Prediction of Stress in High-Strength Strand at Flexural Strength of PSC Beam

Abstract

The tensile strength of prestressing strands which is globally used in PSC members is 1,860 MPa. Recently, 2,160 MPa and 2,400 MPa high-strength PS strands whose tensile strengths are higher than 1,860 MPa PS strand were developed in 2008 and 2011 respectively by domestic technique. Korean industrial standard allowed the use of high-strength PS strands and then the use of high-strength PS strands increased. However, existing design codes do not consider the influence of high-strength PS strands. Therefore, this study examined the applicability of existing approximate equations for PS strand stress at flexural strength in PSC member with high-strength PS strands in design standards. The result shows that existing design standards does not predict nonlinear stress behavior of high-strength PS strands at pre-yielding range. Thus, this study proposed an approximate equation for PS strand stress at flexural strength of a member considering nonlinear stress behavior of high-strength PS strands. With the proposed equation, PS strand stress at flexural strength and flexural strength of member can be predicted accurately even at high-strength PS strands.