Spalling Resistance of Fiber-Reinforced Ultra-High-Strength Concrete Subjected to the ISO-834 Standard Fire Curve: Effects of Thermal Strain and Water Vapor Pressure

The prevention and mitigation of spalling in high-strength concrete (HSC) rely on mixing polypropylene (PP) as an additive reinforcement. The dense internal structures of ultra-high-strength concrete (UHSC) result in risks associated with a high thermal stress and high water vapor pressure. Herein, the effects of pore formation and thermal strain on spalling are examined by subjecting fiber-laden UHSC to conditions similar to those under which the ISO-834 standard fire curve was obtained. Evaluation of the initial melting properties of the fibers based on thermogravimetric analysis (TGA) and differential thermal analysis (DTA) demon strated that although nylon fibers exhibit a higher melting point than polypropylene and polyethylene fibers, weight loss occurs below 200 °C. Nylon fibers were effective at reducing spalling in UHSC compared to polypropylene and polyethylene fibers as they rapidly melt, leading to pore formation. We anticipate that these results will serve as references for future studies on the prevention of spalling in fiber-reinforced UHSC.

Simulating Post-Earthquake Fire Loading in Conventional RC Structures

Post-earthquake fire (PEF) is one of the most complicated problems resulting from earthquake, presenting a serious risk to urban buildings. As most standards and codes ignore the possibility of PEF, buildings are too weak under PEF loads. This chapter is to investigate the effects of PEF loads on partially damaged RC buildings located in urban regions. To do that, a methodology named sequential analysis is introduced here via which the structural performance at various performance levels is evaluated under fire and PEF scenarios. Numerically, in order to simulate the earthquake loads, conventional pushover analysis is employed, with an explanation presented in the chapter to introduce the pushover analysis, its advantages and its limitations. To simulate the fire loads, standard fire curve (ISO 834) is used for simplicity.

Comparison Study of Fire Resistance According to Differences of Length of H-Section Made of Submarine Structural Steels

Submarine structural steels, such as SM 400, SM 490, and SM 520, have the same structural properties and same grades as general structural steels, but those have better weldability than general structural steels. For that reason, their usage is increasing. However, their fire resistance is not well defined, except for individual fire resistance, such as column and beam. The fire resistance of H-section made of submarine structural steels can be applied with various column lengths. The fire resistance of them is not clear to engineers and residents. To determine the fire resistance, in this paper an analysis was conducted using their mechanical properties at high temperature and related theories with a standard fire curve. As the strength of submarine structural steels is increased, the structural stability showed a rapid decrease while the longer the length of column, the less structural stability of the column represented.