Reliability Analysis Of Ultimate Bearing Capacity Of Recycle Aggregate Concrete Filled Steel Tubular Axial Compression Short Column Based On Stochastic Constitutive Model

The rational utilization of recycled aggregate concrete is not only of certain economic value,but also of great social significance.Recycle aggregate concrete filled steel tubular stub column(RACFST)refers to composite components which formed by pouring recycle aggregate concrete into steel tube.Recycling of recycled concrete caters to the requirements of sustainable development.Compared with steel reinforced concrete members with the same amount of steel and sectional areas,RACFST possess higher bearing capacity,better ductility,construction more convenient and many other advantages.Some achievements have been made in the study of the mechanical properties of RACFST members,however,its reliability research still in infancy and lack of normative guidance.It is a vital issue that whether RACFST members can accomplish the scheduled function under specified condition within service life.Based on this,the current paper mainly undertook some research about the reliability of RACFST members.1.A series of 3-D nonlinear finite element models were established by using universal FEA software ABAQUS.Based on three types of RAC constitutive models,the whole process response of RACFST members were simulated,respectively.Furthermore,the numerical simulations were compared with the test result as well.The precision of three constitutive models were discussed through the aspects of bearing capacity,axial stiffness and energy dissipation ability.2.Statistical analysis of RAC members compressive strength were carry out.Meanwhile the distribution parameters were obtained.Based on unified theory constitutive model,the stochastic constitutive model of RACFSTwere established which considering the random distribution of relevant parameters.3.The resistance function was adopted via the expression of the peak stress of stochastic constitutive.The resistance partial safety factor was determined by Target Reliability Method.On this basis,RACFST members reliability index were compared by First Order Reliability Method(FORM),Monte Carlo Direct Sampling Method(MCS)and Monte Carlo Importance Sampling Method(IS),respectively.Through the use of JC method,the influence of RAC compressive strength,steel tube strength,diameter,thickness,steel ratio,hoop coefficient,replacement ratio and variable load type on RACFST reliability index wasconsidered.The influence of the reliability index on the sensitivity of random variables,mean and standard deviation is discussed.4.By using the least square method of resistance,the partial load factor of RACFST members was given while the proportion of variable load effect relatively high.It can be concluded that the proposed stochastic model can be applied to describe the discreteness of RACFST mechanical properties and the discreteness reductionof core concrete because of the confined effect.Meanwhile,the expression of peak stress function can be used to analyze the ultimate bearing capacity of RACFST.The suggested partial load factor can satisfy the RACFST components reliability requirement when the load effect is relatively high.