Experimental Study On Ductility And Shear Capacity Of Frame Structure With Construction Joints

In today's construction,due to human or natural environmental conditions,the concrete pouring can not be completed in a row,so inevitably lead to the existence of construction joints of reinforced concrete frame structure,so a lot of failure phenomena happened frame structure near the construction joints when the earthquake disaster came,largely because the seismic capacity of the frame structure with construction joints isn't enough.So using construction joints and axial compression ratio as the main variable,we carried on the experimental of the low cyclic loading tests of two specimens of reinforced concrete framework and nine columns,through the experimental phenomena,hysteresis curve,skeleton curve,energy dissipation capacity,stiffness degradation and the force model of the frame under the P-delta effect of the frame structure,the influence factors of ductility and shear capacity of the frame structure with construction joints were quantitatively analyzed.The study says:due to the existence of construction joints,the ductility of the reinforced concrete frame structure with construction joints is weakened by thirty percent,but improved five percent after the construction joints were standardized handled,when the axial compression ratio increases to 0.34,the ductility of the columns is decreased by 4.5 percent,during the process,the ductility of the construction joints can be increased by 4 percent,and its shear capacity is almost the same as that of the whole cast-in-place frame columns.Only when the axial compression ratio increases to 0.46,the shear capacity of the frame with simple construction joints will be significantly increased.With the increase of the axial compression ratio,the ductility reduction rate of the columns with construction joints will slow down gradually.in contrast,the overall ductility of the frame structure with construction joints is lower than that of the columns with construction joints.The effect of the P-delta effect on the ductility of the frame structure with construction joints is up to forty percent,while less effect on the shear bearing capacity of the frame structure with construction joints by the construction of the force model.In summary,to take into account both of the ductility and shear capacity of the frame with the construction joints,the construction joints must be standardized treated and the axial compression ratio must be controlled at about 0.34~0.46,and consider the effect of P-delta at the same time before used in actual engineering.