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Strengthening of reinforced concrete beams constructed with substandard steel reinforcement termination
Practical applications for the use of fibre reinforced polymer (FRP) composite materials for the seismic strengthening of reinforced concrete beams that have been constructed with a substandard beam bar termination method were experimentally investigated in this study. Results suggest that the cut-off reinforced concrete beam design does not meet the standard design codes and that if no extra shear reinforcement is arranged in the curtailed region, the beam may be subject to brittle failure. Installation of FRP plates for flexural and shear strengthening can successfully correct the deficiency. The results show that the FRP composite beams could withstand rotation levels greater than those expected to be imposed during an earthquake event. Expenmental results indicate that under some circumstances, the critical moment resisting region of beam frames designed for earthquake resistance, but constructed with the substandard steel reinforcing termination design, may be subject to the formation of negative plastic hinges in apparently unexpected regions. This occurs due to the combined effects of slab reinforcement and longitudinal beam bar curtailment on the overall seismic response of the frame. The experimental results for seismic retrofitting of RC beams with design deficiencies of the beam bar curtailment type, indicate that due to the negative moment, flexural enhancement is necessary. It is recommended that the flexural strength at the bar cut-off points be enhanced to ensure that a strain limit of 0 4% can be imposed on the GFRP plate U-shaped GFRP strips were glued to three sides of the beam frame. These acted as shear steel stirrups in the area of the cut-off region and enhanced the shear capacity of the beams so as to prevent premature flexure-shear cracking from occurring. However, the bonding of this type of strip to the sides of a beam is ineffective in resisting shear unless they are properly anchored at their ends.
Strengthening of reinforced concrete beams constructed with substandard steel reinforcement termination
Practical applications for the use of fibre reinforced polymer (FRP) composite materials for the seismic strengthening of reinforced concrete beams that have been constructed with a substandard beam bar termination method were experimentally investigated in this study. Results suggest that the cut-off reinforced concrete beam design does not meet the standard design codes and that if no extra shear reinforcement is arranged in the curtailed region, the beam may be subject to brittle failure. Installation of FRP plates for flexural and shear strengthening can successfully correct the deficiency. The results show that the FRP composite beams could withstand rotation levels greater than those expected to be imposed during an earthquake event. Expenmental results indicate that under some circumstances, the critical moment resisting region of beam frames designed for earthquake resistance, but constructed with the substandard steel reinforcing termination design, may be subject to the formation of negative plastic hinges in apparently unexpected regions. This occurs due to the combined effects of slab reinforcement and longitudinal beam bar curtailment on the overall seismic response of the frame. The experimental results for seismic retrofitting of RC beams with design deficiencies of the beam bar curtailment type, indicate that due to the negative moment, flexural enhancement is necessary. It is recommended that the flexural strength at the bar cut-off points be enhanced to ensure that a strain limit of 0 4% can be imposed on the GFRP plate U-shaped GFRP strips were glued to three sides of the beam frame. These acted as shear steel stirrups in the area of the cut-off region and enhanced the shear capacity of the beams so as to prevent premature flexure-shear cracking from occurring. However, the bonding of this type of strip to the sides of a beam is ineffective in resisting shear unless they are properly anchored at their ends.
Strengthening of reinforced concrete beams constructed with substandard steel reinforcement termination
Verstärkung armierter Betonträger mit Substandard-Stahlarmierungsenden
Wang, Yung-Chih (author) / Hsu, Kai (author)
Composite Structures ; 85 ; 10-19
2008
10 Seiten, 10 Bilder, 1 Tabelle, 14 Quellen
Article (Journal)
English
| British Library Online Contents | 2002