Paulo Amado Mendes

Paulo Amado Mendes
University of Coimbra | UC · Institute for Sustainability and Innovation in Structural Engineering

PhD

About

120
Publications
14,575
Reads
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798
Citations
Citations since 2017
59 Research Items
552 Citations
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
Introduction
Civil Engineering / Applied Physics and Mechanics Wave propagation in elastic and acoustic media Wave scattering by cracks/thin heterogeneities in elastic and acoustic media Numerical modelling w/ Boundary Element Method, Traction Boundary Element Method and Meshless Methods Non-destructive evaluation techniques Acoustics and Vibrations
Additional affiliations
March 2015 - December 2017
University of Coimbra
Position
  • Professor (Assistant)

Publications

Publications (120)
Conference Paper
Full-text available
Resonators can be effective devices to help to tackle low-frequency insulation, and have been widely investigated in the literature. In building acoustics, literature reports their historical use, leading to the design of new structures for room acoustic optimization, and urban and environmental mitigation. Structures based on sub-wavelength resona...
Article
Full-text available
An important challenge for acoustic engineers in room acoustics design is related to the acoustic performance of multi-purpose auditoriums, which are typically designed to suit several performance requirements. With this intent, the analysis of several scenarios is usually performed individually, and then an acceptable solution, that may be adapted...
Article
Full-text available
Data-driven methodologies are among the most effective tools for damage detection of complex existing buildings, such as heritage structures. Indeed, the historical evolution and actual behaviour of these assets are often unknown, no physical models are available, and the assessment must be performed only based on the tracking of a set of damage-se...
Conference Paper
Full-text available
Urban noise has been recognised as a serious environmental problem in urban centres. The development and application of noise control strategies have thus demanded a recent effort by several researchers. In the present study, the development of an acoustic metamaterial artificially designed to manipulate the wave phenomena has become a recent resea...
Article
The assessment of vibrations induced by railway traffic is a complex issue that demands numerical tools for prediction of its generation and propagation along the track-ground-building system. For that purpose, this paper presents a 2.5D FEM-MFS model for modelling the track-ground system, where the Finite Element Method (FEM) is used to model the...
Article
Full-text available
Understanding urban noise as a serious environmental problem in urban centers, the development and application of noise control strategies have demanded a recent effort by several researches. In this case, the development of acoustic metamaterial artificially designed to manipulate the wave phenomena has become a recent topic, aiming at optimized r...
Article
Full-text available
Sonic crystal acoustic screens have been in progressive research and development in the last two decades as a technical solution for mitigating traffic noise. Their behaviour is quite different from that observed in classical barriers, with the latter being based on physically blocking the direct sound propagation path (only allowing diffracted noi...
Article
Full-text available
The prediction of the sound absorption coefficient in diffuse field conditions is of great interest to an acoustic project. Foams and granular materials like porous concrete have been used in many internal or external applications as sound absorbers. However, many doubts have regularly been discussed in scientific literature. The simple use of expe...
Article
A relatively new concept of sound absorption herein denominated as Metaporous concrete is presented, consisting of a porous concrete-based sound absorber in which different acoustic resonators are embedded. Two finite element models were implemented, using the fluid-equivalent theory to describe Metaporous concrete solutions. A Helmholtz resonator,...
Article
Full-text available
Even small damages in engineered systems can endanger the users or lead to significant economic costs. The detection of damage existence is only the first task within the Damage Identification strategy, nonetheless, it is still very complex, especially for Civil Engineering products. The present study is devoted to the analysis of a global methodol...
Article
There are several international standards that define the way to evaluate the attenuation capacity of noise reducing devices, by single-number quantities representing airborne sound insulation and insertion loss. These two single-value ratings define the quality and performance of acoustic barriers, the former being related to intrinsic and the lat...
