Vibration-based monitoring of civil infrastructure: challenges and successes

Author's manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s13349-011-0009-5© Springer-Verlag 2011Co -published with International Society for Structural Health Monitoring of Intelligent InfrastructureStructural health monitoring (SHM) is a relatively new paradigm for civil infrastructure stakeholders including operators, consultants and contractors which has in the last two decades witnessed an acceleration of academic and applied research in related areas such as sensing technology, system identification, data mining and condition assessment. SHM has a wide range of applications including, but not limited to, diagnostic and prognostic capabilities. However, when it comes to practical applications, stakeholders usually need answers to basic and pragmatic questions about in-service performance, maintenance and management of a structure which the technological advances are slow to address. Typical among the mismatch of expectation and capability is the topic of vibration-based monitoring (VBM), which is a subset of SHM. On the one hand there is abundant reporting of exercises using vibration data to locate damage in highly controlled laboratory conditions or in numerical simulations, while the real test of a reliable and cost effective technology is operation on a commercial basis. Such commercial applications are hard to identify, with the vast majority of implementations dealing with data collection and checking against parameter limits. In addition there persists an unhelpful association between VBM and 'damage detection' among some civil infrastructure stakeholders in UK and North America, due to unsuccessful transfer of technology from the laboratory to the field, and this has resulted in unhealthy industry scepticism which hinders acceptance of successful technologies. Hence the purpose of this paper is showcase successful VBM applications and to make the case that VBM does provide valuable information in real world applications when used appropriately and without unrealistic expectations. © 2011 Springer-Verlag

Mitigation of wind-induced vibration of a tall residential building using liquid column vibration absorber

The most important thing in applying mass type dampers including Liquid Column Vibration Absorber (LCVA) is tuning its natural frequency to an optimum value which is a function of the natural frequency of the building and the mass ratio of damper to the building. However, exact prediction of the natural frequency of the building at design stage is very difficult especially for concrete buildings. Thus, continuous updating of the target frequency and correction of the design of the damper based on field measurement is necessary. In this paper, application of LCVAs to mitigate the wind-induced vibration of 64-story residential buildings is presented. The LCVA were designed to have adjustable dimension for vertical column to take the advantage of ease tuning and wide frequency range. For updating of initial design, the tuning and performance assessment of LCVA several tests and measurement were carried out. The ambient vibration measurement of a partially completed building and a completed building without water in LCVA was performed and final values of the width of vertical column and the height of water were determined from the system identification results based on the collected acceleration data. In addition, ambient vibration measurement of buildings with LCVA water was performed and the system identification results indicated that the apparent damping ratio due to LCVA was increased about 3.13 to 3.89 times

Optimum tuning parameters of tuned mass dampers for vibration control of irregular highrise building structures

Tall buildings have become increasingly one-of-a-kind signature structures that are often irregular in plan and elevation with complicated dynamic behavior. Vibration control of irregular highrise building structures using a recently developed tuned mass dampers (TMD), the bidirectional TMD (BTMD), is investigated. A key issue for effective implementation of a TMD is the determination of their tuning parameters. Eight different sets of equations for tuning the parameters of TMDs are investigated using a 5-story building with plan and elevation irregularity, and a 15-story and a 20-story building with plan irregularity subjected to seismic loading. Appropriate equations are recommended for building structures with a fundamental period of vibrations of greater than one second

Improving the wind‐induced human comfort of the Beijing Olympic Tower by a double‐stage pendulum tuned mass damper

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154522/1/tal1704_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154522/2/tal1704.pd

Sustainable building design

Sustainable building design has become a wide and multidisciplinary research endeavor including mechanical, electrical, electronic, communication, acoustic, architectural, and structural engineering. It involves the participation of owners, contractors, suppliers and building users. There has been a lot of talk about sustainable buildings in the past few years. Most of the published research is concerned with saving energy and water and making the buildings more environmentally friendly by, say, reducing the carbon emissions. In this article, sustainable building design is reviewed from the viewpoint of structural engineering. Different strategies presented in the literature are summarized. Finally, the authors argue that the next big leap in sustainable building design should come from the integration of the smart structure technology including the use of hybrid and semi-active vibration controllers that can result in substantially lighter and more efficient structures

Fatigue Analysis on Wind Turbine Towers in Cyclone-Prone Areas

Wind energy is developing at a rapid pace both onshore and offshore to realize the carbon neutral ambitions set by different countries. However, the promotion of wind turbine in tropical/ subtropical regions encounters challenges from local extreme weathers, e.g., tropical cyclone. The intensity of a common tropical cyclone is far beyond the cut-out wind speed, which will result in drastic vibration of the wind turbine tower. Most of previous research are focused on the strength or stability failure of a wind turbine under cyclones, which is explicitly reflected from several forensic onsite investigations. Nonetheless, this thesis reveals that the implicit fatigue damage accumulation that incurred by cyclones can also be important. To quantify the additional fatigue damage induced by cyclones, the dynamics of an onshore or offshore wind turbine under both normal wind and cyclones should be accurately described. An improved decoupled theory is proposed based on an improved aerodynamic damping theory to successfully realize the soil-structure interaction and the possible nonlinear behavior of a tower, which still cannot be achieved in many wind turbine design software. A basic analysis framework is constructed to include the various external and internal conditions of a wind turbine under both the normal wind and cyclones. Based on this, a novel wind turbine evaluation framework under cyclones is created to classify the potential failure modes of wind turbine towers into three distinct categories with high computational efficiency. In addition, an upgraded fatigue analysis framework for wind turbine under cyclones is proposed with consideration of meteorological data supported time-varying cyclone features, e.g., cyclone direction, intensity, translation speed and track straightness, together with other important cyclone characteristics, e.g., cyclone average recurrence interval (ARI) and cyclone-normal-wind direction misalignment. Last but not least, parametric analysis in terms of wind turbine scale, parking status, wind intensity, section slenderness and material model is presented through this thesis to reflect the significance of the factors concerned. The proposed fatigue analysis frameworks can also be extended to other structures, e.g., the hybrid wind-tidal energy conversion system in cyclone-prone regions

