Dynamic Effects In Progressive Collapse Of Steel Frame And Catenary Action Of Restrained Steel Beam

Due to frequent terrorist attacks on important buildings in some countries, how to design the structure reasonably to improve it's capability for resisting progressive collapse, has already become an important topic in the current anti-terrorist research. Dynamic effects, catenary action of restrained steel beam and ductility of the typical joint during progressive collapse after steel column failure of a steel structure are investigated in this paper. The main works are summarized as follows:(1) Study on dynamic effects following the column failure during progressive collapse, are carried out. The influences of the stories, spans, aspect ratio, column fuction loss position, joint rotational stiffness and space action on the dynamic effects are studied, which can be used as a basis for making a rational design code for structures during progressive collapse.(2) The finite element model of restrained steel beam under impact load is developed focusing on the forming process of catenry action, force mechanisms and failure mode. And the influences of the span, sectional dismension and constraint condition on the catenary action are also discussed.(3) Catenary action of constrained beam with typical connection under impact load is investigated. And Bearing capacity and ductility of constrainted beam with different connection types including dog-bone connection, bolted end-plate connection and T-stub connection are compared.(4) Two retrofit methods consisting of weld reinforcement method and lateral reinforcement method for bolted end-plate connection are put forward. And the retrofit mechanisms are analysed and the feasibility is verified by finite element mothod.(5) Ductility of constrained beam with different connection types are evaluated Using ductility factor. Connection ductility factor used to evaluate ductility of different connection types during progressive collapse following the column failure is also put forward, which can be used for the structure design during progressive collapse.