Beam-Column Joint Retrofitting Using Basalt FiberReinforced Polymer Grid and Cementitious Matrixes

Abstract

This paper focuses on retrofitting reinforced concrete (RC) beamcolumn joints using a new method-namely, fabric -reinforced cementitious matrix (FRCM). This method is expected to be a substitute for externally bonded FRP, as it works better in a moist and flammable environment. In this study, basalt fiber -reinforced polymer (BFRP) grids were used as reinforcement and highstrength mortar and engineered cementitious composites (ECCs) were used as a cementitious matrix. ECC is ductile and good for crack distribution. High -strength mortar is good for its high compressive strength, applicability, shrinkage resistance, lack of pores, and high bonding strength. The retrofitted specimens were originally fabricated by taking out the concrete cover around the joint area, and it was filled back by the cementitious matrix to make up the original dimension using two different retrofitting types. As a result, the overall performances of the retrofitted specimens were improved regarding failure level, ductility, energy dissipation, strength, and stiffness degradation. The working mechanism of the retrofitted specimen tended to change as the stress concentration also attempted to shift from joint to beam for the ECC specimen.