جامعة كولورادو2024-12-252024-12-25https://dspace.academy.edu.ly/handle/123456789/948with CFRP sheets. Thermal loadings ranging from 20oC (68oF) to 170oC (338oF) are associated with various mechanical loading configurations for 18 beams: monotonic, incremental cyclic, and anomalous cyclic. Of interest are the flexural responses, failure modes, and energy development of the strengthened beams subjected to the coupled loadings. The capacity of the beams decreases with an increase in temperature, whereas their individual performance is controlled by the mechanical loading schemes. A threshold temperature is noticed, which classifies the response domains of the cyclically loaded beams. The implications of the monotonic and cyclic loadings become similar above the threshold temperature due to the deteriorated CFRP-concrete interface. The failure modes of the beams are dominated by the thermal loading, rather than the mechanical loadings. Regarding the energy development of the test beams, the influence of the incremental cyclic loading is pronounced relative to its anomalous counterpart. The degree of energy dissipation tends to stabilize as long as the anomalous excitation does not exceed the magnitude of the sinusoidal cyclic loading. To characterize the performance of the strengthened beams under the thermomechanical-coupled loadings, an analytical approach is proposed. The third phase deals with the feasibility of a novel anchor system that mitigates the end-peeling of CFRP sheets usedABSTRACT This dissertation presents a three-phase study on the performance of concrete members strengthened with carbon fiber-reinforced polymer (CFRP) sheets under various hazard environments. The first phase discusses an experimental study characterizing the chemoelectrical response of concrete bonded with CFRP in a corrosive environment. A rapid chloride permeability test is conducted with concrete specimens having variable CFRP-coverage ratios from 0% (uncovered) to 100% (fully covered) according to ASTM C1202 (Standard test method for electrical indication of concrete’s ability to resist chloride ion penetration). Test results substantiate that CFRP sheets are an effective medium impeding the ingress of chlorides into CFRP strengthened concrete structures, thereby alleviating the likelihood of corrosion damage. CFRP bonding causes a decrease in electric current and chloride diffusivity. Microscopic images showing residual sodium chloride crystals accumulated on the surface of the tested specimens corroborate the decreasing rate of the electric current. The resistivity of the concrete and the transport rate of chlorides are controlled by the CFRP-coverage ratio influencing an electrolytic process. The conduction of the CFRP-bonded concrete alters from non-steady state to steady state with time due to the distribution of electric charges. An analytical expression is proposed for modeling chloride diffusion in the vicinity of CFRP-bonded regions.strengthened beams with variable embedment angles and the degree of local debonding.