Research On Performance Of Prestressed Concrete Frame Against Progressive Collapse

The use of prestressed concrete structures is becoming more widespread,with the maturity of prestressing technology,the promotion of high performance materials and the increasing demand for building functionality.After the September 11 th incident,against progressive collapse design of the building structure has received more and more attention.At present,the research on the ability to resist progressive collapse of building structures mainly focuses on the reinforced concrete structure,and rarely focuses on the prestressed structures.Compared with reinforced concrete frame structure,prestressed concrete frame structure has large span,heavy load and complex reinforcement,and its anti-progressive collapse behavior is not clear.In this paper,the capacity of resisting progressive collapse of prestressed frames was studied.The main contents of the research are as follows:(1)The reinforced concrete(RC),bonded prestressed concrete(BPC)and unbonded prestressed concrete(UPC)frame structures were designed by YJK software,and the economics of these three types of floor were compared and analyzed.The analysis shows that when the span and load are small,it is economical to use refinced concrete slabs.For buildings with a span greater than 12 m,large loads and higher requirements for deflection and cracks,it is economical to use prestressed concrete slabs.(2)The RC,BPC and UPC frameworks were established by MSC.Marc software,considering material and geometric nonlinearity,results of the software calculation were in good agreement with the experimental results.The correctness of the model is verified.(3)The force mechanism in the progressive collapse process of RC and PC frames was analyzed.The effects of reinforcement ratio,effective prestress,area and linear arrangement of prestressed tendon,span ratio on the first peak bearing capacity of PC frame during progressive collapse were studied.Finally,the capacity of resisting progressive collapse of different types of frames under the same design conditions was compared.The first peak bearing capacity of the PC frame is significantly lower than that of the RC frame.(4)Based on the Pulldown analysis of the prestressed concrete plane frame,the second kind of redundancy index is adopted to evaluate the robustness of the frame with different structure types,different column positions and different se ismic fortification intensities.