Article
The use of numerical tools to predict and analyze the dynamic response of buildings exposed to railway traffic is essential to face the continuous challenges motivated by the increasing demand for transportation infrastructures in urban context. Given the complexity of the entire system involved, their experimental validation is an essential step....
Conference Paper
Full-text available
The early-stage identification of structural damage still represents a relevant challenge in civil engineering. Localized damages if not readily detected can lead to disruption or even collapse, involving hazard to people and economical losses. Although the final goal of the identification is to localize and quantify the damage, a reliable discrimi...
Conference Paper
Full-text available
Helmholtz resonators (HRs) are widely applied in building acoustics environments. The literature reports their historical use to acoustical optimization in rooms, temples and auditoriums. Several studies have also investigated the use of HRs for noise attenuation, with a wide range of applications which includes improvement of transmission loss in...
Conference Paper
The main objective of this work is to characterize, experimentally and theoretically, the acoustic performance of porous concrete mixtures and their macroscopic parameters. The aggregates used in the mixtures were expanded clay with different grain sizes and Lava. Both sound absorption coefficient and surface impedance were measured in an impedance...
Article
Full-text available
In the framework of Structural Health Monitoring, vibration-based methods are commonly used to assess the condition of a structural system, being the dynamic properties sensitive to damage-induced changes. Within this context, negative selection, a bio-inspired classification algorithm, can be exploited to distinguish anomalous from normal behaviou...
Article
Full-text available
The use of porous concrete solutions with lightweight aggregates has become increasingly common in noise control due to their versatility in exterior and interior applications. In this work, samples of porous consolidated concrete with aggregates of expanded clay were produced, in order to study the influence of the grain size, thickness and water/...
Conference Paper
Seismic protection and vulnerability reduction are very relevant issues in European regions, such as Italy, characterized by the presence of a large stock of cultural heritage structures. This concern increased the interest in Structural Health Monitoring (SHM) as a powerful tool to quantify and reduce uncertainties regarding the structural perform...
Article
Full-text available
Vibration induced by vehicles is a significant problem in large cities causing a major impact on human activities, comfort and health. Besides well-known strategies to mitigate vibrations and their effects, innovative methods are being devised using novel physical concepts. Those are already well-developed for the case of acoustic barriers, for exa...
Conference Paper
Full-text available
Sound diffusers are currently a widely used solution in critical listening rooms, in order to reduce specular reflections without introducing excessive sound absorption. There are several types of diffusers on the market, although the most common are derived from the pioneering work of M. Schroeder in this area almost four decades ago. However, the...
Article
Some of the most extended approaches to widen the sound absorption bandwidth of perforated panel absorbers are the use of different cavity depths or multi-layer arrangements. Unfortunately, these solutions are rarely adopted in practice because of the technical installation difficulties or the large space requirements. This work explores an alterna...
Conference Paper
Full-text available
There are many doubts about the proper calculation of the sound absorption coefficient of the porous materials when applied in a room, under diffuse field. The simple use of impedance tube data for this purpose (according to ISO 10534-2, [1]) is not entirely correct since it considers only incident plane waves. There are several diffuse-field sound...
Conference Paper
Full-text available
The acoustic performance of partition walls is usually based either in their mass or in a layered structure, including materials with different properties (external layers and internal absorbing materials, for example). In recent years, the consideration of additional dynamic effects in the behaviour of such systems has been used to improve their p...
Presentation
Full-text available
There are many doubts about the proper calculation of the sound absorption coefficient of the porous materials when applied in a room, under diffuse field. The simple use of impedance tube data for this purpose (according to ISO 10534-2, [1]) is not entirely correct since it considers only incident plane waves. There are several diffuse-field sound...
Article
Noise abatement provided by acoustic metamaterials is one of the peculiar features presented by these remarkable materials. In fact, the use of local resonant elements and their periodic distribution in the form of so-called sonic crystal arrangements have demonstrated to enhance those attenuation properties. In this work, the authors present an ef...
