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2023 | Book

Dynamics of Civil Structures, Volume 2

Proceedings of the 40th IMAC, A Conference and Exposition on Structural Dynamics 2022


About this book

Dynamics of Civil Structures, Volume 2: Proceedings of the 40th IMAC, A Conference and Exposition on Structural Dynamics, 2022, the second volume of nine from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of the Dynamics of Civil Structures, including papers on:Structural VibrationHumans & StructuresInnovative Measurement for Structural ApplicationsSmart Structures and Automation Modal Identification of Structural SystemsBridges and Novel Vibration AnalysisSensors and Control

Table of Contents

Chapter 1. Smart Active Vibration Control System of a Wind Turbine Blade Using Piezoelectric Material
Vibration suppression has become one of the major issues in sensitive structures. The active vibration control (AVC) has been widely used in the field of vibration damping in rotary structures. In this article, deriving analytical solution of lateral vibration and active vibration control of a wind turbine (WT) blade are investigated. First, a new semi-analytical solution is developed to obtain the lateral deflection of a wind turbine blade under external loadings. We propose a method to map a wind turbine blade to an Euler-Bernoulli beam with the same conditions, in order to find vibration and dynamic responses of the blade by solving analytical vibration solutions of the Euler-Bernoulli beam. Piezoelectric (PZT) material is used in this research as an actuator-sensor to excite the structures and sense the responses. The governing equations of the beam with piezoelectric patches are derived based on the integration of the piezoelectric transducer vibration equations into the vibration equations of the Euler-Bernoulli beam structure. Finite element model of the wind turbine blade with piezoelectric patches is developed. A unique transfer function matrix is derived. The beam structure is projected to the blade by using a unique transfer function matrix which is derived by exciting the structures and achieving responses. The results obtained from the mapping method are compared with the results achieved from the FE model of the blade. A satisfying agreement has been observed between the results. Next, in order to suppress the transverse vibration of the wind turbine blade, piezoelectric ceramic patches are used as an actuator in combination with linear quadratic regulator (LQR) control system. The obtained results show that the proposed smart control system contains PZT patches and LQR control system is able to efficiently suppress lateral vibration.
Ali Hashemi, Jinwoo Jang
Chapter 2. You Put How Many Tuned Mass Dampers in ONE Building?
Tuned mass dampers (TMDs) are devices that oppose the motion of a floor which has been excited by occupant footfalls. They have been demonstrated to be effective when considered during the design process or in mitigation situations. If designed and implemented properly, they achieve three goals: (1) maintain structural motion levels below commonly accepted criteria, (2) optimize the size and configuration of the structural system in order to provide more useable space in a building, and (3) reduce the cost of construction due to fewer and/or smaller structural elements. Traditionally, TMDs have only been used to control perceptible and excessive motions from wind loading and crowd movement. As such, they have not been used in laboratory and other sensitive spaces due to equipment criteria which specify vibration levels far below perceptibility.
This paper presents the case study of a 45,000 sm steel-framed structure originally designed as a core and shell office building with 3 levels of below-grade parking, 12 above-grade levels of tenant space, and 2 mechanical penthouse levels. As construction was beginning, a single pharmaceutical firm chose to lease the entire building and required that more than half of the floor plate of each floor meet the strict VC-A criterion (with some areas requiring VC-C). As the building had been designed for typical office occupancy vibration criterion, major last-minute modifications would be required to stiffen the structure to meet the new criterion. Several options were explored, with the final solution incorporating a combination of stiffening of primary structural members, tying floor masses together using interstitial posts, and installing 166 tuned mass dampers (TMDs) within the depth of the floor framing to counteract floor footfall vibrations. Dynamic characterization tests were completed on every area of each floor during construction in order to tune the TMDs in situ as construction was progressing. Final testing conducted once the structure was complete and the TMDs were tuned indicated that the VC-A criterion was achieved in all relevant areas.
Michael J. Wesolowsky, Melissa Wong, Hannah H. Kim, Rabih Alkhatib
Chapter 3. Temperature Variation Modelling of an Assembled Three-Storey Structure
In the utilisation of a digital twin, one of the most critical aspects is the pairing between the physical and digital systems (or twins). This involves the accurate modelling of the physical twin under realistic loading conditions. A lesser considered loading condition is the environmental conditions on the system, particularly the environmental temperature. This effect of temperature variation is of particular importance when there is a material mismatch, such as reinforced concrete or various metals joined together. This work investigates and compares selected methods for modelling these temperature effects for both high- and low-fidelity finite element models and is validated against experimental tests that were performed in an environmental chamber at the Laboratory for Verification and Validation at the University of Sheffield.
Matthew S. Bonney, David Wagg
Chapter 4. Modal Identification of a Railway Bridge Under Train Crossings: A Comparative Study
