Carlos Moutinho

• University of Porto

This paper presents a study to evaluate the damping effectiveness of Stockbridge dampers on an overhead high-voltage transmission line conductor and their effects on estimating the corresponding fatigue lifetime. To increase the understanding of the dynamic behaviour of Stockbridge dampers, a test setup was designed and constructed to accommodate a...

The assessment of structural degradation from modal characteristics has a long tradition in engineering practice. For the specific case of bridge cables, such features (most notably, natural frequencies) are often employed in the identification of the installed axial force. However, low-order modal properties may be relatively insensitive to small,...

This article presents an experimental work developed in the context of the study of conductors’ fatigue due to the turbulent effect of wind on an overhead high-voltage transmission line. The research is centred on the laboratory study of a conductor segment with a 17 m length. The cable model, fitted with typical anchorages adopted in transmission...

To develop reliable numerical models and better interpret monitoring campaigns experimental data of wind turbines, knowing the structure operation conditions, in particular the rotor angular velocity and blades’ pitch angle, is of paramount importance, but often not known due to confidentiality restrictions, or known with low time resolution (typic...

The continuous application of Operational Modal Analysis (OMA) to time-series recorded on civil engineering structures, and the subsequent tracking of modal properties, allow the characterization of the evolution of their dynamic behaviour, which is particularly important on wind turbines, since their structural performance is highly dependent on i...

Due to the increasing importance of the continuous monitoring of Civil Structures, this research aims to take advantage of new solutions of measurement systems and sensors in the Structural Health Monitoring of bridges, using the reinforced concrete arch Arrábida Bridge as a case study. With the support of customized sensors, this work starts by pe...

The structural performance of wind turbines is highly dependent on their dynamic behaviour, meaning the monitoring of their structural health should take their dynamic response into account, which can be pursued through the continuous application of Operational Modal Analysis (OMA) to time-series recorded on the structure and subsequent tracking of...

The high cost of conventional monitoring systems limits their application range. In this paper, microelectromechanical system (MEMS) accelerometers are adopted together with wireless nodes developed in the Faculty of Engineering, University of Porto (FEUP), in the continuous dynamic monitoring of an arch bridge, and their ability for automated trac...

The Laboratory of Vibrations and Structural Monitoring (ViBest, www.fe.up.pt/vibest) of CONSTRUCT/FEUP has been implementing, since 2007, a significant set of long-term dynamic monitoring systems in large Civil structures with different typologies (e.g. roadway, railway and pedestrian bridges, stadia suspension roofs, wind turbines, concrete dams o...

This work analyzes the difference in stiffness in a steel laboratory structure using clamped joints or bolted joints and analyzes if the stiffness varies in the same way when the frame is subjected to external dynamic loads that bring the joint materials to their yield strength. To make this comparison, the differences between clamp joint and bolte...

Historically, the dynamic testing of concrete dams has been associated with experimental modal analysis (EMA) and the performance of forced vibrations tests. Nevertheless, this type of tests requires the use of a heavy equipment and the interruption of the regular operation of the structure. An alternative to EMA relies on the application of operat...

In the context of vibration based Structural Health Monitoring using automated operational modal analysis, data synchronization methods permit a reduction in the cost of wireless monitoring systems, since the use of extra hardware for perfect data synchronization can be avoided. Furthermore, the relaxation of data synchronization requirements permi...

The reduction in operating and maintenance costs of wind farms is a fundamental element to guarantee the competitiveness and growth of the wind market. Wind turbines are highly dynamic structures prone to wear during their lifetime. Therefore, dynamic monitoring systems represent an excellent option to continuously evaluate their structural conditi...

The main goal of the recently started WindFarmSHM research project is the development, validation and optimization of monitoring strategies to be applied at the level of the wind farm. These strategies should be able to evaluate the structural condition of a set of wind turbines and their consumed fatigue life using the response to operation loads....

The Luiz I Bridge is a century-old double-deck truss metallic structure over the Douro River in Porto, which was built to serve as a road and pedestrian link between the cities of Porto and Vila Nova de Gaia. For many years, this bridge has been submitted to high lateral vibration levels induced by pedestrians during the festivities of the St. John...

Abstract. The main goal of the recently started WindFarmSHM research project is the development, validation and optimization of monitoring strategies to be applied at the level of the wind farm, which should be able to evaluate the structural condition of a set of wind turbines and their consumed fatigue life, using the response to operation loads....

Artificial accelerograms are a very useful tool for designing structures against seismic hazards; in particular, when structures exhibit nonlinear behavior. This paper presents a Matlab code for generating artificial accelerograms to match code‐defined spectra based on the modification of actual earthquake ground motions. In this case, while the co...

p>This paper aims to describe the SMART-OPS research project, present preliminary results of the experimental campaign and foresee the characteristics and advantages of the product under development. In the first stage, a commercial monitoring equipment was adopted. The paper will describe preliminary results obtained with this equipment to demonst...

