Study On The Shear Lag Effects In PC Box Girders

Many researchers have made quite extensive and in-depth investigations onshear lag effects in concrete box girders and have achieved many good results.However, with the ever-increasing width of the box girder employed in bridge,nonlinear effects become more and more prominent,and therefore shear lageffects need to be further addressed. Considering the nonlinear constitutiverelations of materials and with the help of ANSYS, this paper analyzes thedevelopment of shear lag effects in whole process of the box girder experiencingdeformations from linear-elastic stage, nonlinear stage till to the destructionstage, with the load applied step by step. Then results obtained at each stage arecompared to observe the variation of the shear lag with the repect to theload-grades. The major works and conclusions are as follows:(1) A comprehensive review is given to the concepts of shear lag effects,shear-lag coefficient and effective distribution width. Also, a comprehensivereview about the state-of art of shear lag effects is presented, including bothdomestic and abroad status.(2) A detailed introduction is given as to nonlinear finite element theory ofprestressed concrete box girder, constitutive models of the concrete and prestre-ssed tendons, as well as modeling-building method of prestressed concretestructures. Also introduced is the analytical method employed in this paper,including constitutive models of concrete, reinforcements, and FE-modelingmethod.(3) Based on the linear-elastic assumption of the constitutive relation ofmaterials, chapter3probes into the distribution of shear lag effects in thespecified model under different loads, and made the comparative analysis of thecorresponding computational result.(4) Chpter4mainly probes into the distribution of shear lag effects in thespecified model when the constitutive relations of materials are nonlinearelasticity, with different load forms considered in the whole process form linear,nonlinear,to destruction. Numerical results show that considering nonlinearconstitutive relationship of materials shear lag effects in the structure changesalong with the structure at the different force stages. Based on the calculatedresults, several comparisions are performed as to shear lag effects under different load-forms, different stages of loading, and different constitutiverelations. Further, the distribution of shear lag coefficients across the girdersections is summarized with respect to different load-forms and constitutiverelations.(5) Chpter5summarizes the main research results and outlook of shear lageffects in box girders.