Research On Seismic Behavior And A Pseudo-dynamic Testing Investigation On Concrete Perforated Brick Masonry Building

Concrete perforated brick as one of the leading substitute for clay solid brick new materials of wall is, which dimension is similar to that of clay perforated brick. Because it is convenient to constructing and has high mechanical behavior, concrete perforated brick masonry must be widely applied in the future. In this paper, based on substructure pseudo-dynamic test investigation of concrete perforated brick masonry structure, pseudo-static test investigation of concrete perforated brick masonry wall, modal analysis, elastic and elastic-plastic analysis of the seismic response, and capacity-spectrum-method analysis of concrete perforated brick masonry buildings have been carried out. The system analysis and evaluation of seismic behaviors of concrete perforated brick masonry buildings can provide the basis for its design and application in the zones of seismic fortification, conclusions obtained as follows:1. A three-dimension model for elastic time-history analysis has been proposed to analyze modal and elastic dynamic response of model and prototype building. By comparison results of modal analysis, although there are imperfection similarity among front 10-modal, because of dynamic response of model and prototype building dominated by the first modal in-plane of earthquake action and the frequency ratio f1 /f 0=0.83≈1.0, from this point of view, the model and prototype building can approximately satisfy similarity laws. In addition, the seismic response of prototype and model building is approximately consistent; the conclusion that test model can respond the dynamic characteristic of prototype completely. Associated with natural frequency of test model, the influence of frequency spectrum of El-Centro earthquake, Taft earthquake and Ninghe earthquake has been analyzed based on Fourier transform and wavelet transform, and then the period of time of three earthquakes containing with natural frequency of test model has been intercepted to action on test model during pseudo-dynamic test. The result of pseudo-dynamic test shows that the seismic response of test model to Ninghe earthquake is largest, next is El-Centro earthquake, and last is Taft earthquake. A conclusion can be obtained that the influence of the acceleration impulse of earthquake to the seismic response of structure similar to that of frequency spectrum of earthquake must not be negligible. It can provide references for selecting and intercepting earthquake used in pseudo-dynamic test.2. A sub-structure pseudo-dynamic test on 8-storey and 24-meter concrete perforated brick masonry 1/2 scale model building with test sub-structure of two freedom degrees of and compute sub-structure of six freedom degrees has been firstly launched domestic. And, its crack patterns, deformed features, failure models, etc. have been observed and analyzed. The failure mode of test model belongs to shear, and first storey of model that happened to failure firstly and seriously is feeble place of whole structure. At the same time, the failure mode is analogous to that of ordinary clay solid brick masonry buildings; The ultimate shear strength of the wall of first storey is 0.94 N/mm2, and that of second storey is 1.22 N/mm2. Furthermore, as the shear strength calculated by the formula fv = 0 .176f2, the ratio of the shear strength calculated and that of strength tested is up to 1.4. The horizontal ultimate bearing capacity of model is very high; The first storey drift angle homologous with the ultimate load of test model is 1/324; The first storey drift angle homologous with the failure load of test model is 1/193; The first storey ductile coefficient is 2.43. From above all, a conclusion can be drawn out that the deformed capacity is high enough to meet the requirements of concrete perforated brick masonry in the seismic fortification zone. The whole structure can still keep steady after bad damage of first-storey wall resulting from rational connections between structural concrete columns, and walls. Above all conclusions have validated Technical specification of perforated concrete brick building (DBJ43/002-2005), and can provide ideas for research and references for Code for seismic design of buildings (GB50003-2001) and Code for design of masonry structures (GB50010-2001) to supplement the provisions for seismic design of concrete perforated brick masonry buildings.3. In this paper, the influence of axial compression ratio on hysteretic rules of concrete perforated brick masonry has been studied, and a model of hysteretic rules in view of axial compression ratio is proposed. Subsequently, the variety of the stiffness of elastic-plastic phase ratio to that of elastic phaseα1 and the stiffness of damage phase ratio to that of elastic phaseα2along with axial compression ratio is presented. The elastic-plastic time-history analysis method with hysteretic rules in view of axial compression ratio has been developed to analyze dynamic response of model building, which the rationality of hysteretic rules in view of axial compression ratio has been validated. The results of time-history analysis and that of sub-structure pseudo-dynamic test of model building have been validated each other. Above results may be as a reference to elastic-plastic time-history analysis of masonry buildings.4. Seismic behavior of concrete perforated brick masonry buildings under the El-Centro earthquake action has been evaluated with the capacity-spectrum-method and the result of analysis was consistent with that of the test, so it shows that the capacity-spectrum-method may be applied to evaluate the seismic behavior of masonry structures. The maximal elastic storey-displacement calculated and tested of the model was further below the limit 7.5mm prescribed by General rule for performance-based seismic design of buildings (CECS 160: 2004), and the maximal damage storey-displacement calculated and tested of the model was still below the limit prescribed by General rule for performance-based seismic design of buildings(CECS 160: 2004). Thus, it shows that the limit prescribed by General rule for performance-based seismic design of buildings (CECS 160: 2004) was not safe, which can provide the reference for revising the limit of the code in the future.5. Seismic behavior of concrete perforated brick masonry buildings has been deeply and systemically assessed through a sub-structure pseudo-dynamic and a pseudo-static test investigation of test model, pseudo-static test of a great deal of concrete perforated brick masonry panels, elastic time-history analysis of dynamic finite element, elastic-plastic time-history analysis of layer-shear model of and analysis based on capacity-spectrum-method of seismic behavior. A conclusion can be gained that the test model can satisfy requirements in the zones of seismic fortification intensity of 7-degree, which can resist a minor level of earthquake ground motion without damage, resist a moderate level of earthquake ground motion with some nonstructural damage that can be repaired, resist a major level of earthquake ground motion without collapse. Conservatively, the concrete perforated brick masonry buildings may be built up to 8-storey, 24-meter high in the zones of seismic fortification intensity of 6-degree. Thereby, the application of concrete perforated brick masonry becomes broad in the zones of seismic fortification intensity.