Browsing by Author "Matsinhe, Bruno"
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- Numerical models for seismic analysis of arch damsPublication . Alegre, André; Oliveira, Sérgio; MENDES, PAULO; Proença, Jorge; Carvalho, Ezequiel; Matsinhe, BrunoThis paper presents a study on the seismic behaviour of large arch dams under strong earthquakes. The numerical simulations are carried out using DamDySSA, a 3D finite element program developed for dynamic analysis of concrete dams, which includes calculation modules for linear seismic analysis and for non-linear seismic analysis, considering the effects of joint movements and tensile and compressive damage in concrete. The case studies are the 132 m-high Cabril dam, in Portugal, and the 170 m high Cahora Bassa dam, in Mozambique. The seismic response results computed using linear and non-linear models are compared, in order to investigate the influence of the joint movements on the structural response, and to analyse the resulting concrete damage under a strong seismic load. Overall, there was a release of arch stresses in the upper part of both dams, due to the opening of the vertical joints, and consequently an increase of vertical stresses along the main cantilevers, causing concrete tensile failure. Furthermore, this study emphasized the potential of the developed numerical methods and thus of DamDySSA for predicting the non-linear seismic behaviour of arch dams.
- Use of SSHM data for dynamic behavior analysis and damage detection on large dams. The cases of Cabril dam and Cahora Bassa damPublication . Alegre, André; MENDES, PAULO; Carvalho, Ezequiel; Matsinhe, Bruno; Oliveira, Sérgio; Proença, JorgeThis paper presents recent results from studies on the dynamic behavior of large concrete dams in normal operational conditions, based on the comparison between experimental results, extracted from continuous dynamic monitoring data, and numerical results from finite element analysis. The case studies are Cabril dam (132 m high), in Portugal, and Cahora Bassa dam (170 m high), in Mozambique, two large arch dams that have been under Seismic and Structural Health Monitoring since 2008 and 2010, respectively. The monitoring data analysis is performed using DamModalID, a program specifically prepared for automatic frequency domain modal identification, while the numerical simulations are carried out utilizing DamDySSA4.0, a 3D finite element program developed for dynamic analysis of concrete dams. The focus in this work is on studying the evolution of the main natural frequencies over time, namely (i) to analyze the influence of the reservoir water level variations on the dynamic properties of the dam-reservoir-foundation system and hence on the frequencies’ values, and (ii) to evaluate the correlation with the deterioration and ageing of dams, ultimately aiming at the detection of eventual structural changes due to concrete damage. Based on the presented results, the relation between the frequencies’ values and the water level variations made it possible to verify that the dynamic response of both dams is clearly influenced by the reservoir level. Furthermore, the comparison between the identified frequencies and the values computed with reference models, considering linear behavior, enabled to conclude that the dynamic behavior of both dams has not changed over the last decade, despite the existing deterioration phenomena, and thus they can continue operating normally.