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International Concrete Abstracts Portal

Showing 1-5 of 73 Abstracts search results

Document: 

SP275-32

Date: 

March 1, 2011

Author(s):

Amir Mofidi and Omar Chaallal

Publication:

Symposium Papers

Volume:

275

Abstract:

This paper deals with the shear strengthening of reinforced concrete (RC) beams using externally bonded (EB) fiber-reinforced polymers (FRP). The parameters that have the greatest influence on the shear behavior of RC members strengthened with EB FRP and the role of these parameters in current design codes are reviewed. The effect of transverse steel on the shear contribution of FRP was found significant and yet is not captured by any existing codes or guidelines. Therefore, a new design method is proposed, which considers the effect of transverse steel as well as to other influencing factors on the shear contribution of FRP (Vfrp). The accuracy of the proposed equations is verified by predicting the shear strength of experimentally tested RC beams using data collected from literature.

DOI:

10.14359/51682442


Document: 

SP275-62

Date: 

March 1, 2011

Author(s):

Amr El-Ragaby and Ehab F. El-Salakawy

Publication:

Symposium Papers

Volume:

275

Abstract:

The bridge deck slab is a prime example where FRP bars are used as main concrete reinforcement. In Canada, bridge deck slabs are usually subjected to a variation of cold and hot weathering while directly sustain the traffic loads. Both fatigue and thermal loading are expected to adversely affect the overall performance of such structural elements. In this research, a total of 4 large-scale bridge deck slabs totally reinforced with glass FRP bars were constructed and tested under simulated long-term loading and environmental conditions. The slabs were subjected to 3,000,000 cycles of sinusoidal waveform fatigue loading combined with either 100 freeze-thaw cycles or continuous cold temperature for one month. The test parameters included the environmental conditioning and the reinforcement ratio. It was concluded that the overall behavior of GFRP-reinforced bridge deck slabs after being subjected to simulated long-term fatigue load cycles and freeze-thaw or cold temperature is satisfactory according to the current design codes.

DOI:

10.14359/51682472


Document: 

SP275-72

Date: 

March 1, 2011

Author(s):

G. Williams, R. Al-Mahaidi and R. Kalfat

Publication:

Symposium Papers

Volume:

275

Abstract:

Retrofitting of existing concrete structures and civil infrastructure has become necessary due to environmental degradation, changes in usage and heavier loading conditions. The use of advanced carbon fiber composite materials (CFRP) as externally bonded reinforcement has found wide application in recent years and has proven to be an effective method of improving the structural performance of existing structures. A good example of this is the West Gate Bridge in Melbourne, Australia for which the following case study is presented. Key innovations in CFRP technology developed specifically for this project have been described in the areas of design and testing of CFRP anchorage technology, involving the utilization of unidirectional and bidirectional fabrics together with mechanical substrate strengthening. These have all resulted in increases in material utilizations and enabled successful transfer of combined shear and torsional forces. Key aspects of the detailing, application, quality control and monitoring program adopted in the project are also presented along with the key aspects which resulted in the successful execution of this world class project.

DOI:

10.14359/51682482


Document: 

SP275-59

Date: 

March 1, 2011

Author(s):

Martin Noel, Khaled Soudki and Ahmed El-Sayed

Publication:

Symposium Papers

Volume:

275

Abstract:

The results of an experimental investigation on the effects of prestressing on the flexural behavior of GFRP-reinforced SCC slabs are presented. A total of six one-way slab strips were tested up to failure, including one steel-reinforced control slab. The five remaining slabs were reinforced with GFRP bars, three of which also contained two CFRP post-tensioned tendons. Steel stirrups were included in one prestressed and one non-prestressed slab to ensure a flexural mode of failure. The slabs were tested under four-point bending. Results were compared to analytical models for ultimate flexural and shear capacity as well as load-deflection behavior. Prestressing effectively increased the cracking load and post-cracking stiffness of the FRP-reinforced slabs and significantly reduced crack widths at service loads. Slabs without shear reinforcement failed in shear in a brittle manner prior to reaching their full flexural capacity. All of the GFRP-reinforced slabs failed at higher loads than the control slab.

DOI:

10.14359/51682469


Document: 

SP275-71

Date: 

March 1, 2011

Author(s):

Vincenzo Bianco, Giorgio Monti and J.A.O. Barros

Publication:

Symposium Papers

Volume:

275

Abstract:

This paper presents a closed-form procedure to evaluate the shear strength contribution provided to a Reinforced Concrete (RC) beam by a system of Near Surface Mounted (NSM) Fiber Reinforced Polymer (FRP) strips. This procedure is based on the evaluation of: a) the constitutive law of the average-available-bond-length NSM FRP strip effectively crossing the shear crack and b) the maximum effective capacity it can attain during the loading process of the strengthened beam. Once the constitutive law of the average-available-bond-length NSM strip is reliably known, its maximum effective capacity can be determined by imposing a coherent kinematic mechanism. The self-contained and ready-to-implement set of analytical equations and logical operations is presented along with the main underlying physical-mechanical principles and assumptions. The formulation proposed is appraised against some of the most recent experimental results and its predictions are also compared with those obtained by a recently developed more sophisticated model.

DOI:

10.14359/51682481


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