管片-型钢-混凝土组合梁承载性能及优化设计研究OA

[Objective]For station structures in large-section underground spaces constructed by mechanized methods,the composite beams formed by segments and cast-in-situ continuous longitudinal beams play a crucial role in load-bearing.Therefore,it is necessary to investigate the load-bearing performance of such composite beam structures.[Methods]An experimental component of the segment-steel-concrete(SSC)composite beam was designed.On this basis,static loading tests were conducted under two working scenarios,the mid-span positive bending moment region and beam-column joint negative bending moment region,to study the load-bearing capacity of SSC composite beams.Additionally,a three-dimensional refined model of the composite beam was established through numerical simulations to further examine the effects of interface shear studs and the positions of continuous beam steel on the load-bearing capacity.[Results](1)The stress process of SSC composite beams could be divided into four stages,including elastic stage,elastoplastic stage,plastic stage,and failure stage.(2)Under positive bending moment conditions,the failure mode of SSC composite beams exhibited bending-shear failure,whereas under negative bending moment conditions,the failure mode presented pure bending failure.(3)Under bending conditions,the shear studs at the interface of SSC composite beams were prone to shear failure.Increasing the number of shear studs effectively improved the ultimate load-bearing capacity under positive bending.(4)Positioning the steel closer to the longitudinal bars at the bottom of continuous beams improved the ultimate load-bearing capacity of SSC composite beams under positive bending moment conditions,but reduced this capacity under negative bending moment conditions.[Conclusion]The research findings can provide theoretical guidance for the design of composite beam structures in large-section metro stations using mechanized methods.