Abstract This paper presents theoretical descriptions of the key phenomena that govern the behaviour of composite framed structures in fire. These descriptions have been developed in parallel with large scale computational work undertaken as a part of a research project (The DETR-PIT Project, Behaviour of steel framed structures under fire conditions) to model the full-scale fire tests on a composite steel framed structure at Cardington (UK). Behaviour of composite structures in fire has long been understood to be dominated by the effects of strength loss caused by thermal degradation, and that large deflections and runaway resulting from the action of imposed loading on a ‘weakened’ structure. Thus ‘strength’ and ‘loads’ are quite generally believed to be the key factors determining structural response (fundamentally no different from ambient behaviour). The new understanding produced from the aforementioned project is that, composite framed structures of the type tested at Cardington possess enormous reserves of strength through adopting large displacement configurations. Furthermore, it is the thermally induced forces and displacements, and not material degradation that govern the structural response in fire. Degradation (such as steel yielding and buckling) can even be helpful in developing the large displacement load carrying modes safely. This, of course, is only true until just before failure when material degradation and loads begin to dominate the behaviour once again. However, because no clear failures of composite structures such as the Cardington frame have been seen, it is not clear how far these structures are from failure in a given fire. This paper attempts to lay down some of the most important and fundamental principles that govern the behaviour of composite frame structures in fire in a simple and comprehensible manner. This is based upon the analysis of the response of single structural elements under a combination of thermal actions and end restraints representing the surrounding structure.

Fundamental principles of structural behaviour under thermal effects (large composite buildings under compartment fires)

Evaluating the fire risk associated with cladding panels: An overview of fire incidents, policies, and future perspective in fire standards

Although using various innovative materials for ventilated facade systems positively contribute to the energy efficiency of buildings, the application of such materials can also pose a certain risk of fire propagation through the facade. In the last decade, medium and large-scale tests, as well as numerical analysis have been performed to assess the impact of fire barriers on fire propagation through ventilated facades. However, the number of fire barriers and their specific positions can also have an effect on the fire safety of facades, which has not been studied. Consequently, the question arises whether real fire exposure on a facade can be adequately simulated and analysed in sufficient detail, by using large-scale testing methods. This paper aims to conduct a parametric analysis on a broader range of large-scale samples by using the procedure given in the standard BS 8414-1:2015 + A1:2017. To understand better the impact of the number and position of cavity barriers for different types of insulation materials (stone wool/PIR/phenolic foam) used in modern facade systems with non-combustible cladding (ACM-A2). Seven tests were carried out in Croatia between October 2017 and April 2018. In the case of combustible insulation, two horizontal barriers were insufficient in preventing fire propagation. Temperatures accumulated above 600°C, reaching 840°C in PIR insulation and 979°C in phenolic foam insulation. For the same sample designed with non-combustible insulation, the maximum temperature measured was 133°C. Facades with combustible insulation passed the test only when four horizontal barriers were used. The existence of vertical barriers had a positive impact on preventing the fire propagation because the insulation on the left side of the chamber, behind the vertical barrier, remained undamaged. Vertical barriers on the right side of the chamber delayed the horizontal fire propagation from the main wall to the wing wall depending on the type of insulation. The results from these tests can serve as a basis for future research on the effects of fire barriers on fire propagation.

/pdf/influence-of-horizontal-and-vertical-barriers-on-fire-2c191odt0d.pdf

Influence of Horizontal and Vertical Barriers on Fire Development for Ventilated Façades

Multi-objective optimal structural design of composite superstructure using a novel MONMPSO algorithm

Thermal modelling of LSF floor-ceiling systems with varying configurations

https://pure.tue.nl/ws/files/120978512/fsj_de_boer_final_II.pdf

Two-way coupled CFD fire and thermomechanical FE analyses of a self-supporting sandwich panel façade system

The distribution of signaling molecules following mechanical or chemical stimulation of a cell defines cell polarization, with regions of high active Cdc42 at the front and low active Cdc42 at the rear. As reaction-diffusion phenomena between signaling molecules, such as Rho GTPases, define the gradient dynamics, we hypothesize that the cell shape influences the maintenance of the "front-to-back" cell polarization patterns. We investigated the influence of cell shape on the Cdc42 patterns using an established computational polarization model. Our simulation results showed that not only cell shape but also Cdc42 and Rho-related (in)activation parameter values affected the distribution of active Cdc42. Despite an initial Cdc42 gradient, the in silico results showed that the maximal Cdc42 concentration shifts in the opposite direction, a phenomenon we propose to call "reverse polarization". Additional in silico analyses indicated that "reverse polarization" only occurred in a particular parameter value space that resulted in a balance between inactivation and activation of Rho GTPases. Future work should focus on a mathematical description of the underpinnings of reverse polarization, in combination with experimental validation using, for example, dedicated FRET-probes to spatiotemporally track Rho GTPase patterns in migrating cells. In summary, the findings of this study enhance our understanding of the role of cell shape in intracellular signaling.

/pdf/on-the-influence-of-cell-shape-on-dynamic-reaction-diffusion-3zv0mj9ny8.pdf

J.G.G.M. de Boer

Papers

Two-way coupled CFD fire and thermomechanical FE analyses of a self-supporting sandwich panel façade system

On the influence of cell shape on dynamic reaction-diffusion polarization patterns.