Author(s): Sanjana Koirala and Ramesh Thapa

Abstract: This study investigates the field performance of steel-concrete composite beams subjected to cyclic loading, focusing on stiffness degradation, energy dissipation, and interface slip behavior under real environmental and operational conditions. Full-scale beams, extracted from in-service bridge and building structures in Northern India, were tested using a displacement-controlled cyclic loading protocol replicating quasi-static seismic effects. The experimental results revealed that long-term exposure significantly accelerates degradation compared with laboratory-controlled specimens. Beams with higher shear connection ratios and denser reinforcement demonstrated improved cyclic stability, reduced residual deflection, and slower stiffness decay, while older beams exhibited pronounced pinching in hysteresis loops and higher interface slip. Regression analysis confirmed strong negative correlations between service life and stiffness retention, indicating that environmental aging and partial composite interaction play crucial roles in cyclic degradation. Energy dissipation per cycle decreased progressively as the number of cycles increased, highlighting the diminished ability of aged beams to absorb dynamic loads. Comparative analysis with laboratory data showed that field beams suffered approximately 20-25% greater stiffness and strength reduction, emphasizing the importance of incorporating real-world deterioration factors into predictive models. The findings suggest that current design codes should include time-dependent degradation models and field-calibrated parameters to ensure accurate life-cycle assessments. Practical recommendations include the use of corrosion-resistant connectors, protective coatings, advanced monitoring systems, and predictive maintenance strategies to enhance durability. Overall, this research bridges the gap between theoretical models and in-service behavior, offering a realistic framework for evaluating and maintaining steel-concrete composite structures under cyclic loading.

Pages: 19-25 | Views: 24 | Downloads: 15

Download Full Article: Click Here