Experimental Study On Seismic Behaviors Of The Haunched Beam Transfer Structures With Varied Axial Compression Ratio Of Frame-supported Shearwall

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.Through quasi-static experiments on four haunched beam transfer short-leg shearwall structure specimens respectively with the axial compression ratio of wall-leg ranged from 0.15, 0.20, 0.25 to 0.30 under the vertical load and horizontal cyclic load, this paper made a comparative analysis on the results of the haunched beam transfer short-leg shearwall structure with different ratio of section height to section thickness of wall-leg, the macro-phenomenon in the whole course of the experiment, and stress distribution of all the parts as well, reached the conclusion that the ratio of section height to section thickness of wall-leg variations influences mechanical behavior of haunched transfer beam.The experiment and results of analysis researched the stress mechanics, bearing capacity, damage shape, damage mechanism, hysteretic characteristics, distortion ability and ductility factor of the transfer structure under vertical load and horizontal load, and the seismic behavior of the haunched beam transfer frame-supported short-leg shearwall structure under vertical and horizontal load. Rational design suggestions and constructional requirements are proposed to the application of this structure in practical projects.The results of the experiment revealed that the haunched beam transfer frame-supported short-leg shearwall structure has a good yield and damage mechanic, and the rationally designed frame-supported short-leg shearwall structure has a good seismic behavior. This sort of structure has a full hysteretic circle of the hysteretic loops, good ductility nature and dissipation ability, with a uniform distributed rigidity and a stable deformation nature for each layer in elastic and elastic-plastic deformation. Along with the ratio of axial compression being enhanced, the bearing capacity of the structure is enhanced a little, but the ductility nature is noticeable reduced. So dominating the axial compression ratio of the short-leg shearwall is essential.