Axial compression behavior of new seawater and sea sand concrete filled circular carbon fiber reinforced polymer-steel composite tube columns

Abstract

In order to study the feasibility of applying the original seawater and sea sand concrete directly to the concrete filled composite tube, a new structure of seawater and sea sand concrete filled carbon fiber reinforced polymer (CFRP) -steel composite tube composed of internal and external fiber reinforced polymer (FRP) and sandwich steel tube was proposed. Twelve new seawater and sea sand concrete filled circular CFRP-steel composite tube columns were tested under axial compression, and the influence of the number of CFRP layers and the strength grade of core concrete on the axial compression performance was studied. The test results show that the wrapping of inner and outer CFRP can effectively improve the bearing capacity and deformation capacity of the structure. The failure mode of common strength seawater and sea sand concrete filled circular CFRP-steel composite tube columns is concrete crushing, while that of high strength seawater and sea sand concrete filled circular CFRP-steel composite tube columns is shear failure. The ultimate stress of the structure is positively correlated with the number of CFRP layers and the strength of concrete. However, the ultimate strain only increases with the number of CFRP layers, but decreases with the strength of concrete. The contribution of core concrete and steel tube to the ultimate stress almost does not change with the increase of the number of layers of CFRP, and the contribution of CFRP to the ultimate stress of specimens is dominant when two or more layers of CFRP are wrapped.