Study on stress relaxation of simple spiral strand subjected to tensile load based on semi-analytical method.

•The stress relaxation model for the strand is established and solved with the efficient semi-analytical method.•The axial force showing the axial load-carrying capacity of the strand decreases gradually with increasing relaxation time.•Decreasing the axial tensile strain and helix angle are beneficial to reducing the creep strain of the strand.•Increasing the outside wire diameter is beneficial to reducing the creep strain and axial stress of the strand.