Experimental Study And Refined Numerical Simulation On Crumb Rubber Concrete-steel Composite Beam

Crumb rubber concrete is a new type of concrete using crumb rubber as a composition of cement concrete materials.In addition to the environmental-friendly character,its superior deformability,fatigue property,crack resistance,excellent durability,vibration and noise reduction properties create great advantages on its application of highway engineering.Crumb rubber concrete was introduced into steel-concrete composite beams to replace traditional concrete slab in this paper,which made up the gap of crumb rubber concrete's narrow application and it can reduce the fatigue failure of the upper concrete slab to some extent.However,this paper mainly aims at using the strong deformability and superior anti-fatigue property of crumb rubber concrete to improve the ductility and fatigue lives of stud shear connectors and traditional composite beams.“Crumb Rubber Concrete and Steel Composite Beams” is the main object studied in this paper.Experimental study and refined numerical simulation are used to investigate the static and the fatigue behavior of stud shear connectors and also the new type of composite beam:1)Based on the material properties testing of crumb rubber concrete,18 push-out tests were conducted to study the static behavior of single shear stud embedded in crumb rubber concrete.Four different crumb rubber contents,two compressive strengths and two stud diameters were taken as variable parameters.The bearing capacity,ultimate slip,shear stiffness and ductility of single shear stud were studied systematically and compared with several national codes.Finally,the optimum efficiency of rubber content was found and the improvement of the stud's ductility was studied.2)Based on the static research of single shear stud,the crumb rubber concrete and steel composite beam static tests were conducted.The failure modes,bearing capacities,the location of the neutral axis,the ductility and stiffness of the normal concrete composite beams and crumb rubber concrete with the optimum rubber content composite beams were compared through 3 specimens.Moreover,two different degrees of shear connection of composite beams were studied.The test results showed that using crumb rubber concrete can improve the deformability and ductility of composite beams.3)The static behaviors of single stud and the whole composite beams were simulated numerically through refined FEM in ABAQUS.The nonlinear material properties,damage plasticity models of concrete and the reasonable contact algorithms were considered in the numerical modeling.The reliability of the numerical analysis was verified based on the experimental results and an extensive parametric study was conducted for concerning effects of different rubber contents and stud dimensions.Furthermore,the stress mechanism of single shear stud in push-out test was proposed and the fatal position of welding defect was discussed.In addition,the effects of different shear connections and welding defects on the whole composite beams were studied systematically in the numerical study.4)Nine fatigue push-out tests were conducted based on the static ones.Three different rubber contents of concrete,different stress amplitudes and diameters of studs were adopted as main variable parameters.The fatigue lives,ultimate fatigue slips and the fatigue stiffness of stud were studied.The results showed that with the increasing rubber content of crumb rubber concrete,the fatigue properties of stud improved.Through comparison between test results and three national codes,the current national codes can still apply to shear studs embedded in crumb rubber concrete.5)The last part of experimental study was the fatigue testing of composite beams.The parameters were the same as the static ones.The differences of fatigue failure between ordinary concrete and crumb rubber concrete composite beams were studied.The standard of fatigue failure,the fatigue deformation and deflection were analyzed.The test results found that using both crumb rubber concrete and high degree of shear connection were beneficial to increase the fatigue lives of composite beams.6)In the end,the fatigue lives of single shear stud and the whole composite beams were simulated using eXtended Finite Element Method(XFEM),including the process of crack initiation to failure.Furthermore,the S-N curve of stud was obtained based on the simulation results and the fatigue lives of the composite beams was calculated.The simulation results were compared with the test ones and the national codes.It can be concluded that the XFEM has strong ability of crack simulation with easy calculations and accurate results.Thus,it can be used in analyzing this kind of fracture problems.