The Flexural Behavior Study Of Steel-Concrete Composite Continuous Slab

Composite slab has a lot of advantages.The bottom steel plate can works as formwork for the concrete work which saves a significant amount of time.Steel-Concrete Composite Slab is a new-type of composite slab consisting of bottom steel plate and top concrete connected by the shear connectors like stud,perfobond rib connector or any other types of shear connectors which help to behave as a single component together,resulting higher flexural stiffness,bearing capacity,ductility,and better performance than that of ordinary reinforced concrete slab.In order to study the flexural behavior and the mechanical properties of steel-concrete continuous composite slab,static loading test of six specimens including one simply supported composite slab with stud connector,two continuous composite slab with stud at different spacing and three continuous composite slab with different number of PBL shear connector.During the test process,the failure modes,strain development on steel plate,longitudinal rebars and the concrete,deflection at different points,interface slippage,types of cracking and the bearing capacity are considered.The finite element model of six specimens was established using the software ABAQUS,considering geometric nonlinearity and material nonlinearity for the in-depth study of continuous composite slab and the result was verified with the test which were in good agreement.On the basis of FE calculation,some parameters such as concrete grade,concrete depth,steel plate thickness and PBL thickness are chosen for the further analysis of steel-concrete continuous composite slab with stud and PBL shear connector and the following conclusions were obtained for further engineering application.(1)For steel-concrete composite slabs,subjected to four-point static load,all the six specimens with longitudinal and transverse reinforcement and either stud or PBL shear connectors arranged along the span basically showed three stages in the whole loading process: linear elastic stage,elasticplastic stage and plastic stage.After reaching the ultimate load,in CSS-3 and CSP-1,there was a downward softening stage whereas in remaining specimens the plastic stage continues for long time.(2)Among the six specimens,CSP-1 specimen with PBL shear connector had relative large stiffness and ultimate load-carrying capacity than with stud.In addition,the test results indicate that the stud specimens exhibit better mechanical behavior than PBLs with regard to the initial cracking of the concrete slab.But overall,both PBL and stud were effective shear connectors for composite slabs.(3)From the finite element analysis using ABAQUS software,both elastic,inelastic and ultimate stages of the continuous composite slab were predicted accurately.And from these behavior,it concluded that the use of composite slab can enhance the mechanical properties of concrete which is further verified by the FE model analysis.(4)The influence of various parameters on the bearing capacity of composite slabs is analyzed in detail by using the finite element analysis method: with the increase of concrete grade,the bearing capacity of composite slabs increases.The bearing capacity tends to be stable with the increase of the thickness of concrete slabs at certain stage due to increment of self-weight both specimen with stud and PBL shear connectors.In CSP-1,it is seen that PBL thickness has greater significant influence than the thickness of bottom steel plate.Thus,according to the actual needs,it suggests to use appropriate thickness of bottom steel plate and PBL thickness.(5)From the results of experiment and finite element calculation,a simplified flexural calculation method of continuous composite slab with PBL and stud shear connector were proposed and the results were agreed with acceptable errors with experiment results for CSS-1 and CSP-1 at yield stage but did not satisfied for remaining specimens because it was assumed that the connection was full shear which was not occurred in remaining four specimens due to slip.Also at ultimate stage the variation error increases more.So,further detail study should be done on it.