Research On Seismic Behavior And Dynamic Testing Of 100-meter Reinforced-block Masonry Shear Wall Structures

With the rapid development of modern building technologies, lots of novel structural systems have thrived dramatically. Reinforced-block masonry shear wall(RBMW) structure, has the characteristics of RC structures’ high strength, good ductility and excellent dissipation, and holds the merits of short construction period, little amount of steel, saving the template, decreasing the wall plastering, and increasing the housing usable area, etc.. Thus, it meets the requirements of building an economical society advocated by China and has fairly good application prospects. Now, there are few experimental research and numerical analysis on seismic behavior of 100-meter RBMW structure, and the vibration testing under ambient excitation has not been reported yet. Some related scientific and technical problems need to be solved. Correspondingly, revealing the dynamic properties and work behavior characteristics of RBMW structures could have great theoretical significance and the engineering application value to develop this type of system. Based on the above considerations, experimental research and elastic-plastic numerical analysis on seismic behavior of the planned 100-meter RBMW demonstration project were carried out, and the vibration testing under ambient excitation was performed during the construction process. The main contents are summarized as follows:(1) A 1/4 scale, 10-story RBMW structure model was designed and constructed, based on the characteristics and the mechanical properties of one planned 100-meter RBMW structure. The shaking table test was carried out to explore the failure mode and dynamic response rules of this long period high-rise structure with big bay, big holes, and weak coupling beams, and to provide experimental basis for the analysis of the seismic response of the 100-meter RBMW structure. The failure modes, damage states and dynamic response of the model were analyzed. It can be observed from the process of failure that cracks occur firstly at the end of the coupling beam, and the horizontal cracks arise gradually along the mortar seam as the increase of the ground motion intensity. The model presents a bending shear failure mode, and a multi-aseismic resistance aim characterized of strong limbs and weak beams is achieved. The structure model experiences a medium-damage state when subjected to a rare seismic with intensity level of Ⅷ. The tested result indicates that the RBMW structure has a relatively good aseismic capacity as well as a fine deformation capacity.(2) Investigating the seismic mechanism of RBMW, and in order to provide a theoretical basis for the numerical analysis of the 100-meter RBMW structure. Existing pseudo-static testing data of RBMW were collected to investigate relevant parameters effect on the skeleton curves of the walls, and to build the stiffness degradation equations, then to compare the stiffness damage factors conforming to two different stochastic distributions, and then to analyze the relationship between the stiffness degradation coefficient and drift. The relationship between normalized dissipation energy and displacement was obtained by means of regression analysis, meanwhile, the variation laws were discussed between equivalent viscous damping ratio and power ratio index, providing the ranges of energy dissipation coefficient and equivalent viscous damping ratio. Finally, the load-displacement restoring force model suitable for the RBMW was proposed, which can effectively simulate the pinching phenomenon of the hysteretic curves of the walls.(3) In order to construct the 100-meter RBMW office building in seismic zones with intensity level of Ⅵ, the following contents are studied: The INP modeling method is adopted to simulate the tested model structure based on the FEM software ABAQUS. In numerical simulation, the concrete damage plastic model(CDP model) is adopted in grouted masonry and stiffness damage factor provided in the thesis is introduced to the compression constitutive model of the grouted masonry. The frequencies, mode shapes, acceleration and displacement time-history of the model structure are computed, and the results obtained from numerical simulation are in good agreement with those obtained from the experimental outcomes, verifying the accuracy of the modeling method and the chosen material constitutive model. Refered to the above modeling method and the material model, seismic response analysis of the 100-meter RBMW structure are carried out to explore the failure mode and dynamic response. The investigations indicate that the lateral stiffness, the ratio of torsion and shear-weight ratio meet the code requirements. The damages occur firstly at the coupling beam along the weak axis direction, and then the damages are found gradually on the adjacent walls. The damages of the walls at each story emerge from bottom to top with increase of the ground motion intensity, achieving a multi-aseismic resistance aim. The inter-story drift of each floor can meet the code requirement subjected to the rare seismic of level Ⅷ, indicating that the seismic performance of the 100-meter RBMW structure is good.(4) During the construction process of the 100-meter building, the vibration testing under ambient excitation are carried out when the 10 th, 18 th, and 28 th stories of the main structure are progressively completed, and the finite element model is verified by using of the testing results. The modal parameters of the whole structure are identified using Peak-Picking(PP) method and Stochastic Sub-space Identification(SSI) method. The variation laws of the natural frequency and the mode shapes of the building are gained. The frequencies and vibration modes at various heights of the structure are calculated using numerical simulation method, and the results are in good agreement with the experimental results, which verified the accuracy of the modeling method and the mechanical parameters of chosen material.Based on all the above conclusions, it is feasible to generalize the application of the RBMW structure to 100-meter high buildings in seismic zones. The completed 100-meter high office building breaks through the limitations of the application height of this system in Chinese building code, and establishes the foundation and technological support for the development of the system to high-rise, super high-rise, and also provide scientific basis to compile related criterions.