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International Concrete Abstracts Portal

Showing 1-5 of 788 Abstracts search results

Document: 

SP-360_08

Date: 

March 1, 2024

Author(s):

Nadia Nassif , M. Talha Junaid, Salah Altoubat, Mohamed Maalej, and Samer Barakat

Publication:

Symposium Papers

Volume:

360

Abstract:

Fiber-reinforced polymer (FRP) bars can serve as an appropriate substitute for steel rebar due to their lightweight, high strength, and good corrosion resistance. Nevertheless, the long-term success of FRP bars as promising reinforcement in concrete depends on understanding the bond between FRP bars and concrete. ACI 440.1R-15 recommends utilizing CSA S806-12 Annex S ‘‘Test Method for Determining the Bond-Dependent Coefficient of FRP Rods” for estimating the design value of the bond-dependent coefficient (kb). However, this testing method requires a four-point loaded 3.0-meter-long beam with continuous assessment of developed crack width. Due to the complexity of the test, studies were scarce in assessing the factors affecting the kb. Therefore, this study aimed to relate the experimental kb obtained from large-scale testing to a relatively simpler bond strength value, τu , obtained from smaller-scale FRP pull-out test. The relation was established utilizing data collection for both tests from experimental studies. Three machine learning techniques (Ensembled Trees Artificial Neural Network and Gaussian Process Machines) were then applied to mimic and understand the complex bond-behaviour at varying FRP and concrete properties. The results have shown promising relation (R2>0.8) between kb and τu for different surface textures and fibre types.


Document: 

SP-360_03

Date: 

March 1, 2024

Author(s):

Abubakar S. Ishaq, Maria M. Lopez, Charles E. Bakis, and Yoseok Jeong

Publication:

Symposium Papers

Volume:

360

Abstract:

This study evaluates the bond performance of concrete epoxy bonds using an image segmentation-based image processing technique. The Concrete Epoxy Interface (CEI) plays a crucial role in the structural performance of FRP-repaired concrete as it transfers stresses from the concrete to the epoxy. By employing the image segmentation technique, the performance of the CEI is assessed through the ratio of Interfacial Failure (IF) to other failure types, namely cohesive failure in Epoxy (CE) and Cohesive cracks in Concrete (CC). The effects of sustained loading duration on CEI bond performance are quantitatively analyzed using 21 single-lap shear (SLS) specimens and 28 notched 3-Point Bending (3PB) specimens. The findings highlight vital conclusions: CE is the least failure mode in SLS and 3PB specimens. In contrast, CC is the predominant failure mode, indicating the susceptibility of the concrete substrate in FRP-repaired concrete. Moreover, IF generally increases with longer sustained loading durations in 3PB specimens but decreases with increased loading duration in SLS specimens. The study also demonstrates the effectiveness of the image segmentation approach in evaluating CEI performance in 3PB specimens, where color distinguishes epoxy, FRP, and concrete substrate.


Document: 

SP-360_20

Date: 

March 1, 2024

Author(s):

Emmanuel Ferrier, Laurent Michel, Andrea Armonico

Publication:

Symposium Papers

Volume:

360

Abstract:

This paper presents the crack monitoring of reinforced concrete beams strengthened with fiber reinforced polymer (FRP) sheets. Emphasis is placed on the development of a smart FRP bonded material that can measure the crack opening of a reinforced concrete beam strengthened by FRP. The reliability measured by a conventional digital image correlation (DIC) and by the proposed smart FRP is employed to assess the contribution of the FRP to control the crack. The monitoring process is based on a large set of experimental database consisting of 19 test beams. The effect of FRP to control the crack opening is studied depending on the steel ratio, FRP ratio and the level of damaged of RC beams when FRP is applied. The results were compared with the theoretical values of crack width and spacing predicted using the Eurocode 2 (EC2) formula, calibrated for non-strengthened RC elements. The corresponding results were compared in order to clarify the effect of external bonded FRP on the cracking behaviour of RC beams.


Document: 

SP-360_51

Date: 

March 1, 2024

Author(s):

Todor Zhelyazov, Eythor Rafn Thorhallsson, Jonas Thor Snaebjornsson

Publication:

Symposium Papers

Volume:

360

Abstract:

The study delves into modeling the interface between Fiber-Reinforced Polymer (FRP) and concrete, with a specific emphasis on simulating the gradual deterioration of bond strength. A model rooted in continuum damage mechanics is integrated with an empirically derived relationship to address interfacial shear failure. Material models are defined for the concrete, the externally bonded FRP reinforcement, and the adhesive layer. These material models are implemented in finite element simulations, replicating experimental setups widely used to investigate the FRP-concrete interface. Key results are reported and discussed. More precisely, the numerically obtained load-slip relationships for the interface and visualizations of the damaged zones in concrete are provided. The numerical results are in close agreement with existing experimental data. The finite element analyses suggest that concrete degradation is not limited to the areas near the adhesive joint. This implies that the adhesive joint could influence the overall behavior of the structural elements, even when debonding failures are prevented by anchorage devices.


Document: 

SP-360_04

Date: 

March 1, 2024

Author(s):

Ali Alatify and Yail J. Kim

Publication:

Symposium Papers

Volume:

360

Abstract:

The serviceability and ultimate limit states of a concrete member are reliant upon the bond of reinforcement. The performance of glass fiber reinforced polymer (GFRP) reinforced concrete structures is influenced by multiple parameters and one of these parameters is the bond length of GFRP rebars. The scope of the present research is to experimentally study the effects of fully and partially bonded rebars on the load-bearing capacity and cracking of GFRP-reinforced concrete beams. The beams with partially bonded reinforcement show reduced capacities compared with those with fully bonded reinforcement, and the former reveals localized cracks. The partially bonded beams fail as a result of concrete splitting, while their fully bonded counterparts fail by concrete crushing.


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