Seismic retrofit of beam-column joints using prestressing wire

摘要

An effective external prestressing technique is presented for the seismic retrofit of reinforced concrete beam-column joints with prestressed high-strength steel wires. This method is to improve the seismic performance and enhance the shear strength of beam-column joints with non-seismic design as well as to overcome the shortcomings of traditional seismic retrofitting techniques for the joints. Six large-scale interior beam-column joints were tested under reversed cyclic loading, where five were strengthened by the proposed technique and one was un-retrofitted as a control specimen. Particular emphasis was placed on the effects of the ratio of prestressed high-strength steel wires, prestressing level of wires and polymer grout layer. Test results showed that the joint shear capacity was increased significantly and cracks in beam-column joints were controlled effectively after retrofitting. All retrofitted joint specimens failed in a ductile mode of beam flexural failure, whereas the control specimen failed in a brittle mode of joint shear failure. In addition, the energy dissipation capacity as well as ductility of the retrofitted joint specimens was enhanced significantly compared with the un-retrofitted specimen.