Long-Term effects of Environment on Seismic Performance of Dez Concrete Arch Dam

Volume 4 - Issue 1

Mojtaba Labibzadeh¹*, Alireza Firouzi² and Hamid R. Ghafouri³

Received: August 13, 2020;   Published: September 04, 2020

DOI: 10.32474/TCEIA.2020.04.000176

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In the first part of this paper, the degradation of the mechanical properties of the mass concrete of the Dez concrete arch dam under the long-term effects of its environment as well as its loading history has been investigated using an innovate inverse analysis method. For performing that inverse analysis, an objective function was defined and then it was attempted to minimize that. That function was defined as the sum of the squared differences between the displacements obtained from a developed enhanced FE model in the ABAQUS standard software by the authors in the current study for each assumed set of the degraded mechanical properties of the dam as input variables and those obtained from the inverse pendulum’s records of the dam. For the sake of the generality of the problem, in performing such FE analyses, it was assumed that the behavior of the concrete material of the Dez dam has transformed gradually from initial homogeneous and isotropic undamaged behavior to the heterogeneous and orthotropic deteriorated behavior under the long-term effects of the environment as well as load agencies. Hence, the vertical sections of the dam were divided into nine and six subsections along the thickness and height directions of the dam, respectively. In each subsection, a transversely isotropic degraded elastic constitutive law was considered for characterizing the concrete long-term deterioration phenomenon. Obtained results revealed that the long-term deterioration of the mass concrete of the Dez dam is in fact a heterogeneous and anisotropic process because that the magnitude of the above mentioned defined objective function was obtained smaller than the corresponding value in the previous study of the authors which was performed based on the homogeneous and isotropic damage evolution assumptions. Core test results from the mass concrete of the dam reported by a consulting engineer company confirmed the concrete degradation predicted by the proposed model. After that, the behavior of this dam against an earthquake excitation was investigated considering the above-mentioned degradation of its mechanical properties and the obtained results were compared with its corresponding behavior considering its initial un-damaged mechanical properties for the mass concrete. Comparisons revealed considerable growth in the enveloped tensile stresses which can change the initial assumed safety margin design factors of the dam and necessitates the re-evaluating of the dam stability.

Keywords: Concrete; Thermal inverse analysis; Heterogeneous; Transversely isotropic; Long-term damage; Arch dam; Seismic response

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