a b s t r a c tWhen building fires occur in large, open compartments they rarely burn uniformly across an entire floor plate of a structure. Instead, they tend to travel, igniting fuel in their path and burning it out as they move to the next fuel package. Current structural fire design methods do not account for these types of fires. This paper applies a novel methodology for defining a family of possible heating regimes to a framed concrete structure using the concept of travelling fires. A finite-element model of a generic concrete structure is used to study the impact of the family of fires; both relative to one another and in comparison to the conventional codified temperature-time curves. It is found that travelling fires have a significant impact on the performance of the structure and that the current design approaches cannot be assumed to be conservative. Further, it is found that a travelling fire of approximately 25% of the floor plate in size is the most severe in terms of structural response. It is concluded that the new approach is simple to implement, provides more realistic fire scenarios, and is more conservative than current design methods.
A large-scale fire test was conducted on a compartment constructed from cross laminated timber (CLT). The internal faces of the compartment were lined with non-combustible board, with the exception of one wall and the ceiling where the CLT was exposed directly to the fire inside the compartment. Extinction of the fire occurred without intervention. During the fire test, measurements were made of incident radiant heat flux, gas phase temperature, and in-depth temperature in the CLT. In addition, gas flow velocities and gas phase temperatures at the opening were measured, as well as incident heat fluxes at the facade due to flames and the plume leaving the opening. The fuel load was chosen to be sufficient to attain flashover, to achieve steadystate burning conditions of the exposed CLT, but to minimize the probability of uncertain behaviors induced by the specific characteristics of the CLT. Ventilation conditions were chosen to approximate maximum temperatures within a compartment. Wood cribs were used as fuel and, following decay of the cribs, selfextinction of the exposed CLT rapidly occurred. In parallel with the large-scale test, a small scale study focusing on CLT self-extinction was conducted. This study was used: to establish the range of incident heat fluxes for which self-extinction of the CLT can occur; the duration of exposure after which steady-state burning occurred; and the duration of exposure at which debonding of the CLT could occur. The large-scale test is described, and the results from both the small and large-scale tests are compared. It is found that selfextinction occurred in the large-scale compartment within the range of critical heat fluxes obtained from the small scale tests.
The mechanical properties of different adhesives at elevated temperatures can change differently due to the differences in adhesive molecular chain structure. Therefore, a profound understanding of the effect of these property changes on the bond behaviour of carbon fibre reinforced polymer (CFRP)-to-steel bonded joints is of great importance when designing bonded CFRP strengthening systems for steel structures. Existing studies on CFRP-to-steel bonded joints under monotonic loading have clearly shown that both adhesive mechanical properties and geometrical properties of the bonded joints (e.g. bond length) may significantly influence the bond strength. Existing studies on adhesive mechanical properties under elevated temperatures have shown that the variation of adhesive mechanical properties, especially fracture energy with temperature depends significantly on the adhesive type. No comprehensive study exists so far on understanding the effects of key mechanical and geometrical parameters of a CFRP-tosteel bonded joints at elevated temperatures on bond strength. This paper presents a study aimed at understanding the effects of different parameters such as temperature dependent mechanical properties of adhesive and bond length on the behaviour of CFRP-to-steel bonded joints at elevated temperatures.Results of this study showed that (1) load-displacement behaviour of the bonded joints is sensitive to temperature variations, (2) for bonded joints with sufficiently long bond length, the ultimate load depends only on the fracture energy of the final temperature, and (3) the maximum load of the bonded joints depends on the ratio between the loading and heating rates.
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