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International Concrete Abstracts Portal

Showing 1-5 of 1088 Abstracts search results

Document: 

SP-360_13

Date: 

March 1, 2024

Author(s):

Girish Narayan Prajapati, Shehab Mehany, Wenxue Chen, and Brahim Benmokrane

Publication:

Symposium Papers

Volume:

360

Abstract:

This paper presents an experimental study that investigated the physical and mechanical properties of the helical wrap glass fiber-reinforced polymer (GFRP) bars. The physical tests are conducted to check the feasibility and quality of the production process through the cross-sectional area and evaluation of the fiber content, moisture absorption, and glass transition temperature of the specimens. While the mechanical tests in this study included testing of the GFRP specimens to determine their tensile properties, transverse shear, and bond strength. Four bar sizes (#3, #4, #5, and #6), representing the range of GFRP reinforcing bars used in practice as longitudinal reinforcement in concrete members subjected to bending, are selected in this investigation. The GFRP bars had a helical wrap surface. The tensile failure of the GFRP bars started with rupture of glass fibers followed by interlaminar delamination and bar crushing. The bond strength of the GFRP bars satisfied the limits in ASTM D7957/D7957M. The test results reveal that the helical wrap GFRP bars had physical and mechanical properties within the standard limits.

DOI:

10.14359/51740625


Document: 

SP-360_23

Date: 

March 1, 2024

Author(s):

Raphael Kampmann, Tim Rauert, Niklas Pelka, und Bastian Franzenburg

Publication:

Symposium Papers

Volume:

360

Abstract:

Corrosion of reinforcement steel is a major issue for many structural concrete components, because it leads to strength reduction and may significantly reduce the service life. For this reason, fiber-reinforced polymer rebars (FRP rebars) have been developed, as they represent a viable alternative that may replace reinforcing steel for structures that are particularly susceptible to corrosion issues. However, structural design philosophies for these new materials are still in development and further research is needed to implement FRP rebars properly and safely in design codes but also to ensure that design calculations properly predict the actual behavior and performance of FRP reinforced structures.

This study was conducted to evaluate the strength and structural deformation behavior of flexural beams that were designed according to Eurocode 2 and, for comparison, according to different design methods pro-posed for FRP reinforced structures. With regard to the development of a uniform design concept for alternative reinforcement materials existing in Germany/Europe, different bending design concepts includ-ing the serviceability limit state were evaluated. In addition, the theoretically calculated and predicted strength/deformation were compared to the experimentally obtained measurements. A total of 15 flexu-ral beams, with ans overall length of 4.5 m (177 in.), a width of 200 mm (7.8 in.), and a height of 400 mm (15.8 in.), were cast; three of these beams (designed according to Eurocode 2) featured traditional steel rein-forcement, to serve as control group. The remaining 12 flexural beams were evenly allocated to capture the two alternative reinforcement materials, while generating three different reinforcement distribution patterns with comparable reinforcement ratios (equivalent cross-sectional areas). Thus, a total of six subgroups –three with GFRP and three with BFRP – each with two specimens, were analized. To test all beam in pure bending and to eliminate the influence from shear forces, two equally increasing loads were applied at the (longitudinal) third-points of the beams. Both deflections and loads were measured at several points to evaluate the structural performance of the FRP reinforced structural members.

The results showed that the deflection of the glass fiber reinforced bars at the design load capacity measured twice as much as the deflection of the control group. Almost three times as much deflection (at the same load) was observed for the concrete beams reinforced with basalt fiber rebars. In addition, it was observed that the concrete beams with glass and basalt fiber reinforcement bars showed a nearly elastic-elastic behavior up to the point of failure, whereas the steel-reinforced concrete beams showed an elastic-plastic behavior. However, the deformational behavior differed between the various beam types. While the prevailing equations properly captured the post-cracking performance of traditionally reinforced concrete beams, they do not adequately predict the deflections of FRP reinforced concrete beams. From the measurements and analyses, it was concluded that the serviceability limit state (SST) is more critical than the ultimate limit state (LTS) for the design of concrete flexural beams reinforced with FRP rebars.

