Rsearch On Several Problems Of Reinforced Concrete Composite Component Reliability

The composite member has the advantages of good integrity,high degree of mechanization,convenient and rapid construction,which promotes the application of reinforced concrete composite member in the structure more and more widely.However,it is necessary to study and analyze the reliability before design and application of the composite component,in order to determine the key factors affecting the reliability of composite structures,but researched domestic and foreign literatures on the reliability are less.So this paper researched on the ultimate bearing capacity reliability and crack reliability of composite members.The mainly researched on the method of structural reliability analysis,reliability analysis of ultimate bearing capacity of concrete composite beams,reliability analysis on cracking width of reinforced concrete in serviceability limited state,specific contents as follows:（1）This article described several common structural reliability calculation method,a second moment method（center method,design checking point method,checking point JC method）,quadratic second ordered moment method,asymptotic integration method and Monte Carlo simulation method（direct sampling,importance sampling method）,compared the advantages and disadvantages,the scope of application of each calculation was determined.And the reliability of ultimate bearing capacity of concrete composite beams was calculated by JC method.The reliability of crack on concrete composite beams was calculated by Monte Carlo simulation method.（2）Using the MATLAB large numerical calculation software,the reliability of the bearing capacity of the composite member was calculated,which mainly considered two factors: the load ratio k of first stage and the second stage,the load effect ratio n.The results show that these two factors have great influence on the reliability of bearing capacity of the composite members,when k is 1.0,the bearing capacity is the highest,and the reliability is reduced from 1.0;With the increase of n,the reliability of bearing capacity decrease gradually.The influence factors of the reliability of the shear bearing capacity of the inclined section also included a factor: composite parameter α_h（the ratio of the height of the prefabricated interface h₁ and the height of the composite component h）.When composite parameters is about 0.7,the composite members shear capacity have maximum reliability,reliability decrease far from 0.7.Considering the influence of k and n on the reliability of bearing capacity of the composite members,the influence of k on the reliability of the bearing capacity is consistent with that of k alone;And the effect of n on its reliability is opposite to that of n alone,this is because when considering k and n,with n increased the reliability of the calculation of the selected load is reduced,resulting in increased reliability.（3）Monte Carlo simulation method was used to calculate the crack reliability of the composite before and after folding.The results show that the composite member of the crack reliability increase with the increasing of the live load;under the same conditions,after folding crack reliability is higher on average than that of before folding;crack reliability before and after folding relatively are close,and both low to be further improved.