Study On Seismic Behavior Of Flexible Connection Frame Structure Infilled With New Masonry

Considering the complex interactions between the main frame and infill walls, the masonry-infilled frame structure can use two design calculation methods as follows depending on the particular case: for the first method in which the infill walls are taken as structural members, the design calculations consider the effect of infill walls on the structural stiffness and bearing capacity, then the infill walls should be reliable connected with peripheral frames, forming composite walls; for the second method in which the infill walls are taken as non-structural members, the design calculations only consider the weight of infill walls and simplified consider or not consider the effects on the structural stiffness and bearing capacity, then enough spaces should be obligated between the infill walls and frame beams or columns to isolate the interactions by using flexible connection construction scheme between the wall and frame.In this dissertation, aiming to the new material of infill walls-- Fly-ash thermal insulation hollow block, the following researches were performed around the topic of ‘seismic behavior of hollow block masonry-infilled framework with flexible connection between infill wall and frame’:According to the model of filled wall materials – fly-ash thermal insulation hollow block, around the "wall- frame flexible connecting masonry infilled wall frame structure seismic performance" this topic, carried out the following research:(1) Compressive and shear strength tests of fly-ash hollow block masonry were performed. The mechanical indexes of hollow block masonry such as calculation formulas of compressive and shear strengths, Poisson’s ratio, elastic modulus and shear modulus were obtained based on the test results. The compressive and shear stress-strain relationships were proposed, as well as shear strength calculation formula of hollow block masonry under the combined action of shear and compression.(2) The low cyclic load tests of hollow block walls were performed. The test results show that the horizontal bearing capacity, stiffness, ductility and energy dissipation capacity were improved significantly by arranging core column for the walls.(3) Through the low cyclic load test of 7 specimens of 1:2 hollow block infilled reinforced concrete frame structures, the failure mechanism and seismic behavior of hollow block masonry infilled framework with flexible and rigid connection between infill wall and frame, or setting core column and not setting core column in the wall end, or with all-height and half-height infill wall were studied. The hysteresis character, bearing capacity, displacement ductility, stiffness degradation, strength retrogression, energy dissipation and deformation index of structure were analyzed. The results showed that flexible connection specimens had lower bearing capacity than rigid connection specimens, but the other performance indexes were better. As a result, flexible connection scheme can reduce interaction between infill wall and frame and can improve seismic performance of infilled frame structure. Meanwhile, flexible connection schemes reduced or eliminated the additional shear effects on frame columns of infill walls, improved mechanical properties of frame column, reducing the damage extent of infill walls. Also, the setting of core column in the filler wall improved the structure bearing capacity, stiffness and global stability effectively.(4) Through the nonlinear finite element analyses of hollow block walls under monotonic horizontal loading by using homogeneous modeling method, the reliabilities of the proposed recommended value of Poisson’s ratio, compressive strength, calculation formula of elastic modulus, and compressive stress-strain relationship of fly-ash hollow block masonry were verified.(5) Two modeling methods were utilized for numerical simulation analysis of hollow block masonry wall-infilled frames: one method performed static pushover analysis under horizontal cyclic loading by simulation of infill walls using homogeneous modeling; the other method performed static pushover analysis under monotonic horizontal loading by simulation of infill walls using equivalent spring elements. The calculation results agree well with the experimental results of the two methods.