DOI:

10.14359/51740635


Document: 

SP-360_01

Date: 

March 1, 2024

Author(s):

Junrui Zhang, Enrique del Rey Castillo, Ravi Kanitkar, Aniket D Borwankar, and Ramprasath R

Publication:

Symposium Papers

Volume:

360

Abstract:

A systematic literature review was conducted on pure tension strengthening of concrete structures using fiber-reinforced polymer (FRP), specifically for larger FRP tie applications. This work yielded a dataset of 1,627 direct tension tests, and highlighted the limitation of existing studies on studying thick and long FRP ties, which are typical in real construction scenarios. To overcome this shortcoming, 51 single lap shear tests were conducted on thicker and longer FRP ties, with the dimensions being 0.5 to 6 mm [0.02 to 0.24 in.] thickness, and 300 to 1,524 mm [12 to 60 in.] long. The critical parameters under consideration were concrete compressive strength, FRP thickness, and bond length. The findings demonstrate that thicker and therefore stiffer FRP ties have higher debond force capacity, while longer ties exhibit greater post-elastic deformation capacity but do not affect the debond force capacity. Concrete had a limited effect on either debond force or deformation capacity. A strength model is proposed for FRP systems under axial pure tension, which aligns well with both the published and tested results. This paper focuses on the development of design guidelines and codes to predict the debond strain for EB-FRP systems incorporating thicker and longer FRP ties, aiming to enhance the applicability of FRP to real-world construction scenarios.

DOI:

10.14359/51740613


Document: 

SP-360_11

Date: 

March 1, 2024

Author(s):

Mohamed Ahmed, Slimane Metiche, Radhouane Masmoudi, Richard Gagne, and Jean- Philippe Charron

Publication:

Symposium Papers

Volume:

360

Abstract:

his paper presents preliminary experimental and numerical results of a research program aimed at investigating the residual capacity of 60-year-old reinforced concrete bridge girders strengthened using CFRP sheets. Two 4.5 m and 5.0 m long, bridge girders were deconstructed from a bridge located in Canada. The two 60-year-old girders have been strengthened with CFRP for the last six years of the service life of the bridge. The two full-scale girders were tested at the structural lab of Sherbrooke’s University after having suffered under real service conditions. A finite element model using the ANSYS program had been validated with the experimental results before it was used as a control sample for non-strengthened conditions. The test results revealed that the CFRP strengthening technique can extend the service life of the bridge element by keeping their shear capacity safe. The CFRP strengthening configuration of the two girders increased the maximum shear capacity by 35.5 % and 30 % over the finite element control model. The presented outcomes show the effectiveness of using the external CFRP sheets as an external technique for bridge rehabilitation. The test results were compared with the ACI 440 2R-17 and CSA S6-19 design guidelines. The theoretical comparison between guidelines, experimental and numerical results shows that the two guidelines are considered overly conservative.

DOI:

10.14359/51740623


Document: 

SP-360_40

Date: 

March 1, 2024

Author(s):

Lin S-H, Kim I, Borwankar A, Kanitkar R, Hagen G, Shapack G

Publication:

Symposium Papers

Volume:

360

Abstract:

Fiber reinforced polymers (FRP) are commonly used to seismically retrofit concrete structural walls. Limited design guidance for the seismic application of FRP strengthening is currently available to designers in guidelines such as ACI PRC-440.2-17 or standards like ASCE/SEI 41-17. This paper presents the description and results of an experimental effort to investigate the effectiveness of FRP retrofitted concrete walls. The specimen wall thickness was either 6 in or 12 in, which represents a typical range of wall thickness seen in older buildings. To better reflect the most common applications seen in the industry, the walls were retrofitted with FRP, and anchored with fiber anchors only on one side of the wall. The study demonstrates that the effectiveness of FRP is reduced as the wall thickness increases and that the FRP must be anchored to the wall for any tangible benefit. The results are used to assess the current provisions in ACI PRC-440.2-17 and ASCE/SEI 41-17. It is apparent that additional testing is required to better understand the complexities involved in the FRP strengthening of shear walls and such testing is scheduled for the near future.

DOI:

10.14359/51740652


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