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.

Test Results and Nonlinear Analysis of RC T-beams Strengthened by Bonded Steel Plates

Wei Ren,Lesley H. Sneed,Yiting Gai,Xin Kang 한국콘크리트학회 2015 International Journal of Concrete Structures and M Vol.9 No.2

This paper describes the test results and nonlinear analysis of reinforced concrete T-beams strengthened by bonded steel plates under increasing static loading conditions. The first part of this paper discusses the flexural tests on five T-beams, including the test model design (based on similarity principles), test programs, and test procedure. The second part discusses the nonlinear numerical analysis of the strengthened beams, in which a concrete damage plasticity model and a cohesive behavior were adopted. The numerical analysis results are compared with experimental data and show good agreement. The area of bonded steel plate and the anchor bolt spacing were found to have an impact on the cracking load, yield load, and ultimate load. An increase in the area of steel plate and a reduction of the anchor spacing could significantly improve the cracking and ultimate loads and decrease the damage of the beam.

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.

Numerical Simulation of Prestressed Precast Concrete Bridge Deck Panels Using Damage Plasticity Model

Wei Ren,Lesley H. Sneed,Yang Yang,Ruili He 한국콘크리트학회 2015 International Journal of Concrete Structures and M Vol.9 No.1

This paper describes a three-dimensional approach to modeling the nonlinear behavior of partial-depth precast prestressed concrete bridge decks under increasing static loading. Six full-size panels were analyzed with this approach where the damage plasticity constitutive model was used to model concrete. Numerical results were compared and validated with the experimental data and showed reasonable agreement. The discrepancy between numerical and experimental values of load capacities was within six while the discrepancy of mid-span displacement was within 10 %. Parametric study was also conducted to show that higher accuracy could be achieved with lower values of the viscosity parameter but with an increase in the calculation effort.

Bond Behavior Between Steel Fiber Reinforced Polymer (SRP) and Concrete

Xingxing Zou,Lesley H. Sneed 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.5

Steel fiber reinforced polymer (SRP) composite materials, which consist of continuous unidirectional steel wires (cords) embedded in a polymeric matrix, have recently emerged as an effective solution for strengthening of reinforced concrete (RC) structures. SRP is bonded to the surface of RC structures by the same matrix to provide external reinforcement. Interfacial debonding between the SRP and concrete is a primary concern in this type of application. This study aimed to investigate the bond characteristics between SRP and concrete determined by single-lap direct shear tests with different composite bonded lengths and fiber sheet densities (cord spacings). Specimens with medium density fibers failed mainly due to composite debonding, whereas those with low density fibers failed due to fiber rupture. Results of specimens that exhibited debonding were used to determine the bond-slip relationship of the SRP-concrete interface and to predict the full-range load response, which was in good agreement with the experimental results. A database of SRP-concrete direct shear tests reported in the literature was also established. Four analytical equations derived for fiber reinforced polymer (FRP)-concrete debonding were evaluated based on the database results and were found to predict the maximum load within approximately 15% error on average, however, they all underestimated the effective bond length.

Review of Anchorage Systems for Externally Bonded FRP Laminates

Stephen V. Grelle,Lesley H. Sneed 한국콘크리트학회 2013 International Journal of Concrete Structures and M Vol.7 No.1

The most recent report by ACI Committee 440 on externally bonded fiber reinforced polymer (FRP) strengthening systems states that systems designed to mechanically anchor FRP should be studied in detail and substantiated by physical testing. To select and design an appropriate anchorage system for use in an FRP strengthening system, it is important that findings from previous research studies be known. This paper presents a comprehensive literature review of the performance of different mechanical anchorage systems used in FRP strengthening applications. Each anchorage system is discussed in terms of its purpose and performance. Advantages and disadvantages of each system are discussed, and areas in need of future research are explored.

Review of Anchorage Systems for Externally Bonded FRP Laminates

Grelle, Stephen V.,Sneed, Lesley H. Korea Concrete Institute 2013 International Journal of Concrete Structures and M Vol.7 No.1

The most recent report by ACI Committee 440 on externally bonded fiber reinforced polymer (FRP) strengthening systems states that systems designed to mechanically anchor FRP should be studied in detail and substantiated by physical testing. To select and design an appropriate anchorage system for use in an FRP strengthening system, it is important that findings from previous research studies be known. This paper presents a comprehensive literature review of the performance of different mechanical anchorage systems used in FRP strengthening applications. Each anchorage system is discussed in terms of its purpose and performance. Advantages and disadvantages of each system are discussed, and areas in need of future research are explored.