Correction for axial tension measurement of CFRP strand cable using slant axial strain method

Experimental study and finite element analysis were conducted to investigate the correction factor for tension measurement of carbon fiber reinforced polymer (CFRP) strand cables using slant axial strain method. Axial tensile tests were performed on 6 CFRP strand cables. A multi-scale finite element (MSFE) model was developed and validated against the test results. Parametric analysis was performed and a practical formula for predicting the correction factor was developed. Finally, the difference in the correction factors between anisotropic and isotropic strand cables was identified by studying effect of anisotropy. The obtained results demonstrated that the correction factors of CFRP strand cables with different diameters (10.2 mm and 12 mm) and same lay distance-diameter ratio (50) were experimentally determined as 1.013 and 1.019, respectively. Effects of lay distance-diameter ratio and the number of strand wires on the correction factor are significant, while influences of cable diameter, fiber volume content ranging of 65~75%, and material properties of resin are marginal. The correction factors of 7, 19 and 37-wire CFRP strand cables with a lay distance-diameter ratio of 15 range from 1.084 to 1.149. The correction factor of CFRP strand cables with significant anisotropy and a small lay distance-diameter ratio (15) is much greater than that of isotropic strand cables.