Research On Resist Progressive Collapse Performance 5A Grade Office Building In Lanzhou Center

Nowadays,with the increase of the terrorist activities,the frequent occurrences natural disasters and accidents occur from time to time,the possibility of continuous collapse of structures will greatly increased.The safety requirements of the high-rise building,large-scale and complex structure are becoming higher and higher,the study on the anti progressive collapse of structures under accidental action also becoming more and more urgent.Based on the background of 5A grade Office Building In Lanzhou Center,the finite element analysis model is established by PKPM and the preliminary design is completed,establish the finite element space model of 5A grade office building In Lanzhou Center by Midas/Gen software,determine the initial failure by the method of removing component,the continuous collapse performance of 5A grade office building in Lanzhou Center was studied,which based on the static and nonlinear static analysis of the residual structure,the main conclusions are as follows:(1)The demolition of the columns in different positions,the structure of the progressive collapse resistance and the degree of damage are obviously different,and there are some differences in the capacity of the continuous collapse of the remaining structure.The influence on the removal of side column is bigger than the removal of the Peripheral middle column to the structure,so take side column as an important component in the design,strengthen its construction measures,at the same time,increase the reinforcement ratio s properly,the method for increasing stirrup constraint;the structure system also can be reasonably arranged;it is also to adopt the method of adding steel and so on to the structure has a good transmission path when subjected to accidental action,so as to improve the ability of resisting progressive collapse of the structure.(2)It is the direct cause of the continuous collapse of the structure that the load is connected with the failure column,and the load is transferred to the adjacent column through the connection beam.(3)The failure of the column doubled the span of the beam,the bending moment of beam member is directly connected with the failure column,the distal and proximal moment symbols or absolute value change,the zero moment position change,the bending moment at middle span is correspondingly increased and caused beam span damage,and beam column joints of adjacent pillars produce large angle and side shift,increase the effect of P-?,in a word,the bending moment of the local area,especially the position of the column take great changes.After the redistribution of the internal force of the residual structure,the local area becomes the weak part of the whole structure,the structure eventually leads to progressive collapse.(4)The degree of continuous collapse of the structure is related to the arrangement of the columns,the number of the replacement paths and the magnitude of the unbalanced load.(5)The structure with high redundancy,the failure component of the upper framework as a whole force after the failure of local bearing column,formed a new load transfer path,the more close to the failure of column beam,the load is larger,but the structure is far from the failed component,a relatively small impact.(6)When dismantling the column,the whole upper structure of the failure component to form a new alternative load path,the more force transmission path,the higher of structure progressive collapse resistance;when the beam span is large,the capacity of beam span decreased significantly after dismantling column,the structure progressive collapse resistance is low.