Test And FiniteElement Analysis Of Hysteretic Behavior Of Hexagonal Castellated Beam

Nowadays,most of the researches on castellated beams are based on static force.-These researches mainly focus on stiffness,strength,local stability and overall stability.However,the study of the effect of local repeated buckling of the web on ductility and energy dissipation capacity under cyclic load is rare.In order to study the influence of the local buckling of the web on the hysteretic behavior under cyclic load,three castellated beams with same web depth-thickness ratio but different opening ratio are designed.And two castellated beams with transverse stiffeners and the same opening ratio but different web depth-thickness ratio are designed.Based on theoretical analysis,experimental research and finite element simulation,the influence of different web depth-thickness ratio,different opening ratio and the different location of the transverse stiffener on the failure mode are studied.The local stability and hysteretic behavior of the castellated beams under cyclic loading are researched.The mechanism of stress migration,the development law of elastic-plastic deformation and the forming mechanism of plastic hinge are studied.Five different parameters of castellated beams were studied by quasi-static test.Based on the experiment,the finite element method was used to simulate the specimens and verify the accuracy of the finite element model.The analysis of different parameters is expanded with the finite element method.The results show that for the specimen with higher depth-thickness ratio,its carrying capacity,stiffness,energy dissipation capacity and ductility decreased.And the plastic development is not sufficient.With the decrease of web depth-thickness ratio,the carrying capacity,stiffness and energy dissipation capacity of specimen increase.As the depth-thickness ratio of the web has a certain correlation with width-thickness ratio of the flange,the ductility begins to decreased when the depth-thickness ratio of the web is more than 55.Under the same web depth-thickness ratio,when the opening ratio is small,the stress concentration of the pier plate is serious,and the local buckling is easy to occur,which leads to the rapid reduction of the carrying capacity,stiffness,energy dissipation capacity and ductility of the castellated beams;With the increase of opening ratio,the carrying capacity and stiffness of the specimen are reduced,while the energy dissipation capacity and ductility increased.But when the opening ratio exceeded 70%,the energy dissipation capacity and ductility began to decrease.For specimens with transverse stiffener at the pier plate position,due to the lateral constraint of transverse stiffeners,the effect of local buckling of the web is reduced.The failure mainly occurs in the location of holes.Compared with those without transverse stiffener,the hysteretic behavior of specimens with transverse stiffeners is improved significantly.Due to the different placement positions of transverse stiffeners,the failure modes of specimens change,and the hysteretic properties of castellated beams are greatly influenced,and the reasonable placement position of stiffeners can effectively improve the hysteretic behavior of castellated beams.According to the related research results,the limit value of the depth-thickness ratio and the opening ratio are put forward,and the reasonable placement position of stiffeners are determined,which will provide reference for engineering application.