Billie F. Spencer

Billie F. Spencer
University of Illinois, Urbana-Champaign | UIUC · Department of Civil and Environmental Engineering

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577
Publications
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25,514
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Publications

Publications (577)
Article
Full-text available
Bridge strikes by over-height vehicles or ships are critical sudden events. Due to their unpredictable nature, many events go unnoticed or unreported, but they can induce structural failures or hidden damage that accelerates the bridge's long-term degradation. Therefore, always-on monitoring is essential for deployed systems to enhance bridge safet...
Article
The deflection of railroad bridges under in-service loads is an important indicator of the structure's health. Over the past decade, an increasing number of studies have demonstrated the efficacy of using vision-based approaches for displacement tracking of civil infrastructure. These studies have relied primarily on external processing of manually...
Article
Understanding the dynamic behavior of as-built structures is important, because structural condition can often be inferred from changes in its dynamic response. To this end, modal properties such as natural frequencies, damping ratios, and mode shapes can be extracted from acceleration measurements. Associated installations require sensors, cabling...
Article
This article proposes the use of generalized hierarchical Bayesian inference for fatigue life prediction based on general multi-parameter Weibull models. First, a five-parameter Weibull model for corrosion-stress-life (C-S-N) is introduced; neglecting the influence of corrosion, the model degenerates into a three-parameter Weibull model for stress-...
Article
This research proposes an approach for vision-based autonomous navigation planning of unmanned aerial vehicles for the collection of images suitable for the rapid post-earthquake inspection of reinforced concrete railway viaducts. The proposed approach automatically recognizes and localizes critical structural components, columns in this case, and...
Article
Full-text available
Civil infrastructure worldwide is subject to factors such as aging and deterioration. Structural health monitoring (SHM) can be used to assess the impact of these processes on structural performance. SHM demands have evolved from routine monitoring to real-time and autonomous assessment. One of the frontiers in achieving effective SHM systems has b...
Article
Full-text available
Data-driven structural health monitoring (SHM) of civil infrastructure can be used to continuously assess the state of a structure, allowing preemptive safety measures to be carried out. Long-term monitoring of large-scale civil infrastructure often involves data-collection using a network of numerous sensors of various types. Malfunctioning sensor...
Article
In-service cables made of fiber-reinforced polymer (FRP) wires experience repeated loading during their service life, which gradually degrades their load-carrying capacity. This paper proposes a mechanistic model to predict the residual tensile strength of the FRP wire, based on the state of damage inside the FRP wire as a function of the loading c...
Article
画像データを用いた構造物の維持管理の高度化の技術が近年急速に発展しており,様々な手法が提案されている.それらの手法を実構造物に効果的に適用するためには,対象とするシナリオを模した実験的環境において手法を実際に適用し,ユーザーの経験を蓄積するとともに得られる効果を定量評価・最大化することが重要である.一方,画像データを用いた点検・モニタリング手法は対象とする構造物や環境,期待されるアウトプットによって内容や要求が大きく異なり,それら個々の適用シナリオに即した解析と評価をおこなうのは困難である.本論文では,この問題への解決策として,コンピュータグラフィックスを活用した構造物のシミュレーションに着目し,点検・モニタリングへの適用手法と事例について述べたのち,今後の展望について議論する.
Article
Full-text available
Seismic structural health monitoring (SHM) of structures is critical not only to detect earthquakes to send early warning, but also to enable rapid structural condition assessment to ensure safety. Traditional monitoring systems using wired sensors are expensive. Wireless sensors offer tremendous opportunity to reduce costs, which remains elusive f...
Article
This paper proposes an approach for the optimal design of nonlinear energy sinks (NES) installed in structures subjected to stochastic excitation. The response of these nonlinear systems subjected to stationary or non-stationary stochastic excitations has been characterized by the time-history of its covariance matrix. However, time-invariant equiv...
Article
Full-text available
One of the most critical components of the US transportation system is railroads, accommodating transportation for 48% of the nation's total modal tonnage. Despite such vital importance, more than half of the railroad bridges, an essential component of railroad infrastructure in maintaining the flow of the network, were built before 1920; as a resu...
Article
Full-text available
Manual visual inspection is the most common means of assessing the condition of civil infrastructure in the United States, but can be exceedingly laborious, time-consuming, and dangerous. Research has focused on automating parts of the inspection process using unmanned aerial vehicles for image acquisition, followed by deep learning techniques for...
