Experimental Study And Theoretical Analysis On PVA-ECC Diagonally Reinforced Coupling Beams With Small Span-to-Depth Ratio

Under earthquake loading,the most important parts of coupled shear wallsstructure,loading-bearing walls,will be protected if couping beams from plastic hinge whichdissipate earthquake energy. The seismic response and deformation of the coupling beam withsmall span-to depth ratio have much difference with commom frame beam and simply supporteddeep beam. Domestic and foreign scholars do the earthquake resistant behavior research throughthree aspects which are new reinforcement arrangment、new section forms and using highperformance concrete. This article research the earthquake resistant behavior of the type ofcoupling beam which plus new materials PVA-ECC(Polyvinyl Alcohol-Engineered CementitiousComposires) on the basis of diagonally reinforced coupling beams with small span-to-depth ratio.The research of five coupling beam specimens show that this kind of coupling beam havehigh carrying capacity and deformation capacity,satisfy the demand of carrying capacity anddeformation under strong earthquakes.The test shows that the fiber in PVA-ECC coupling beams plays a good bridging role after thecracks appear. That makes the load-carrying capacity of the coupling beams continue to improveafter the yield of diagonally reinforced and the cracks carried out more slowly than ordinaryconcrete coupling beams. Before the onset of the main diagonal cracks,the coupling beams have ahigh deformability and load-carrying capacity already.This meets the bearing capacity anddeformation demand of the coupling beam under strong earthquake.Finally,the paper analysis this experimental using the finite element softwareABAQUS. Comparison between the calculated and the experimental results reveals Thereasonableness of the model. Through the model analysis and experimental results,theaffect of span-to-depth ratio、cube compressive strength and ratio of stirrup to theload-carrying capacity and deformability of the coupling beams is revealed.The resultshow that the type of coupling beam which plus new materials PVA-ECC on the basis of diagonally reinforced coupling beams with small span-to-depth ratio can improve the ductility andenergy dissipating capacity of coupling beams effectively.As the uniaxial tensile strain-hardeningproperties and high tensile strain of PVA-ECC,the ensile strength of the oblique rod can beimproved and the stiffness degradation of coupling beam is slow.At last,compared several differentreinforcement and matrix material coupling beam with the existing test results, Further validate thatPVA-ECC diagonally reinforced coupling beams have good seismic performance.