Xuan Hong Vu

Experimental Approach to Identify the Thermomechanical Behaviour of a Textile Reinforced Concrete (TRC) Subjected to High Temperature and Mechanical Loading

Textile reinforced concrete (TRC), a new generation of cementitious material, is used for different applications in civil engineering. The aim of this paper is to propose a methodology to identify the thermo-mechanical behaviour of the TRC material. The studied TRC composite is made with a cementitious matrix and grid alkali-resistant glass textile. In this study, TRC specimens are subjected to two types of thermomechanical test designated by the loading path 1 and the loading path 2. The results of the thermo-mechanical tests are discussed. This study presents also an experimental methodology, using the digital image correlation (DIC) technique, which permits to identify the specific cracking mode, the crack width and the distance between the cracks of the preheated-cooled TRC specimens as a function of the uniaxial monotonic axial stress. The experimental study is then followed by an analytical model that aims to calibrate existing analytical models (Gibson and Bisby models) for the prediction of the evolution of properties (ultimate stress and post-cracked stiffness) of the TRC material as a function of the temperature.

Experimental Study on the Thermo-Mechanical Behavior of Hand-Made Carbon Fiber Reinforced Polymer (H-CFRP) Simultaneously Subjected to Elevated Temperature and Mechanical Loading

Among two common forms of CFRP used in strengthening/repairing construction structures (pultruded and hand-made), hand-made CFRP is popularly used with column and other structures where the strengthening surfaces are complicated. Normally, the hand-made CFRP (H-CFRP) includes woven carbon fibers, prefabricated in the factory and the polymer matrix which is added during the installation process. When a fire happens, structures and reinforced material are simultaneously exposed to high temperatures (up to 1200 °C) and mechanical loadings, which are complicated and difficult to be experimentally simulated. As far as the authors concern, the studies of CFRP and structure reinforced with CFRP in fire are rare due to expensive cost of experiments and insufficient theoretical calculations. For these reasons, this study aims to investigate the thermo-mechanical behavior of H-CFRP via two different elevated-temperature and mechanical load regimes. The first regime studies the ultimate-strength evolution as the exposed temperature increases while the second studies the variation of rupture temperature when applied load changes. The results from the first regime show that the ultimate strength and the Young modulus of H-CFRP generally reduce 50% and 25% when the applied temperature level increases from 20 °C to 400 °C. The second series show that the rupture temperature of H-CFRP steadily reduces from about 640 °C to about 467 °C as its mechanical stress ratio increases from 0.1 to 0.5 (of its ultimate strength at 20 °C). Remarkably when the mechanical stress ratio of H-CFRP increases to 0.75, the rupture temperature dramatically drops to about 50 °C. The rupture modes and correlation between two regimes will also be discussed.