Simulation Of The Bending Behaviors Of Reinforced SFRELC T-Beams By Nonlinear Finite Element Method

Steel fiber reinforced expanded-shale lightweight concrete(SFRELC)has the advantages of light weight,strong tensile capacity,good thermal insulation effect and good ductility under compressive.It is suitable for large span and tall building structures and it has been gradually applied in engineering structures.However,the finite element simulation analysis of SFRELC components needs to be further studied.Numerical simulation by nonlinear finite-element(FE)is widely used in the field of civil engineering.For both linear and non-linear materials,their material properties can be well simulated by FE models.The advantage of FE simulation is that the force situation of each part of the structure can be calculated in detail,and the structure's force can be analyzed to predict the weak position of the structure.Popularizing the application of FE numerical simulation in structure can reduce the waste of resources and time caused by real experiments,which is the trend of structural analysis in recent years.This dissertation mainly focuses on the non-convergent issue of nonlinear FE analyses.The elastic and elasto-plastic properties of five steel fiber reinforced expanded-shale lightweight concrete(SFRELC)T type beams with different steel fiber volume ratios(0%,0.5%,1.0%,1.5%,and 2.0%)were studied by virtual-test.The main work done in this dissertation includes:(1)The 50 mm for FE dimension was selected to match the actual crack spacing.The loading by displacement was applied to perform the complete loading procedure,and was divided by the linear elastic part and plastic part of materials.The elastic portion was converged well,and the load step is refined in order to obtain the precise cracking moment.The Newton-Raphson method was used to help convergence.The convergence tolerance was enlarged but lower than 0.1 in order to prove the accuracy,and the loading substeps was adjusted in the plastic portion to ensure the convergence of the nonlinear portion.(2)The finite element software ANSYS was used in this dissertation.With the rational constitutive models of SFRELC,steel bars and their bond-slip,the numerical results of reinforced SFRELC T-beams are obtained including the cracking moment and bearing capacity,the strains and the stress of SFRELC and steel bar and the complete load-deflection curve and ductility.Meanwhile,the total width of cracks is computed by using the displacement difference between the longitude rebar and the SFRELC along the barycenter of longitude rebar.The adaptability of the numerical model was confirmed by the comparison of experimental results of five reinforced SFRELC T-beams with a varying volume fraction of steel fiber.This provides a feasible and reliable method for the virtual-test by using the nonlinear finite-element analyses to investigate the complete bending performance of reinforced SFRELC T-beams.(3)The over-reinforcement SFRELC T-beams were simulated.The damage of the over-reinforcement was analyzed from the deflection-bending moment curves and ductility and crack width.The study has shown that the maximum reinforcement ratio of the SFRELC T-beam was increased with the increase of volume ratio of steel fibers.(4)The under-reinforcement SFRELC T-beams were analyzed by FE simulation combined with the reinforcement stress calculation.The study has shown that the minimum reinforcement ratio of the SFRELC T-beam was decreased with the increase of volume ratio of steel fibers.