In this paper, efficiency and effectiveness of textile-reinforced mortars (TRM) on upgrading the shear strength and ductility of a seismically deficient exterior beam-column joint has been studied. The results are then compared with that of carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP)-strengthened joint specimens. Five as-built joint specimens were constructed with nonoptimal design parameters (inadequate joint shear strength with no transverse reinforcement) representing an extreme case of preseismic code design construction practice of joints and encompassing the vast majority of existing beam-column connections. Out of these five as-built specimens, two specimens were used as baseline specimens (control specimens) and the other three were strengthened with TRM, CFRP, and GFRP sheets, respectively. All five subassemblages were subjected to quasi-static cyclic lateral load histories to provide the equivalent of severe earthquake damage. The response histories of control and strengthened specimens were then compared. The test results demonstrated that TRM can effectively improve both the shear strength and deformation capacity of seismically deficient beam-column joints to an extent that is comparable to the strength and ductility achieved by well-established CFRP, and GFRP-strengthening of joints.

Mechanical properties of hybrid fibre-reinforced concrete (HFRC) are studied and the role of constituent fibres on overall response of HFRC is investigated. HFRC was produced using different proportions of hooked-ended steel, crimped polypropylene and plain Kevlar fibres with a total fibre volume fraction of 1·2% and 1·4%. The test results indicate that the incorporation of hybrid fibres in concrete improve the compressive and tensile strengths moderately and toughness considerably. Analytical models are developed to quantify the effect of individual fibres on compressive and tensile strengths, stress–strain curves and flexural toughness ratio of HFRC in terms of a comprehensive fibre reinforcing index. The proposed models show a marked improvement over existing models. The existing models are for single (steel) fibres only, whereas the proposed models are general and applicable to HFRC containing any number of fibres.

Shear failure of exterior beam-column joints is identified as the principal cause of collapse of many moment-resisting frame buildings during recent earthquakes. Effective and economical strengthening techniques to upgrade joint shear resistance and ductility in existing structures are needed. In this paper, efficiency and effectiveness of carbon fiber-reinforced polymer (CFRP) sheets in upgrading the shear strength and ductility of seismically deficient exterior beam-column joints have been studied. Four as-built joints were constructed with nonoptimal design parameters (inadequate joint shear strength with no transverse reinforcement) representing preseismic code design construction practice of joints and encompassing most of existing beam-column connections. Out of these four as-built specimens, two specimens were used as baseline specimens (control specimens) and other two were strengthened with CFRP sheets under two different schemes (strengthened specimens). In the first scheme, CFRP sheets were epo...