Research On The Substructure Pseudodynamic Test Of The Frame-Supported Reinforced Concrete Short-Leg Masonry Shear Wall Structure

Frame-supported reinforced concrete short-leg masonry shear wall structure is used as an alternative to solid clay brick masonry structure for building multi-storey structure. A competitive development space can be provided by the proposed structural system to build the bottom big-space structure in the multi-storey structural system with such advantages as follows: firstly, architectural function can be gained easily by using the structural system; secondly, the structure system has the advantages of both lower cost and more convenient construction process than the reinforced concrete frame structure with the same architectural function. However, so far any theoretical and experimental studies on the proposed structural system have not been done home and abroad. Some scientific problems need to be solved urgently to popularize the structural system and reduce earthquake losses in our country. The first one is how to get the failure mode and failure mechanism through the real earthquake action. The second is whether the proposed structural system can meet the 3-level seismic requirements of no damage under frequent earthquake, repairable damages under basic earthquake and no collapse under rare earthquake or not. The third is whether the proposed structural system can stand the test of the earthquake or not. Without the experimental results, it is hard to validate the seismic theory and harder to apply it to the practical engineering. Especially to the masonry which is the extremely complicated nonlinear material, it is more important to accomplish the full-scale model test. The substructure pseudo-dynamic test method is an effective method that combines the calculation and control of the computer. This method is both convenient and economical to simulate the true seismic action, so it completely fits to simulating the seismic response of the large and complex structure.According to the engineering practice and the testing condition, a full-scale three-storey frame-supported reinforced concrete short-leg masonry shear wall test model was constructed in the structural & seismic laboratory of Harbin Institute of Technology. In accordance with the feature of the model, the algorithm and the control method of the substructure pseudo-dynamic test were investigated. Simultaneously this paper studied the failure mode, the failure mechanism and seismic performance under earthquake action. After that, the preliminary study on the strengthened method was finished to the test model damaged by earthquake.As an unconditionally stable implicit algorithm, the high-order single-step method has been successfully applied to nonlinear seismic response analysis, semi-active, active vibration control and smart vibration control, the dynamic response analysis for analytic expression of stiffness, and so on. Based on the previous research, this paper introduces the equivalent shear stiffness, and proposes the high-order single-step pseudo-dynamic or substructure pseudo-dynamic testing method. The pseudo-dynamic or substructure pseudo-dynamic test is easily conducted with the assumption of calculated stiffness through the implicit high-order single-step algorithm. The numerical simulation and the test results indicate that the proposed method is more accurate and stable than the central difference method, so it is feasible to apply it to the pseudo-dynamic or substructure pseudo-dynamic test.This paper proposes the force-control high-order single-step substructure pseudo-dynamic testing method to solve the problem that the stiffness of test model is relatively large under small peak acceleration. The MDOF testing results show that the force-control testing method is feasible for the large-stiffness model before descent segment of structure restoring force properties that it can improve and develop the existing substructure pseudo-dynamic test method.Because of the coupling effect of actuators, the substructure pseudo-dynamic test of MDOF structure model becomes especially complex. Lots of algorithms validated by the numerical and SDOF testing results are invalid for the MDOF model, which either leads to the divergence of the used algorithm or makes the calculated command signal hard to be executed exactly. Therefore, the development of the control technique becomes more and more important for the substructure pseudo-dynamic test home and abroad. Firstly, this paper studies the soft coupling load system control method which is used to approach the command signal step by step. The test results show that the soft coupling load system control method can partly reduce, but can not fundamentally solve the coupling effect of actuators. With the increment of degree of freedom, the control of model test is getting harder, which will result in absolute invalidness of the soft coupling load system control method. Therefore, this paper tries to investigate equivalent force control method. The numerical and testing data demonstrate that equivalent force control method has well robustness. The displacement control of the MDOF system can be realized by rationally setting equivalent force controller that the equivalent force control method can effectually provide a control measure for the substructure pseudo-dynamic test of the MDOF model.Using the proposed and validated substructure pseudo-dynamic technique, the systemic substructure pseudo-dynamic test of the full-scale model was finished under the different peak accelerates of the earthquake motion which were 35 gal, 70 gal, 110 gal, 220 gal, 260 gal, 310 gal and 350gal, separately. Then the main conclusions can be got by the test results. The major damage intensively appeared in critical areas which were the bottom frame floor and the shear wall floor in connection with the frame floor and the surrounding parts of the structure were slightly damaged, which shows that the obvious weak parts of the structure don't appear. Therefore, the frame-supported reinforced concrete short-leg masonry shear wall structure has better seismic performance and can meet the check requirements of elastic-plastic deformation and the 3-level seismic requirements in the 7~8 degree seismic intensity region.After the systematic substructure pseudo-dynamic test on the full-scale three-floor frame-supported reinforced concrete masonry short-leg shear wall structure, different damage degrees of model elements such as beams, plates, columns and walls appeared. Therefore, this paper assesses the damage degree of the whole structural model and draws up the corresponding reinforcement scheme. Then, the strengthened model was tested through the same substructure pseudo-dynamic testing method. The applicability of the proposed strengthening technique was discussed for the building damaged by earthquake. Thus, the seismic performance of the strengthened model is proposed to explore the strengthening technique for the structure damaged by earthquake and provide the important reference value for the post-disaster reconstruction.