Moment Redistribution in Continuous Fiber-Reinforced Polymer-Strengthened Reinforced Concrete Beams

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Title: Moment Redistribution in Continuous Fiber-Reinforced Polymer-Strengthened Reinforced Concrete Beams

Author(s): Maria Antonietta Aiello and Luciano Ombres

Publication: Structural Journal

Volume: 108

Issue: 2

Appears on pages(s): 158-166

Keywords: continuous beams; fiber-reinforced polymer; moment redistribution; reinforced concrete

Date: 3/1/2011

Abstract:
The analysis of continuous reinforced concrete (RC) beams strengthened by externally bonded fiber-reinforced polymer (FRP) sheets is still an interesting research field that requires further investigation. Some recent studies carried out on this topic proved the possibility of achieving a certain degree of stress redistribution by using a proper design approach for strengthening—namely, the appropriate choice of the FRP reinforcement configuration and an appropriate reinforcement anchorage, aiming to eliminate or at least delay the occurrence of premature failures. In this paper, the structural behavior of RC continuous beams externally strengthened by FRP laminates is investigated from both an experimental and a theoretical point of view. In particular, the analysis of moment redistribution is addressed; the main items are related to the influence of the strengthening configuration and the evaluation of moment redistribution, not only at ultimate but also throughout the entire loading process. To this end, tests on six FRP-strengthened RC continuous beams subjected to a single point load at each span were performed and the results are discussed. In addition, a theoretical nonlinear model is proposed— taking into account bond characteristics and concrete cracking— to get a deeper understanding of the structural behavior both at ultimate and at the service conditions. The good agreement between the theoretical predictions and experimental results shows the effectiveness of the proposed model and its possible use for assessing design relationships.