Post-tensioned NSM CFRP strips for strengthening PC beams: A numerical investigation

This paper presents a numerical investigation into the flexure of prestressed concrete girders strengthened with post-tensioned near-surface mounted (NSM) carbon fiber reinforced polymer (CFRP) strips subjected to service load. Three-dimensional finite element analysis, validated with theory and test data, is conducted with 51 girder models to evaluate the efficacy of the post-tensioned NSM CFRP with an emphasis on strengthening schemes, deflection and strain responses, a stress-sharing mechanism, and deformability. A strengthening coefficient is proposed to identify adequate CFRP bond length that can exploit such a strengthening method (i.e., the location of anchorage for post-tensioning the CFRP). The effective length of the post-tensioned NSM CFRP is determined, beyond which the post-tensioning action does not influence the behavior of the concrete adjacent to the anchorage. The concept of potential energy is utilized to quantify the performance of the strengthened girders, including the contribution of the CFRP to the functionality of the strengthened girders.