The existing railway bridge infrastructure of Europe is aging rapidly. Yet, rapid increases in technology and consumption bring about higher demands on railway bridges in the form of higher train speeds and axle loads. In order to ensure the safety of railway infrastructure, their dynamic response must be studied in detail and health be monitored. Vibration signatures of railway bridges are commonly used to fulfill these tasks. In particular, ambient or free vibration signals measured on railway bridges are utilized to determine their dynamic characteristics and, subsequently, to update the finite element models. However, the effects of train crossings on the dynamic behavior of bridges have not been investigated thoroughly via experimental testing. This study investigates the modal identification results of a five-span reinforced concrete railway bridge under different vibration sources. Specifically, it focuses on the variations in the dynamic behavior of the bridge observed under train crossings and those obtained from ambient vibrations. The bridge, whose dynamic response is under scrutiny, presents peculiarities in terms of its boundary conditions. They significantly differ from the original design and affect the dominant dynamic response. Fifty train crossing cases are examined, and their results are compared to those obtained using ambient and free vibrations. The results highlight the importance of bridge-train interaction and the influence of the structure’s higher vibration modes. The implications of this interaction for model updating and damage detection are also addressed.
Semih Gonen, Kultigin Demirlioglu, Emrah Erduran
Chapter 5. Real-Time and Web-Based Structural Damage Detection Network for Multiple Structures
A structural damage detection system specifically designed to monitor multiple structures at a network level is introduced in this paper. Such a monitoring system improves resiliency and helps manage the operation and maintenance of structures in an optimum way. The authors have focused on stadia-type laboratory structures for this network. Health monitoring of stadia has been conducted at multiple places in the world; however, a network of stadia monitored simultaneously with comprehensive monitoring purposes is not known to authors. For structural monitoring of multiple structures at a network level, the work presented in this paper explains and characterizes the major steps to reach this goal by focusing on three laboratory structures with a collaborative research effort among contributors from multiple universities across the globe.
Onur Avci, Mustafa Gül, F. Necati Catbas, Ozan Celik, Turker Ince, Serkan Kiranyaz
Chapter 6. Identification of Damage in Composite Beams Involving Both Flexural and Shear Link Damages
Composite structures are widely used in bridge and building construction. In fact, the majority of bridge structures, which are arguably the main subject of structural monitoring and damage identification, involve some form of composite components. The structural performance of a composite structure is dependent upon the conditions of the basic flexure-pertinent constituents, e.g., the material degradation (reduced Young’s modulus) or cracking in the concrete slab of a slab-beam system, as well as the constituents that enable the composite effect, i.e., the shear connectors. It is therefore imperative that damages in a composite structure need be distinguished between “flexural” and “composite” nature. However, in the existing damage identification literature, especially when vibration-based techniques are employed, composite structures such as bridge decks are often treated as monolithic structures, and accordingly, structural parameters are identified in terms of gross flexural parameters without differentiating between flexure and shear link properties. This could lead not only to incorrect identification of the actual flexural properties but also potentially to misleading results in case serious damage to shear links occurs. In this paper, we will provide an overall discussion on the distinctive effects of flexural and shear link damages on the global structural stiffness in a composite beam. On this basis, the possibility and rationale to identify the mixed presence of flexural and shear link damage parameters using modal data from typical vibration tests are discussed. A genetic algorithm-based finite element model updating procedure is then implemented. The results show that separation of the flexural and shear link parameters is possible and satisfactory accuracy can be achieved with the FE model updating the proposed scheme.
Yu Gu, Yong Lu
Chapter 7. Anomaly Detection Through Long-Term SHM: Some Interesting Cases on Bridges
The growing demand for health assessment of civil infrastructure has allowed for a dense control, among others, of many bridges. The new industrial design of monitoring systems, based on cheaper hardware, at the same time granting satisfactory performances, is making available huge data flows, allowing researchers not just to create a wide database but also to create logbooks of possible anomalies and defects, which can be both related to the infrastructure and the monitoring system. When prompt alarms are to be sent to the bridge manager, to avoid failures, there is the risk to produce false positives, due to specific data features or ambiguous recorded structural behaviors that may appear as damage, therefore requiring a deeper knowledge level of the expected structural response, to be fully understood and classified as not dangerous in terms of risk for the human life (structural reliability).
Only the combination of a continuous monitoring with the availability of an updated digital twin and a meticulous data interpretation of an expert engineer in the monitoring field can lead to a thorough understanding of the structural behavior and a proper asset management. In the present paper, an apparent damage identified by monitoring the dynamic response of a reinforced concrete bridge, under operational conditions, has proven to be a change of the static scheme of the structure, with a consequent bi-stable periodic variation of the structural behavior, explained, thanks to a fit-to-the-purpose numerical modeling.
D. La Mazza, F. Basone, M. Longo, P. Darò, A. Cigada
Chapter 8. A Framework for Developing Efficient Vehicle-Bridge Interaction Models Within a Commercial Finite Element Software
