A Study On The Seismic Performance Of Three-dimensional Reinforced Concrete Frame Structures Reinforced With High-strength Steel Bars

Promoting the application of high strength steel is an important measure to implement the scientific development concept, promote the transformation of economic development mode, realize green development, and in the process of promoting the application of high strength steel, there are still a lot of problems to be analyzed and studied. In China, many scholars have done a lot of experiments and theoretical analysis on the different aspects of the application performance of high strength steel, which is relatively lack of theoretical research on the seismic performance of high strength reinforced structure. Therefore, this paper analyzes the inelastic seismic response of concrete frame structure reinforced with high strength steel bars of HRB400、HRB500、HRB600 in the intensity region 7、8 and 9 under bi-directional earthquake motions based on OpenSEES framework. Meanwhile, as a lot of plastic hinges develop in the space frame column and story side-sway mechanism develops, the analysis adopts uniform section substitution principle by using high strength reinforcements in columns in order to control the structure yielding mechanism and get the following conclusions:(1)In the displacement response, the HRB500 and HRB600 steel frame structures using overall equal strength substitution show similar response characteristics of those using HRB400 under bi-directional earthquake motions, and structure maximum top displacement and story drift have increased limitedly, meet the requirements of the standard for the displacement limit. In the local reaction, with the increase of the strength grade of reinforcement, the maximum rotation angle of the structural member is increasing, the output of hinge is decreased, and the angle ductility demand of the beam and column end has both decreased. On the whole, high strength steel bars concrete frame structure has a great seismic performance.(2)The number of joints, the ductility demand and the maximum rotation angle of the column end are significantly larger than that of the beam end, which indicates that the bi-directional seismic action intensified the elastic plastic damage of the column. Although the overall strength of high-strength steel can reduce the substitution of hinge number space frame beam and column end, but still formed on the whole a column hinge dominated beam column hinge hybrid energy dissipation mechanism, failed to form the expected seismic design of "strong column weak beam" yield mechanism.(3)Using the method of uniform section substitution principle in column with high strength steel bars cannot completely avoid column hinges, but can significantly improve the the yield mechanism of the structures. The number of hinges at column end is significantly reduced, and the ductility demand of the beam is increased, which indicates that the space frame beam will be more involved in seismic energy consumption, which can greatly reduce the collapse probability of the structure caused by the hinges at column end. At the same time, the frame structure of high strength steel in the column has not changed greatly, and it is further explained that this method can realize the optimal allocation of high strength steel and improve the safety reserve of the frame column.