force between elastic-plastic stage and elastic stage great different, at the same time, the capacity of the column is influenced by the variable axial force, It is necessary to study whether the fixed “Strong Column and Weak Beam” coefficient can effectively and economically achieve these factors or not. The method based on the design of expected failure mode under strong earthquake in Japanese code considers the influence of the redistribution of force under strong earthquake and the variable axial force to some extent, it is more reasonable in theory and worth improved by Chinese code, however, its application in current Chinese code needs to be further studied.The article focuses on the presupposed reasonable failure mode of equivalent structure model based on equivalent linearization method, seismic design of structure based on strong earthquake elastic internal force. The different intensity areas(6 degrees 0.05 g district~8 degrees 0.3g district), different height(15.9m, 24.9m, 30.9 m and 39.9m), different axial compression ratio(large axial compression ratio and small axial pressure ratio) of the models are compared and analyzed. Study on the equivalent linearization method under strong earthquake and the method of code control the failure mode of RC frame structure and compare the advantages and disadvantages of two methods, the simplified method of equivalent linearization is put forward.Two plane frame model are designed according to two methods on the basis of analysis, comparison test is carried out,the control of failure mode is further verified.① The curvature ductility demand factors of beams and columns based on the presupposed failure mode of different intensity area are counted,the curvature ductility demand factors of beams and columns are between 1~3.5, the maximum ductility demand of beams occurs at the floor of maximum drift or nearby, the curvature ductility demand factors of beams and columns in the higher intensity area are larger, the curvature ductility demand factors of beams and columns in the structure of greater axial compression ratio are larger, the curvature ductility demand factors of columns in the higher struture are smaller.② Comparing with Chinese seismic code and equivalent linear method under strong earthquake show that equivalent method under strong earthquake can reduce the number of beams and columns hinges and the curvature ductility demand factors of beams and columns, it is more obvious with the increasing of intensity area. The increasing of floor and the decreasing of axial compression ratio are more in favor of “Beam Hinge” failure mode.③ In order to practical application, the simplified parameters of equivalent linearization method under strong earthquake is proposed and its effectiveness is verified through example.④ The results of the frame structure’s test show that the equivalent method under strong earthquake is better than the method in the code, the equivalent method is in favor of “Beam Hinge” failure mode under earthquake.