Seismic and Structural Health Monitoring of Dams in Portugal

Oliveira, Silvia Paula De; Alegre, André

doi:10.1007/978-3-030-13976-6_4

Cited by 14 publications

(4 citation statements)

References 2 publications

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“…With a view to address the concerns about long-term safety, Cabril dam was instrumented in 2008 with a pioneering SSHM system, developed to monitor dam behavior under ambient/operational conditions and to measure the response during seismic events [4][5][6]. The system was designed to continuously measure vibrations on the dam, using a) 16 uniaxial accelerometers to record accelerations along the upper part of the dam, 9 in the upper gallery, at el.…”

Section: Case-study: Cabril Dam Portugalmentioning

confidence: 99%

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

OLIVEIRA,

ALEGRE,

RAMOS

et al. 2023

Proceedings of the 14th International Workshop on Structural Health Monitoring

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This paper presents a complete study on the dynamic behavior of the 132 m high Cabril arch dam (Portugal). In operation for almost 70 years, horizontal cracks appeared on the downstream face after the first reservoir filling, and in the 1980s the dam started showing signs of concrete swelling. To address the concerns about its long-term safety, a pioneering continuous vibration monitoring system, designed for Seismic and Structural Health Monitoring, was installed in Cabril dam in 2008. In this work, the vibrations recorded under ambient/operational conditions for more than a decade are analyzed to estimate the modal parameters of the dam, which are then used to calibrate and validate a finite element model of the dam-reservoir-foundation system with the horizontal cracking. After that, the dynamic behavior of Cabril dam is simulated for the next decades, considering a computationally generated scenario of progressive damage due to concrete swelling. The results show that a) the dynamic behavior of Cabril dam is not being affected by the existing swelling phenomenon, and b) vibration-based analysis can be effective for detecting structural changes due to progressive damage. Lastly, the calibrated model is adapted for conducting non-linear seismic simulations, considering joint movements and tensile and compressive concrete damage. A method based on Endurance Time Analysis method is applied to assess the seismic safety of the dam with respect to the Operating Basis Earthquake and the Safety Evaluation Earthquake. The results confirm that Cabril dam can withstand accelerations several times greater than both earthquake levels, showing its adequate seismic capacity.

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Section: Case-study: Cabril Dam Portugalmentioning

confidence: 99%

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

OLIVEIRA,

ALEGRE,

RAMOS

et al. 2023

Proceedings of the 14th International Workshop on Structural Health Monitoring

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“…The authors concluded that electro-mechanical impedance based on PTZ (pan-tilt-zoom) sensors (based on the perspective distortion correction method and also can increase the monitoring range) can detect the seismic damage and the model can measure the damage level. Another study explored the seismic and structural health of the Baixo Sabor dam and Cabril dam in Portugal and modeled them using the 3D FE method [140]. A 2D FE model was applied [141] to assess the impact of an earthquake on the Sefidrud buttress dam potential failure zone.…”

Section: D Dam Modelingmentioning

confidence: 99%

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

Yaseen‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

Ameen

Aldlemy

et al. 2020

Sustainability

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Dam and powerhouse operation sustainability is a major concern from the hydraulic engineering perspective. Powerhouse operation is one of the main sources of vibrations in the dam structure and hydropower plant; thus, the evaluation of turbine performance at different water pressures is important for determining the sustainability of the dam body. Draft tube turbines run under high pressure and suffer from connection problems, such as vibrations and pressure fluctuation. Reducing the pressure fluctuation and minimizing the principal stress caused by undesired components of water in the draft tube turbine are ongoing problems that must be resolved. Here, we conducted a comprehensive review of studies performed on dams, powerhouses, and turbine vibration, focusing on the vibration of two turbine units: Kaplan and Francis turbine units. The survey covered several aspects of dam types (e.g., rock and concrete dams), powerhouse analysis, turbine vibrations, and the relationship between dam and hydropower plant sustainability and operation. The current review covers the related research on the fluid mechanism in turbine units of hydropower plants, providing a perspective on better control of vibrations. Thus, the risks and failures can be better managed and reduced, which in turn will reduce hydropower plant operation costs and simultaneously increase the economical sustainability. Several research gaps were found, and the literature was assessed to provide more insightful details on the studies surveyed. Numerous future research directions are recommended.

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“…The importance of the observation and analysis of the behaviour of large concrete dams has been widely recognized for decades (Pedro 1999;Ramos 1994), especially when experimental data is used in combination with numerical modelling results. Regarding dynamic behaviour monitoring for structural safety control of large concrete dams, the popularity of continuous dynamic monitoring systems has grown significantly over the last decade (Oliveira and Alegre 2019) due to the recognition of the advantages of continuous ambient vibrations monitoring for increasing knowledge on the dynamic behaviour of dam-reservoir-foundation systems (Alegre et al 2019;Bukenya, et al 2014a, b;Bukenya & Moyo, 2017;Oliveira et al 2012), as well as for detecting and controlling concrete deterioration (Oliveira and Alegre 2020), which can be induced by phenomena like concrete swelling or occur due to exceptional events such as floods or major earthquakes.…”

Section: Introductionmentioning

confidence: 99%

Seismic and structural health monitoring systems for large dams: theoretical, computational and practical innovations

Oliveira

Alegre

Carvalho³

et al. 2022

Bull Earthquake Eng

Self Cite

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This paper is focused on the study of the dynamic behaviour of two large arch dams, and it presents some innovations for the improvement of Seismic and Structural Health Monitoring (SSHM) systems for dams. The work describes a methodology based on the integrated use of software for automatic monitoring data analysis and of computational 3D finite element (3DFE) models for dam dynamic behaviour simulation. The monitoring data analysis software was developed for automatic modal identification, in order to obtain natural frequencies and mode shapes, for automatic detection of vibrations induced by seismic events, to be distinguished from those caused by other operational sources, and for comparison between results retrieved from measured vibrations and numerical results from 3DFE modelling. The numerical simulations are carried out using a 3DFE program developed for dynamic analysis of dam-reservoir-foundation systems, based on a solid-fluid coupled formulation and considering the dam-water dynamic interaction, including calculation modules for complex modal analysis and for linear and non-linear seismic analysis. The case studies are two large arch dams that have been under continuous dynamic monitoring over the last ten years: Cabril dam (132 m high), the highest dam in Portugal, and Cahora Bassa dam (170 m high), in Mozambique, one of the highest dams in Africa. The SSHM systems installed in both dams have similar schemes and were designed to continuously record accelerations in several locations at the upper part of the dam body and near the dam-foundation interface, using uniaxial and triaxial accelerometers. The most significant experimental results from continuous dynamic monitoring are presented and compared with numerical results for both dams, with emphasis on the evolution of natural frequencies over time, including the vibration mode shapes for various water levels, and on the measured accelerations during low-intensity seismic events. Furthermore, the main results of non-linear seismic response simulations are provided, considering the effects due to joint movements and tensile and compressive concrete damage, aiming to assess the seismic performance of both dams based on the Endurance Time Analysis method.

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Seismic and Structural Health Monitoring of Dams in Portugal

Cited by 14 publications

References 2 publications

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

Seismic and structural health monitoring systems for large dams: theoretical, computational and practical innovations

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