Article
In seismically active regions, buildings are inevitably exposed to extreme ground motions. Traditionally, the main structural system is designed iteratively to resist these loads, which provides safe systems, but is usually suboptimal. Topology optimization provides an approach to obtain optimal material layout; however, most approaches only accomm...
Article
Full-text available
The implementation of a wireless smart sensor network (WSSN) to monitor a structure subjected to sudden events (e.g., earthquakes) poses many challenges. One typical challenge is to synchronize the data from different sensors during event-triggered sensing, because each wireless sensor has its own independent clock and their triggering time is gene...
Article
Ground penetrating radar (GPR) has been widely used for detection and localization of reinforced steel bar (rebar) in concrete in a non-destructive way. However, manual interpretation of a large number of GPR images is time-consuming, and the results highly depend on practitioner experience and the available priori information. This paper proposes...
Article
Full-text available
Miter gates are structures that act as both the damming surface and doorway of lock chambers and are commonly found on American rivers. Miter gates are assumed to have very little torsional stiffness, and their geometry causes the gate to twist under its own weight. Thus, long, slender, post-tensioned steel members (termed diagonals) are attached a...
Conference Paper
Full-text available
Dynamic laboratory testing is an integral part of our understanding of the performance of structural systems under earthquake loading. The two main approaches for dynamic testing have been shake table and pseudo-dynamic (PsD) methods. The shake table approach typically uses servo-hydraulic means to excite a moving base and an onboard structural sys...
Article
Full-text available
The upstream lock gate at The Dalles Lock and Dam on the Columbia River is a radial, or Tainter, gate. Tainter gates operate by being raised and lowered through a circular path by means of hoisting cables. The continued operability of the gate is of extreme economic importance to the Columbia River basin region, as the gates facilitate the transpor...
Article
After a seismic event, buildings need to be inspected to confirm their safety prior to reoccupation. As such, the rapid evaluation of the condition of individual buildings is important for minimizing disruption to lives and business. However, traditional manual inspection by experts is laborious and time-consuming. Structural health monitoring prov...
Article
Full-text available
This research investigates a framework for the efficient development of vision-based dense three-dimensional displacement measurement algorithms to support reliable structural health monitoring of civil structures. The framework exploits the use of a photo-realistic synthetic model, termed a physics-based graphics model, to simulate the entire proc...
Article
Full-text available
The use of digital accelerometers featuring high sensitivity and low noise levels in wireless smart sensors (WSSs) is becoming increasingly common for structural health monitoring (SHM) applications. Improvements in the design of Micro Electro-Mechanical System (MEMS) based digital accelerometers allow for high resolution sensing required for SHM w...
Article
Full-text available
Damage detection is one of the most important tasks for structural health monitoring of civil infrastructure. Before a damage detection algorithm can be applied, the integrity of the data must be ensured; otherwise results may be misleading or incorrect. Indeed, sensor system malfunction, which results in anomalous data (often called faulty data),...
Article
Full-text available
Ground-penetrating radar (GPR) has been widely applied to the nondestructive inspection of concrete structures such as tunnel lining, bridge deck, and retaining wall, which are usually reinforced by steel bars. The scattering of electromagnetic (EM) waves caused by the dense steel rebar embedded in the concrete structures has a severe influence on...
Article
Nonlinear fluid viscous dampers have been widely used in energy-dissipating structures due to their stable and high dissipation capacity and low maintenance cost. However, the literature on stochastic optimization of nonlinear viscous dampers under nonstationary excitations is limited. This paper is devoted to the stochastic response and sensitivit...
Article
Full-text available
Hybrid simulation (HS) is a cost-effective alternative to shake table testing for evaluating the seismic performance of structures. HS structures are partitioned into linked physical and numerical substructures, with actuators and sensors providing the means for the interaction. Load application in conventional HS is conducted at slow rates and is...
Article
Track nonlinear energy sinks (track NESs) have been shown to be an effective and applicable strategy to mitigate structural response in recent years. However, previous studies on track NESs has mainly focused on demonstrating the benefits of track NESs through numerical simulations and experiments, with relatively little attention paid to the analy...
Article
Full-text available
The torsional effect of the tracks on curved segment intensifies the ambient vibration response induced by Metro operation. This paper studies the ambient vibration responses induced by the operation of the Metro train on curved rail segments. By taking the curved segment of Hangzhou Metro Line 1 of China as an example, the wheel-rail model employi...