Article
The use of periodic structures in acoustic applications has interested the scientific community in the last two decades. Although in-depth research has been thoroughly performed, many issues have still not been solved. Computational analysis of sonic structures using realistic 3D models still poses significant problems, and most of the published re...
Article
The interest of scientific and technical communities in the re-radiated noise phenomenon has been increasing over the last years, motivated by complaints of inhabitants living in buildings located next to sources of vibrations. The study and quantification of low-frequency noise levels inside these buildings demand accurate methods of prediction. T...
Conference Paper
Full-text available
The main objectives of Structural Health Monitoring (SHM) are the characterization and the assessment of the health condition of structural systems. Combined with appropriate Damage Identification (DI) strategies, SHM aims to provide reliable information about the localization and quantification of the structural damage by using an inverse formulat...
Conference Paper
Full-text available
The authors, in previous works, proposed an alternative technique to define new shapes for efficient sound diffusion based on the use of radial basis functions (RBF) and, using a genetic algorithm (GA), optimized those curvilinear surfaces, maximizing the diffusion coefficient. This parameter is computed within the optimization procedure using the...
Conference Paper
Vibration induced by vehicles is a significant problem in large cities causing a major impact on human activities, comfort and health. Innovative protection strategies based on “phononic” crystals have recently been developed. Previous research already demonstrated the possibility to filter the most dominant vibration frequencies. The work presente...
Article
The topic of vibrations induced by rail traffic has received a special attention from the scientific community over the last decades, which is justified by the increase of health awareness and comfort demands by the communities living nearby such infrastructures. Regarding mitigation of sound waves propagation, innovative solutions based on the pho...
Conference Paper
The present paper describes a study on the concept of using a periodic buried structure, made of rigid elements (e.g. concrete), disposed with a geometrical arrangement that may allow an efficient filtering of vibrations at specific frequencies. The work makes use of a 3D finite element model, formulated using tetrahedral elements, to perform a set...
Article
Full-text available
In the last decades, the field of structural health monitoring (SHM) has grown exponentially. Yet, several technical constraints persist, which are preventing full realization of its potential. To upgrade current state-of-the-art technologies, researchers have started to look at nature’s creations giving rise to a new field called ‘biomimetics’, wh...
Conference Paper
Variations in dynamic properties are commonly used in Structural Health Monitoring to assess the conditions of a structural system, being these parameters sensitive to damage-induced changes. Yet, such variations can also be due to changes in environmental parameters, like fluctuations in temperature, humidity, etc. By performing a continuous monit...
Conference Paper
Well-known classical strategies to mitigate vibrations induced by vehicles include buried trenches and inertia blocks. Besides these strategies, innovative methods are being devised by researchers using novel physical concepts. Periodic structures and metamaterials are one such concept, which seem to be a very promising for real engineering applica...
Article
Heterogeneous perforated panels are of great interest as sound absorbers, while achieving a smart high-end decoration in meeting rooms, showrooms, conference halls, etc. However, their uneven nature may pose a difficulty when trying to predict their acoustic performance using traditional impedance models. This work explores the use of four differen...
Article
The acoustic behavior of periodic structures has been a subject of intense study in recent years. From the computational point of view, these devices have mostly been analyzed using strategies such as the multiple scattering theory (MST) or numerical methods such as the finite element method (FEM). Some recent works propose the use of boundary meth...
Article
Phononic crystals have been extensively studied, and their capacity to attenuate the propagation of sound waves at specific frequency bands is well known and documented in the literature. However, few studies exist concerning the behaviour of such structures in the context of elastic media, with the purpose of attenuating the transmission of vibrat...
Article
Full-text available
The search for innovative mitigation solutions that can be adopted in urban areas to efficiently reduce the effects of induced vibrations by increasing numbers of vehicles has motivated a significant number of researchers from different fields. An interesting concept seems to be the use of buried elastic inclusions, periodically arranged parallel t...
