Abstract
This paper presents an experimental investigation on the behavior of retrofitted beam-column joints subjected to reversed cyclic loading. The experimental program comprises 8 external beam-column joint connection subassemblages tested in 2 phases; one was the damaging phase and second was the repairing phase. The Beam-column joints were designed only for gravity loads. The joints had no beam-column joint transverse reinforcement and special stirrups in beam and column critical zones. These Non-Seismically designed (NS) joints were damaged with different levels at the first phase of the experiment. In the second phase, the damaged joints were strengthened with externally bonded carbon-fibre-reinforced polymers (C-FRP) sheets. From the observed responses of the examined specimens it can be deduced that the technique of externally bonded retrofitting (EBR) using C-FRP sheets is appropriate for the rehabilitation of the joints seismic capacity. This technique had a significant improvement of the energy dissipation and the performance level and finally it leads to improved type of damages compared with the damage modes of the specimens during the initial loading. Shortcomings of the application of C-FRP sheets for practical use are also pointed out.
Highlights
The repair and rehabilitation of reinforced concrete structures damaged by earthquakes are challenging fields of study in earthquake engineering, which have been developed during the last two decades
Similar to NS1R specimen according to Figure 7, NS2R specimen increased the load-carrying capacity on average to 3% compared to the ultimate capacity of NS5 specimen up to the drift 5% without any failure of FRP layers
Since the structural performance levels are determined from the plastic rotation of beams and columns, beam and column plastic rotation-moment curves are used to evaluate of the joint performance levels
Summary
The repair and rehabilitation of reinforced concrete structures damaged by earthquakes are challenging fields of study in earthquake engineering, which have been developed during the last two decades. Research in this area is essential since engineers in seismic-prone regions often face the problem of designing the repair or strengthening of damaged buildings without quantitative guidance. An effort to use carbon-fiber-reinforced plastic (C-FRP) sheets in the improvement of the seismic capacity and stiffness of reinforced concrete exterior beam–column connections is presented. The joints had no beam-column joint transverse reinforcement and special stirrups in beam and column critical zones These Non-Seismically designed (NS) joints were damaged up to the different levels at the first phase of the experiment. The results are presented as tables and hysteresis response curves, and eventually evaluated and compared
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