The Seismic Performance And Failure Mechanism Analysis Of Small Span-to-Depth Ratio Coupling Beams With Fiber-reinforced Concrete And Diagonal Bars

As an important components of the tall building structures, the coupling beams play an important role in transmitting force and dissipating seismic energy between the shear wall limbs. In recent years, with the development of high-rise buildings, the shear wall structure has been widely used. Therefore, how to make the coupling beams that plays a link role between single shear walls can yield firstly when under the stronger earthquake strikes is absolutely important. And the purpose is to make it dissipates more seismic energy. However, practically, due to the requirements and restrictions on the building function and the entire lateral stiffness of structure, the designers must consider the choice of coupling beams with small aspect ratio. So, in order to find out a small-span-to-depth-ratio coupling beam, which is both convenient to construct and with good anti-seismic performance, this paper designed a set of tests considering the form of reinforcement and the materials of coupling beams with small aspect ratio. On the basis of the test, the large universal finite element software-ABAQUS is used to analyze it, and the seismic performance and failure mechanism are studied.The scientific of finite element model is verified by analyzing the hysteresis curve, skeleton curve, ductility performance and energy dissipation capacity. On this basis, the paper established 38 finite element models. And the paper mainly studied the influence of mechanical performance of small span-to-depth ratio coupling beams with fiber-reinforced concrete and diagonal bars by changing the strength grade of concrete, breadth of section, span-depth ratio, reinforcement ratio and other parameters. The main conclusions by this paper are as follows:First, with the increase of strength grade of concrete, the bearing capacity of the coupling beams improves, the ductility reduces, but within small extent.Second, by increasing the width of beam sections can improve the bearing capacity, but the ductility performance reduces correspondingly.Third, by increasing the span-depth ratio of small span-to-depth ratio coupling beams can reduce the bearing capacity, but the ductility performance improves correspondingly. And the failure mode of the coupling beams gradually transforming from initial shear mode into bending-shear mode.Fourth, by increasing the stirrup ratio can improve the bearing capacity and ductility of beams, and the improvement extent of each point shows similar patterns. The increase rate is obvious when the stirrup reinforcement ratio is less than 0.59%, but the increase rate is minimal while you keep increasing stirrup reinforcement ratio.Fifth, by adjusting the longitudinal reinforcement and slope reinforcement of small span-to-depth ratio coupling beams in this paper, it thinks that increasing the amount of longitudinal reinforcement or slope reinforcement can improve the bearing capacity of beams. However, to increase the amount of longitudinal reinforcement reduces the deformation ability of beams; to increase the amount of slope reinforcement improves the deformation ability of beams. Therefore, the ratio of unilateral longitudinal reinforcement of this kind of coupling beam should be no greater than 0.55% is suggested, and the ratio of the consumption of slope reinforcement and longitudinal reinforcement should be no less than 1.3.Lastly, this paper amends the formula of shear-bearing capacity of existing coupling beams by using the Strut-and-Tie theory based on the test and finite element analysis results, gives the recommended formula of shear-bearing capacity of small span-to-depth ratio coupling beams with fiber-reinforced concrete and diagonal bars.