Proposal for Development of Positive Moment Reinforcement
S.-G. Hong and D.-J. Kim
Appears on pages(s):
bar; beam; flexural bond; positive moment
This study proposes a new design formula for the development of positive moment reinforcement in tension. A review of current design code provisions for the end anchorage at simply supported beams shows unsatisfactory requirement for flexural bond strength and that an additional length beyond simple supports is needed. The code provisions neglect a tensile force increase due to shear force and hence, the formulas assume zero tensile force at simple support locations. This paper shows that the treatment for both the flexural bond strength and anchorage requirements is necessary for the safe detailing of reinforcement at beam end regions. Investigation of bond-related failures in these regions shows that it is necessary to differentiate between the anchorage force and flexural bond strength along the bar. Comparison between bond strengths required by current design concept and the proposed formula shows a need for modification of current code provisions for end anchorage.