Bar stress-slip relationship in reinforced concrete joints with large inelastic bar strains
Tan, Kang Hai
Date of Issue2012
International Conference of Design and Analysis of Protective Structures (4th : 2012 : Jeju, Korea)
School of Civil and Environmental Engineering
NTU-MINDEF Protective Technology Research Centre
Experimental results indicate that for reinforced concrete (RC) members under large deformations, such as catenary action, wide cracking and severe concrete crushing are concentrated at the beam-column connections. Bar slip at wide cracks adjacent to joint interfaces results in large fix-end rotations and discontinuity that are not included in flexural analysis. Moreover, a large slip mainly results from elongation of a bar embedded into the beam-column joints, in particular, when the bar is in post-yield stage with a large inelastic strain. For cases of continuous bars or lap-spliced bars with adequate embedment lengths in joints, bar strains at the crack interfaces can even develop up to bar fracture. Therefore, bar stress-slip relationship at the crack interfaces is very critical to accurately predict structural behavior under large deformations and rotation capacity of RC members. In this paper, a macro-bar-stress-slip model is proposed based on the assumptions that (1) the distribution of bond stress within an elastic part or an inelastic part of a reinforcing bar remains uniform; (2) the slip of a reinforcing bar at the crack interfaces is computed directly from the bar extension over the embedment length within the joints and the slip at the free end; and (3) the constitutive model of reinforcement is bilinear. In addition, the proposed model considers the effects of short embedment length and high post-yield strain on bar stress-slip relationships. The proposed model will be validated by limited pullout test results and be verified by a micro-model with consideration of local bond-slip behavior.
DRNTU::Engineering::Civil engineering::Structures and design
© 2012 The Author(s).