The development of vehicle-bridge interaction (VBI) models is a popular technique to characterize the dynamic properties of vehicles and bridges. However, there is inherent complexity in the development of VBI models which must account for multibody dynamics of vehicles, structural dynamics of bridges, and vehicle-bridge contact relationships. Within the literature, three distinct frameworks exist for handling the model complexity of VBI: (1) hard coding the equations of motion of the vehicles and bridges while numerically coupling them in an arbitrary programming language; (2) developing a co-simulation that leverages a commercial finite element (FE) software to model the bridge and separately solve for the equations of motion of a vehicle; or (3) develop high-fidelity representations of both the bridge and vehicle through a commercial FE environment alone. While these unique frameworks offer accurate and reliable results, there exists a trade-off between frameworks that require sophisticated coding of the user but result in high computational speed (1 and 2) and frameworks with simple implementation but longer computation times (3). The present study attempts to bridge this gap and formulate a computationally efficient framework for implementing VBI modeling into a commercial FE software (Abaqus). This requires minimal coding by the user and could then be used by both the industrial and the research community. A VBI model of a passenger vehicle traveling across a bridge is modeled using the bicycle model concept and Euler beam element formulations within Abaqus. Robust node-to-surface contact algorithms within Abaqus are implemented to couple the vehicle to the bridge during the analysis. The dynamic responses of both the vehicle and bridge are verified with data from the literature. The study primarily follows a 2D scheme but concludes with a discussion of how these methods can be extended to a 3D scheme.
Omar R. Abuodeh, Laura Redmond
Chapter 9. Damaged Metamaterials: Structural Health Monitoring and Damage Tolerance
Locally resonant metamaterials have been gaining intense interest recently for their ability to greatly attenuate shock and vibration. All existing studies of metamaterials assume that the structure is intact and undamaged. However, all real-world structures will eventually experience some damage (e.g., due to manufacturing defects, material inclusions, handling damage, corrosion, etc.). For metamaterials to be placed in service in real applications, an understanding of their behavior in the presence of damage is necessary. This chapter explores two related concepts: structural health monitoring (i.e., damage detection) and damage tolerance (i.e., robust performance in the presence of failures). Central to both concepts is the fact that metamaterial damage creates highly localized modes near the damaged location, which may cause undesirable high local stresses. Damage can be detected by observing the presence of these modes, and damage tolerance can be improved by designing the metamaterial in such a way as to tailor these local modes to mitigate the stress increases.
Daniel Kiracofe, Utkarsh Wani, Y. F. Xu
Chapter 10. Indirect Bridge Health Monitoring Using Time-Frequency Analysis: Analytical and Experimental Studies
Bridges are among the crucial elements of public infrastructure and are inspected regularly for maintenance purposes. Often, these inspections are conducted visually, which can be particularly limited to detecting hidden and minor damage, for instance, fatigue cracks, delamination, and corrosion of embedded reinforcement. Ideally, the bridge inspectors need to identify any changes in dynamic parameters of the bridge, such as natural frequencies, damping ratio, and stiffness. Recently, there has been a shift from using fixed sensor networks to moving sensor networks that can detect changes in these dynamic parameters. Moving sensor networks rely on indirect measurements taken from within the vehicle while traveling over the bridge. The signal collected from within a passing vehicle contains the bridge’s structural response, vehicle suspension input, and surface roughness-induced vibrations. This paper investigated the feasibility of drive-by bridge monitoring using numerical and experimental assessments and addressed their challenges using the time-frequency method. The proposed methodology uses Wavelet Packet Transform (WPT), which extracted modal responses and delineated the bridge frequency components from the driving and vehicle frequencies using the wavelet packet coefficients. The performance of the proposed method was validated using both numerical simulations and a laboratory experiment. The effects of vehicle parameters on vehicle acceleration response were studied using analytical modeling. In the laboratory experiment, a moving cart was used as a vehicle traveling over a scaled bridge model. The results demonstrated that the proposed method could efficiently extract and separate the bridge dynamics from the vehicle response.
Premjeet Singh, Ayan Sadhu
Chapter 11. Bayesian Uncertainty Assessment for Modulus of Elasticity of Concrete and Mechanical Properties of Steel Reinforcing Bar
The variability in the mechanical properties of the concrete and reinforcing steel used in reinforced concrete (RC) in Colombia affects structural systems’ design process and performance. It leads to struggling to comply with the requirements of local building codes. This study presents and discusses the uncertainty quantification (UQ) of both the mechanical parameters of the stress–strain curve of steel reinforcing bars and the modulus of elasticity of concrete. The database comes from experimental programs, including monotonic axial tests on steel bars from different manufacturers in the country, and axial compression tests reported in 22 studies on concrete made in 13 different cities of Colombia. Bayesian inference methods were used to update the Raynor model of the monotonic stress–strain curve of the steel and the equations proposed by the Colombian and the ACI 318–19 building codes for E c as a function of concrete strength and unitary weight. Distributions for both materials are then presented, and predictive check tests are performed for validation. The Bayesian statistical analysis allowed to contrast the mechanical properties obtained experimentally, with nominal properties specified by the manufacturers, in the case of the steel bars. New equations and their associated uncertainties are proposed for representative estimates of the modulus of elasticity of the concrete in Colombia
Felipe Guerrero, Albert R. Ortiz, Julian Carrillo
Dynamics of Civil Structures, Volume 2
Hae Young Noh
Matthew Whelan
P. Scott Harvey
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