Experimental study on charring properties of bamboo scrimber exposed to three-and four-side fire

Abstract:

As a new structural material, bamboo scrimber has been widely adopted in construction engineering. However, considering that bamboo scrimber is a combustible material similar to timber, it is urgent to complement and improve the fire resistance design of bamboo scrimber structures. To study the charring properties of bamboo scrimber, a total of 16 specimens in 4 groups exposed to three-and four-side fire were tested to analyze effects of section size, exposure time, and exposure surface number on charring depth and charring with furnace temperatures following the requirements of ISO 834. Results show that the charring rate decreases as the exposure time increases due to the thermal resistance of char layer. The effective section decreases and the cross-section changes to corner rounding due to the double heating process. The difference of the charring depth between the corner and non-corner areas is significant. Comparing with the charring properties of bamboo scrimber exposed to one side fire, the charring depth in multi-side fire is larger than that in one side fire. The simulation model of charring depth is further revised by considering multi-side charring factor. To simplify the fire resistance design, the notional charring rate is suggested to be 0.7 mm/min based on the corner rounding effect. Therefore, the reliable data can be used in residual cross-section simulation of bamboo scrimber structures after fire.