Abstract

In the present work, a simplified hydro-thermal model for pore pressure calculation in concrete exposed to high temperatures is presented. The model is based on heat and mass transfer analysis in multi-phase porous media. The model has been structured in such a way that it is possible, due to assumptions, to reduce the numbers of inputs without compromising the results of the predictions. The validation process has been performed, and it has shown that the computational model is capable to reproduce with a high reliability and accuracy the mass losses reported in the experimental tests and the evolution of temperatures on concrete due to thermal exposure, both at the exposed surface and inside the element. Likewise, pore pressure estimated by the model agrees with the experimental results.

Abstract

In this work, the study of smoke fire transportation inside of a subway passenger platform is presented. The study includes a set of numerical simulations to observe the behavior of the air inside the platform. Two smoke transport simulations using the FDS program are also included. Subsequently, the development of a 3D - 1:100 scale model is described and it was used to perform an experimental observation of the phenomenon. The model was built by using a 3D printer which allowed to include more architectural details of the real scenario. The inclusion of these details allowed to observe qualitative similarity between the results of the simulation and the experimental work. Although there are clear differences between what could happen in a real scenario and what was observed in the scale model, it was identified that the model is an important complement to the simulations. In addition to the simulations, the use of this type of 3D models allows the observation of the phenomenon by different specialists such as firefighters, policeman, medical personnel, etc., in the same place and its intention is to provide a more interactive tool to the observation group, increasing the time devoted to the development of contingency actions and reducing the costs associated with the logistics of a real simulacrum. The model allows to better identify the strengths, opportunities, weaknesses and threats of the contingency procedures developed by the safety and hygiene groups and to make their corresponding adjustments if necessary.

Abstract

Abstract

The objective of this study is to develop a tsunami evacuation simulation system that takes into account building collapse and fire spread. Road blockage is determined by calculating the road blockage probability due to building collapse, taking into account the size of the assumed earthquake, location of buildings, and type of building. For fire spread simulation, an existing simulator based on the fire spread rate equation is used. Under average wind direction and speed conditions for the target area, arbitrary fire points are set up and fire spread is represented using fire times for each building obtained from the simulation. The applicability of this system as a scenario is extended. The present system is applied to several examples to demonstrate the validity and effectiveness of the system.

Abstract

Reinforced concrete (RC) structures deteriorate over time and therefore, need to be strengthened. Despite the fact that RC structurtes have a decent fire rating, the performance of the strengthening system under fire exposure needs to be evaluated. One of the main restrictions associated with Fibre Reinforced Polymer (FRP) systems is their poor resistance to high temperatures, which originates from the combustible polymer matrix. Therefore, Fibre Reinforced Cementitious Matrix (FRCM) systems have been introduced due to their improved performance during fire exposure. The potential of Poly-paraphenylene-ben-zobisoxazole (PBO) FRCM to strengthen circular RC columns is evaluated using a nonlinear finite element analysis (FEA). The commericial software ABAQUS is used to develop 3D FE models to investigate the axial performance of the strengthening system. The modeling approach is performed by first conducting a thermal analysis to generate the nodal tempertaures. The second step of the model includes a displacement-controlled loading condition with imported nodal temperatures from the first model. The temperature dependent material properties are incorporated in both models. The modeling approach is validated against published literature and a parametric study is conducted on PBO FRCM strengthened and unstrengthened columns heated at durations of 1, 2, and 4 hours following the ASTM standard fire temperature-time curve. Results indicated a decrease in the axial capacity and stiffness of the strengthened and unstrengthened columns upon heating. Moreover, an increase in the columns' ductility due to the increase in temperature was observed. A decrease in ultimate strength of up to 78 and 68% was observed for the unstrengthened and strengthened columns respectively.

Abstract

Abstract

In this work we present the progress in the development of an algorithm for the simulation of thermal fluid–structural coupling in a tunnel fire. The coupling strategy is based on a Dirichlet/Neumann non‐overlapping domain decomposition of the problem, which is carried out by developing a master code that controls solvers dedicated to the fluid mechanics and to the solid mechanics simulation. The computational fluid dynamics formulation consists of a stabilized finite element approximation of the low Mach number equations based on the subgrid scale concept, that allows us to deal with convection‐dominated problems and to use equal order interpolation of velocity and pressure. The thermo‐structural model of the tunnel vault, that considers a multiphase porous material where pores are partly filled with liquid and partly by gas, is specially devised for the simulation of concrete at high temperatures and consists of balance equations for mass conservation of dry air, mass conservation of water species (both in the liquid and gaseous state), enthalpy conservation and linear momentum conservation taking phase changes into account. The developed algorithm is applied to the problem of the response of a tunnel to a fire. We consider the combustion process as a heat release which can vary usually from 1thinspaceMW for small car fires to 100 MW for catastrophic fires. The released heat is transferred to the concrete walls of the tunnel which could cause extensive and heavy damage of the structure.

Abstract

Abstract