David E. Kosnik

Application of Statistical Process Control for Structural Health Monitoring of a Historic Building

AbstractThe authors apply a statistical process control framework to support structural health monitoring of the Grace Church building in Charleston, South Carolina. Specifically, they conduct a post-hoc analysis of displacement data acquired via remote monitoring of delamination between two wythes of brick in a clerestory wall. The framework consists of formulation and estimation of statistical models to explain the progression of the measurements under ordinary conditions and use of control charts to detect unusual events. One such event was excessive displacement in September 2011 that led the engineer of record to close the building to public access and order immediate repairs. The analysis also reveals a few unusual events that were not apparent from visual interpretation of the data, including a possible precursor to the aforementioned event.

Design and Interface Considerations for Web-Enabled Data Management in Civil Infrastructure Health Monitoring

We present principles and techniques for design of Web-enabled data aggregation, storage, and visualization software for structural health monitoring of civil infrastructure: the process of collecting and analyzing sensor data related to the condition or behavior of constructed facilities (e.g., bridges, dams, tunnels) to promote safe and efficient service at a reasonable cost. Due to widely variable user requirements and the vast range of data types and display methods required, good human-computer interfaces for engineering applications are still difficult to design and implement, and continue to be constructed in more-or-less ad hoc manners. We approach human-computer interaction in the civil engineering domain through common HCI methods, such as user interviews, use case design and analysis, representation in UML, and so on. However, this paper is focused on two special techniques that are not commonly found in HCI development: (1) a rigorous analysis of the nature of the data and how it will be used, and (2) a general method for sending data into functions for display on the user interface. The addition of two techniques like the above adds new tools to the engineering HCI toolkit and increases HCI designers’ ability to meet the needs of engineers who examine large volumes of engineering data.

Acoustic emission monitoring for assessment of steel bridge details

Acoustic emission (AE) testing was deployed on details of two large steel Interstate Highway bridges: one cantilever through‐truss and one trapezoidal box girder bridge. Quantitative measurements of activity levels at known and suspected crack locations were made by monitoring AE under normal service loads (e.g., live traffic and wind). AE indications were used to direct application of radiography, resulting in identification of a previously unknown flaw, and to inform selection of a retrofit detail.

Autonomous Monitoring of Dynamic Response of In-Service Structures for Decision Support

AbstractThis paper describes instrumentation and autonomous, Web-enabled remote monitoring of in-service structures to resolve concerns. Structures were subject to dynamic excitation from blasting, construction equipment, and passing trains. An integrated approach to sensing, data acquisition, communication, data aggregation, and display was developed and successfully applied to structures ranging from bridges to homes. Challenges encountered and best practices developed over many multiyear continuous remote monitoring deployments are discussed. Deployment of monitoring and communication hardware and software and development of robust, autonomous, data aggregation, dissemination, and interpretation strategies are emphasized. Three selected case studies provide context and demonstrate applications of field monitoring to real-world situations on in-service structures. Autonomously acquired data were used to allay fears of construction vibration-related damage to a historic building, possible loss of capacit...

Continuous Remote Monitoring of Structural Health for Life Extension of Uplift Bearing Assembly on Large Cantilever Truss Bridge

A situation on a large cantilever through-truss bridge, the John F. Kennedy Memorial Bridge, which carries I-65 over the Ohio River at Louisville, Kentucky, provides significant opportunities for applying innovative health monitoring techniques to transportation infrastructure. One of four anchor bolts restraining an uplift bearing at one end of the bridge fractured as a result of corrosion fatigue; the fracture led to concerns about the continuing safety and serviceability of the compromised bearing assembly. Short- and long-term instrument-based monitoring systems were deployed on the bearing assembly to (a) characterize the behavior of the damaged bearing and its intact counterparts, (b) quantify the load transfer due to the retrofit, and (c) monitor the performance of the retrofit continuously for the long term. The monitoring strategy has been successful on all counts; in particular, during Part 3 the system detected a significant shifting of loads that was later confirmed to correspond to fracture of a threaded rod that had been used to replace the failed anchor bolt; this result showed the utility of continuous remote monitoring in detecting failures between inspections. This paper describes the instrumentation plan and strategies for data acquisition, communication, and autonomous operation used on the bridge. The data and implications for management decisions are also discussed.

Case Studies in Integrated Autonomous Remote Monitoring

This paper will describe the technology that enables autonomous collection and Internet display of measurements from a wide variety of geotechnical sensors. In order for continuous monitoring to be economical, data must be collected without travel to the site, and ideally with no human intervention. Northwestern Universitys Infrastructure Technology Institute (ITI) has developed and deployed several techniques for the effective continuous remote monitoring of geotechnical facilities, all of which employ the same Internet display. These techniques include systems for control, data acquisition, and power management of instruments in the field as well as methods for data distribution and display. These technologies are readily adapted and scaled to sites ranging from a single-family home to projects covering entire city blocks. The case studies described herein include monitoring sinkhole-like subsidence on a Florida highway, monitoring soil movement adjacent to deep excavations in downtown areas of two major cities, and monitoring the effects of mine blasting vibration on a house in Kentucky.