Evaluation of Effective Stiffness of Engineered Cementitious Composite (ECC) and its practical implementation.

Abstract

Engineered Cementitious Composites (ECC) have emerged as a promising alternative to conventional Reinforced Cement Concrete (RCC) due to their unique micro-crack bridging and tension hardening properties. These characteristics enable ECC to exhibit superior ductility, damage tolerance, and durability compared to traditional concrete materials. Despite the numerous advantages of ECC, its widespread adoption in the construction industry has been hindered by the lack of comprehensive design guidelines and the reliance on stiffness modifiers derived from RCC. This thesis aims to address this gap by investigating the flexural effective stiffness of ECC at various scales and proposing stiffness modifiers specifically tailored for ECC members. The initial part of the study primarily concentrates on the material scale, specifically examining the comprehensive stress-strain behavior of Engineered Cementitious Composites (ECC) under both compression and tension. This analysis is carried out in great detail using a predictive model, which is further validated through experimental investigations. Subsequently, the focus of the study shifts to the section scale, specifically examining the flexural behavior of Engineered Cementitious Composites (ECC) members. Experimental tests are conducted on various beams and columns to determine the moment-curvature curve. The experimental results are then validated using Abaqus software, a widely used computational tool. The study considers various cross­ sectional shapes and sizes, as well as different fiber types and volume fractions. The results reveal that the effective stiffness of ECC members is significantly influenced by the fiber reinforcement and the cross-sectional geometry. This finding underscores the importance of considering these factors when developing stiffness modifiers for ECC. At the structural scale, the study examines the performance of ECC beams and columns under various loading conditions. The analysis considers the interaction between the material, section, and structural properties of ECC, as well as the effects of long-term creep and shrinkage. After the implementation of our proposed stiffness modifiers performance assessment of structures has been done. The results demonstrate that ECC members exhibit superior performance in terms of load-carrying capacity, deflection control, and energy absorption compared to their RCC counterparts. This further highlights the potential benefits of using ECC in the construction industry. Based on the findings at the material, section, and structural scales, the study proposes stiffness modifiers for ECC members. In conclusion, this study provides valuable insights into the effective stiffness of ECC at various scales and proposes stiffness modifiers that are specifically tailored for this material. The findings contribute to a better understanding of the unique properties ofECC and their implications for structural design. By addressing the current limitations in the design guidelines for ECC, this research has the potential to promote the widespread use of this innovative material in the construction industry, leading to more resilient, sustainable, and cost-effective infrastructure.