Performance of Exterior Beam-Column Joints with U-Shaped Bars for Different Stirrups Detailing: Numerical Study | ||||
| Engineering Research Journal | ||||
| Article 6, Volume 172, Issue 0, December 2021, Page 131-150 PDF (847.42 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/erj.2021.208523 | ||||
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| Authors | ||||
| Mohamed H. El-Naqeeb* 1; Salah E. El-Metwally2; Basem S. Abdelwahed3 | ||||
| 1Teaching Assistant, Structural Engineering Department, Badr University in Cairo (BUC), Cairo, Egypt | ||||
| 2Prof. of Structural Concrete,Structural Engineering Department, Mansoura University, El-Mansoura, Egypt | ||||
| 3Lecturer of Structural Engineering, Structural Engineering Department, Mansoura University, El-Mansoura, Egypt | ||||
| Abstract | ||||
| The relevant detailing of joint reinforcement plays a major role in ensuring adequate performance of reinforced concrete frames in terms of strength and ductility. The reinforcement detailing of joints with U-shaped bars in most common codes is achieved by providing a minimum stirrups reinforcement ratio and a maximum spacing between them; however, the contribution of the cross ties configuration within the joint core in the shear resisting mechanism is not considered. The nonlinear finite element analysis using ABAQUS software has been employed in this study to numerically investigate the influence of different joint reinforcement configurations on joint performance. Four sets of beam-column connections with different joint stirrups configurations have been modeled for achieving this purpose, considering two validated experimentally tested beam-column connections as reference. This study reveals that achieving the codes minimum joint reinforcement ratio using both internal cross ties and outer stirrups instead of outer stirrups only is more efficient in terms of joint strength and deformation capacity which indicates that the contribution of the cross ties considering its shape and location in the shear strength resistance should be considered. It has been observed that both the joint strength and deformation capacity have been significantly improved with the use of two closed rectangular cross ties or one polygon cross tie within the joint region. Hence, those two layouts are considered as the most practical solutions in which the maximum spacing between the stirrups can be considerably increased without affecting the joint performance. The results also proved that the induced stress in the joint stirrups doesn’t necessarily reach their yield strength even at the instant of joint failure. Hence, the yielding assumption for all layers of joint reinforcement in some analytical models and different international codes is unsafe and needs some revision. | ||||
| Keywords | ||||
| Reinforced concrete frames; Exterior joints; Nonlinear finite element analysis; U-shaped bars; Stirrups detailing; Cross ties; Shear strength; Yielding | ||||
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