Structural health monitoring and damage detection techniques are tools of great importance in the off-shore, civil, mechanical and aeronautical engineering communities, both for safety reasons and because of the economic benefits that can result. The need to be able to detect damage in complex structures has led to the development of a vast range of techniques, of which many are based upon structural vibration analysis. In the present article, some of the latest advances in Structural Health Monitoring and Damage Detection are reviewed, with an emphasis on composite structures on the grounds that this class of materials currently has a wide range of engineering applications. FOREWORD-It should be noted that this review is not intended to be a general, all-encompassing review covering the whole range of structural health monitoring (SHM); it was planned as the starting point for a study focusing on damage detection, localization and assessment for certain kinds of structure. Thus, the line of thought behind the search and the structure of this review is a result of objectives beyond the scope of the paper itself. Nevertheless, it was considered that, once the above was understood, an updated synopsis such as this could also be useful for other researchers in the same field. ©2006 SAGE Publications.

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A review of vibration-based structural health monitoring with special emphasis on composite materials

An approximate method to estimate the maximum lateral deformation demands in multistory buildings responding primarily in the fundamental mode when subjected to earthquake ground motions is presented. This method permits a rapid estimation of the maximum roof displacement and of the maximum interstory drift for a given acceleration time history or for a given displacement response spectrum. A multistory building is modeled as an equivalent continuum structure consisting of a combination of a flexural cantilever beam and a shear cantilever beam. The simplified model is used to investigate the ratio of the spectral displacement to the roof displacement and the ratio of the maximum interstory drift ratio to the roof drift ratio. The effect of the distribution of lateral forces along the height of the building and of the ratio of overall flexural and shear deformations is examined. Lateral deformation demands of a 10-story steel building computed with the simplified method when subjected to various earthquake...

Approximate Seismic Lateral Deformation Demands in Multistory Buildings

Structural Response to Earthquakes

Natural frequencies of frames with axially loaded Timoshenko Members

http://basin.earth.ncu.edu.tw/download/courses/seminar_MSc/2009/1105-2_A%20review%20of%20earthquake%20occurrence%20models%20for%20seismic%20harzard%20analysis.pdf

A review of earthquake occurrence models for seismic hazard analysis

In order to evaluate unit stresses or to estimate possible damage in multistory buildings from earthquake or ground motion from underground nuclear explosion it is essential to determine how much of the dynamic response at any level is due to various types of freedom. The effects of shear deformation between floors, joint rotation, over-all flexure, and ground compliance are considered. Joint rotation and over-all flexure are evaluated over a wide range of building characteristics with simply determined indices. A period synthesis concept and a pseudo-stiffness procedure are proposed to enable the determination of periods, mode shapes and stiffnesses with consideration of joint rotation, over-all flexure and ground compliance while performing simple labor-saving analyses for assumed rigid-floor shear buildings. The first three modes of vibration are considered in elastic free vibration. The buildings and models are symmetric in plan without torsional coupling.

Dynamic Characteristics of Multistory Buildings

Recent research efforts utilizing high-speed digital computers and electric analogs have indicated vast differences between design and code values for structures and their actual earthquake shears and behavior. This paper attempts to reconcile these differences with the aid of comprehensive structural and dynamic analyses and research efforts on two office buildings–one the traditional filler-wall type and the other a modern glass-wall structure. Included are strengths, rigidities, and energy-absorption values for the former building under various distortions up to failure and also the results of a comprehensive series of analog tests for the modern 20-story structure using four complete earthquake records with 16 various systems of damping and rigidity values. Certain inconsistencies and pitfalls in present-day design practice are demonstrated and new considerations are suggested for resisting the occasional but extreme energy releases of Nature.

Structural Dynamics in Earthquake-Resistant Design

A low-cost wireless sensing unit is designed and fabricated for deployment in a structural monitoring system that uses wireless radios as the sole channel for communications. The finite operational life of portable power supplies such as batteries necessitates optimization of the wireless sensing unit design to attain power efficiency. To attain far reaching communication ranges required in structural monitoring applications, the wireless communication channel consumes significant amount of power. To reduce the quantity of raw time-history data for transmission and reception, a computational core that can accommodate localized processing of data is designed and implemented. To illustrate the ability of the computational core to execute embedded engineering analyses, a two-tiered time-series damage detection algorithm is implemented. Local execution of the embedded damage detection method is shown to save energy by avoiding utilization of the wireless channel to transmit raw time-history data.

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Design of Wireless Sensor Units with Embedded Statistical Time-Series Damage Detection Algorithms for Structural Health Monitoring

There exists a clear need to monitor the performance of civil structures over their operational lives. Current commercial monitoring systems suffer from various technological and economic limitations that prevent widespread adoption. The wires used to route measurements from system sensors to the centralized data server represent one of the greatest limitations since they are physically vulnerable and expensive from an installation and maintenance standpoint. In lieu of cables, the introduction of low-cost wireless communications is proposed. The result is the design of a prototype wireless sensing unit that can serve as the fundamental building block of wireless modular monitoring systems (WiMMS). The prototype unit is validated with a series of tests conducted in the laboratory and the field. In particular, the Alamosa Canyon Bridge is employed to serve as a full-scale benchmark structure to validate the performance of the wireless sensing unit in the field.

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Laboratory and Field Validation of a Wireless Sensing Unit Design for Structural Monitoring

Strong interest in applying wireless sensing technologies within structural monitoring systems has grown in recent years. Wireless sensors are capable of passively collecting response measurements of a dynamic structural system at low-costs. However, the role of wireless sensing within structural monitoring systems can be expanded if sensors are provided a direct interface to the physical system in which they are installed. Capable of exciting a structural system through actuators, a wireless “active” sensor would be a valuable tool in structural control and damage detection applications. In this study, a wireless active sensing unit is proposed and fabricated. After fabrication of a prototype, a series of validation tests are conducted to assess the unit’s performance. A piezoelectric pad mounted to an aluminum plate is commanded by the wireless active sensing unit to impart lowenergy Lamb waves in the plate surface. Simultaneously, the same unit collects response measurements obtained from a second piezoelectric pad also surface mounted to the plate. To illustrate the potential of the wireless active sensing unit to locally perform system identification analyses, the computational core is provided the task of calculating autoregressive time-series models using input-output time-history data collected from the excited system.

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John A. Blume

Papers

Dynamic Characteristics of Multistory Buildings

Structural Dynamics in Earthquake-Resistant Design

Design of Wireless Sensor Units with Embedded Statistical Time-Series Damage Detection Algorithms for Structural Health Monitoring

Laboratory and Field Validation of a Wireless Sensing Unit Design for Structural Monitoring

Piezoelectric Structural Excitation using a Wireless Active Sensing Unit