| Partially-encased Composite Open-web beam is a new type of composite structure with more advantages based on Partially-encased Composite beam.The characteristics of this structure are that some webs are dug out on the basis of the Partially-encased Composite beam,with internal connecting rods to connect the upper and lower flange of the steel and anti-cracking bars,and filling the abdomen with concrete so that it can work together with the steel.In practical application,Partially-encased Composite Open-web beam has many advantages,not only has high flexural capacity,good ductility and fire resistance and corrosion resistance,but also can realize factory prefabricated and field assembly construction,in addition,Partially-encased Composite Open-web beam can make concrete pouring at one time,so as to shorten the processing cycle,and less steel makes the structure towards more lightweight and economic direction,it is a new type of steel-concrete composite structure with good prospects.In this paper,Partially-encased Composite Open-web beams are tested and studied,and two kinds of best construction methods are selected from them.On this basis,the flexural performance tests and theoretical studies are carried out.The main research contents are as follows:(1)Four-point flexure tests were carried out on five kinds of Partially-encased Composite Open-web beam(steel-bars truss beam,π-shaped truss beam,angle steel truss beam,open-web truss beam and castellated truss beam),By observing and analyzing the failure phenomenon,load-deformation curve,strain development of concrete,strain development of steel,ductility,flexural capacity and other mechanical indexes of five kinds of Partially-encased Composite Open-web beam,two optimal construction methods of steel-bars truss beam and π-shaped truss beam were selected,and the flexural performance was studied on this basis.(2)Four-point flexure tests of steel-bars truss beam and π-shaped truss beam were carried out to study the influence of section height,flange thickness and web opening rate on the flexural performance of Partially-encased Composite Open-web beam by failure phenomenon,load-deformation curve,strain development of concrete,strain development of steel,steel and concrete slip and crack width.The test results show that the flexural bearing capacity and stiffness of the beam increase with the increase of Partially-encased Composite Open-web beam section height and flange thickness,the influence of section height is more obvious.The web opening ratio has little effect on the flexural capacity and stiffness of beams.(3)ABAQUS finite element analysis software was used to analyze the flexural performance of steel-bars truss beam and π-shaped truss beam,and the simulation results are compared with the test results to verify the rationality of the finite element model.Based on this model,the influence of concrete strength、steel strength and web thickness on the flexural bearing capacity of beams are investigated to broaden and supplement the tests.(4)Based on the full-section plastic criterion,the flexural bearing capacity formulas of steel-bars truss beam and π-shaped truss beam are derived,and the ultimate bearing capacity is tested for comparison to verify the rationality of the formulas.The flexural stiffness and deflection of the beams are calculated on the basis of the reduced stiffness averaging method and compared with the actual value of the test. |
