Experimental Study On Seismic Behavior Of Frame-supported Short-leg Shearwall Structure With Haunched Transfer Beam

At present, transfer beam finds a wide application as the transfer structure in high-rise buildings. As far as the load transferring mode of the structure is concerned, transfer beam has many advantages such as clear and direct load transferring path. However, transfer beam has also many disadvantages such as low headroom caused by great depth of beam, such as strong beam and weak column phenomenon caused by great stiffness of the beam, such as construction difficult caused by too dense steel bars in the support, such as uneconomical cost caused by great deadweight of the beam itself, and so on. In actual structural design, section dimensions of the transfer beam are at the mercy of bearing capacity for shear. It requires more great bearing capacity for shear in the support than in the mid-span of a transfer beam, and so it is unreasonable that a prismatic beam be adopted in design. If a way to reinforcing the bearing capacity for shear in the support can be found, section dimensions of the transfer beam will be diminished so as to make up the inborn deficiency of the transfer beam. Based on the idea above, this paper propounds a frame-supported short-leg shearwall structure model, which adopts haunched transfer beam. In this paper, experiments on the two model specimens subject to vertical load and horizontal cyclic load have been carried out. In the experiments, the cracking load, the yield load and the development of cracks are observed and recorded; the crack width, the story sway and the strain development of steel bars and stirrups in the transfer beam are measured and recorded; the breakage status, the breaking load and the failure mode are studied and recorded. Then, many analyses are all completed including load-displacement hysteretic loops analysis, structural bearing capacity attenuation analysis, structural elastic-plastic deformation analysis, structural ductility analysis, structural energy dissipation capability analysis, structural stiffness attenuation analysis, breakage characteristic analysis, and strain analysis of steel bars. According to the results of the analyses, the seismic behaviors of this model can be revealed and be assessed. Based on the experimental study, a comparison is made between the results of experiments and the results of nonlinear FEA using ANSYS about frame-supported short-leg shearwall structure with haunched transfer beam subject to vertical load and horizontal cyclic load. The comparison contains appearing and development of crack and crush of concrete, stress distribution in the concrete of the transfer beam and in the short-leg shearwall, steel bar stress in the transfer beam and the short-leg shearwall and the frame-supported columns. The reliability of the application of ANSYS on complex RC model is evaluated. Then parameters such as the depth of haunch of the transfer beam are changed for further analysis whose purpose is to find how and to which degree the change of the parameters influences the mechanical behavior of the structure.