Hygrothermal Modeling in the Application of Fiber-Reinforced Polymers for Structural Upgrade of Unreinforced Masonry Walls

摘要

The Army maintains an aging inventory of over 143,000 structures, many of which are in urgent need of maintenance and repair. In some instances, these aging structures fail to meet prevailing seismic engineering codes. In the United States alone, 30 percent of the Army's structures use unreinforced masonry (URM) walls. As such, URM structures have inadequate plane lateral strength and are prone to failure during seismic events. Upgrading these structures to meet existing seismic codes often requires the use of new materials and systems such as fiber-reinforced-polymer (FRP) composites. The versatility and resilience of such advanced composites make them ideal candidate materials for reducing the cost of seismic rehabilitation of DOD facilities. Though many studies have demonstrated the effectiveness of FRP reinforcements as structural upgrades for masonry walls, little has been done to explain their impact on the building envelope. This study was undertaken to discover and define the combination of building envelope and hygrothermal conditions that might result in vapor liquefaction at the ceramic-epoxy interface, and subsequently debond or delaminate the applique. This research developed fundamental models and associated material parameters to predict thermal and moisture transport across dissimilar building materials specifically FRP composite appliques to concrete masonry units (CMUs) used for seismic upgrades.