Experimental Investigation On Collapse Performance Of RC Frames Using External Prestressing Tendons

Major accidents that have taken place in recent years,have shown that progressive collapse is the important reason for the collapse of structure.The progressive collapse in the event of an earthquake,terrorist attack or fire will result in serious economic losses,casualties and adverse social impacts.Therefore,the study on the mechanism of progressive collapse and the ultimate resistance to collapse has become an important research topic.The research mainly focuses on the reinforced concrete(RC)structure,but the research on RC frames using external prestressing tendons is nearly empty.This thesis was based on the National Natural Science Foundation of China project"Study on progressive collapse behavior of RC frame structures using external prestressing t endons "("No.51308556").Pseudo-static tests of single-story RC frames using external prestressing tendons were carried out to study the axial constant,extemal prestressing,and prestressed tendons arrangement on influence on collapse performance.The main conclusions are as follows:(1)External prestressing tendons can improve cracking load,the peak load of arch stage and ultimate load of catenary stage.(2)When restraint is weak,collapse resistance of RC frame with external prestressing tendons decreases with the increase of vertical displacement.(3)The "catenary action" of the external prestressed tendon can directly increase the collapse resistance of the frame.The horizontal component can strengthen the flexural bearing capacity of frame structure.(4)The straight-through arrangement and the fold line arrangement of external prestressing tendons can both increase the collapse resistance of the frame structure,and the later one more efficient,the ultimate collapse resistance of the catenary line stage is mainly provided by the external prestressing tendons.(5)The straight-through arrangement of external prestressing tendons can increase the collapse ultimate deformation ability of the frame,and its collapse ultimate deformation is about 1.5 times that of the RC frame.(6)A formula for the calculating ultimate load of RC frames using external prestressing tendons was derived,which can be used to estimate ultimate bearing capacity of the catenary action.