Analysis Model Of Seismic Behavior Of Masonry Walls And Its Engineering Application

Among the in-serve civil constructions in our country, there are a great number of masonry and masonry infilled frame structure. The complete-set renovation on these kind of old buildings is an important aspect of energy-saving and emission-reduction in the construction field.According to the current related codes of China, these buildings can hardly pass the structural safety evaluation in the complete-set renovations. How to properly estimate the safety and seismic performance of these existing buildings, and provide reasonable renovation scheme, analysis model and design method, is still the hot topic of research.Basing on the fine finite element modeling method, a great number of finite element numerical simulations were made on three groups of typical masonry wall specimens by using ABAQUS. A 3D solid element model considering the contact and friction, a shell element model using improved constitutive model and an improved cross-strut model considering hysteric behavior, were respectively proposed and systematical compared with model test. Basing on this work, reasonable simplified models and analysis methods for masonry walls were proposed, and the whole structural seismic time-history analysis and the safety assessment after reinforcement were made on an actual project. This research can provide reasonable analysis models and theoretic basis for the green energy-saving renovation,local reinforcement and safety assessment of old masonry and masonry infilled frame structure, and provide reference for the selection of appropriate reinforcement and reconstruction scheme in practical engineering.The main research contents are as follows:(1)The numerical simulation on masonry infill walls basing on the equivalent diagonal strut theory. A relatively accurate model was established by adopting the improved formula of equivalent diagonal strut width and considering the hysteric behavior. Compared with exist experiment results, the model was proved to be reasonable. Using this model, systematic analysis and comparative research were made on the seismic dynamic time-history response of an actual multi-story infilled frame structure.(2)Separated fine finite element model of masonry walls basing on the three-dimensional solid element and cohesive interface. Compared with exist experiment results, the model was proved to be reasonable. On this basis, a modeling method based on shell element was proposed, and the masonry constitutive relation is modified.(3)For the reinforcement project of an actual multi-story masonry structure before and after adding story, seismic elastoplastic dynamic analysis was made by using the modeling method basing on shell element.According to the analysis results, the vertical walls of the structure were reinforced. Comparing the seismic response of the structure before and after reinforcement, reasonable suggestions were provided for the reinforcement and reconstruction scheme of practical engineering.