Flexural Performance of Concrete Beams Strengthened using Different Repair Techniques

The main objective of this research project is to evaluate the flexural performance of reinforced concrete (RC) beams repaired and strengthened using four different techniques. The techniques are External Prestressing (EP) using various types of metallic and non-metallic tendons, Fiber-Reinforced Ferrocement Composite (FR-FC) thin sections, Fiber-Reinforced Self Consolidating Concrete (FR-SCC), and Fiber-Reinforced Polymers (FRP) sheets. These implementations have been widely used and implemented to upgrade existing structures (such as parking structures, concrete bridge beams and decks, pier caps, substructures elements, etc.) but at different loading conditions. The ultimate goal of this research is to comparatively investigate the efficiency of the proposed techniques when applied on small and large scale specimens under the same loading conditions. Deflection at several locations, load-carrying capacity, concrete and steel rebar strain, failure modes and crack patterns of the strengthened beams during testing will be measured, collected, and analyzed for comparison purposes. In addition to the experimental program, analytical models will be developed and calibrated based on test data, and the load carrying capacity for each strengthening method will be predicted. The obtained results of the proposed models can be used as input parameters in the analysis and design of strengthened members. This study will have three phases: (1) The first phase (which is almost completed using funds from New Jersey Department of Transportation (NJTA)) focused on upgrading the conventional Ferrocement and SCC mixes with steel and polypropylene fibers. Several trial mixes are prepared and strength and shrinkage test are performed. In addition, the mechanical properties of the sheets and the strands implemented in the repaired specimens will be evaluated; (2) The second phase include the application of proposed mixes and techniques on small scale and large scale reinforced concrete beam specimens in order to evaluate the effect of such techniques on the overall structural performance; and (3) The final phase will focus on the finite element modeling of the tested specimens using ABAQUS and propose analytical models that will be applied to enhance equations and procedures in repair codes and to predict the beams capacity for design purposes. At the end of this project, the team will use the outcomes of the material research namely, deterioration functions and estimated costs to perform life cycle cost analysis (LCCA) with the ultimate goal of optimal network-wide project selection. The team will make recommendations to the (NJDOT) and NJTA for field implementation of the most promising repair technique.