Mitigation of wind-induced vibration of a tall residential building using liquid column vibration absorber

The most important thing in applying mass type dampers including Liquid Column Vibration Absorber (LCVA) is tuning its natural frequency to an optimum value which is a function of the natural frequency of the building and the mass ratio of damper to the building. However, exact prediction of the natural frequency of the building at design stage is very difficult especially for concrete buildings. Thus, continuous updating of the target frequency and correction of the design of the damper based on field measurement is necessary. In this paper, application of LCVAs to mitigate the wind-induced vibration of 64-story residential buildings is presented. The LCVA were designed to have adjustable dimension for vertical column to take the advantage of ease tuning and wide frequency range. For updating of initial design, the tuning and performance assessment of LCVA several tests and measurement were carried out. The ambient vibration measurement of a partially completed building and a completed building without water in LCVA was performed and final values of the width of vertical column and the height of water were determined from the system identification results based on the collected acceleration data. In addition, ambient vibration measurement of buildings with LCVA water was performed and the system identification results indicated that the apparent damping ratio due to LCVA was increased about 3.13 to 3.89 times

5 European & African Conference on Wind Engineering

The 5th European-African Conference of Wind Engineering is hosted in Florence, Tuscany, the city and the region where, in the early 15th century, pioneers moved the first steps, laying down the foundation stones of Mechanics and Applied Sciences (including fluid mechanics). These origins are well reflected by the astonishing visionary and revolutionary studies of Leonardo Da Vinci, whose kaleidoscopic genius intended the human being to become able to fly even 500 years ago… This is why the Organising Committee has decided to pay tribute to such a Genius by choosing Leonardo's "flying sphere" as the brand of 5th EACWE

Safety Assessment of Road Vehicle in Crosswind Considering Driver Behavior

With expansion of the economy, more and more highway networks extend to coastal areas and mountain valley areas. Vehicles will be exposed to strong crosswinds when driven on these highway roads, especially in hurricane season and in winter in these two different topographic areas. Strong crosswinds threaten the safety of transportation infrastructure and passing vehicles in forms of vehicle accidents that usually result in traffic blockage and driver injury, posing negative effects on economic growth. This dissertation aimed to evaluate the vehicle safety when running through crosswinds in consideration of driver behaviors. Firstly, the aerodynamic characteristics of road vehicles were identified using computational fluid dynamic method. Aerodynamic coefficients of a high-side lorry running in crosswinds using both traditional resultant-wind velocity method and relative-motion approach were compared. In addition, the aerodynamic coefficients of multiple types of vehicles were investigated. The curves of aerodynamic coefficients for different vehicle types against wind yaw angles were obtained. Secondly, an experimental investigation on the vehicle performance and driver behavior was conducted by taking advantage of the LSU’s driving simulator. This study revealed the repeatability of driver behavior and the effect of crosswind speeds on the vehicle performance and drivers’ behavior through a statistical analysis. More scenarios were considered, such as driving in windy-rainy conditions. A regression model of the steering wheel angle turned by drivers was obtained. Finally, safety assessment of vehicles was performed based on an improved wind-vehicle-bridge coupled system and considering driver’s behavior using a series of driver behavior models. For different types of road vehicles, rigid frame vehicle model and flexible frame vehicle model were developed. Accident criteria of lateral side slip, rotational deviation, and rollover were considered. To investigate the influence of driver models, four driver models were considered in different integration methods. Results between cases from different driver models were compared

Ocean Remote Sensing with Synthetic Aperture Radar

The ocean covers approximately 71% of the Earth’s surface, 90% of the biosphere and contains 97% of Earth’s water. The Synthetic Aperture Radar (SAR) can image the ocean surface in all weather conditions and day or night. SAR remote sensing on ocean and coastal monitoring has become a research hotspot in geoscience and remote sensing. This book—Progress in SAR Oceanography—provides an update of the current state of the science on ocean remote sensing with SAR. Overall, the book presents a variety of marine applications, such as, oceanic surface and internal waves, wind, bathymetry, oil spill, coastline and intertidal zone classification, ship and other man-made objects’ detection, as well as remotely sensed data assimilation. The book is aimed at a wide audience, ranging from graduate students, university teachers and working scientists to policy makers and managers. Efforts have been made to highlight general principles as well as the state-of-the-art technologies in the field of SAR Oceanography