Abstract
The objective of this paper is to investigate the effect of thickness and moisture on temperature distributions of reinforced concrete walls under fire conditions. Toward this goal, the first three wall specimens having different thicknesses are heated for 2 h according to ISO standard heating curve and the temperature distribution through the wall thickness is measured. Since the thermal behavior of the tested walls is influenced by thickness, as well as moisture content, three additional walls are prepared and preheated to reduce moisture content and then tested under fire exposure. The experimental results clearly show the temperatures measured close to the fire exposed surface of the thickest wall with 250 mm thickness is the highest in the temperatures measured at the same location of the thinner wall with 150 mm thickness because of the moisture clog that is formed inside the wall with 250 mm of thickness. This prevents heat being transferred to the opposite side of the heated surface. This is also confirmed by the thermal behavior of the preheated walls, showing that the temperature is well distributed in the preheated walls as compared to that in non-preheated walls. Finite element models including moisture clog zone are generated to simulate fire tests with consideration of moisture clog effect. The temperature distributions of the models predicted from the transient heat analyses are compared with experimental results and show good agreements. In addition, parametric studies are performed with various moisture contents in order to investigate effect of moisture contents on the thermal behaviors of the concrete walls.
Highlights
Reinforced concrete wall structures are widely used in Korea, especially for residential buildings
Because moisture clog zone delays heat propagation, the predicted temperatures in the dry zone increase rapidly during heating, while temperatures behind the moisture clog zone are not increased effectively. Such delay in heat propagation becomes significant in the models of W25 and W25V, as moisture content increases with wall thickness
To investigate the effects of wall thickness and moisture content in concrete on the temperature distribution, six walls are heated on one side according to the ISO 834 standard fire curve
Summary
Reinforced concrete wall structures are widely used in Korea, especially for residential buildings. It is important to study the fire resistance of reinforced concrete walls, because the number of fire accidents in residential buildings is increasing every year. In Korea, concrete walls must be designed according to Korean building code specifications to meet required fire resistance ratings, which is determined by occupancy of the building and number of floors (Regulation for refuge and prevention of fire in building 2015). The fire resistance rating determines required length of time period that a structural member or system is able to function properly under fire. ACI 318-11 (2011) provides the chart for determining the fire resistance rating of concrete walls based on thickness and concrete type. Eurocode 2 provides a chart of minimum thickness of walls and cover based on the required fire resistance rating, which is determined by the number of exposure surface and loading condition
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
