A modular, wireless damage monitoring system for structures

With the significant negative impact that extreme events and long term deterioration can have on the built environment, monitoring of civil structures holds promise to provide critical information for near real-time condition assessment. This information can be used in the prudent allocation of emergency response resources after earthquakes and also for identification of incipient damage in structures experiencing long-term deterioration. To meet this need, the research in this study aims to provide an information system, consisting of a hardware, software, and system level solution.; The vast majority of published work on monitoring civil structures focuses on developing algorithms to advance the detection of damage to structures. An equally important task is the establishment of a flexible hardware platform for near real-time data acquisition. This study developed an instrumentation system based on embedded systems and wireless networks. The vision of this study is realized in the prototype Sensor Unit; a wireless, modular, and battery powered data acquisition device.; A methodology for installing and operating a structural monitoring system is presented. Software data analysis tools are developed for data reduction in the field, modal analysis incorporating sample statistics, and near real-time damage indicators for earthquakes.; Practical issues of monitoring are investigated through experimental testing of a highway bridge. In particular, a study of the sensitivity of the vibrational properties, used in the majority of damage analysis procedures, to the surrounding environment is made. The results indicate that structures may experience large reversible changes in their vibrational properties due to changes in temperature. The changes may be several times larger than the modal property changes expected from the onset of structural damage.; The prototype monitoring system is validated with an experimental test on the same highway bridge. Specific testing objectives include speed of installation, basic functionality, applicability to high and low level excitation sources, and a direct side-by-side comparison to a conventional monitoring system. In the field, the prototype system performed well with some signal processing issues related to aliasing and impedance loading. The prototype system met all but one of the stated design goals, operating life, primarily due to commercial component choices.