Bond–slip behaviour of deformed reinforcing bars embedded in well-confined concrete

• Main Authors: Kang, Shao-Bo, Tan, Kang Hai
• Other Authors: School of Civil and Environmental Engineering
• Format: Article
• Language: English
• Published: 2017
• Subjects: Concretes; Reinforcement
• Online Access: https://hdl.handle.net/10356/83640; http://hdl.handle.net/10220/42705
• Institution: Nanyang Technological University

Precast concrete beam–column sub-assemblages may exhibit pull-out failure of reinforcing bars embedded in the middle joint when subjected to column removal scenarios. This failure mode has to be considered in analytical study through a component-based joint model. However, current bond–slip models incorporated in design guidelines are incapable of predicting the load capacity and potential failure mode of reinforcing bars with inadequate embedment length in beam–column joints. Therefore, it is necessary to re-evaluate the bond–slip behaviour of embedded reinforcement. This paper presents an analytical approach to predict the force–slip relationship of reinforcement. In the approach, bond stress at the post-yield stage of reinforcement is calculated from existing test data of deformed rebars embedded in well-confined concrete under pull-out loads. The approach is calibrated by experimental results of steel bars with various embedment lengths. Simplified approaches are also developed in accordance with the bond stress profile along the embedment length and the average bond stress. Finally, a component-based joint model is established for precast concrete beam–column sub-assemblages, in which the force–slip relationships of reinforcement are derived from the proposed approach. The joint model yields reasonably good predictions of the compressive arch action and catenary action capacities of sub-assemblages under progressive collapse scenarios.