Summary In this paper, a comparative simulation study on 3 large‐scale facade testing methods, namely, the SP Fire 105, BS 8414‐1, and the ISO 13785‐2 methods, is presented. Generally good correspondence between simulations and experimental data has been found, provided that thermal properties of the facade material and heat release rates are known; however, the correspondence deviates in close proximity of the fire source. Furthermore, a statistical ensemble for evaluating the effects stemming from uncertainty in input data is used. Here, it was found using this statistical ensemble that the variability was smaller in the ISO 13785‐2 compared to the BS 8414‐1 method. The heat release rates (HRR) used in the simulations were adopted from measurements except for the ISO method where the information in the standard was used to approximate the HRR. A quantitative similarity between the HRR in the ISO method and the British method was found.

High-performance concrete (HPC) is now used routinely in building and civil structures. . The development of using HPC in structural applications and the growing need for justification of the fire resistance has led several laboratories to carry out research on properties at high temperature. This letter presents some main aspects related to physicochemical changes, thermal properties and mechanical properties for HPC at high temperature. It introduces a State of The Art prepared by the RILEM Technical Committee 227-HPB (Physical properties and behaviour of HPC at high temperature) and titled "Behaviour of HPC at high temperatures". This State of the Art will be published in the near future.

An experimental study of the influence of an exposed combustible ceiling on compartment fire dynamics has been performed. The fire dynamics in compartments with combustible cross-laminated timber ceilings vs non-combustible reinforced concrete ceilings in otherwise identical compartments with three different ventilation factors were investigated. The experimental results are compared against predictions from two theoretical models for compartment fire dynamics: (a) the parametric fire model given in EN 1991-1-2, and (b) a model developed at Technische Universität Braunschweig, which are the parametric fire models currently used in Germany. It is confirmed that the introduction of a combustible timber ceiling leads to higher temperatures within the enclosure, both under fuel-controlled and ventilationcontrolled scenarios. It is also demonstrated that the theoretical models considered in this article require refinement in order to adequately represent all relevant scenarios when combustible ceilings are present. A refinement of the German model, by adding the fuel from the combustible ceiling to the occupancy fuel load, was shown to not adequately capture the response for the ventilation-controlled fires.

Summary Standard fire resistance tests have been used in the design of structural building elements for more than a century. Originally developed to provide comparative measures of the level of fire safety of noncombustible products and elements, the recent resurgence in engineered timber construction raises important questions regarding the suitability of standard fire resistance tests for combustible structural elements. Three standard fire resistance floor tests (5.9 m × 3.9 m in plan), one on a concrete slab and two on cross‐laminated timber (CLT) slabs, were undertaken to explore some of the relevant issues. The fuel consumption rate within the furnace was recorded during these tests, and the energy supplied from this was determined. An external fuel supply (from natural gas supplied to the furnace) equating to approximately 3 MW was recorded throughout the concrete test, whereas this was about 1.25 MW throughout the CLT tests. The total heat release rate was calculated using carbon dioxide generation calorimetry; this yielded values of approximately 1.75 MW during the CLT tests (ie, an additional energy contribution of approximately 0.5 MW from the timber). This demonstrates that considerably more energy input (by about 1.25 MW) was needed to heat the system when the test sample was noncombustible. A further series of six large‐scale compartment fire experiments (6 m × 4 m × 2.52 m) was undertaken to further explore comparative performance of combustible versus noncombustible construction when the external fuel load is kept constant and is governed by more realistic compartment fire dynamics. For a fuel‐controlled case, the peak temperatures in the compartment with an unprotected CLT ceiling were approximately 200°C higher than in the compartments with a concrete ceiling, whereas for a ventilation‐controlled case, the compartment with a CLT slab ceiling displayed a burning duration that increased by approximately 15 minutes. Potential implications for standard fire resistance testing of combustible specimens are discussed.

Summary The impact of different passive protective measures against external vertical fire spread was investigated using the numerical tool Fire Dynamics Simulator (FDS). The numerical study was divided into a validation study and a comparative analysis. The validation study was performed to evaluate FDS as a calculation tool for modelling external vertical fire spread and was conducted using experimental results from a large‐scale fire test done on a SP FIRE 105 test rig at SP, Sweden. It was concluded that FDS 6.2.0 could reproduce the experimental results with a reasonable level of detail. In the comparative analysis, the impact on the external fire from a smaller apartment was studied in FDS with different configurations of horizontal projections and spandrels in the building exterior. Also, the effects of an upper and lower facade set‐back configuration were studied. The results show that facade solutions based on a horizontal projection or an upper facade set‐back configuration result in comparable or better protection compared with a defined spandrel height. The results also show that a spandrel height of at least 1.2 m can be replaced by a 60‐cm‐deep horizontal projection, given that the balcony is wider than the underlying opening.