Flexural Strength Of Prestressed Concrete Beams With Openings And Strengthened With CFRP Sheets
Dr. Mustafa B. Dawood, Haider H. A. Al-Katib
Index Terms: Flexural, Pretensioned, Prestressed Concrete Beams, Opening Width, Opening Depth, CFRP Sheets, Strengthening at Compression and Tension Zone.
Abstract: This paper presents an experimental investigation of flexural strength of pretensioned prestressed concrete beams with openings and strengthened with (CFRP) sheets, tested as simply supported span subjected under two-point loading. The experimental work includes testing of nine prestressed concrete beams specimens with dimensions (effective length 1800mm × depth 300mm × width 130mm), two of which were without openings as a control beams (one without and the other with strengthening by CFRP), three were with openings, and the remaining four with openings and strengthened with CFRP sheets. The opening was made at square shape (100×100) mm in flexure zone at mid span of beam. Several design parameters were varied such as: opening width, opening depth and strengthening of openings of beams by CFRP sheets at compression and tension zone. Experimental results showed that the presence of square opening (with ratio h/H= 0.333) and rectangular opening (with ratio h/H from 0.333-0.5) at mid span of beams decreased the ultimate load about (5.5)% and (5.5-33.1)% respectively when compared with beam without openings (control beam). The externally strengthened prestressed concrete beams with bonded CFRP sheets showed a significant increase at the ultimate load, this increase was about (10.9-28.8)% for flexure beams when compared with the unstrengthened beams. Moreover, the load-deflection curves for flexure beams strengthened with CFRP sheets were stiffer than the unstrengthened beams. Therefore, this results gave a good indication about using CFRP sheets in improvement of deflection.
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