Effects of Individual Strand Tensile Force Deviation on Structural Behavior of Post-Tensioned Beams

For the construction of large-scale building or civil structures, multi-strand post-tensioning method is widely used. Due to the construction errors and the nature of multi-strand tendons having ‘initial slack’, deviation... [ view full abstract ]

For the construction of large-scale building or civil structures, multi-strand post-tensioning method is widely used. Due to the construction errors and the nature of multi-strand tendons having ‘initial slack’, deviation of individual strand tensile forces inevitably occurs. However, the effect of individual strand force deviation of multi-strand tendon on the structural behavior of post-tensioned structures has not been studied thoroughly. Given this gap, in this study, the influence of individual strand force deviation on the flexural strength of post-tensioned beams is analyzed through a series of numerical analysis.

Nonlinear finite element analysis for 12 bonded and unbonded post-tensioned beams is conducted, with a primary parameter of standard deviation of individual strand forces. The numerical analysis results show that the ultimate flexural capacity of post-tensioned beams is substantially reduced when the individual strand force deviation increases beyond 10% C.O.V. Whereas, flexural strength reduction is found to be negligible at the realistic level of 10% C.O.V. or smaller. From the analysis, it is found that the strength reduction caused by individual strand force deviation highly depends on the tensile stress at ultimate state (f_ps).