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The full-scale RC interior beam-column joints with slab and orthogonal beams, namely with real boundary conditions, were designed and tested under reversed cyclic lateral loading. The effects of the columns and beams strengthened by CFRP on the seismic performance and failure modes of the beam-slab-column joint were investigated. The failure modes, hysteretic behavior, envelope curves, energy dissipation, displacement ductility, stiffness degradation and joint shear deformation were investigated and compared in detail. The test results show that the failure mode of the control interior joint is the column-hinging mechanism of strong-beam-weak-column due to the presence of slab and orthogonal beams. After the retrofitting at columns or both columns and beams with CFRP wraps，the average peak load capacities basically do not increase but the ductility and energy dissipation of joints are effectively improved. The failure modes of retrofitted joints are transformed from column-hinging mechanism to beam-hinging mechanism of strong-column-weak-beam. The retrofitting at columns only is a more effective scheme. Due to the presence of orthogonal beams, the joint core regions do not appear obvious shear damages even at large drift ratios. [ABSTRACT FROM AUTHOR]

Using a significant number of transverse hoops in the joint's core is one recognized way for achieving the requirements of strength, stiffness, and ductility under dynamic loading in a column joint. The shear capacity of a joint is influenced by the concrete's compressive strength, the anchoring of longitudinal beam reinforcement, the number of stirrups in the joint, and the junction's aspect ratio. Seismic motion on the beam may produce shear capacity and bond breaking in the joint, causing the joint to fracture. Furthermore, due to inadequate joint design and details, the entire structure is jeopardized. In this study, the specimens were divided into two groups for corner and interior beam–column joints based on the joint reinforcement detailing. The controlled specimen has joint detailing as per IS 456:2000, and the strengthened specimen has additional diagonal cross bars (modified reinforcement technique) at the joints detailed as per IS 456:200. The displacement time history curve, load-displacement response curves, load-displacement hysteretic curve, and load cycle vs. shear stress were used to compare the results of the controlled and strengthened specimens. The findings show that adding diagonal cross bars (modified reinforcing techniques) to beam–column joints exposed to cyclic loads enhances their performance. The inclusion of a diagonal cross bar increased the stiffness of the joint by giving an additional mechanism for shear transfer and ductility, as well as greater strength with minimum cracks. [ABSTRACT FROM AUTHOR]

The post-tensioned precast concrete system (PPS) developed in this study consists of U-shaped precast wide beams and concrete columns, where the continuity of wide beam-column joint is provided with the cast-in-place concrete on the U-shaped precast wide beam and the post-tensioning to the beam after casting of slab. The PPS structure can overcome the defect of discontinuity in the connections of precast members using cast-in-place concrete on precast members, and complement the low sectional efficiency of wide beam by applying the post-tensioning. In this study, an experimental investigation was performed with three half-scale specimens of interior connection fabricated employing PPS structure. Specifically, this paper presents the response of PPS interior beam-column joint subjected to cyclic lateral loading and evaluates the relevance of the beam-to-column width ratio criteria specified in ACI 318-05. The test results indicate that the PPS specimens can resist properly seismic loads maintaining overall structural integrity. [ABSTRACT FROM AUTHOR]