Study On Seismic Behavior And Design Of Replaceable Steel Coupling Beams With RC Slabs

The replaceable steel coupling beam(RSCB)is an innovative energy-dissipating structural component,which can enhance the seismic resiliency of high-rise buildings.Through experiments and numerical analysis,this thesis investigated the link overstrength,studied the seismic performance of RSCB with reinforced concrete(RC)slab,and proposed the design methods and fragility curves used for performance assessment of the RSCBs as well.Finite element analysis(FEA)was conducted to investigate the overstrength of “fuse” shear link.Five FE models of shear links with various length ratios were built using Abaqus 6.10 program.Analysis results indicate that the large overstrength generated in short shear links is attributed to the contribution of flanges and cyclic hardening of web steel.For the shear link with smaller length ratio,the flanges can provide larger shear contribution.For the shear links with length ratio less than 1.0,the shear contribution of flanges could be over 15%.The cyclic hardening of web steel could increase the shear strength by 65%-75%.Quasi-static tests were conducted on five specimens to examine the seismic behavior and damage of the RSCBs with RC slabs.Four different types of RC slabs were adopted,including the composite slab,bearing slab,elevated slab and slotted slab.The test results indicate that the presence of RC slabs provides very limited contribution to the shear strength and inelastic deformation capacity of the RSCBs.RC slabs increase the initial elastic stiffness of RSCBs,while they have no influence on the stiffness of RSCBs in plastic stage.The composite slab suffered most significant damage,as a result of pulling out of shear studs and followed pouching failure of the slab,thus shear connectors are not recommended between the RSCB and RC slab.No severe concrete crushing was observed in the bearing slab and slotted slab,while a large number of cracks occurred.By full separating from the RSCB,The elevated slab had much fewer cracks with relatively smaller width,which enable an easy repair compared with other types of slabs.Based on the existing researches,this thesis proposes the design method,procedure and recommendations of RSCBs.Following the capacity design philosophy,the strengthes of the beam segments and shear link are appropriately proportioned so that inelastic deformation and damage are concentrated in the shear link during a severe earthquake.The formulas used to calculate the strength of both components are presented.To allow easy replacement for the shear link after being damaged,this thesis suggests two types of specialized link-to-beam connections,i.e.,the end plate connection and splice plate connection,and provides their design methods.In order to mitigate the damage of the RC slab and the beam-to-wall connection,two types of RC slabs and embedded beam-to-wall connection are recommended with the associated design requirements and details.In addition,this thesis presents the analytical model and parameters for RSCBs,which are able to use in the nonlinear analysis of the entire structure.The fragility curves of RSCBs at various damage states are developed as well,which provide fundamental fragility data for the performance-based design and assessment of RSCBs.