Research On Fire Resistance Of Similar Existing Masonry Structure With Bottom Frame Under Different Seismic Intensity Areas

In the 1980 s and 1990 s,a large number of reinforced concrete bottom frames of multi-story masonry buildings were built in China.Large space in the bottom frame is usually used for commercial with large fire load,and once under fire,damage will be serious.In addition,this kind of structure with rigid top and flexible bottom results in poor vertical stiffness and earthquake resistant behavior,the security of which under fire is worth digging into.Hunan Hengyang fire in 2003 and Harbin Nanxun market "1.2" fire in 2015,with an accident of buildings' partly collapse,led to the losses of life and property.The structure of buildings that partly collapsed above is masonry structure with bottom frame and the buildings were built in the 1980 s and 1990 s in seismic intensity 6 degree areas.If they were built in seismic intensity 7 or 8 degree areas,what would they be? The proposition is the question that this project tries to study.Based on software ABAQUS,this paper studies the fine modeling technology of reinforecd concrete under fire,and then fire resistance of similar exsiting masonry structure with bottom frame under different seismic intensity is researched,which is designed to study the fire resistance design method and the fire resistance corresponding to seismic resistance under different seismic intensity of the masonry structure with bottom frame and can be used as a reference for safety assessment in real project and fire rescue.Main contents are as follows:1)Based on general finite element software ABAQUS,the relative parameters in fine modeling technology of reinforced concrete structure under fire are studied,and then model,calculate and compare the data to the existing experiment in the literature using the research results above,thus the research results are verified.2)Based on a series of 1989 stanndards,commercial and living buildings are designed under different seismic intensity,and then choose a piece of masonry structure with bottom frame in each seismic intensity area as research objects with contrasting section and reinforcement in these substructures.3)The performance of substructure in seismic intensity 7 degree area is konwn by the research of load transfer of the upper masonry,load distribution on the top of the joist and mechanical properties of the bottom frame,which is in the condition of fire on the first and scecond floor respectively.4)Fire resistance of the substructures under each seismic intensity in the condition of fire on the scecond floor are compared and analyzed,which shows fire endurance of frame-supporting columns under each seismic intensity are beyond the reach of "code for fire protection design of buildings(GBJ16-87)".