Stage-wise analytical modeling and full-scale validation of TRC-strengthened RC beams under sustained loading: application to 30-year-old bridge members

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Abstract

This study presents a stage-wise sectional analytical model for reinforced concrete (RC) beams strengthened with carbon textile-reinforced concrete (TRC) under sustained loading. The formulation accounts for pre-cracking, partial unloading, residual curvature, and TRC activation under non-zero initial strain. The TRC layer is modeled with bilinear tensile behavior, while tension stiffening and residual tensile effects of cracked concrete are included. The model is validated using full-scale bridge beams after about 30 years of service, tested under realistic conditions. The strengthened beam shows an increase of about 25% in ultimate load and improved crack control, with crack width and spacing reduced to one-third to one-half of the control beam. Strain results confirm effective stress redistribution and high textile utilization. Predictions agree well with experiments, with discrepancies within 5–10%. Compared with design guidelines, Z-31.10-182 is closest, while ACI 549.4R-20 and CNR-DT 215/2018 overestimate capacity. The model provides a reliable framework for assessing TRC-strengthened RC members under realistic conditions.

Author Biographies

Huy Cuong Nguyen, University of Transport and Communications

Construction Engineering Faculty

Dang Dung Le, University of Transport and Communications

Construction Engineering Faculty

Van Hiep Vu, University of Transport and Communications

Construction Engineering Faculty

Cong Hau Nguyen, University of Transport and Communications

Construction Engineering Faculty

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Published

04-05-2026

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Original Article