| Short-limbed wall (SLW) is defined as the shear wall with a ratio of section depth to width (RDW) being 5-8. Usually, the section width is 200-250 mm, and the depth is between 1 000 and 2 500 mm. It is an intergradation structure style between erose-section-column frame and conventional shear wall structure. Because of versatile advantages on architecture and structure mechanism, it has become the most important structure form for residence projects with fewer than 25 stories. However, even the newly promulgated National Code on Reinforced Concrete Structure gives no items on SLW design, and no previous horizontal cyclic loading tests on SLW structure has ever been published domestic or oversea. Till now, the failure mode, energy dissipating property and internal force distribution status in SLW structures are still unknown. The horizontal cyclic loading experiments on SLW are the first of their kind accomplished in China, and consequent nonlinear Finite Element Method (FEM) analysis complements the experiment results on internal force distribution. Based on strain distribution acquired in experiment, the internal force evaluation model is set up, then, the structural behavior of SLW are investigated in detail. Combined with the nonlinear FEM results, the structure behaviors are expressed in the concepts of "principal limb" (PL) and "load effect bearing ratio" (LEBR), and the function for LEBR determining is put forward, which may be used in the practical section design.The main achievements of the dissertation are listed as following.1 The definition of SLW is given to clarify some misunderstanding on the new structure style. The typical experiment results on parallel structure forms, such as erose-section-column frame and conventional shear wall are compared in the point of view of energy dissipating property.2 Horizontal cyclic loading experiments are carried out on six specimens, which are divided into two groups: one with flanged-wall, the other without. The two groups consist of 3 specimens each, and RDWs are 5, 6.5 and 8 respectively. The specimens are all in the forms of "pseudo-structure", rather than the commonly used specimens in the forms of "member", and the experiment results are inevitable more reasonable.3 The results denote that for non-flanged SLW, when the limb is shallow, the longitudinal bar in the limb will firstly yield; on the other hand, when the limb is deep, the stirrup in the linking-beam will firstly yield. For the flanged- SLW, the longitudinal bar in the limb or flange will firstly yield no matter what value the section ratios are. From the point of view of load bearing capacity and energy dissipating, with RDW being 6.5, the specimens behavior best.4 All the failure modes are interpreted in the view of structure mechanism. The hysteresis loops and their envelop curves are given, then the characteristic parameters are determined, such as cracking load, yielding load, ultimate load, ductile index, energy-dissipating index and so on. The stress/strain re-distribution processes are exposed step by step, which denote that the SLW structures develop a large scale of stress/strain re-distribution under high stress. The final strain distribution is quite different from the one given by elastic analysis. No matter with or without flange, the longitudinal strain in limbs roughly coincides with Bernoulli's principle.5 Based on strain distribution status found in experiments, the internal force evaluation approaches are suggested. Then, the structural behaviors are investigated in detail, and the concepts of PL and LEffR are introduced. Integrating the results obtained by nonlinear FEM analysis and structural behavior analysis, with the section shape and RDW being variables, the function for LEBR is proposed.6 All the reinforcement in the specimens, longitudinal bar and transverse stirrup, is of grade HRB400. The experiment results justify the conclusion that the HRB400 steel works harmoniously with moderate strength concrete. It yields no matter in tension or co... |
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