The study of the human‐structure interaction (HSI) using biodynamics models has gained attention lately. Several studies have demonstrated that the passive (standing still) and active (bobbing/bouncing or walking) persons can act for the benefit of the structural system by considering their body dynamic properties. Nevertheless, little concern has...

At present time, the accurate estimation of modal properties of large civil structures (e.g. buildings, bridges, chimneys, wind turbines) can be easily achieved by applying state of art output-only modal identification methods (e.g. SSI-cov, SSI-Data, p-LSCF) to the data obtained with ambient vibration tests performed with appropriate sensors and d...

Wireless sensor networks are prone to synchronization discrepancies, due to the lack of intrinsic global clock management from a centralized server. In wireless structural health monitoring (SHM) systems, synchronization discrepancies may lead to erroneous estimations of structural parameters of monitored structures. To avoid errors in the estimati...

This paper describes the work involving the implementation of a control system aimed at reducing vibrations in a slender footbridge located at FEUP campus. This structure was extensively studied in the past, mainly due to the clear exhibition of very perceptible vibrations induced by pedestrian loads. For that reason, a passive tuned mass damper (T...

This paper evaluates the results that can be obtained with different strategies of instrumentation for an utility-scale wind turbine, considering variations on the number of sensors, on their distribution in the wind turbine tower and on their noise level. With the goal of reducing the investment in monitoring equipment, layouts based on a reduced...

Tuned mass dampers (TMDs) are a well-established technology for passive structural vibration control involving harmonic vibrations. Some design issues are critical to guarantee the proper functioning of the device, in particular, the adequate tuning and the adequate space to accommodate the TMD stroke. With regard to the first aspect, semiactive TM...

Excessive vibration problems related to building floors concerning the human comfort have been reported by several researchers in the past two decades. The reason for those vibrations is mainly related with the current trend for the design of slender and flexible structural systems, with the inherent low damping. Consequently, such floors are prone...

This paper aims at stressing the major role that Dynamic Identification and Continuous Dynamic Monitoring can play in the observation and understanding of the structural behaviour of bridges along the different phases of their life cycle, based on the authors’ experience got at the Laboratory of Vibrations and Structural Monitoring (ViBest) of the...

p>This paper investigates the effect of crowd walking in the dynamic response of a footbridge. For this purpose, the modal parameters of a single walking pedestrian are identified on the basis of the measurement of the applied load and body acceleration. These parameters are then extended to the characterization of a crowd. Noticing that the mass r...

The paper describes two dynamic monitoring systems installed in lively footbridges with the purpose of characterizing the dynamic behavior and response of these structures and possibly detecting damage at early stages. Some monitoring results illustrate the capabilities of the presently existing technology.

Present traffic loads on bridges often exceed the actions anticipated at the time of construction. In Germany several prestressed concrete bridges with deficits in their load bearing capacity had been identified. An established retrofitting method is the installation of external tendons with deviation and anchorage blocks. Since the later proved to...

This paper characterizes the extensive research activity developed by the Laboratory ofVibrations and Structural Monitoring (ViBest) of FEUP in the fields of dynamic testing and continuous dynamic monitoring of long span bridges, briefly presenting results of some relevant applications as, for instance, the dynamic tests ofVasco da Gama Bridge, in...

The paper describes two dynamic monitoring systems installed in civil engineering structures, a footbridge and a suspended stadium roof. These systems are used for characterization of environmental and operational effects and, in the limit, for the early detection of damage. Some examples of collected data and results are presented.

The demo will focus on two dynamic monitoring systems installed in footbridges with the purpose of characterizing the dynamic behavior and response of these structures and possibly detecting damage at early stages.

This paper is focused on the control problems related to semi-active tuned mass dampers (TMDs) used to reduce harmonic vibrations, specially involving civil structures. A simplified version of the phase control law is derived and its effectiveness is investigated and evaluated. The objective is to improve the functioning of control systems of this...

The fatigue behaviour of steel railway bridges is a complex phenomenon. On the one side, the Engineer must face the problem of dynamic amplification of the loads and their randomness, on the other side, the fatigue resistance is highly dependent on the load itself, since for different stress levels the material can sustain different number of cycle...

This paper makes a brief characterisation of some aspects related with the extensive research activity of the Laboratory of Vibrations and Structural Monitoring (ViBest) of the Faculty of Engineering of the University of Porto (FEUP) in the field of Continuous Dynamic Monitoring of Bridges and Special Structures, selecting four examples where large...

