Research For Seismic Performance Of Reinforced Concrete Frame Structures Reinforced With HRB500 Steel Bars

In order to improve environmental quality, achieve energy conservation and sustainable development in the construction industry, our country is going to promote the use of high-strength steel of 500 MPa. HRB500 is a new type of steel bar with high strength and the application of this kind of steel bars is advised by the latest code for the Design of concrete structures. In these years, domestic universities and scientific research institutes have completed a certain number of researches for concrete structure and components which is reinforced with HRB500 steel bars. These researches have provided test and theoretical analysis basis for the popularization of the high strength steel. However, only few institutes have focus on the seismic performance of reinforced concrete structures reinforced with HRB500 steel bars.In this paper, reinforced concrete frame structures of different storeys were designed respectively in the intensity region 7, 8 and 9 according to the codes. And, these frame structures were respectively reinforced with HRB500 and HRB335 steel bars. Then the author used the software “Open System For Earthquake Engineering Simulation”(Open SEES for short)to finish nonlinear dynamic response analysis of these 18 structures under earthquake. After the further comparison and research, main conclusions from the works were got as following:1) Frame structures reinforced with HRB500 steel bars show similar response characteristics to the traditional structure reinforced with HRB335 steel bars under the action of earthquake, but the specific amount of reaction is different.2) Under the earthquake of same intensity, higher displacement response were shown by the structures reinforced with HRB500 comparing to the structures reinforced with HRB335 generaly, including the most unfavorable storey drift angle and the maximum displacement of top storey.3) Frames reinforced with different kinds of steel bars show the similar distribution of plastic hinge under the rare earthquake. With the storey and seismic grades increase, the destruction form of these frames would appear a change from column hinge failure mechanism to column-beam hinge failure mechanism and then to beam hinge failure mechanism. However, the number of plastic hinges were formed in the frames reinforced with higher strength steel bars is less while the rotation angles of components are larger.4) Frame structures which were designed according to the codes and reinforced with HRB500 steel bars show a safty deformation scale that is under the codes’ limit. We can make a judgement that this kind of structure can fufill the requirements of seimic resistance.