Durability of Seawater and Sea Sand Concrete (Ssc)-Filled Bfrp- Steel Composite Tube Columns in Simulated Marine Environment

Abstract

To address the durability challenges of marine infrastructure, this study investigated the durability of seawater and sea sand concrete (SSC)-filled BFRP-steel composite tube (SFSCT) columns under simulated seawater exposure. The SFSCT structure consists of inner and outer layers of BFRP, a steel tube, and a core of SSC, combining the corrosion resistance of BFRP with the high capacity of the steel tube. A total of 40 SFSCT short columns were subjected to artificial seawater corrosion tests. The influence of curing duration (0–240 days) and number of BFRP layers (0–3 layers) on the axial compressive performance degradation of the columns was analyzed. The results show that BFRP jackets effectively inhibit the development of steel corrosion. While corrosion had a negligible effect on the failure modes, it caused a notable initial reduction in both ultimate stress and strain, which gradually stabilized over time. After 240 days of corrosion, the specimens retained over 80% of their compressive strength and over 85% of their ultimate strain. Based on the experimental results, a full stress–strain degradation model was developed for SFSCT, incorporating both material degradation behavior and composite structural effects. The proposed model accurately captures the axial compression response of SFSCT columns under corrosive environments.

Keywords: Durability evaluation, Seawater and sea sand concrete, BFRP-steel composite tube, Marine environment, Axial compression