International Institute for FRP in Construction (IIFC)
Abstract
The near surface mounted (NSM) technique is a strengthening method that provides additional reinforcement by
means of strips or bars embedded into grooves made in the concrete cover of reinforced concrete (RC) elements.
The effectiveness of using NSM fibre reinforced polymer (FRP) bars or strips to enhance the shear and flexural
capacity of RC elements has been demonstrated over the past decade. However, the idea of using NSM FRP
reinforcement to address issues related to deficient torsional performance is yet to be explored. Torsional
strengthening of RC elements (e.g. bridge girders, transfer beams) may be necessary due to degradation of
materials, changes in the design codes, deficiencies in the initial design, changes in building usage etc. This paper
investigates the torsional strengthening of thin walled tubular RC beams using NSM CFRP laminates.
The experimental program involved testing of six box sectioned RC beams, including two reference beams (with
and without shear reinforcement) and four beams strengthened with different arrangements of NSM CFRP
reinforcement, providing varying longitudinal and transverse reinforcement ratios. All the strengthening proposals
resulted in significant increase in torsional moment capacity, ductility, stiffness in the elasto-plastic range and
were very efficient in arresting crack propagation, proving the effectiveness of NSM strengthening technique for
torsional strengthening. The proposed experimental program is described in detail and the main results are
presented and discussed.CASA -Center for Arabic Study Abroad, University of Texas, Austin(undefined
