Victor J. Hunt

Performance of Five-Span Steel Bridge with Fiber-Reinforced Polymer Composite Deck Panels

To better understand the performance of bridges with fiber-reinforced polymer (FRP) composite decks, the short-term and long-term responses of a 207-m, five-span bridge retrofitted with four different FRP panel systems were monitored through controlled truck load and modal tests at various stages and through long-term monitoring of key load-transfer mechanisms and panel responses. The overall aspects of the panel systems, connection details, construction techniques, and experimental program are presented followed by presentation of the measured responses. Key design issues (impact factors, girder distribution factors, level of composite action, and overall structural stiffness) for FRP and reinforced concrete decks are evaluated and compared against published design provisions. Performance of panel-to-panel connections and panel-to-girder connections is also discussed.

Cable-Stayed Bridges: Case Study for Ambient Vibration-Based Cable Tension Estimation

A cable-stayed bridge recently constructed by the Ohio Department of Transportation incorporates measures put forth by a Federal Highway Administration study to mitigate stay motion. In following recent trends, the stays at this bridge are built without the use of grout for the purposes of inspection and, if necessary, replacement. Several experiments were performed to determine the viability of using traditional vibration techniques, which assume an integral sheath, to estimate cable tension with this new configuration.

Abnormal behavior detection in the Jeremiah Morrow Bridge based on the long term measurement data patterns

Calibration of a finite element model based on measurement-data for complex structures is usually costly and sometimes not applicable. In this article, a methodology for detecting abnormal behavior including slow aging degradations of a structure solely based on historical patterns of the measurement data will be introduced. In the first step, principal components of the truck load test measurement data - that is centered and scaled - are calculated. In the second step, unsupervised classification is applied to the score data that is regenerated based on the major principal components. The same algorithm is applied to the measurement data of the bridge response to the sharp temperature change as well. Finally, the specified algorithm is applied separately to the collected static data from the Jeremiah Morrow Bridge (more than four years) using the calculated truck load test principal components. The optimized clustering model detected the outliers that are caused by heavy truck loads; clustering result is detailed. In summary, a simple data model that is able to find any known data signature such as truck load test in the daily measurement data is proposed. The proposed method is part of an ongoing effort in University of Cincinnati Infrastructure Institute to use the correlation between collected readings from different members of a bridge in order to interpret abnormal trend changes in the measurement data.

Structural identification for condition assessment of civil infrastructure

The experimental aspects of structural identification for global and local condition assessment of constructed facilities are summarized. Experimental techniques suitable for meaningful field testing have been explored on an operating reinforced concrete deck-on-steel stringer highway bridge which served as a test bed. Modal analysis and instrumented monitoring applications conducted on this bridge serve to exemplify the experimental steps of a possible global structural identification methodology for health monitoring of civil infrastructure. The results given indicate that this is a feasible approach to for condition assessment and structural health monitoring.

Instrumentation and intelligence issues in bridge health monitoring

A comprehensive market survey and laboratory evaluation was conducted for the Ohio Department of Transportation and the Federal Highway Administration to identify the most promising sensors and data-acquisition systems for infrastructure application. A pilot system for highway bridge monitoring was implemented on a typical steel-stringer bridge in Cincinnati for high-speed traffic and long-term environmental monitoring. Static tests were performed with known truck loads to confirm monitoring results and to calibrate finite-element and section analysis models of the bridge. A complete and accurate characterization of the as- is structural condition has been related to the structural capacities and reliability. This multi- disciplinary research improves our understanding of the actual loading environment and the corresponding bridge responses. Instrumented monitoring is expected to complement inspection methods, provide an objective measure of the state-of-health, and alert officials to bridge deterioration or failure.

