Research On The Mechanical Behavior Of Deconstructable Composite Beam And Beam-to-Column Joints Of Steel Structure In Full Life-Cycle

Facing up to the increasingly serious environmental pollution problems such as construction dust and construction waste in the process of urban construction,a novel sustainable building system is urgently needed.At present,prefabricated buildings have been widely applied in construction engineering,and its characteristics of prefabrication and on-site assembly may effectively solve the problems of construction dust that generated during the process of “constructing”.However,there are still problems dominated by extensive demolition in the deconstruction of buildings nowadays.Therefore,this paper focuses on the deconstructable steel-concrete composite structures with full-life cycle.From the structural type characteristics and mechanical properties,this paper comprehensively investigates the mechanical performance of deconstructable shear connectors,the flextural behavior of composite beams and the static as well as cyclic performance of deconstructable beam-to-column composite joints,and their fundamental mechanism is clarified by experimental,numerical and theoretical research,with design methods being proposed.The present work is of certain significance to the engineering industrialization of new green buildings in China.Following reseach works are maily carried out:（1）Three push-out tests are carried out on the shear connectors in new deconstructable steel-concrete composite beams.Their shear mechanism is clarified,and the calculation methods of the friction type shear capacity and bearing type shear capacity of this new shear connection are put forward.Then the mechanical constitutive model of the shear connection of deconstructable composite beams is proposed,with each parameter being determined.（2）Three bending tests of the deconstructable steel-concrete composite beams are carried out.Comparison of the test results with that calculated by flexural capacity and stiffness of composite beams specified in national standards is conducted.Based on the shear-slip constitutive of the deconstructable shear connectors proposed herein,a finite element model is established and validated.Furthermore,the mechanism of deconstructable composite shear connection is analyzed.The effects of shear connection degree influenced by different parameters on flexural capacity,stiffness and interface slip are discussed by parametric analyses,and the design suggestions of flexural capacity and stiffness of deconstrcutable composite beam are given.（3）Four static and seismic tests of decon strcutable steel-concrete composite beam-to-column joints are carried out.The finite element model of the joint is established,and the failure mechanism is studied.Based on the Chinese standard,the panel zone shear capacity,the end-plate bending capacity and the flexural capacity of at the composite beam section in positive and negative moment region of deconstrcutable beam-to-column composite joint are put forward in this paper,and hence the design suggestions of bending capacity in seismic design of deconstructable beam-to-column composite joints are given.Finally,suggestion for their configuration details are given.