Effect of spiral reinforcement on flexural-shear-torsional seismic behavior of reinforced concrete circular bridge columns

Abdeldjelil Belarbi,Suriya Prakash,Young-Min You 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2

This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.

Effect of spiral reinforcement on flexural-shear-torsional seismic behavior of reinforced concrete circular bridge columns

Belarbi, Abdeldjelil,Prakash, Suriya,You, Young-Min Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2

This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.

Damage Assessment of Square RC Bridge Columns Subjected to Torsion Combined with Axial Compression, Flexure, and Shear

Qian Li,Abdeldjelil Belarbi 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.3

Reinforced Concrete (RC) bridge columns can be subjected to combined flexure, shear, axial and torsional loadings under multidirectional earthquake motions and significant vertical motions, specifically in skewed and curved bridges, bridges with specific structural restraints, and bridges with unequal spans or column heights. This paper presents experimental and analytical studies to assess the damage progression of square RC bridge columns under combined loadings including torsion. The main variable in this study is the ratio of Torsional-to-bending Moments (T/M). The effects of combined loadings on the torsional and flexural hysteretic responses, strength, plastic hinge distribution, and progression of damage states are highlighted in this paper. A unified equivalent damage index model is proposed to couple the flexural and torsional actions for combined loadings. Quantified damage indices value under combined loadings can be correlated to the categorized damage states from a performance-based point of view. Based on the experimental and analytical results, the progression of damage was found to be amplified by the torsion effect, and the rotational ductility was decreased due to the effect of combined loadings.

Effective Bond Length of FRP Sheets Externally Bonded to Concrete

Mongi Ben Ouezdou,Abdeldjelil Belarbi,Sang-Wook Bae 한국콘크리트학회 2009 International Journal of Concrete Structures and M Vol.3 No.2

Strengthening and repair of concrete structures using externally bonded fiber reinforced polymer (FRP) composite sheets has been popular around the world during the last two decades. However, premature failure due to debonding of the FRP is one of the important issues still to be resolved. Numerous research studies have dealt with the debonding problem in terms of Effective Bond Length (EBL), however, determination of this length has not yet been completely assessed. This paper summarizes previous works on the EBL and proposes a new relationship of the EBL with the FRP stiffness based on the existing experimental data collected in this study.

Effective Bond Length of FRP Sheets Externally Bonded to Concrete

Ben Ouezdou, Mongi,Belarbi, Abdeldjelil,Bae, Sang-Wook Korea Concrete Institute 2009 International Journal of Concrete Structures and M Vol.3 No.2

Strengthening and repair of concrete structures using externally bonded fiber reinforced polymer (FRP) composite sheets has been popular around the world during the last two decades. However, premature failure due to debonding of the FRP is one of the important issues still to be resolved. Numerous research studies have dealt with the debonding problem in terms of Effective Bond Length (EBL), however, determination of this length has not yet been completely assessed. This paper summarizes previous works on the EBL and proposes a new relationship of the EBL with the FRP stiffness based on the existing experimental data collected in this study.

Crack mapping in RC members using distributed coaxial cable crack sensors: modeling and application

Gary Greene, Jr.,Abdeldjelil Belarbi,Genda Chen 국제구조공학회 2005 Smart Structures and Systems, An International Jou Vol.1 No.4

The paper presents a model to calculate reinforcement strain using measured crack width in members under applied tension, flexure, and/or shear stress. Crack mapping using a new type of distributed coaxial cable sensors for health monitoring of large-scale civil engineering infrastructure was recently proposed and developed by the authors. This paper shows the results and performance of such sensors mounted on near surface of two flexural beams and a large scale reinforced concrete box girder that was subjected to cyclic combined shear and torsion. The main objectives of this health monitoring study was to correlate the sensor response to strain in the member, and show that magnitude of the signal reflection coefficient is related to increases in applied load, repeated cycles, cracking, and reinforcement yielding. The effect of multiple adjacent cracks, and signal loss was also investigated. The results shown in this paper are an important step in using the sensors for crack mapping and determining reinforcement strain for in-situ structures.

