Effect Of V-Eccentrically Braced On The Progressive Collapse Resistance Of Steel Frames

In recent years,some public buildings such as office buildings,hotels,and large shopping malls have suffered from various accidental disasters(such as accidental loads such as explosions and impacts)that led to the continuous collapse of structural members caused by the failure of structural members,resulting in huge casualties and property losses.It also makes people pay more attention to the continuous collapse resistance of the structure.Domestic studies on the continuous collapse resistance of structures are mostly directed to reinforced concrete structures or concrete-steel frame structures.For ordinary steel frame structures,some scholars have studied the effect of central support on the continuous collapse resistance of steel frames,while eccentric supports have resistance to steel frames.There are not many studies on the effect of continuous collapse ability.This thesis is based on a three-span 6-story steel frame office building proposed by Jiaozhou,Qingdao.A V-shaped eccentric support is provided around the second floor of the frame to study the effect of the V-shaped eccentric support on the continuous collapse of the steel frame.It provides reference basis for the selection of other similar engineering support arrangement schemes.In this paper,the original steel frame model and the steel frame model with V-shaped eccentric support were first established by using SAP2000 finite element software.According to the requirements of China’s "Code for anti-collapse design of building structures"CECS 392:2014,combined with the US GSA and DOD standards,the The method of dismantling components considers the three cases of failure of the first corner column,short-side center column and long-side center column.Non-linear static analysis and non-linear dynamic analysis are carried out.The two models are compared under the three conditions.Based on the results of nonlinear static and dynamic analysis,the internal force change law of the structure,the vertical displacement of the failure node,the speed change law and the development law of the plastic hinge of the structure are obtained.Then,using SAP2000 finite element software,the V-eccentrically braced steel frame model with different parameters was established for the three working conditions.By changing the length,slenderness ratio and supporting arrangement position of the energy dissipating beam section of the V-eccentrically supported,the changes were obtained The influence of the above parameters on the continuous collapse resistance of the steel frame.The following main conclusions are obtained:(1)Through non-linear static and dynamic analysis,it is found that the non-linear static analysis using the dynamic amplification factor specified in China’s specifications,the analysis results are basically consistent with the dynamic response state of the structure in the nonlinear dynamic analysis when the structure fails,and can be used to initially judge the structure safety.(2)Under the three working conditions,the degree of danger caused by the failure of the first-layer peripheral column of the three-span 6-layer steel frame model in descending order is:long-side center column,short-side center column,corner column.After the V-shaped eccentric support is installed,the degree of danger caused by the failure of the peripheral column at the first floor increases with the increase in the amount of structural steel.Columns are second,and the longest center column is the smallest.(3)By comparing the analysis results of the frame model and the model after setting the V-shaped eccentric support,it is found that after the frame is set with the V-shaped eccentric support,the amount of structural steel does not increase much,but the maximum vertical displacement and velocity of the nodes above the failure column are significantly reduced,and the structural The ability of continuous collapse is obviously improved,which is consistent with the existing research conclusions.(4)Comparing the analysis results of the V-shaped eccentric support model with different parameters,it is found that as the steel consumption of the frame increases,the continuous collapse resistance of the structure is slowly improved;when the length coefficient of the energy dissipation beam is between 1 and 1.6,the V-eccentric support supports the frame The ability to resist continuous collapse is most obvious,and it can be used as a reference for the relevant project when choosing a support layout.