F.P. Álvarez Rabanal

Evaluation of the damage in the vault and portico of the pre-Romanesque chapel of San Salvador de Valdediós using frictional contacts and the finite-element method

Monuments are by definition unique buildings which cannot be reduced to any standard structural scheme. In this study, we have used quasi-static loads, which is common practice in many finite-element (FEM) analyses of masonry structures. Thus it is difficult to evaluate their reliability, because in addition to the many uncertainties that exist in all ‘old’ buildings, no statistics on the behaviour of similar buildings are available. In this paper we describe a study of the structure of the chapel of San Salvador de Valdediós and proposals for its restoration. The non-linear analysis is based on the application of FEM to each of the stone blocks in this ancient structure. The blocks are assembled side by side using ‘contact elements’ in order to reproduce the mechanical behaviour of the mortar and the surface conditions of the blocks, some of which are seriously damaged. A clear understanding of the structural behaviour, based on sophisticated analysis tools, can reduce the extent of the remedial measures necessary for the restoration of the chapel vault and portico. In this case, severe damage to the chapel vault has affected the portico, resulting in the possibility of a structural collapse. Finally, based on the numerical results obtained for different load cases and hypotheses, we propose a solution for the repair of this part of the chapel using either traditional materials or compatible substitutes.

Non-linear thermal analysis of the efficiency of light concrete multi-holed bricks with large recesses by FEM

Abstract This paper shows how advanced numerical methods can help to improve the thermal efficiency of walls made up of multi-holed bricks with large recesses. In order to get this objective, a new methodology based on different numerical simulations is presented here. With the help of the finite element analysis (FEA), we present an optimization procedure in order to determine the best candidate brick with large recesses from the thermal point of view. With respect to the ecological design and the energy saving for housing and industrial structures, there is also a great interest in light building materials with good physical and thermal behaviours, which fulfils all thermal requirements of the new CTE Spanish rule for further energy savings. On one hand, we want to validate the numerical analysis procedure, based on the simulation of three-dimensional walls by the finite element method (FEM). On the other hand, we have analyzed the material conductivity for different compositions of the light concrete. The FEM technique is used for finding accurate solutions of the heat transfer equation in walls made up of light concrete multi-holed bricks with large recesses. Mathematically, the non-linearity is due to the radiation boundary condition inside the inner recesses of the bricks. Next, the thermal optimization of the walls is carried out from the FEM technique of several hollow brick geometries using the average mass overall thermal efficiency and the equivalent thermal conductivity. In order to select the appropriate wall satisfying the CTE requirements, detailed instructions are obtained and indicated to the readers. Finally, conclusions of this paper are exposed.

Improvement alternatives for determining the watertightness performance of building facades

The accurate determination of a facades watertightness performance is important for optimizing design. Different micro-climatic conditions can affect water penetration. The recently developed Bayesian method allows this performance to be estimated for any operating condition and location, based on the results of standardized watertightness tests. This performance-based method uses semi-empirical calculations for wind-driven rain, estimates of wind velocity based on the wind profile power law and analyses of the annual maximum climatic data. This method determines the return period of climatic conditions that each facade system can withstand. Alternative approximations are studied that may be implemented using the Bayesian method to obtain more precise or functional estimations: improved friction coefficients, peaks-over-threshold analyses or catch ratios from computational fluid dynamics (CFD), among others. The effects of these alternatives on the results of the Bayesian method were evaluated by analysing different case studies in two cities in Spain. This analysis suggests that the original formulation of the method underestimates watertightness performance and highlights the fundamental importance of wind velocity to estimate the performance of any facade accurately. This will provide greater precision for estimating facade performance and provides potential for introducing performance-based codes for watertightness.

Acoustic Analysis of a Sandwich Non Metallic Panel for Roofs by FEM and Experimental Validation

In this paper we have studied the acoustic behavior of a sandwich non metallic panel for roofs by the finite element method (FEM). This new field of analysis is the fully coupled solution of fluid flows with structural interactions, commonly referred to as fluid‐structure interaction (FSI). It is the natural next step to take in the simulation of mechanical systems. The finite element analysis of acoustic‐fluid/structure interactions using potential‐based or displacement‐based Lagrangian formulations is now well established. The non‐linearity is due to the ‘fluid‐structure interaction’ (FSI) that governs the problem. In a very considerable range of problems the fluid displacement remains small while interaction is substantial. In this category falls our problem, in which the structural motion influence and react with the generation of pressures in two reverberation rooms. The characteristic of acoustic insulation of the panel is calculated basing on the pressures for different frequencies and points in th...

Numerical simulation of bus aerodynamics on several classes of bridge decks

ABSTRACT This paper is focused on improving traffic safety on bridges under crosswind conditions, as adverse wind conditions can increase the risk of traffic accidents. Two ways to improve traffic safety are investigated: improving vehicle stability by means of wind fences installed on the bridge deck and by modifying the design parameters of the infrastructure. Specifically, this study examines the influence of different parameters related to the bridge deck configuration on the aerodynamic coefficients acting on a bus model under crosswind conditions. The aerodynamic coefficients related to side force, lift force and rollover moment are obtained for three classes of bridge deck (box, girder and board) by numerical simulation. FLUENT was used to solve the Reynolds-averaged Navier–Stokes (RANS) equations along with the shear stress transport (SST) k–ω turbulence model. Two crash barriers located on the box bridge deck were replaced with an articulating wind fence model and the effect of the angle between the wind fence and the horizontal plane on the bus aerodynamic was investigated. The risk of rollover accidents was found to be slightly influenced by the bridge deck type for a yaw angle range between 75° and 120°. In order to study the effect of the yaw angle on the aerodynamic coefficients acting on bus, both the bus model and the bridge model were simultaneously rotated. The minimum value of the rollover coefficient was obtained for an angle of 60° between the wind fence slope and the horizontal plane. The only geometry parameter of the box bridge deck which significantly affects bus aerodynamics is the box height. The present research highlights the usefulness of computational fluid dynamics (CFD) for improving traffic safety, studying the performance of the articulating wind fence, and determining which geometry parameters of the box deck have a significant influence on the bus stability.

Nonlinear analysis of the pressure field in industrial buildings with curved metallic roofs due to the wind effect by FEM

HighlightsReliable results for pressure were obtained by using steady RANS-CFD simulations.We have determined the forces and moments on the cover with accurateness.A standard k-e model is integrated to investigate the wind effect by FEM. In this paper, an evaluation of distribution of the air pressure is determined throughout the laterally closed industrial buildings with curved metallic roofs due to the wind effect by the finite element method (FEM). The non-linearity is due to Reynolds-averaged Navier-Stokes (RANS) equations that govern the turbulent flow. The Navier-Stokes equations are non-linear partial differential equations and this non-linearity makes most problems difficult to solve and is part of the cause of turbulence. The RANS equations are time-averaged equations of motion for fluid flow. They are primarily used while dealing with turbulent flows. Turbulence is a highly complex physical phenomenon that is pervasive in flow problems of scientific and engineering concern like this one. In order to solve the RANS equations a two-equation model is used: the standard k-? model. The calculation has been carried out keeping in mind the following assumptions: turbulent flow, an exponential-like wind speed profile with a maximum velocity of 40m/s at 10m reference height, and different heights of the building ranging from 6m to 10m. Finally, the forces and moments are determined on the cover, as well as the distribution of pressures on the same one, comparing the numerical results obtained with the Spanish CTE DB SE-AE, Spanish NBE AE-88 and European standard rules, giving place to the conclusions that are exposed in the study.