Upgrading of Deficient Disturbed Regions in Precast RC beams with Near Surface Mounted (NSM) Steel Bars

Qasim Muhammed SHAKIR, Ruqyia ALLIWE


An experimental study has been conducted to explore the response of self-compacting RC drop in- beams retrofitted with NSM steel bars under short-term static loading. Eleven specimens have been tested in this program, each of (200x400x1600 mm) dimensions with two values of (a/d), namely (1.0 and 1.5). Two of these beams have been considered as reference beams (efficiently reinforced). Three beams with reduced reinforcement, two with deficient main nib steel, while the third with reduced steel in hanger. The rest have been upgraded with different arrangements to retire the expected drop in strength. It was found that reduction of nib reinforcements to the half, results in decreasing load failure of about (11% & 5%) for (a/d) values of (1 and 1.5) respectively. Also, it is observed that retrofitting the nib region with horizontal NSM steel bars led to increase the failure load capacity by about (28.7%) for (a/d) =1. While, the enhancement in strength for specimen with (a/d) =1.5 was about (24%). The increase in the strength capacity for upgraded hanger regions vertical and inclined bars for a/d (1) was about (21.4% and 14.2%) respectively.


Disturbed regions; High strength; Upgrading of dapped ends; NSM steel bars

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