Nonlinear Seismic Analysis Of Masonry Infilled RC Frame Structures

Masonry Infilled RC frame structures become the first choice in multi-story civil buildings, because of its good performance characteristics and structural properties. But in recent years, during a lot of earthquake investigation, we find that the damage of masonry infilled and the structural damage caused by infilled walls are serious. At present, in structural design, the main way is adding the gravity of infilled walls as an external load on the structures. In earthquake-resistant calculation, people usually make corresponding reduction depending on the number of the infilled walls; in seismic analysis, people also fail to pay attention to infilled walls, and just think they only play a role in maintenance and separation of structures, and have little impact on structural stressing properties. But a lot of earthquake investigations show that the effect of masonry infilled is not just so-called filling effect, on the contrary, in quite extent it determines the damage performance of masonry infilled RC frame structures. So we should review the dynamic properties of masonry infilled and the influence of structural dynamic performance caused by masonry infilled.The reduction of structure performance and anti-seismic capacity caused by uneven decorating infilled walls along the vertical structure are the key contant of this paper. Use the fiber model based on stiffness method and elasto-plastic seismic analysis of 3d frame structure. This paper sysmatically analysis the impact of whole structural dynamic performance and seismic performance by tdifferent types of masonry infilled layout, using the nonnear finite element software MSC. MARC and the secondary development program THUFIBER based on it.First of all, more comprehensively summary the seismic design, analysis the various failure pattens, failure characters of masonry infilled, the interactions between frame and infilled walls, and analyze the influence of masonry infilled to the whole structure's dynamic performance and anti-seismic capability during earthquake.Secondly, determine the numerical simulation methord being used to nonlinear seismic response analysis of masonry Infilled RC frame structures. This paper compares the advantages and disadvantages of various calculation models, establishes beam-column member based on THUFIBER fiber model theory, use micro finite element method to establish masonry infilled, and use LINK cell which can transfer the in-plane load characteristic to simulate the joint between frame and masonry infilled. Establish numerical model and go deep to study the influence of structural dynamic performance caused by masonry infilled.Thirdly, taking a five-layer infilled frame as the example, the paper researches the contribution of infilled walls and the frail-layer phenomenon caused by masonry infilled, when the infilled decorated uneven along the vertical structure. Make the structure produce low, middle and top frail-layer respectively, according to arrangement of infilled walls. Then create multiple models classified to conduct seismic response analyses and comprehensive discussion, and systematically compare the result. Give a reasonable initial interlayer lateral stiffness ratio contrasting norms. Otherwise, choose two properties of materials differing considerably to analyze the regular of different materials of infilled walls affecting the structures.