Structural Health Monitoring System for Ironton–Russell Bridge, Ohio and Kentucky: Phase 1. Substructure Construction

The monitoring of bridge structures during construction has received significant attention in recent years as accelerated construction techniques are being used more frequently. Continuous monitoring systems can verify that quality and safety are maintained during construction by minimizing construction uncertainties and aiding designers to compare the actual behavior of a structure with the design models. Additionally, the behavior of structures in different stages of construction may be important in the definition of abnormal responses (e.g., the loss or reverse of a previously measured dead load) during the life span of a bridge. This paper gives an overview of the monitoring system for substructure construction that was considered for the Ironton–Russell Bridge between Ironton, Ohio, and Russell, Kentucky, during its design and service stages. First, the sensory network of the bridge will be detailed. Second, data processing (which involves two anomaly detection algorithms) and other components of the monitoring system will be presented. Finally, some of the data collected by the monitoring system during construction will be analyzed, and a comparison between the theoretical and actual response to a major vertical posttensioning event will be made. The result showed that the actual response matched the expected response and that the newly developed algorithm has a promising potential for tracking daily thermal responses.

Measuring Displacement of Tall Concrete Columns During Construction

Multiple-span, segmental concrete bridges built by balanced cantilever construction demand precise geometric control so that adjoining tips align at the time the closure segment is cast. When this type of bridge superstructure is cast monolithically on tall piers, moment redistribution, as well as creep, shrinkage, and temperature effects, can cause excessive demand on the exterior end spans and piers of the structure. To compensate, designers often use horizontal forces (jacking) to induce a counteractive moment in the pier columns. However, designers often do not make the effort to ensure that the intended displacement is realized at the needed structural elements. A methodology for measuring deflections of tall pier elements with tiltmeters during construction is presented in this paper for the Jeremiah Morrow Replacement Bridge, Interstate 71, Lebanon, Ohio. Fast-sampling data collection systems and postprocessing algorithms, including thermal effect removal, are detailed. In addition to the deflections from unbalanced cantilever moment during the casting cycle, fast-sampling data for the first horizontal jacking event are discussed and compared with the data collected through traditional laser survey techniques. The data were valuable information. They allowed the designer to fine-tune the geometry setup during the segment casting cycles, and they provided real-time displacement readings that permitted field decisions about the final force application during the jacking event.

Decoupled flux control for molecular beam epitaxy

Improvement of the manufacturing capability for the molecular beam epitaxy (MBE) process is demonstrated with respect to the consistent achievement of effusion cell flux stability of 1% of setpoint values. This performance was obtained by decoupling the principal sources of flux variability from each cell temperature control system including: cell shutter opening flux disturbances with implementation of a feedforward compensator that precisely cancels evaporant mass enthalpy transients; electric power frequency-correlation flux disturbances with substitution of heater DC drivers for the standard AC triac drivers; and flux process disorder resulting from coupled temperature controller proportional-integral-derivative (PID) tuning values with identification of decoupled trapezoidal PID tuning values. >

Issues in implementation of structural monitoring to constructed facilities for serviceability with damageability considerations

A comprehensive market survey and laboratory evaluation was conducted for the Ohio Department of Transportation and the Federal Highway Administration to identify the most promising sensors and data-acquisition systems for infrastructure application. A pilot system for highway bridge monitoring was implemented on a typical steel-stringer bridge in Cincinnati for high-speed traffic and long-term environmental monitoring. Static tests were performed with known truck loads to confirm monitoring results and to calibrate finite-element and section analysis models of the bridge. A complete and accurate characterization of the as-is structural condition has been related to the structural capacities and reliability. This multi-disciplinary research improves understanding of the actual loading environment and the corresponding bridge responses. Instrumented monitoring is expected to complement inspection methods, provide an objective measure of the state-of-health, and alert officials to bridge deterioration or failure.

A novel approach for detection of anomalies using measurement data of the Ironton-Russell bridge

Data models have been increasingly used in recent years for documenting normal behavior of structures and hence detect and classify anomalies. Large numbers of machine learning algorithms were proposed by various researchers to model operational and functional changes in structures; however, a limited number of studies were applied to actual measurement data due to limited access to the long term measurement data of structures and lack of access to the damaged states of structures. By monitoring the structure during construction and reviewing the effect of construction events on the measurement data, this study introduces a new approach to detect and eventually classify anomalies during construction and after construction. First, the implementation procedure of the sensory network that develops while the bridge is being built and its current status will be detailed. Second, the proposed anomaly detection algorithm will be applied on the collected data and finally, detected anomalies will be validated against the archived construction events.