Seismic resistance of precast GFRP-reinforced concrete columns with grouted corrugated duct connections

This is the authors' abstract. We don't add key points for this paper.

This study investigates the seismic resistance of precast concrete columns reinforced with glass fibre-reinforced polymer (GFRP) bars and spirals, connected to cap/base elements using grouted corrugated duct connections (GCDCs). Four precast specimens and one cast-in-place (CIP) specimen, serving as a control, were tested under simultaneous axial and lateral cyclic loading. Different construction techniques for GCDC were evaluated, including conventional methods with GCDC in the base/cap to accommodate the protruding column reinforcement, L-starter bars of various sizes from the cap/base with GCDC in the column, and an innovative approach using fully precast connections with separate straight bars through GCDC in both elements. The latter innovative technique is without protruding reinforcement to reduce the risk of damaging the bars during transportation and to address the rigidity of GFRP bars, which cannot be adjusted on-site in case of misalignment. The seismic performance in terms of cracking, failure mode, hysteresis behaviour, stiffness, energy dissipation and residual drift was discussed. The precast specimens exhibited a comparable seismic performance to the CIP, with similar cracking patterns, failure modes, and hysteretic responses, all governed by a gradual flexural failure of the columns. Additionally, the specimens demonstrated acceptable deformability, achieving a drift ratio of up to 7 % without significant strength degradation. They also exhibited a relatively small residual drift, reflecting adequate self-centring capacity despite the accumulated damage from repeated cycles. The innovative straight-bar connection demonstrated superior performance compared to the conventional methods. It achieved a 4.5 % increase in lateral load capacity compared to the CIP specimen and improvements ranging from 2 % to 11 % over the various conventional GCDC configurations. In terms of energy dissipation, it performed comparably to the CIP specimen, with a 3 % increase, and outperformed the conventional methods with improvements ranging from 8 % to 20 %. These findings highlight the viability of GFRP-reinforced concrete precast columns for seismic applications, particularly with the innovative construction approach. This approach simplifies workflows, reduces costs, and accelerates timelines, making it ideal for modern precast structures using GFRP.