Experimental Study On Hysteretic Behaviors Of The Deep Beam Infilled Steel Frame

Steel frame and shear wall infilled steel frame reflect two endpoints of the amplitude of the structural stiffness. The increasement of stiffness is transilient. Deep beam infilled steel frame can meet the required stiffness between the two endpoints and can ajust the structual stiffness within a wide range. The simple structure and easy connections of deep beam infilled steel frame actualize the convenience for assembly and disassembly for prefabrication. The position of deep beam in steel frame is flexible and therefore the doors and windows can be arraged freely. This structure can applied to both new buildings and the reinforcement of established buildings. So it shows great theoretical research value and broad application foreground.At present, the research of deep beam infilled steel frame abroad is at the very initial stage. In China, this research is nearly blank. In this paper, low-cycle loading test method is employed, considering nonlinear factors of different materials and height-width ratios, deep beams from three kinds of materials(steel, reinforced concrete and composite) are studied. For each kind of material, two deep beams of different sizes are tested. Plus the comparative test of pure steel frame, seven model tests are accomplished in total.For each specimen, the hysteretic loops, distribution of stress and deformation behaviour under low-cycle loading are represented, the principle of energy dissipation is analyzed, and the ductility and strength degeneration are calculated. Based on experiment results, the affects of material and height-width ratio of deep beams are concluded.The experiment data demonstrated that comparing to pure steel frame, deep beam infilled steel frame structure apparently enhanced the intial stiffness and ultimate bearing capacity, solved the problem of stiffness insufficiency of pure frame. By changing the height to width aspect ratio, the modulation of stiffness could be realized. The transition between pure frame and frame-shear wall provided more accurate and economical structural form for engineering design.Comparing to pure frame, the ductility of deep beam infilled steel frame structure is enhanced, individuals could be more than doubled. It is shown that deep beam infilled steel frame structure has good plastic deformation capacity to risist the structure collapse. In seismic design process, the awareness of setting multi-channel seismic line of defense is an important component. When earthquake occurs, deep beam plays a role as the first line of defense, firstly consumes seismic energy, protects the framework to some extent, avoids serious damage to the overall structure, thereby the energy consumption capacity of steel frame is enhanced.The experience of installation and disassemblence proves that, after earthquake, by replacing damaged deep beam by new one via the easy connection of the bolts, the overall structure can continue to be used through a simple repair. From the structural point of view, deep beam infilled steel frame structure once again reached the the requirements of "Earthquake Resistant Design Code".The performance of deep beam infilled steel frame structure under low-cycle load test embodies theoretical value and broad prospects for engineering applications.