Abstract
Beam-column joints are critical regions for reinforced concrete (RC) frames subjected to earthquakes. The steel reinforcement is, in general, highly concentrated in these zones. This is why in many cases, headed bars are used. A headed bar is a longitudinal steel reinforcement whose end has a special button added to reduce the bonding length of the steel rebar. This paper establishes a formula predicting the shear strength of exterior RC beam-column connections where the beam longitudinal reinforcements use headed bars. A database was collected, which contained 30 experimental data about the exterior beam-column joints using headed bars and subjected to quasi-static cyclic loading. First, from the collected database, a statistical study was carried out to identify the most influencing parameters on the shear strength of the beam-column joints tested. The three most important parameters were identified and an empirical modified formula was developed based on the formula existing in the standards. The study showed that the results obtained from the modified formula proposed in the present study were closer to the experimental results than that obtained from the formula existing in the standards. Finally, a numerical study was performed on two T-form RC structures and the numerical results were compared with the prediction calculated from the modified formula proposed. For two investigated cases, the proposed formula provided the results in the safety side and the differences with the numerical results were less than 20%. Thus, the proposed formula can be used for a rapid assessment of the shear strength of RC joints using headed bars.
Highlights
Beam-column joints are commonly considered as critical regions of reinforced concrete (RC) frame structures, especially when an RC structure undergoes seismic loading
The proposed formula can be used for a rapid assessment of the shear strength of RC joints using headed bars
These values for the prediction of the AJI model were AVG = 0.77, coefficient of variation (COV) = 26.9 and average error (AVE) = 41.7%. These figures show that for the database of 30 specimens studied in this paper, the formula proposed in ACI and AIJ standards overestimate the shear strengths of the specimens in the most of cases, while the results predicted by the model proposed in the present study (Vmodel ) provided closer results to the experiments than two standards
Summary
Beam-column joints are commonly considered as critical regions of RC frame structures, especially when an RC structure undergoes seismic loading. The prediction of the beam bending moment capacity is relatively relevant, while the prediction of the joint shear strength is still to be investigated [1,2,3,4,5] This is why numerous studies have been performed to investigate the behavior of beam-column joints. The two most important requirements are the anchored length of the beam reinforcement bars into the joint and the amount of the horizontal stirrups at the joint. Sustainability 2018, 10, 401 two most important requirements are the anchored length of the beam reinforcement bars into the joint and the amount of the horizontal stirrups at the joint. To meet these two requirements, the beam are currently bentbent in ain. The relevancy of the formula proposed was verified by comparing the results obtained by the empirical formula and that from the numerical models
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
