Anchors for shear strengthening of damaged rc beam using bonded steel plate
Md Ashraful Alam, Mohammad Al-Amin
Department of Civil Engineering, University of Asia Pacific, Dhaka, Bangladesh
Appropriate anchor system has very important role for effective retrofitting of structure specially to prevent debonding of bonded plate for shear strengthening of damaged reinforced concrete beam. The debonding happens at concrete interface of externally bonded (EB) plate due to lower interfacial bond strength. Proper anchor system would enhance interfacial strength to prevent debonding failure. The main aim of the research work was to investigate the effectiveness of various anchor systems for externally bonded steel plate to enhance shear strength of damaged RC beams. A total of five full scale reinforced concrete beam had been fabricated, all beams were fully damaged in shear before strengthening. The damaged beams were then strengthened for shear using steel plates with double connector, multiple connector, welded connector and near surface embedded bar anchor systems. Design guideline had been proposed to obtain dimension of steel plate for shear strengthening of damaged RC beam. Results exhibited that all anchors prevented debonding of steel plate at concrete-adhesive interface. Welded connector (WC) and embedded bar (EB) anchors had completely prevented debonding failures of steel plate at concrete-adhesive and plate-adhesive interfaces. Double and multiple connector anchors failed due to crushing of concrete at anchor zone followed by debonding of plate. Whereas, un-anchored strengthened beam showed premature debonding of plate at concrete-adhesive interface followed by shear failure. The results of the research exhibited that double and welded connector anchors had excellent performance in increasing shear strength to re-store original shear capacities of damaged beams. The theoretical results were comparable with the experimental findings.
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