Research On Mechanical Behavior Of The Synthetically Reinforced Coupling Beams With Span-to-Depth Ratio 1.5<L/H?2.5

The seismic performance such as the ductility and the energy dissipation will be better if we add a set of composite diagonally reinforced coupling beams with the diagonal reinforcement and L reinforcement on the basis of small span-to-depth ratio coupling beams with conventional reinforcement. But there exists a big lack of understanding such as the force mechanism and the force analytical method of composite diagonally reinforced coupling beams with small span-to-depth-ratio under the seldom occurred horizontal earthquake action, along with the force condition of coupling beams under the interaction effect between the coupled shear wall limb and the coupling beams. On the basis of the test result analysis of five compositely diagonally reinforced coupling beams with span-to-depth ratio 1.5<L/h?2.5 and the finite element analysis of coupled shear walls, major research work and outcomes of this paper are listed below:(1) According to crack distribution characteristics of test specimen and analysis of stress and strain distribution of various types of steel, compositely reinforced coupling beams(CRCB) with span-to-depth ratio 1.5<L/h?2.5 is proposed. The CRCB comprises four categories of transfer model: diagonally reinforced truss model consists of two-way diagonal reinforcement, longitudinal reinforcement and diagonal concrete main strut; diamond reinforced truss model consists of bidirectional diamond reinforcement and secondary strut; beam end stirrup reinforced truss model consists of stirrups, secondary strut and main strut; beam span stirrup reinforced truss model consists of stirrups, secondary strut. Then, using joint working model with four types of transfer mechanism describes the force mechanism of CRCB with span-to-depth ratio 1.5<L/h?2.5.(2) Based on reasonable assumptions, a statically indeterminate strut-and-tie model of CRCB is established.28 formula are solved with geometric equations, deformation compatibility equations, physical equations and general equilibrium conditions at first. Then, stress analysis macro model program is written with FORTRAN language. Finally, the mechanical properties of coupling beams are reflected at all stages through the iterative program in detail, including strain of all kinds of steel and concrete.(3) Through the calculated and experimental results' comparative analysis of CX-1 program of 5 CRCB specimens, the effectiveness of the program was verified. Program screened proportion of bending and shear deformation in the coupling beam quantitatively. Besides, shear proportion was assumed by various shear mechanisms, Failure modes of the coupling beams were simulated successfully at last.(4) Three 12-story frame- shear wall structure examples with span-to-depth ratio of 1.5 and 2.0 and pier length of 3.0m and 3.6m respectively were designed. The influence of coupling beam stiffness reduction coefficient on CRCB and pier internal force was researched with SATWE.(5) Y-direction coupled shear wall of two 7-story shear wall structure with pier length of 3.6m and 4.5m and span-to-depth ratio of 2.0 under three seismic waves were analyzed with ABAQUS. What's more, the factors of interaction of coupling beam and pier, pier deformation difference on the mechanical properties of compositely reinforced coupling beams with small span-to-depth ratio were researched. Considering more actual stress conditions, ductility capacity and ductility demand of compositely reinforced coupling beams with small span-to-depth ratio in the coupled beam were analyzed at last.