Experimental Study On Small-Span-to-Depth-Ratio Coupling Beams With New Reinforce Scheme And Design Method

Coupled walls or coupled core-walls are primary elements of the lateral resisting systems in the RC high-rise structure. Coupling beams combining two coupled walls not only influence the lateral stiffness of the coupled walls, the moment to axial force ratio and the moment to shear ratio of the single wall by span-to-depth ratio, but also are the primarily energy dissipating elements in the coupled walls under severe earthquake. Coupling beams play a key role in improving seismic resistance behavior. According to the practical structure, small-span-to-depth-ratio coupling beams are adopted in the design. It is proved by the test outcome in home and abroad that the shear failure happening early cannot be avoided and the ductility cannot be satisfied if the coupling beams are designed with the conventional method of frame beams. In recent years, the effective design method that small-span-to-depth-ratio coupling beams in coupled walls improve seismic resistance behavior is discussed in home and abroad. In the code for design of reinforced concrete high—rise structure (JGJ32002), although, active method that the shear-compression of small-span-to-depth-ratio coupling beams is strictly controlled and amount of ties are increased, is mentioned, that method need to be perfected because of strict shear-compression control and small displace ductility. Since 1999, the advice on new reinforcement scheme of small-span-to-depth-ratio coupling beams, i.e. adding diagonal bars and rhombic inclined bars on the basis of traditional reinforcement, have been given. By the experiment of 20 specimens,well seismic resistance behavior and project applicability of new reinforcement scheme have been proved.In order to perfecting this research, the main study work of this thesis is as following:1. Complete 5~6 tests of coupling beams with span-to-depth ratio of 2.0~2.5 under low-cyclic repeated loads in order to research:1) Seismic resistance behavior of coupling beams with new reinforcement scheme.2) Seismic resistance behavior of conventional reinforcement scheme of coupling beams with span-to-depth ratio of 2.5 in the range of various shear compression.2. Complete analysis, summarization and evaluation of completed small-span-to-depth-ratio specimens with new reinforcement scheme;3. Present integrated design advice of small-span-to-depth-ratio coupling beams with new reinforcement scheme.