COMPARATIVE STUDY OF STEEL AND AFRP TENDONS WITH OPTIMIZED PRE STRESSING FORCE FOR SCPC JOINTS

Abstract

This thesis presents a comprehensive investigation into the seismic performance of Self-Centering Prestressed Concrete (SCPC) joints reinforced with steel tendons and the innovative Aramid Fiber Reinforced Polymer (AFRP) tendons under cyclic loading conditions. The primary objective is to evaluate and optimize the structural behaviour of these joints to enhance their seismic resilience and facilitate rapid post-earthquake recovery. Extensive numerical simulations were conducted using the advanced finite element software Abaqus, enabling a detailed comparison of the load-displacement response, energy dissipation capabilities, and residual deformations of SCPC joints reinforced with steel tendons and AFRP tendons, respectively. The results revealed distinct behavioural differences between the two tendon materials. SCPC joints with steel tendons exhibited high initial stiffness due to the inherent properties of steel. However, upon reaching yield, the steel tendons underwent plastic deformation, contributing significantly to energy dissipation but leaving the joints susceptible to permanent residual displacements after unloading. This residual deformation can necessitate extensive post-earthquake repairs, hindering rapid recovery efforts. In contrast, SCPC joints reinforced with AFRP tendons demonstrated comparable initial stiffness to steel tendon joints but maintained elastic behaviour throughout the loading cycles, even at higher load levels. This elastic response allowed the AFRP tendon joints to exhibit superior self-centering capabilities, with minimal residual displacements observed upon unloading. However, the lack of plastic deformation in AFRP tendons resulted in lower energy dissipation compared to their steel counterparts, highlighting the need for optimization. To address this limitation, extensive parametric studies were conducted to investigate the effects of varying prestressing forces and damper dimensions on the performance of AFRP tendon joints. The findings indicated that increasing the prestressing force improved initial stiffness and self-centering abilities, albeit with a risk of tendon rupture at excessively high stress levels. Adjustments to the damper leg width, on the other hand, proved to be a more effective strategy for enhancing energy iv dissipation while maintaining self-centering performance. The optimal damper leg width was identified to be in the range of 20-21 mm, striking a balance between maximizing energy absorption and preserving the self-centering capabilities of the AFRP tendon joints. The outcomes of this research contribute significantly to advancing the understanding of SCPC joint behaviour under seismic loading and provide valuable insights into the potential use of AFRP tendons as a promising alternative to traditional steel tendons. The optimized design recommendations derived from this study can facilitate the wider adoption of SCPC technology in construction, promoting the development of more resilient built environments in seismic-prone regions worldwide.