An Active Confined End-Beam Connection for Pre-Cast Rc Frames

Abstract

In this paper, a new pre-cast end-beam connection is proposed. Regarding the hypothesis that the transverse compressive stress can increase the bond strength between embedded reinforcements and surrounding concrete, a new detail for minimizing the connection's length at the end of the pre-cast beam is proposed. In this approach, active confinement works on the spliced length of the reinforcements. The effectiveness of the proposed method was verified through the pull-out tests on half-scaled T-shape specimens. Four pull-out tests were examined under different levels of active confinement. T-shape specimens, including one benchmark cast-in-place and three specimens with different details and active confinement levels, were tested under cyclic loading tests. Based on the results of pull-out tests, a good estimation was obtained to calculate the bond strength of rebars under active confinement. The results of the T-shape specimen confirmed the efficiency of the suggested method. The T-shape specimens passed the requirements of ACI T1.1-01 for new connections under cyclic loading tests.

Keywords: Bond resistance, Pre-cast connection, Friction resistance, Transverse confinement