Comparison of Prestress Loss According to ACI 423.10R and AASHTO Standards

Abstract

This study compares the calculation of prestress loss in prestressing steel according to the ACI-423.10R (the standard referred by ACI-318 for RC building design as ACI-318 has no calculation details of prestress loss) with the calculation using AASHTO-LRFD (2012) which is the standard mostly used for Bridge design but may not appropriate for buildings. The study analyzed the prestress loss in prestressing steel of 8 examples including 4 cases of Pretension structures and 4 cases of Post-tension structures. Moreover, reduction of prestressing steel area in structure from 0-50% for assuming corrosion in structure has been considered in calculation. Comparison of the moment capacity between using both different standards has be calculated for the last example of the real bridge in Thailand using a post-stressed continuous box girder. The results show that calculation using ACI standard gives higher prestressing loss than using the AASHTO standard for about 3.84%. Moreover, the corrosion of the prestressing steel causes increasing of the tensile stress in the remained prestressing steel which results in more flexural strength requires in the section to compensate for the corroded steel area.