Article
The time‐integration algorithm is an indispensable element to determine response of the boundary of the numerical as well as physical parts in a hybrid test. Instability of the time‐integration algorithm may directly lead to failure of the test, so stability of an integration algorithm is particularly important for hybrid testing. The explicit algo...
Article
This paper investigates the framework of vision-based dense displacement and strain measurement of miter gates with the approach for the quantitative evaluation of the expected performance. The proposed framework consists of the following steps: (i) Estimation of 3D displacement and strain from images before and after deformation (water-fill event)...
Article
This study is carried out based on field investigation data obtained over more than 20 days after the 20 April 2013 Lushan Ms7.0 earthquake in Sichuan Province, China. The investigation includes detailed seismic damage data from 3,684 buildings in 428 districts. This research summarizes the seismic characteristics of buildings with different struct...
Article
For the seismic design of structures in which the respective supports are located at long distances from each other, the assumption of uniform ground motion may be inadequate. In this study, an efficient time domain method is proposed to determine seismic structural response considering the effect of stochastic multiple-support excitation (MSE). Th...
Article
Full-text available
This work is aimed at studying the mechanics characteristics of the self-anchored suspension bridge with extra-wide concrete girder during girder erection and system transformation. First, the determination and implementation processes of reasonable completion state were introduced briefly, taking the Hunan Road Bridge as the background project, wh...
Article
Inland navigation infrastructure like locks and dams form a vital part of the global economy. Locks facilitate the transport of hundreds of millions of dollars’ worth of goods on a daily basis. A primary cause for downtime of locks in the United States is damage to lock gates. Current inspection methods involve the complete closure of locks to visu...
Article
This paper presents a track nonlinear energy sink (track NES) and a single‐sided vibro‐impact track nonlinear energy sink (SSVI track NES) as effective control strategies to mitigate the seismic response of high‐rise buildings. The study commences with the analytical models of the track NES and the SSVI track NES and the state‐space description of...
Article
The experimental investigation of the effects of blasts and other impulsive‐type loads on large‐scale structures provides valuable data to inform design decisions for structures and structural control devices; however, this type of testing presents significant security, safety, logistical, and economic challenges. In particular, only a limited numb...
Article
Damage detection is one of the primary purposes of structural health monitoring. Since neutral axis location changes have been considered to be sensitive damage indicators, extensive research efforts have been devoted to developing effective and accurate neutral axis estimation methods, although challenges remain in real-world applications. This st...
Article
The transportation sector contributes up to 27% of the total greenhouse gas (GHG) emissions in the United States; on-road transportation is responsible for 84% of the entire sector, implying that vehicles are a major cause of global warming. To understand the fuel energy dissipated through a vehicle’s suspension and tires, researchers have recently...
Article
This research investigates vision‐based automated bridge component recognition, which is critical for automating visual inspection of bridges during initial response after earthquakes. Semantic segmentation algorithms with up to 45 convolutional layers are applied to recognize bridge components from images of complex scenes. One of the challenges i...
Conference Paper
Full-text available
Traditional seismic monitoring systems for civil infrastructure using wired sensors can be prohibitive, due to onerous and expensive cabling networks. Wireless smart sensors (WSS) offer tremendous opportunity to reduce cost and realize the promise of pervasive sensing. However, seismic structural monitoring using WSS remains elusive, and main obsta...
Article
Although wireless smart sensor platforms have been available over a decade, only a limited number of full-scale wireless smart sensor-based structural health monitoring implementations have been realized. Most wireless smart sensor platforms that are validated in full-scale implementations have now become obsolete and are no longer commercially ava...
Article
Guided waves have been studied for monitoring defects on switch-rails. However, few researchers study monitoring of spallings. Previous studies on switch-rail damage detection are not suitable for this kind of damage at the edge of the rail web. In addition, wired configurations have the challenges of power supply and more cost. This paper proposes...
Conference Paper
Full-text available
Because of their competitive advantages (e.g. cost and ease of installation), wireless smart sensors (WSS) have gained increasing attention for structural health monitoring applications. Various strategies have been developed to improve wireless data acquisition, in which measurement data is usually sent back in either centralized or decentralized...
Poster
Full-text available
The development of smart IoT solution for rapid condition assessment of bridges under impact events
Article
Obtaining timely information about the health of civil infrastructure is critical to ensuring safe and reliable operation. Structural health monitoring (SHM) has been proposed as a means to provide such information; however, most SHM systems provide only raw data, rather than actionable information. It is necessary to develop automated modal analys...
