Experimental Research On Overall Stability Behavior Of Castellated I-beam With A Rectangular Concrete-filled Steel Tube Top Flange

Based on the I-Beams with Top Flange of Rectangular Concrete-filled Steel tube,castellated beam was formed by opening hole in the original web.From the perspective of material,the tensile strength of steel and compress strength of concrete was fully used in this new component,because steel and concrete in this new component can work together.Meanwhile,this component has the advantages of high bearing capacity and high stiffness and good ductility and steel-saved.From the component form,it not only can reach the requirement of structure function,but also has the advantages of economy and beauty.In this paper,three castellated I-Beams with Top Flange of Rectangular Concrete-filled Steel tube were designed and made.Experiment on Global Stability of CFSFCB with concentrated load at middle span was executed.From the experimental phenomenon,instability with global eccentric compression CFSFCB-1,global instability happens to CFSFCB-2,distortional buckling happens to CFSFCB-3.Meanwhile,top flange of CFSFCB-3happens local buckling during the process of experiment.Displacement in and outer plane,dip of top and bottom Flange,dip of both sides of web,strain of solid web and strain around the hole were measured and analyzed.The form of instability to this component was judged by the phenomenon and displacement and angle of experiment.The strain distribution of solid web and the stress distribution of web around the hole are analyzed.Initial defects of three castellated I-beams with top flange of rectangular concrete-filled steel tube were measured.The finite model with true initial defects was established by method of reverse modeling.MATLAB and AUTOCAD and Pro/Engineer and ANSYS were used to establish.The results of numerical simulation were same to it of the test.Meanwhile,the results of numerical were same to it of the model with initial defects of eigenvalue buckling first mode L/1000 time deformation.The influence of concrete strength and steel strength on the bearing capacity of stability of castellated I-beams with top flange of rectangular concrete-filled steel tube was studied by the finite software ANSYS.