Article
Structural Health Monitoring (SHM) of historical building is an emerging field of research aimed at the development of strategies for on-line assessment of structural condition and identification of damage in the earliest stage. Built heritage is weak against operational and environmental condition and preservation must guarantee minimum repair and...
Article
Full-text available
In the last decades, the number of railway projects in urban environment has continuously increased. This rising requires a significant level of knowledge from the scientific and technical communities about the phenomena of generation and propagation of vibrations with emphasis on its interference in nearby buildings and the consequent nuisance of...
Article
European Directive 2002/49/EC indicates that strategic noise maps are the main tool for assessing the exposure of the population to environmental noise. When these are made through computational methods , the presence of lines of parked vehicles on the sides of urban streets is not usually considered, but recent studies suggest the possibility that...
Conference Paper
The optimization of diffusers' design has been a topic of intense research in the last years. In this paper, the authors propose an alternative technique to define new shapes of sound diffusion configurations, based on the use of radial basis functions (RBF). In addition, to allow the definition of optimal surface shapes for a given frequency band,...
Conference Paper
Full-text available
The optimization of diffusers’ design has been a topic of intense research in the last years. In this paper, the authors propose an alternative technique to define new shapes of sound diffusion configurations, based on the use of radial basis functions (RBF). In addition, to allow the definition of optimal surface shapes for a given frequency band,...
Conference Paper
Full-text available
This work presents an experimental analysis of the acoustic behaviour of microperforated MDF panels. The experimental tests are performed over small specimens, using the impedance tube method (ISO 10534-2). The main objectives are the experimental evaluation of the efficiency of such solutions for different assembly conditions and the study of the...
Conference Paper
O presente estudo apresenta o desenvolvimento de um modelo numérico BEM 2D para representação da absorção sonora de materiais porosos com superfícies irregulares. No desenvolvimento desse modelo são utilizadas metodologias analíticas, numéricas e experimentais. Através do método inverso torna-se possível a obtenção dos cinco parâmetros macroscópico...
Conference Paper
Full-text available
The interest of scientific and technical communities on the re-radiated noise phenomenon is increasing over the last years. This paper presents an experimental validation of a 3D FEM-MFS numerical model to predict vibrations and re-radiated noise inside an enclosure. The experimental work carried out consisted in the excitation of a reduced size ac...
Article
The acoustic behavior of periodic structures has been a subject of intense study in recent years. From the computational point of view, these devices have mostly been analyzed using strategies such as the multiple scattering theory (MST) or numerical methods such as the finite element method (FEM). Some recent works propose the use of boundary meth...
Conference Paper
Noise abatement provided by acoustic metamaterials, is one of the peculiar features presented by these very interesting materials that has been investigated in detail by many researchers in recent years. The use of local resonant elements and their periodic distribution in sonic crystal arrangements, has demonstrated to be a valid approach to enhan...
Conference Paper
Full-text available
Civil engineering structures are continuously exposed to the risk of damage whether due to ageing effects, excessive live loads or extreme events, such as earthquakes, blasts and cyclones. If not readily identified, damage will inevitably compromise the structural integrity, leading the system to stop operating and undergo in-depth interventions. T...
Article
The growing of railway infrastructures in urban environments demands accurate methods to predict and mitigate potential annoyance of the inhabitants of the surrounding buildings. The present paper aims to contribute to the goal by proposing a numerical model to predict vibrations and re-radiated noise due to railway traffic. The model is based on a...
Article
Grooved acoustic panels are rigid plates consisting of an interconnected network of periodically arranged slits and circular holes. These devices are traditionally used as resonant absorbers in building acoustics. This paper presents a model to predict the acoustic properties of such absorbers. For this purpose, the classical Johnson-Champoux-Allar...
Article
Sound diffusers are a common technical solution used in the last four decades for conditioning performance rooms with greater acoustic requirements. A significant number of the acoustic diffusers commercially available are based on the phase grating diffusers or Schroeder-type diffusers. However, in some particular cases, the visual appearance of t...
