Modeling the hygro-thermo-mechanical response of a masonry structure with fiber reinforced polymer composites reinforcement

Fiber reinforced polymer (FRP) composite laminates have been used effectively to strengthen structures constructed by unreinforced masonry units. The long-term interface bonding degradation due to moisture and temperature environmental effects needs to be addressed further for the practical application of this reinforcement method. In this dissertation, a finite element modeling procedure for analyzing the hygro-thermo-mechanical response of multi-layered structures constructed with distinctive permeable materials was developed based on the coupled moisture/temperature governing equations proposed by Phillips and DeVries.; The modeling procedure was used to analyze the response of a concrete block reinforced with a unidirectional glass/epoxy FRP composite laminate. The nonlinear moisture and temperature transport properties of both the concrete and FRP materials were taken into account in the analyses. The results showed that the interfacial stresses increased with the increase of the humidity diffusion time and monotonically approached the stress state at the steady-state humidity diffusion. It was demonstrated that the effect of temperature gradient on the moisture distribution, i.e., heat-induced moisture movement, resulted in an accumulation of moisture at the interface, and induced interfacial stresses even in the absence of a moisture gradient. The current finite element modeling procedure provides a general method for hygro-thermo-mechanical analysis of multi-layered permeable structures. It can be used to aid with the design of FRP/masonry structure or other similar structures for minimizing interfacial stresses induced due to the mismatch of moisture swelling and thermal expansion properties of the constituent materials.; In addition, a novel distributed moisture sensor using the Electronic Time Domain Reflectometry (ETDR) technique was developed. Its application in measuring distributed moisture content in a concrete/FRP specimen was also successfully conducted.