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  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-5 of 11 Abstracts search results

Document: 

SP304-01

Date: 

October 27, 2015

Author(s):

Junwon Seo, Yail J. Kim, and Shadi Zandyavari

Publication:

Symposium Papers

Volume:

304

Abstract:

This paper presents the performance reliability of reinforced concrete beams strengthened with fiber reinforced polymer (FRP) sheets, including structural fragility. Emphasis is placed on the development of effective strains that can represent FRP-debonding failure. The reliability predicted by a conventional standard log-normal cumulative probability density function and by the proposed response surface metamodel (RSM) combined with Monte-Carlo simulation (MCS) is employed to assess the contribution of physical attributes to debonding failure. The models are constructed based on a large set of experimental database consisting of 230 test beams collected from published literature. Another aspect of the study encompasses the effect of various RSM parameters on the variation of effective strains, such as FRP thickness (tf), steel reinforcement ratio (ρ), concrete strength (fc), beam height (h), beam width (w), span length (L), and shear span (a). The mutual interaction between these parameters indicates that those related to beam geometry (i.e., L, w, h, and a parameters) and the tf parameter are significant factors influencing the effective strain of FRP-strengthened beams.

DOI:

10.14359/51688551


Document: 

SP304-10

Date: 

October 27, 2015

Author(s):

Hamid Y. Omran and Raafat El-Hacha

Publication:

Symposium Papers

Volume:

304

Abstract:

A nonlinear 3D Finite Element (FE) analysis was performed to predict the post-exposure load-deflection responses of Reinforced Concrete (RC) beams strengthened in flexure using prestressed Near-Surface Mounted (NSM) Carbon Fibre Reinforced Polymer (CFRP) strips. Five RC beams (5.15 m [16.90 ft] long) were modeled including one un-strengthened control beam and four beams strengthened using NSM-CFRP strips prestressed to 0, 20, 40, and 60% of the ultimate CFRP tensile strain. The beams were severely deteriorated due to applying accelerated environmental conditions consisting of 500 freeze-thaw cycles: three cycles per day between +34°C [93°F] to -34°C [-29°F] with fresh water spray for 10 minutes at a rate of 18 L/min [4.8 gallon/min] at temperature +20°C. The accelerated environmental conditions used in this study equivalent to 0.46 year of exposure inside a chamber, corresponds to a minimum lifetime of 12.8 years in Canada. Simultaneously, each beam was subjected to a sustained load equal to 62 kN [13.9 kip] representing 47% of analytical ultimate load of the non-prestressed NSM-CFRP strengthened RC beam. The degradation which occurred in the concrete properties, concrete-epoxy interface, and steel reinforcement was considered in the FE model. Also, debonding at the concrete-epoxy interface was simulated by assigning shear and normal fracture energies and the prestressing was applied to the CFRP strip using an equivalent temperature. The FE model was validated with the experimental test results. However, the experimental and numerical load-deflection curves were comparable up to yielding but after yielding, the predicted curves were not in good agreement with the experimental ones.

DOI:

10.14359/51688560


Document: 

SP304-05

Date: 

October 27, 2015

Author(s):

Gordon Salisbury and Vicki Brown

Publication:

Symposium Papers

Volume:

304

Abstract:

This paper presents a detailed investigation into the load-deformation response of reinforced concrete beams strengthened with mechanically fastened fiber-reinforced polymers (MF-FRP). A bearing-slip model was developed for MF-FRP connections fastened with concrete expansion anchors. The model was used to predict the interfacial change in strain between the concrete and the FRP. When combined with load deformation constitutive equations, the bearing-slip model better predicted the load-deformation behavior in MF-FRP strengthened concrete beams. Comparisons to experimental data showed that the developed method reasonably predicts (typically within 8%) actual beam response at ultimate load. Moment-curvature diagrams were also developed and used to predict midspan deflection, typically within 30% of experimental results.

DOI:

10.14359/51688555


Document: 

SP304

Date: 

October 27, 2015

Publication:

Symposium Papers

Volume:

304

Abstract:

Editors: Yail J. Kim, Baolin Wan, Isamu Yoshitake

Since the major milestones of sustainability, such as the Hannover Principle in 1991 and the Kyoto Protocol in 1997, the concept of sustainability has been broadly adopted by various disciplines. New construction consumes considerable amounts of energy and materials, and CO2 emission in 2020 is expected to increase by 100%, compared with that of today. Technical communities are responsible for improving the sustainability of the built-environment by using more durable and highly efficient materials to reduce the need for replacement, maintenance, or repair. When subjected to aggressive environments, the performance of constructed concrete bridges and their elements is of interest from socioeconomic perspectives. Advances in a variety of aspects are required to achieve such a goal, including the durability of concrete members, performance monitoring technologies, evaluation methodologies, damage assessment, and structural rehabilitation. This Special Publication (SP) includes 10 papers selected from the three special sessions held at the ACI Fall convention in Washington, DC, October 2014. Each submitted manuscript has been rigorously reviewed and evaluated by at least two experts. The editors wish to thank all contributing authors and anonymous reviewers for their endeavors.

Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-304

DOI:

10.14359/51688550


Document: 

SP304-04

Date: 

October 27, 2015

Author(s):

R. Koch and J. Karst

Publication:

Symposium Papers

Volume:

304

Abstract:

With constrained transportation budgets there is a great need to increase the service life of bridges. Typically the deck is the weak link in the durability of a bridge with the corrosion of the reinforcing being the primary deterioration mechanism. Using Glass Fiber Reinforced Polymer (GFRP) to replace the traditional steel reinforcing eliminates reinforcing-related corrosion and should significantly increase the service life of the deck. The I-635 Bridges over State Ave in Kansas City, KS were built in the late 60’s and had an extensive history of repairs and overlays. In 2013 KDOT decided to replace the decks with traditional epoxy coated steel in the northbound bridge and GFRP reinforcing in the southbound bridge. There was a small premium to use GFRP rebar over traditional steel reinforcing which is expected to be offset by an increase in the service life of the deck. A picture of the reinforcing for the new bridge deck is shown in Figure 1.

DOI:

10.14359/51688554


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