Structural Control and Health Monitoring

doi: 10.1002/stc.1795pmid: N/A

No abstract is available for this article.

Lai, Yong‐An; Yang, CS Walter; Lien, Kuan‐Hua; Chung, Lap‐Loi; Wu, Lai‐Yun

doi: 10.1002/stc.1834pmid: N/A

In this paper, an optimal energy dissipation control algorithm is applied into a semi‐active suspension‐type tuned mass damper (SA‐STMD) to suppress excessive vibration by means of variable pendulum length. The SA‐STMD mechanism consists of a mass block, a suspension rope, and a movable fulcrum that can be a short tube driven by a linear motor to vertically move along the suspension rope. As the fulcrum goes up, the pendulum length is extended, resulting in a smaller stiffness of the SA‐STMD, and vice versa. Accordingly, the restoring force in the SA‐STMD can be adjusted by varying the fulcrum positions. In the case where the energy dissipation ability by the original STMDs is insufficient, the movable fulcrum in the SA‐STMD system can compensate the STMDs for stiffness according to the proposed optimal energy dissipation control algorithm to provide controllable restoring forces. The controllable restoring forces are designed to act as viscous dampers that can make up for the lack of energy dissipation capacity. The numerical results from the time domain and frequency domain analyses show that the proposed approach utilizing the optimal energy dissipation control algorithm to adjust the pendulum length can induce controllable restoring forces with a butterfly‐shaped hysteresis loop, supplying a sufficient energy dissipation capacity to reduce responses to the unexpectedly large external vibration. Another potential benefit is cost reduction because of use of a less number of conventional viscous dampers in the STMD system. Copyright © 2016 John Wiley & Sons, Ltd.

Li, Suchao; Guo, Anxin; Li, Hui; Mao, Chenxi

doi: 10.1002/stc.1835pmid: N/A

Seismic‐induced pounding between adjacent structures that are insufficiently separated can cause significant structural damage, even collapse, during severe earthquakes. This paper presents an experimental and numerical investigation into mitigating pounding on highway bridges using novel shape memory alloy pseudo‐rubber shock‐absorbing devices (SMAPR‐SADs). The mechanical properties and a theoretical model of SMAPR‐SADs are briefly introduced and investigated. Next, a series of shaking table tests on a 1:30 model of a steel highway bridge are conducted to investigate the effectiveness of the SMAPR‐SADs in mitigating the pounding of the structures. Based on the experimental results, the pounding‐induced stress waves are analyzed using wave theory and the cross‐wavelet transform method. Subsequently, numerical models of highway bridges with and without SMAPR‐SADs are proposed. The pounding mitigation mechanism of SMAPR‐SADs is analyzed using the momentum theorem, their ability to dissipate energy, and stress wave absorption theory. Two indexes representing the energy absorption and dissipation abilities of SMAPR‐SADs are proposed and investigated. Finally, the effect of the axial stiffness of SMAPR‐SADs on pounding mitigation is analyzed. The experimental and theoretical results demonstrate that SMAPR‐SADs are able to absorb energy stably and can significantly reduce the pounding response of highway bridges under seismic excitations. Copyright © 2016 John Wiley & Sons, Ltd.

Cramer, Nick; Swei, Sean Shan‐Min; Cheung, Kenneth C.; Teodorescu, Mircea

doi: 10.1002/stc.1837pmid: N/A

This paper presents the modeling and control of an aircraft wing structure constructed by lattice‐based cellular materials/components. A novel model reduction process is proposed that utilizes the extended discrete‐time transfer matrix method (E‐DT‐TMM). Through recursive application of the E‐DT‐TMM, an effective reduced‐order model can be obtained in which a decentralized discrete‐time linear quadratic regulator (LQR) controller can be designed. To demonstrate the efficiency of the proposed concept, a prototype wing structure is studied. The analysis and simulation results show that the performance of the proposed E‐DT‐TMM based decentralized LQR controller is comparable with that of the full‐state continuous LQR controller. Copyright © 2016 John Wiley & Sons, Ltd.

OBrien, Eugene J.; Malekjafarian, Abdollah

doi: 10.1002/stc.1841pmid: N/A

This paper presents a novel algorithm for bridge damage detection based on the mode shapes estimated from a passing vehicle. The bridge response at the moving coordinate is measured from an instrumented vehicle with laser vibrometers and accelerometers. A modified version of the Short Time Frequency Domain Decomposition method is applied to the measured responses. The bridge mode shape is estimated with high resolution, which is appropriate for damage detection. A damage index based on mode shape squares is used to detect the presence and location of the damage. A numerical case study of a half‐car model passing over a bridge is described in this paper, which validates the performance of the proposed approach. Several damage scenarios are considered including different locations and severities. It is shown that the presence and location of the damage can be detected with acceptable accuracy when the vehicle is moving very slowly. In addition, the performance of the method using higher vehicle speeds is investigated and shows that the approach works well for speeds up to 8 m/s. The sensitivity of the algorithm to measurement noise is also studied by adding several levels of noise to the responses measured on the vehicle. Copyright © 2016 John Wiley & Sons, Ltd.