Experimental Study On Seismic Behavior Of Steel Plate Reinforced Concrete Coupling Beams

As an important energy dissipation component in coupled shear wall structuresand the structure system composed by coupled shear walls, the strength, ductility andenergy dissipation capacity of the coupling beams have significant influence on theperformance of the whole structure system under earthquake excitation. In order toimprove the seismic performance, especially to enhance the shear resisting capacity ofreinforced concrete coupling beams, a new type of coupling beam, named steel platereinforced concrete coupling beams (SPRCCB), embedding one or several steel platesalone the beam span, was investigated in this study.In this paper, 6 specimens, 4 with a span-depth ratio of 1.5 and 2 with aspan-depth ratio of 2.5, were tested under cyclic loads. The test results show that theSPRCCB possess higher strength, better ductility and energy dissipation capacity thanthe conventionally reinforced coupling beams. Steel plate can prevent the beam fromflexural sliding failure. Flexural failure, flexural shear failure and shear failure are thethree types of possible failure modes of SPRCCBs. Test results show that beforeyielding of the longitudinal bars, the beam wall interface remains as a plane, but afterthat, such conclusion was not always true. As the appearance of flexural shear crack,the zero strain point of longitudes gradually moves towards compression zone,causing tension-lag in the beam span. Based on the test results, analysis was carriedout on the bending moment, shear force and axial tension of steel plate and the shearforce in stirrups of each specimen under different displacement level. Based on theanalysis results, a modified formula was put forward to calculate the shear strength ofSPRCCB. The results also suggest that in order to achieve the advantage of steel platereinforcement, the plate should be fully anchored in wall piers and that the two linesof deformed bars welded on both sides of steel plate is effective in anchoring plates insurrounding concrete.The paper also includes the non-linear finite element analysis (FEA) of two testspecimens, with span-depth ratio of 1.5 and 2.5 respectively, using MSC.MARC. TheFEA results, which agree with the test results, show that the shear resistingmechanism of the beam with span-depth ratio of 1.5 and 2.5 are different: arch actionis significant in beams with smaller span-depth ratio. The paper also investigates theinfluencing factors of the shear strength of SPRCCB including the steel platereinforcement ratio, thickness, depth and the depth-thickness ratio of the steel plate.From the results of the parameter study, the following conclusions can be drawn: theshear strength of SPRCCB increases with the steel plate reinforcement ratio;theincrease of thickness and depth of the steel plate will elevate the shear strength ofSPRCCB and the increase of strength will be more obvious when the depth of thesteel plate is larger. To two SPRCCBs with same ratio of steel plate reinforcement, theshear strength of the one with larger depth-thickness ratio will be larger. Based on theanalysis results, some design suggestions are proposed.