Flexural Performance Of New Type Partially Steel Encased Concrete Composite Beam

The new partially steel encased concrete composite beam is a new type of composite flexural member formed by partially I-steel encased concrete composite beam.The beam has the characteristics of high bearing capacity,high rigidity,convenient construction,industrial production,and excellent comprehensive economic indicators.It is a new composite beam component with good application prospects.In this thesis,the flexural behaviour of steel encased concrete composite beams is systematically studied by means of experiment,and Finite Element Analysis.The mechanical behaviour of a new composite beam is studied by the static test of three new encased concrete composite beams with full-scale specimens.The failure mode,load-deflection curve,load-strain curve,and the strain distribution along the section height were analyzed.While,the stress-deformation characteristics and failure mechanism of the new partially steel encased composite beam were clarified,which can provide experimental data for further software analysis.By using the large-scale finite element analysis software,the nonlinear analysis model of the specimen was established.The four parameters used in this study were changed accordingly.These parameters are the thickness and strength of the concrete,the strength of the steel cross-section,as well as the thickness of the steel cross-section web.The influence of the new composite beam on the flexural capacity and deformation of the cross-section is investigated.The results of this study show that the new composite beam has higher bearing capacity and has good ductility and is not prone to brittle fracture failure,which is equivalent to the failure of the normal composite beam.Moreover,The strain along the section height of the new composite beam was also linearly distributed,which confirms the plane section assumption.The comparison between the experimental and FE results indicates that the finite element models established in this research were reasonable and can reflect the flexural behaviour of the composite beam accurately.Therefore,FE parametric investigation based on the validated FE models was carried out to study the influence of different parameters on the flexural behavior of the new composite beam.The results of the parametric study show that the increase of concrete strength has a small effect on the initial stiffness,ductility,and load bearing capacity of the new composite beam while the steel grade and web thickness have little effects on the initial stiffness and play a major role on the load bearing capacity of the new composite beam.