Conference Paper
Full-text available
Development of sound diffusion technical solutions has been a topic of intense research in the last years. Many diffuser shapes, based on mathematical series or in different optimization techniques, have been suggested. In this paper, the authors propose an alternative technique to define new shapes of sound diffusion configurations, based on the u...
Conference Paper
Full-text available
Buried structures may be used to control elastic wave propagation in soils and help reducing vibrations in sensible structures. The analysis of these effects using numerical tools is of high importance and is usually a demanding computational task. In the present work, the authors analyse the possibility of using a meshless method for such simulati...
Conference Paper
Full-text available
The concept of microperforated panels as an absorptive element was first introduced in the 1970's by Maa, and was initially based on the use of metallic or acrylic plates with small thickness (1mm) and with very small perforations (of the order of 1mm). The main idea was to use such materials when fibrous absorptive materials were not adequate. The...
Conference Paper
Full-text available
The high number of railway projects in urban environment requires significant level of knowledge from the scientific and technical communities about the phenomena of generation and propagation of vibrations with emphasis on its interference in nearby buildings and the consequent nuisance of their occupants. In this context, a numerical model to pre...
Article
Vibrations induced by underground railway traffic have been receiving special attention from the technical and scientific communities, and different models for their prediction can be found in the literature. Since the tunnel can be seen as a longitudinally invariant structure, a 2.5D approach can be applied, minimizing the computational requiremen...
Conference Paper
Full-text available
There are several acoustic diffuser solutions, using different materials and configurations. However, the intrinsic characteristics of the materials constituting the diffusers (density, sound absorption, etc.) may significantly influence the performance of these solutions. In the present work, the performance of the same diffuser (a QRD type) confi...
Conference Paper
Full-text available
Acoustic diffusers and absorbing materials can be jointly used in acoustic conditioning of spaces, allowing a mix that ensures proper acoustic properties without excessive absorption, by scattering the sound more evenly around the room, but still absorbing sound where needed. Acoustic defects such as echoes or shadow areas are thus eliminated. Much...
Article
Most of the analytical models devoted to determine the acoustic properties of a rigid perforated panel consider the acoustic impedance of a single hole and then use the porosity to determine the impedance for the whole panel. However, in the case of not homogeneous hole distribution or more complex configurations this approach is no longer valid. T...
Article
Acoustic barriers are a well-known environmental noise mitigation solution, which is widely used nowadays. In this work, it is expected to contribute to the body of knowledge regarding the physical and technical behavior of those barriers by developing and implementing a set of models that allow an accurate analysis of noise barriers with new confi...
Article
In the present work, a three-dimensional (3D) formulation based on the method of fundamental solutions (MFS) is applied to the study of acoustic horns. The implemented model follows and extends previous works that only considered two-dimensional and axisymmetric horn configurations. The more realistic case of 3D acoustic horns with symmetry regardi...
Article
This paper presents a coupling strategy between the Method of Fundamental Solutions (MFS) and the Meshless-Local-Petrov-Galerkin (MLPG) for the analysis of soil-structure interaction problems in the frequency domain. In the proposed approach, the MFS is used to model the outer infinite (or semi-infinite) medium, correctly accounting for the far-fie...
Conference Paper
Full-text available
In the present work, an experimental analysis of the behaviour of microperforated panels made of MDF is performed using the impedance tube method (ISO 10534-2). The main objective is to test the efficiency of such solutions with different perforation dimensions and spacings, and including air gaps with different sizes and characteristics. The exper...
Article
Full-text available
In the present paper, the authors present a numerical analysis of the sound reduction provided by simple acoustic protective measures to attenuate the noise emitted by equipment placed near a fac¸ade. The noise source is assumed to be surrounded by an enclosed space, defined as a parallelepiped chamber with a rectangular opening. To perform the nume...