Design Of Steel Structures

The non-destructive evaluation technique using a piezoceramic (PZT) as an actuator–sensor has a potential to efficiently detect structural damage. In this technique, a PZT actuator–sensor patch is bonded on a structure. Through the measurement of its electrical impedance, which is related to the mechanical impedance of the structure being bonded, the change in structural properties due to damage can be detected. This paper presents the use of a PZT actuator–sensor in conjunction with numerical model-based methodology in structural health monitoring to quantitatively detect damage of bolted joints. The structure used in this study consists of two aluminium beams connected by a bolted joint. The damage was simulated by loosening the bolts. To quantitatively monitor the damage, a numerical model of the structure was formulated. A spectral element method (SEM), based on a wave propagation approach, was used to model the structure. A bonded-PZT beam and a bolted joint element were developed by using the SEM. The equations of motion were derived by using Hamilton's principle and then the spectral element matrices were formulated. Experimental results show the effectiveness of this method to detect the damage. By using the proposed model, the loosening of bolts can be quantitatively identified as the change in stiffness and damping at the bolted joint, indicating a high potential of this method in order to quantitatively monitor structural damage.

Quantitative health monitoring of bolted joints using a piezoceramic actuator-sensor

This paper presents the results of applying a non-parametric technique to the detection of the presence of damage and the monitoring of damage progression in concrete. The electromechanical impedance method using smart piezoceramic material is utilized in this study. The smart piezoelectric lead-zirconate-titanate (PZT) transducers bonded onto the structures are used to actively provide the local excitation and simultaneously sense the structural dynamic response in high frequency band. The frequency-dependent electric admittance signatures of the piezoelectric transducer are compared with the baseline signatures to determine the status of the health of structures. The damage is quantified by the root-mean-square deviation (RMSD) index. The correlation of the RMSD index with the location and extent of damage is investigated. In this paper, two sets of experimental tests are performed on the concrete beams instrumented with PZT transducers. The findings summarized from the experimental results are confirmed by a series of numerical simulations using finite element analysis. The experimental and numerical results demonstrate the suitability of using the smart PZT transducers for in situ health monitoring of structural integrity in civil infrastructures using concrete.

https://iopscience.iop.org/article/10.1088/0964-1726/13/5/006/pdf

Smart piezoelectric transducers for in situ health monitoring of concrete

Bolted joint are among the key components that enable the robust assembly of a wide variety of structures. However, due to wear and tear over time, bolted joint may loosen, and if not detected in its early stages, can lead to devastating results. A monitoring method that can detect bolted joint looseness prior to bolt failure will be essential for the continued operation of the host structure and depending on the situation, the safety of the occupants. Prior research has proven the electromechanical impedance method (EMI) to be an effective technique for detecting the loosening of bolted joints, however, EMI-based methods until now are focused on qualitative health monitoring, which can only provide limited information about the damage. Thus, this paper attempts to quantify EMI based methods through the integration of fractal contact theory, the result of which is a novel electromechanical impedance model for quantitative monitoring of bolted looseness. The method determines the effective impedance of the bolted joint and is applied to develop the relationship between the electrical impedance of a piezoceramic patch installed on the joint and the mechanical impedance of the bolted joint. The mechanical impedance of the bolted joint under various preloads is computed by using the fractal contact theory. Then, the bolted looseness can be monitored quantitatively. At last, a set of verification tests under different applied preload of bolted joint are conducted to verify the validity of the proposed model in this paper.

A Novel Fractal Contact-Electromechanical Impedance Model for Quantitative Monitoring of Bolted Joint Looseness

Bolt early looseness monitoring using modified vibro-acoustic modulation by time-reversal

Analytical Study on Shear Capacity of Steel I-Girders with Local Corrosion nearby Supports

A non-destructive evaluation technique using piezoceramic (PZT) as an actuator-sensor has an ability to efficiently detect structural damage. In this technique, a PZT actuator-sensor patch is bonded on a structure. Through the measurement of its electrical impedance, which is related to mechanical impedance of the structure being bonded, the change in structure properties due to damage can be detected. This paper presents the use of PZT in structural health monitoring to quantitatively detect damage of bolted joints. The structure used in this study consists of two aluminum beams connected by a bolted joint. The damage is simulated by loosening of the bolts. To quantitatively monitor the damage, a numerical model of the structure is formulated. Spectral element method (SEM) based on wave propagation approach is used to model the structure. A bonded-PZT beam and a bolted joint element are developed by using SEM. The equations of motion are derived by using Hamilton's principle subsequently, the spectral element matrices are formulated. Experimental results show the ability of this method to detect the damage. By using the proposed model, the loosening of bolts can be quantitatively identified as the change in stiffness and damping at the bolted joint. Therefore, this method has high potential to quantitatively monitor damage of bolted joints.

Quantitative health monitoring of bolted joints using piezoceramic actuator-sensor

This paper presents the development of a high precision three-dimensional measurement system using laser doppler 
vibrometers. Two measurement systems were developed. Then, the following fundamental issues were studied and the 
results presented: measurement principle, accuracy with respect to long distance measurements and laser beam angles. 
As examples of possible applications of the system, measurements of ground motion, measurement of wave propagation 
in a plate and vibration measurement of a steel railway bridge were treated.

Development of 3D vibration measurement system using laser doppler vibrometers

ある鉄道鋼箱桁橋において発生した主桁ウェブの垂直補剛材下端回し溶接部付近の変状の原因を明らかにすることを目的として，1)レーザードップラー振動計を複数台用いた振動計測システムを構築し，2)垂直補剛材下端部に設置した補強材がある状態と一時的に撤去した状態の常時微動計測から局部振動モード形を同定し，さらに，3)局部応力と局部振動，列車速度との関係を詳細に計測および調査し，変状の主要因は台車の規則的な通過による主桁下フランジの局部的な振動であることを明らかにした．最後に，実測データを用いた簡易な解析モデルにより列車走行時の振動現象を説明し，局部振動に対する高速運転の影響を予測した．

Takeshi Miyashita

Papers

Quantitative health monitoring of bolted joints using a piezoceramic actuator-sensor

Analytical Study on Shear Capacity of Steel I-Girders with Local Corrosion nearby Supports

Quantitative health monitoring of bolted joints using piezoceramic actuator-sensor

Development of 3D vibration measurement system using laser doppler vibrometers

Understanding of high-speed-train-induced local vibration of a railway steel bridge using laser measurement and its effect by train speed