Study on Seismic Performance of Interrupted Shear Wall Structure and Bias Performance of Shear Wall after Fire
|Course||Architecture and Civil Engineering|
|Keywords||high-rise structure shear wall interruption seismic performance shear wall after fire bending performance|
Reasonably interrupting or reducing quantity of shear wall of high-rise buildingstructure on the upper floor can improve the seismic performance of the overallstructure, reduce the amount of concrete and make the upper space layout more agile.It is expected to be widely used in the design of high-rise building structure. At thesame time, the high temperature of fire can obviously damage the bias capacity ofconcrete shear wall. Intensive study on the bearing performance of concrete shearwall after fire is of great significance to safey appraisal and repairing of the structureof the reinforced concrete. At present, the study of seismic performance of theasymmetric frame shear structure with shear wall interruption and high-rise buildingstructure with variable section height of shear wall, and the study of the rest bearingperformance of reinforced concrete shear wall after fire are seldom reported in theliterature. The research of three aspects above is made in this paper, main work andconclusions are as follows:1. The three dimension finite element model of frame-shear wall structure can becreated by using PKPM software. The existing three interrupt conditions in shear wallinflection point, in maximum inter-story displacement angle and in zero shear placesare adopted to make the interruption. The modal analysis method by responsespectrum can accurately analyze asnd compare the seismic response of these modelsin natural period of vibration, vertex maximum displacement and basal maximumshear. More over, it can also comparatively analysis the changing displacementbetween floors, shear forces of the general shear wall and average shear forces of theframe column along the height of the structure. The calculation results show that:(1)If all interrupt the upper shear wall, the influence to the vertex maximumdisplacement and vibration model cycle is relatively small, but the displacementbetween layers in intermitting position increased by24.4%~41.5%and the averageshear of the frame column increased by86.6%~137.1%. And part interruption ofupper shear wall can avoid the above mutation.(2) The asymmetric structure after the shear wall interruption has an approximately same variation with symmetricalstructure in displacement between floors, the shear forces of total shear wall and theaverage shear of the frame colunmn along the height of the structure, but the averageshear forces of frame colunmn increase slightly larger than the symmetric structure.(3) The order of shear wall interruption position from low to high is: inflection pointlocation, in maximum inter-story displacement angle and in zero shear places. Amongthem, the average shear forces of frame column have a minmum mutation wheninterrupt the shear wall from zero shear places to the upper.2. The three dimension finite element model of high-rise building structure withvariable section height of shear wall can be created by using PKPM software. Thechange form of section height of shear wall of frame-shear wall structure is thatsection height of shear wall from one floor to the top are reduced to the same value,and that in shear wall structure is opening hole in the upper shear wall. The modalanalysis method by response spectrum is used to analyze the seismic response ofthese models, the calculation results show that:(1) The section height of shear wall offrame-shear structure is shorten to the column on three different positions above, atthe beginning of the shorten-area of section height, the displacement between layersincreased by48%~62%and the average shear of the frame column increased by94.3%~118.8%. But when it is shorten to short-leg shear wall, the correspondingresult are14.9%~32.3%and7.3%~18.4%, so it is more reasonable.(2)The sectionheight of shear wall is shorten in shear wall inflection point, in maximum inter-storydisplacement angle and in zero shear places, and the average shear of the framecolumn have a minmum mutation when the section height of shear wall is shortenfrom zero shear places to the upper.(3) By opening hole in the upper shear wall toimprove the seismic performance of the structure is feasible, but the attention shouldbe paid to select the hole size reasonably. When the hole size is too big, it may bringthe adverse influence to the seismic performance of structure.3. Taking bending capacity tests for5reinforced concrete short shear wall, inwhich3of them heated by ISO834standard are taken to analyze the rule of the effectof the fire time and the load eccentricity on the bias performance of the reinforcedconcrete after fire. The test results show that:(1) The stiffness and bias capacity of the concrete short shear wall are reduced after fire. Small eccentric specimen’s ultimateload drop respectively16.6%and52.9%after fired60minutes and120minnutes.Large eccentric specimen reduced by10.1%after fired60minutes.(2) Loadeccentricity can greatly affect the bias performance of the reinforced concrete shortshear walls after fire or not. When the eccentricity is increased from150mm to380mm, ultimate load of specimen under normal temperature and after fire60min arereduced respectively49.8%and45.9%.(3) The degree of stiffness degradation ofspecimen after fire is not proportional to the fire time. Increased the load eccentricity,the stiffness degradation of specimen is more apparent, but it is helpful to improve theductility of the shear wall.