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RISS 인기검색어
- 검색키워드
- 저자 : M. Reza Esfahani (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Strengthening of Two-way RC Slabs with Central Opening
Amirhossein Eskandarinadaf,M. Reza Esfahani 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.3
Although creating an opening in an existing Reinforced Concrete (RC) slab is permitted under specific circumstances, it may lead to a weakened slab. To investigate the strengthening of two-way RC slabs with an opening, six full-scale two-way RC slabs with a central opening, in addition to one reference slab without opening, were tested up to failure under monotonic and cyclic loading. These six slabs consisted of one control un-strengthened slab and five strengthened slabs. The strengthening methods used in this study were either Externally Bonded Glass Fiber Reinforced Polymer (EB-GFRP) or embedded extra steel bars at the tension side of the slabs, as proposed by ACI 318-14 (2014). Failure modes, cracking patterns, ultimate loads, and load -deflection relationships of all slabs are reported. The test results show that using GFRP strengthening method could increase the ultimate strength and flexural stiffness of the slabs significantly. Moreover, embedding extra steel bars around the opening as proposed by ACI 318-14 (2014) may not enhance the load-carrying capacity of the slab to the value of the continuous slab. The test results also show that the deflections of the strengthened slabs with opening under service loads are more than that of the slab without opening.
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Javad Sabzi,M. Reza Esfahani,Togay Ozbakkaloglu,Ahmadreza Ramezani 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.1
The present study experimentally and analytically investigates the effect of tensile reinforcement ratio and arrangement on the behavior of FRP strengthened reinforced concrete (RC) beams. The experimental part of the program was comprised of 8 RC beams that were tested under four-point bending. Results have shown that by keeping the total cross-section area of tensile reinforcing bars constant, in specimens with a low reinforcement ratio, increasing the number and decreasing the diameter of bars in the section lead to 21% and 29% increase in the load-carrying capacity of specimens made with normal and high compressive strength, respectively. In specimens with high reinforcement ratio, a different behavior was observed. Furthermore, the accuracy of the existing code provisions and analytical models in predicting the load-carrying capacity of the FRP strengthened beams failed by premature debonding mode were evaluated. Herein, a model is proposed which considers the tensile reinforcement ratio (as opposed to code provisions) to achieve more accurate results for calculating the load carrying capacity of FRP strengthened RC beams.
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Behavior of exterior concrete beam-column joints reinforced with Shape Memory Alloy (SMA) bars
Hossein Rezaee Azariani,M. Reza Esfahani,Hashem Shariatmadar 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.1
This research was conducted to study the behavior of exterior concrete beam-column joints with reinforced shape memory alloy (SMA) bars tested under cyclic loading. These bars benefit from superelastic behavior and can stand high loads without residual strains. The experimental part of the study, 8 specimens of exterior concrete beam-column joints were made and tested. Two different types of concrete with 30 and 45 MPa were used. Four specimens contained SMA bars and 4 specimens contained steel bars in beam-column joints. Furthermore, different transverse reinforcements were used in beams investigate the effects of concrete confinement. Specimens were tested under cyclic loading. Results show that SMA bars are capable of recentering to their original shape after standing large displacements. Due to the superelastic behavior of SMA bars, cracks at the joint core vanish under cyclic loading. As the cyclic loading increased, bending failure occurred in the beam outside the joint core. In the analytical parts of the study, specimens were simulated using the SeismoStruct software. Experimental and analytical results showed a satisfactory correlation. Plastic hinge length at the beam joint for specimens with SMA and steel bars was calculated by empirical equations, experimental and analytical results. It was shown that Paulay's and Priestley's equations are appropriate for concrete beam-column joints in both types of bars.
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