A Master of Science thesis in Civil Engineering by Ghanim Kashwani entitled, "Sustainability of Composite Columns under Repeated Load and Harsh Environment," submitted in January 2013. Thesis advisor is Dr. Adil Kahwash Abid Al-Tamimi. Available are both soft and hard copies of the thesis.
Strengthening and rehabilitation are important operations for structural building to ensure sustainability. Enhancing the performance for the structural elements against the various loads and extreme conditions is the key challenge in these operations. Fiber Reinforced Polymer (FRP) materials are universally known for their ability to improve the load capacity for the damaged structural elements because of their linear-elastic behavior. Therefore, fiber wrapping technique on concrete structures is now prevalent in different regions in the world. Increasing the axial resistance and dissipated energy of confined concrete in a compression mode is a critical issue for the stability and integrity of the structural columns. During the last two decades, many experimental studies investigated the mechanical properties of confined concrete under monotonic loading and extreme conditions such as elevated temperatures and freeze/thaw cycles. These studies led to development of standards like ACI-440 to assist engineers in designing FRP materials. However, there is lack of studies examining the effects of repeated loading combined with harsh environmental factors. This study focuses on analyzing experimentally the behavior and response of confined and unconfined concrete cylinders (300mm x 150mm) under repeated compression and severe environmental exposures such as high temperature, high humidity and salt water splash zone. Confining the concrete samples with Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) sheets has increased the load capacity compared to control sample at room temperature by 101% and 76%, respectively. Results showed that the average value of compressive strength for the confined concrete exposed to high temperature and sea water splash zone conditions has decreased by 6% and 26%, respectively compared to the confined concrete in the room temperature. GFRP samples showed higher performance in compressive strength and stiffness under sea water splash zone than those of the CFRP samples. Other mechanical properties are evaluated such as ultimate strain, stiffness and elastic modulus, for all the tested samples. Different mode of failures such as delamination, de-bonding and combination of such modes were observed and related to various exposure factors and mechanical properties