SUMMARY The paper reviews some of the most recent aspects involved in the dynamic testing and continuous monitoring of bridges. This includes a discussion of testing techniques, instrumentation, modal identification and damage detection. On the basis of their experience, the authors described several case studies in which some of the most recent de...

This paper aims at analyzing the feasibility of applying a vibration based damage detection approach, based on Principal Components Analysis (PCA), to eliminate environmental effects using the large amount of high quality data continuously collected by the dynamic monitoring system of Pedro e Inês footbridge since 2007. Few works describe real data...

It is well established that small tuned mass dampers (TMDs) attached to structures are very effective in reducing excessive harmonic vibrations induced by external loads but are not as interesting within the context of earthquake engineering problems. For this reason, large mass ratio TMDs have been proposed with the objective of adding a significa...

This paper aims at describing some applications recently developed by the Laboratory of Vibrations and Structural Monitoring (www.fe.up.pt/vibest) of FEUP in which an accurate monitoring of the effects of environmental factors on modal frequency estimates was continuously performed, and appropriate statistical techniques were employed to remove or...

Tese de doutoramento. Engenharia Civil. Faculdade de Engenharia. Universidade do Porto. 2007

This article describes the research work involving the analysis and control of a flexible stress-ribbon footbridge located at the campus of Faculty of Engineering of University of Porto (FEUP). This structure has several natural frequencies around 2 Hz which makes it vulnerable to the occurrence of resonance phenomena related to the excitation indu...

This article describes the research work involving the implementation of an Active Bracing System aimed at the modification of the initial dynamics of a laboratorial building structure to a new desired dynamics. By means of an adequate control force it is possible to assign an entirely new dynamics to a system by moving its natural frequencies and...

This document demonstrates the usefulness, operation and design of Tuned Mass Dampers (TMDs) in the structural control of seismic response. This vibration control system, which main asset is the introduction of additional damping on structural system, can improve the structural behavior particularly in terms of forces and displacements, in case of...

This paper describes the experimental work involving a laboratorial im-plementation of an active system to increase the damping ratios of a plane frame physical model of a building structure of three storeys. For this purpose, the use of an Active Mass Driver commanded by the Di-rect Velocity Feedback control law is suggested. The study developed t...

This paper describes the development of computational tools for modal identification and long term dynamic monitoring in LabVIEW environment. These tools mainly consist of two individual toolkits for structural modal identification (SMI) and continuous monitoring (CSMI), respectively. The SMI toolkit implements the frequency domain Peak-Picking (PP...

The construction in Portugal of a relatively long and slender footbridge prone to vertical and lateral vibrations induced by the action of pedestrians motivated the full assessment of the corresponding dynamic behaviour with the purpose of installing a control system. The current paper describes the studies undertaken at a design stage and the resu...

The construction in Portugal of a relatively long and slender footbridge prone to pedestrian-induced vertical and lateral vibrations motivated an extensive study for the design and implementation of a control system based on a set of lateral and vertical tuned mass dampers (TMDs). This paper discusses the strategy adopted in the design and assessme...

The paper describes a study to characterize intentional human dynamic loads (vandal loads) and their induced effects on a footbridge. A numerical model to characterize the dynamic behavior of the footbridge has been developed, is experimentally validated, and is used to numerically simulate the response induced by groups of pedestrians synchronized...

This paper presents a brief characterization of the evolution of Experimental Modal Analysis in the Civil Engineering field, from Input-Output to Output-Only Modal Identification Techniques, taking particularly into account the experience of the authors at the Laboratory of Vibrations and Monitoring (VIBEST, www.fe.up.pt/vibest) of FEUP.

The modal parameters of the Heritage Court Tower in Vancouver, Canada, were identified using a spectral approach in the frequency domain, in the context of the IMAC-XVII benchmark. This benchmark was based on the experimental data base previously created by researchers from the University of British Columbia. The natural frequencies and mode shapes...

This paper, apart from making a brief general reference to vibration problems in pedestrian bridges, as well as to the form of modelling of dynamic pedestrian loads, presents the use of a predictive control strategy for the numerical simulation of the dynamic response of actively controlled structures of this type. The consideration of this control...

Website: www.fe.up.pt/vibest. 1. ABSTRACT Coimbra footbridge is a new structure that connects both banks of Mondego River. Preliminary studies conducted during design stage indicated some vulnerability to vibrations induced by pedestrians, both for lateral and vertical directions. As result, it was decided to install Tuned Mass Dampers in 5 differe...

Dissertação apresentada para obtenção do grau de Mestre em Estruturas de Engenharia Civil, na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Prof. Dr. Álvaro Cunha