Study On Mechanical Properties And Failure Mechanism Of PBL Shear Connectors Based On Steel-concrete Composite Beams

Steel-hybrid composite beams,taking into account the advantages of both steel and concrete structures,are more and more widely used in bridge projects and building structures,and are one of the main development directions of future structural systems in China.Perfobond Leiste(PBL)shear key is an important force transmission element to balance the rigidity of steel structure and reinforced concrete and to ensure the stability of their connection.The mechanical performance of PBL shear keys is one of the key influencing factors that affect the service life and reliability of steel-hybrid composite beam structures.The study of the damage mechanism and ultimate bearing capacity of PBL shear keys in steel-hybrid composite beam structures not only helps to improve the understanding of the force transmission mechanism and damage process,but also has important significance for practical engineering applications.This paper combines theoretical analysis and experimental research to analyze the damage morphology of steel fiber concrete PBL shear bond by establishing a finite element model.The load slip curve and damage morphology of PBL shear bond obtained from the simulation are consistent with the experimental results,and the factors influencing the shear bearing capacity of PBL shear bond are further analyzed based on finite element simulation.In addition,a Triangular Multistep Cuckoo Search Algorithm(TMCS)is proposed for the problem of the lack of universality of the current PBL shear load capacity calculation method,and a BP Neural Network(Back Propagation Neural Network,BPNN)is proposed for the problem of the lack of universality of the current PBL shear capacity calculation method.(BPNN)and Extreme Learning Machine(ELM)are optimized,and then TMCS-BPNN and TMCS-ELM prediction models are established to predict the ultimate load capacity of PBL shear keys with an average error of 2.16%.Finally,the functional functions of PBL shear keys were calculated according to the design requirements of steel-composite composite beams in the relevant codes,and the Monte Carlo(MC)method,Sequential Importance Sampling(SIS)method and Kriging agent model-based SIS(Kriging-SIS)method to calculate the reliability of PBL shear keys,comparing the number of function calls,the SIS method and Kriging-SIS method reduce 98%and 99.5%,respectively,compared with the MC method.In addition,the time-varying reliability analysis of PBL shear bonds according to the carbonation process of concrete and reinforcement showed that the failure probability showed a trend of decreasing and then increasing,and the failure probability reached 5.92% at 100 years of service.In summary,in this paper,experimental and finite element analyses were performed on the PBL shear key,and the effect of each design factor on the ultimate bearing capacity of the PBL shear key was obtained by extreme difference analysis based on the calculation results of the finite element model.In addition,TMCS-BPNN and TMCS-ELM models were constructed to predict the ultimate load carrying capacity of PBL shear keys.Finally,the reliability calculations of PBL shear keys based on MC,SIS and Kriging-SIS methods were compared based on the design requirements of steel-hybrid composite beams.