Mechanical properties of pultruded basalt fiber-reinforced polymer tube under axial tension and compression

Abstract This paper explores mechanical properties of pultruded basalt fiber-reinforced polymer (BFRP) tubes for truss structures subjected to tensile and compressive axial loading. The tensile and compressive strength of BFRP tubes were first tested. For the stability under compression, the slenderness ratios varying from 6 to 90 were adopted while the failure modes were recorded. The effects of confinement on the buckling by an additional layer of fiber sheets were investigated. Based on the experimental results, stability equation for predicting compressive strength of slender BFRP tubes were derived and validated. The results show that the tensile strength of short BFRP tube could reach 1011 MPa, while the compressive strength has been around 40% of tensile strength with relatively larger variation. Compared with the single tensile failure mode of BFRP tubes, three types of compressive failure modes, including micro-buckling, local buckling and overall buckling were observed. It can be concluded that a layer of fiber sheet slightly decreases the compressive strength. However, with the increase of slenderness ratios, the positive effect on the compressive strength by fiber sheets becomes significant. The accuracy of the proposed equation was validated by additional five groups of BFRP tubes with different slenderness ratios. It is also shown that the existing prediction equation of GFRP in literature is not suitable for predicting the stability of BFRP.