Crack mapping in RC members using distributed coaxial cable crack sensors: modeling and application

Greene, Gary Jr.,Belarbi, Abdeldjelil,Chen, Genda Techno-Press 2005 Smart Structures and Systems, An International Jou Vol.1 No.4

The paper presents a model to calculate reinforcement strain using measured crack width in members under applied tension, flexure, and/or shear stress. Crack mapping using a new type of distributed coaxial cable sensors for health monitoring of large-scale civil engineering infrastructure was recently proposed and developed by the authors. This paper shows the results and performance of such sensors mounted on near surface of two flexural beams and a large scale reinforced concrete box girder that was subjected to cyclic combined shear and torsion. The main objectives of this health monitoring study was to correlate the sensor's response to strain in the member, and show that magnitude of the signal's reflection coefficient is related to increases in applied load, repeated cycles, cracking, and reinforcement yielding. The effect of multiple adjacent cracks, and signal loss was also investigated. The results shown in this paper are an important step in using the sensors for crack mapping and determining reinforcement strain for in-situ structures.

Rapid Repair of Severely Damaged RC Columns with Different Damage Conditions

Ruili He,Lesley H. Sneed,Abdeldjelil Belarbi 한국콘크리트학회 2013 International Journal of Concrete Structures and M Vol.7 No.1

Rapid and effective repair methods are desired to enable quick reopening of damaged bridges after an earthquake occurs, especially for those bridges that are critical for emergency response and other essential functions. This paper presents results of tests conducted as a proof-of-concept in the effectiveness of a proposed method using externally bonded carbon fiber reinforced polymer (CFRP) composites to rapidly repair severely damaged RC columns with different damage conditions. The experimental work included five large-scale severely damaged square RC columns with the same geometry and material properties but with different damage conditions due to different loading combinations of bending, shear, and torsion in the previous tests. Over a three-day period, each column was repaired and retested under the same loading combination as the corresponding original column. Quickset repair mortar was used to replace the removed loose concrete. Without any treatment to damaged reinforcing bars, longitudinal and transverse CFRP sheets were externally bonded to the prepared surface to restore the column strength. Measured data were analyzed to investigate the performance of the repaired columns compared to the corresponding original column responses. It was concluded that the technique can be successful for severely damaged columns with damage to the concrete and transverse reinforcement. For severely damaged columns with damaged longitudinal reinforcement, the technique was found to be successful if the damaged longitudinal reinforcement is able to provide tensile resistance, or if the damage is located at a section where longitudinal CFRP strength can be developed.

Rapid Repair of Severely Damaged RC Columns with Different Damage Conditions: An Experimental Study

He, Ruili,Sneed, Lesley H.,Belarbi, Abdeldjelil Korea Concrete Institute 2013 International Journal of Concrete Structures and M Vol.7 No.1

Rapid and effective repair methods are desired to enable quick reopening of damaged bridges after an earthquake occurs, especially for those bridges that are critical for emergency response and other essential functions. This paper presents results of tests conducted as a proof-of-concept in the effectiveness of a proposed method using externally bonded carbon fiber reinforced polymer (CFRP) composites to rapidly repair severely damaged RC columns with different damage conditions. The experimental work included five large-scale severely damaged square RC columns with the same geometry and material properties but with different damage conditions due to different loading combinations of bending, shear, and torsion in the previous tests. Over a three-day period, each column was repaired and retested under the same loading combination as the corresponding original column. Quickset repair mortar was used to replace the removed loose concrete. Without any treatment to damaged reinforcing bars, longitudinal and transverse CFRP sheets were externally bonded to the prepared surface to restore the column strength. Measured data were analyzed to investigate the performance of the repaired columns compared to the corresponding original column responses. It was concluded that the technique can be successful for severely damaged columns with damage to the concrete and transverse reinforcement. For severely damaged columns with damaged longitudinal reinforcement, the technique was found to be successful if the damaged longitudinal reinforcement is able to provide tensile resistance, or if the damage is located at a section where longitudinal CFRP strength can be developed.