Advanced Prestressing Strategies for Curved Spans in Segmental Bridges: A Comprehensive Procedure for Segmental Bridge Design and Analysis

The analysis and design of post-tensioned composite concrete segmental bridge structures represent significant challenges because of their complex geometric arrangement and their highly challenging construction requirements. Conventionally adopted practices for the design of such bridge structures often struggle to address the core issues, such as tendon profile, anchorage zones and the stress distribution in the large curved spans, where any minor anomaly or error that occurs during the on-site execution may lead to a catastrophic structural failure. Key aspects involved are the assessment of tendon layouts or profiles, anchor zones and the stress distribution under the diverse loading conditions to ensure optimal structural performance and stability. To overcome these limitations, this study conducts a detailed parametric investigation into the influence of curvature radius, high tensile tendon profiles, and jacking force on the structural response of curved bridge spans. An advanced Finite Element Analysis Method (FEAM) was employed to evaluate the performance and to compare the conventional design and on-site methods with modern practices prescribed by the Indian Standard Codes (IS), Indian Roads Congress (IRC) and Ministry of Road Transport and Highways (MoRTH) specifications. Under the exceptional conditions, the maximum allowable overstressing observed during the prestressing operations is 95% of 0.1% proof load or proof stress, which is almost 0.826 times the Ultimate Tensile Strength (UTS). The results also indicate that the variations in cable lengths between the inner and outer webs can lead to overstressing of the inner web tendon bars by a factor of 1.05 times, increasing the stress variation at the bottom fibre and altering the bending moment distribution across the span. The findings also highlight the critical correlations between the prestressing parameters and the span curvature, offering practical insights for improving the design accuracy and execution of safety in post-tensioned curved bridge structures.