Research On Seismic Collapse Resistance Of Reinforced Concrete Frames Based On Pushover Analysis

Structures collapse under the action of earthquake is one of the important reasonscausing casualties and economic losses. How to prevent structures collapsing under theearthquakes has long been one of engineering and academic research focus. The reinforcedconcrete frame structure is widely applied in our country, and this kind of structure damagesseriously under strong earthquakes, so we must pay more attention on its safety problem.How to estimate seismic capacity of the reinforced concrete frame structure and how toguarantee the ability of this kind of structure to resist collapse under the action ofearthquake is an important scientific problem. This paper carried out a systematic researchon the above problems and the main work has been done as follows:(1) The paper takes a six storey reinforced concrete frame structure as the researchobject, pushover analysis of the framework is carried out by using OpenSees to estimate itsseismic capacity. Though pushover analysis to find out the failure paths as well as the weaklinks of the structure under the nonlinear static pushover. The analysis results show that thisframe structure fails for story drift of the third floor greater than the limiting value, and thisframe structure fails for end section of beams failure.(2) For the further study of factors affecting the seismic performance of the reinforcedconcrete frame structure, the paper designed frame structures with the different parameters,then pushover analysis was conducted based on OpenSees. According to the analysis result,the paper gets the relation curve between structural base shear force with top displacement.After the comparison and analysis, the paper gets conclusions as follows:1) Reinforced concrete frame structure seismic collapse resistance decreases alongwith the increase of the height of layer, number of layer and structure span. The leadingcause is that the increase of these structural parameters will lead to structure axialcompression ratio increase and cause deformation of frame column capacity and safetyreserves insufficient. Thus in meet the premise of structure’s using function, controlling theheight of layer, number of layer and structure span is beneficial to improve the structure’s collapse resistance.2) Seismic collapse resistance of high-intensity fortification (8,9degrees) framestructure is better than low-intensity fortification (6,7degrees) ones. On the one handstructure axial compression ratio affects the capability of the reinforced concrete framestructure, on the other hand structural design of high-intensity fortification frame structureis generally controlled by seismic design, while structural design of low-intensityfortification frame structure is generally controlled by non-seismic design. Seismicresistance of low-intensity fortification reinforced concrete frame structure is congenitallyweaker, once a great earthquake comes, the damage will be more serious. So designersshould pay special attention to seismic design of reinforced concrete frame structure oflow-intensity fortification areas.3) Axial compression ratio has a decisive impact on the collapse resistance and theoverall carrying capacity reserves of the reinforced concrete frame structure. So it’snecessary to control axial compression ratio of structure, guarantee the ductility anddeformation capacity of the frame columns and especially frame columns of the first layer.