Experimental study of seismic behavior and modification of the failure region of mechanical bar splices

Articles in Press

Document Type : Research Note

Authors

1 Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Professor IIEES

10.24200/j30.2024.63880.3292

Abstract

The problem of overcrowding at the junction of the rebars is very significant, particularly for seismic details. Due to bar length limits, splicing of reinforcing bars is unavoidable in reinforced concrete (RC) structures and may alter the overall behavior of structures under static and dynamic stresses. Mechanical couplers can thus offer an appealing solution that eliminates the disadvantages of traditional reinforcement splicing. In the mechanical splice method, couplers are rigid components that are used to join reinforcement bars together. According to existing research, the failure mechanism of a thread splice under tensile and cyclic loads has not been sufficiently investigated. In addition, the use of the thread splice needs further investigation in the plastic hinge areas of ductile members in seismic areas. In this study, two types of patches are introduced by modifying the method of making a threaded splice and combining it with rotary friction welding. The goal is to modify the coupler's failure area with a threaded bar and use it in the plastic hinge areas of ductile members in seismic areas. The splice area in the suggested method is large. Two techniques are used to increase the splice area: cold rolling and rotating friction welding. In total, 96 samples were tested (three repeated samples of each type).  Threaded couplers (TC), oversize-threaded couplers (OTC), rotary friction welding splices with threaded couplers (RFWTC), and non-spliced (NS) reference specimens were tested with and without concrete in uniaxial tensile and cyclic tests.  Evaluations were conducted on the sensitivity to bar diameter, bar strength, ductility, energy absorption, and failure mode performance. The RFWTC and OTC exhibited superior performance in terms of strength, ductility, energy absorption, and failure mode, making them appropriate for use in high seismic zones. The TC is also suitable for use in zones with low to medium seismic activity. Furthermore, the anticipated model is enough for estimating the threaded couplers' ultimate tensile strength.

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Sharif Journal of Civil Engineering

Articles in Press, Accepted Manuscript
Available Online from 20 March 2025

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