Article
Full-text available
This paper provides a new approach to incorporating the stochastic nature of damage constitutive relations in the finite-element analysis of concrete structures. Within the framework of stochastic damage mechanics, the spatial variability of concrete was modeled as a two-scale stationary random field. At the microlevel, the damage evolution law of...
Article
Computer vision techniques for extracting dynamic structural displacements from videos are gaining increasing acceptance for the purposes of system identification and structural health monitoring. However, the application of video-based techniques for modal analysis of full-scale civil infrastructure has been limited, because obtaining measurements...
Article
Progressive collapse is an important failure mechanism that must be considered in the design of critical and essential buildings. For steel moment structures, beam-column joints, which act as transportation hubs of forces, are crucial members to resist progressive collapse. This research investigated the effectiveness of beam-column joints with cas...
Article
Rolling resistance because of road roughness is often the largest contributor to energy consumption in the environmental assessment of pavement life cycle. Although fuel consumption of passenger vehicles caused by roadway roughness is well studied, further research is needed for truck fuel consumption models utilizing mechanistic approaches. Existi...
Article
Cables are prone to vibration due to their low inherent damping characteristics. Recently, negative stiffness dampers have gained attentions, because of their promising energy dissipation ability. The viscous inertial mass damper (termed as VIMD hereinafter) can be viewed as one realization of the inerter. It is formed by paralleling an inertial ma...
Article
Faulty sensor data often occur in structural health monitoring (SHM) systems using wireless smart sensor networks (WSSN). Serious sensor faults in the raw data may negatively affect SHM analysis and subsequent informed decisions. This issue is more critical for WSSN running decentralized data acquisition, because raw data are not transmitted back,...
Preprint
Damage detection is one of the primary purposes of structural health monitoring. Since neutral axis location changes have been considered to be sensitive damage indicators, extensive research efforts have been devoted to developing effective and accurate neutral axis estimation methods, although challenges remain in real-world applications. This re...
Article
A full-scale experimental study was carried out on a two-story steel frame to investigate the progressive collapse behavior of beam-column joints with cast steel stiffeners (CSS). The frame was divided into four vertical sections, and each section had a specific joint arrangement of (1) joints with CSS and (2) welded joints without stiffeners. Seve...
Article
Data loss is a critical problem in structural health monitoring (SHM). Probability distributions play a highly important role in many applications. Improving the quality of distribution estimations made using incomplete samples is highly important. Missing samples can be compensated for by applying conventional missing data restoration methods; how...
Article
Serviceability performances of the long span bridge during strong winds, including the safety and comfort condition of driving road vehicle on the bridge, have attracted more and more attention in recent years. The dynamic behavior of the riding vehicle is essential for serviceability performance assessment. The vehicle-bridge coupling (VBC) simula...
Article
Full-text available
The field of topology optimization has progressed substantially in recent years, with applications varying in terms of the type of structures, boundary conditions, loadings, and materials. Nevertheless, topology optimization of stochastically excited structures has received relatively little attention. Most current approaches replace the dynamic lo...
Article
Full-text available
Computer vision techniques, in conjunction with acquisition through remote cameras and unmanned aerial vehicles (UAVs), offer promising non-contact solutions to civil infrastructure condition assessment. The ultimate goal of such a system is to automatically and robustly convert the image or video data into actionable information. This paper provid...
Article
For grid structures, damages of structural members such as crookedness significantly affect the overall structural safety. Traditional assessment methods can hardly evaluate the impact of crooked members in existing grid structures accurately due to difficulties lying in crookedness measurement and residual load-bearing capacity analysis. In this p...
Article
Full-text available
Wireless smart sensors (WSS) have been proposed as an effective means to reduce the high cost of wired structural health monitoring systems. However, many damage scenarios for civil infrastructure involve sudden events, such as strong earthquakes, which can result in damage or even failure in a matter of seconds. Wireless monitoring systems typical...
Article
More than 40% of the bridges in mountainous areas of Southwest China are constructed with piers having a height of over 40 m. The seismic response of such tall pier structures is usually estimated by nonlinear response history analysis and/or adaptive pushover procedures; while providing satisfactory results, these methods can be quite time consumi...
Article
More than 40% of the bridges in mountainous areas of Southwest China are constructed with piers having a height of over 40 m. Such piers are characterized by large structural flexibility and distributed mass. To investigate the effects of higher modes on the seismic performance of this class of bridges, shake table tests on two 1/7-scale, tall-pier...