Study On Mechanical Properties Of Non-prismatic Composite Girder With Corrugated Steel Webs

As a new type of steel-concrete structure,the composite girder with corrugated steel webs(CSWs),which have been widely used in the construction of modern bridges,can bring strength of each material itself into full play.The existing design of composite girder bridge with CSWs is only for prismatic structures.Under the influence of variable depth,the basic mechanical behavior of non-prismatic composite girder with CSWs differs remarkably from that of the prismatic cases.Accordingly,the traditional calculation assumption may be no longer suitable for the nonprismatic composite girder with CSWs.Thus,a study on shear effect,restrained torsion and nonlinear buckling of non-prismatic composite girder with CSWs is carried out based on theoretical analysis,experimental testing and numerical simulation.(1)The study verifies Resal effect of non-prismatic composite girders with CSWs,which is the major factor that contributes to significant differences in the basic mechanical behavior between prismatic and nonprismatic composite girders with CSWs.Then a practical theoretical formula for calculating shear stress of non-prismatic girders with CSWs is proposed by considering Resal effect.By comparing the theoretical results with both the experimental data and finite element simulation results,the correctness of proposed formula is verified and the traditional calculation assumption cannot be applied to the shear stress calculation of nonprismatic composite girders with CSWs.(2)Based on Umansky’s second theory,differential equations of restrained torsion with variable coefficients are deduced by difference method,thereby obtaining the calculation of restrained torsional stress of non-prismatic composite girder with CSWs.Numerical analysis shows that this method has high precision,and the influence of discretization of girder on the calculation accuracy is analyzed quantitatively.(3)Considering the influence of materials,geometric nonlinearity and initial defects,the whole loading process of non-prismatic girder with CSW is simulated from linear elastic deformation to inelastic instability.Numerical analysis shows three stages from elastic deformation to buckling failure,buckling modes and buckling load of structure.It is proposed that non-prismatic girder with CSW under uniform loading are expected to achieve a higher strength-to-weight ratio compared with prismatic case due to the influence of Resal effect.