DSpace Collection:
http://repositorio.lnec.pt:8080/jspui/handle/123456789/177
Wed, 18 Nov 2020 20:01:59 GMT2020-11-18T20:01:59ZEstudo das condições de fundação dos contrafortes da barragem do Caia
http://repositorio.lnec.pt:8080/jspui/handle/123456789/1013046
Title: Estudo das condições de fundação dos contrafortes da barragem do Caia
Authors: Silveira, A. F.; Peres Rodrigues, F.; Barroso, M.Fri, 01 Apr 1966 00:00:00 GMThttp://repositorio.lnec.pt:8080/jspui/handle/123456789/10130461966-04-01T00:00:00ZDevelopment of DamDamage3D1.0 - A MATLAB program for non-linear analysis of arch dams using a damage model
http://repositorio.lnec.pt:8080/jspui/handle/123456789/1012092
Title: Development of DamDamage3D1.0 - A MATLAB program for non-linear analysis of arch dams using a damage model
Authors: Alegre, A.; Oliveira, S.
Abstract: The main goal of this report is to present DamDamage3D1.0, a 3D finite element-based program for non-linear static analysis of arch dams, developed using MATLAB. The non-linear simulations are performed using a damage law and an iterative numerical method based on the stress-transfer technique, considering the redistribution of unbalanced forces in each iteration due to material damage. The concrete’s non-linear behaviour up to failure is simulated using an isotropic damage model with softening, considering two independent scalar damage variables: d+ for tension damage and d- for compression damage. The implemented code was verified and optimized for a simple test structure, more specifically a concrete frame structure with three columns. According to the defined material properties for the structural elements, the concrete failure is expected to occur only at the central column without causing the collapse of the structure, which remains in equilibrium. DamDamage3D1.0 is used to evaluate the structural safety of Cabril arch dam (132 m high) for the concrete strength decrease scenario, considering the material deterioration under tension and compression. This failure scenario is usually considered in the scope of the safety control of dams, and the main goal is to obtain a global safety factor λs that indicates how many times the material’s resistance can be reduced without causing the dam’s structural collapse. This way λs is the maximum admissible multiplying factor of the applied loads. The non-linear behaviour of the dam is analysed for the load combination with the self-weight (SW) and the hydrostatic pressure (HP) at the upstream face (full reservoir), using a 3D finite element mesh with three elements in thickness. The numerical simulations are performed using two different constitutive damage laws to evaluate the influence of the compression softening phenomenon in the global resistant capacity of the dam. The main results include displacements and stress fields and the distributions of tension and compression damage in the dam body.Fri, 01 Nov 2019 00:00:00 GMThttp://repositorio.lnec.pt:8080/jspui/handle/123456789/10120922019-11-01T00:00:00ZDevelopment of GDams2D 1.0 - A MATLAB code for structural analysis of gravity dams using Lagrangian finite elements with 9 nodes
http://repositorio.lnec.pt:8080/jspui/handle/123456789/1011822
Title: Development of GDams2D 1.0 - A MATLAB code for structural analysis of gravity dams using Lagrangian finite elements with 9 nodes
Authors: Rodrigues, M.; Oliveira, S.
Abstract: In this work we present the version 1.0 of the GDams2D 1.0 program developed for 2D analysis of gravity dams using the finite element method. This initial version of the program is prepared to analyze the structural behavior of gravity dams for static loads, considering linear-elastic behavior, and using Lagrange finite elements of 4 sides, with 9 nodal points. The GDams2D 1.0 program, developed in MATLAB, includes a module for automatic generation of meshes with a great level of refinement (generated from coarse meshes of quadrilaterals, with 4 nodal points at the vertices) and is designed for easy adaptation to non-linear analyzes, using stress-transfer modules such as those recently developed for the DamSlide3D and DamDamage3D programs. After a brief reference to the fundamentals of solid mechanics and to the simplified hypotheses of plane elasticity, the Fundamentals of the Finite Element Method (FEM) are presented, referring in particular the formulation of the four-node, linear and isoparametric, finite element (FE4nos), with two translation d.o.f per node, and the quadrangular FEs of 9 nodes (FE9nos) used in GDams2D 1.0. Based on some examples of application to simple 2D structures whose response is known
analytically, the advantages of FEs are emphasized in relation to FE4nos and the verification and operability of GDams2D 1.0 is made using various discretizations. Finally, the case of a gravity dam (25 m high) is presented. The dam’s structural behavior for the main loads, self-weight and hydrostatic pressure, is simulated with GDams2D 1.0. The results obtained are analyzed based on the post-processing module of GDams2D 1.0, also developed in MATLAB in the scope of the present work. This module allows several types of representation of the displacement field and stress field.Sun, 01 Sep 2019 00:00:00 GMThttp://repositorio.lnec.pt:8080/jspui/handle/123456789/10118222019-09-01T00:00:00ZStructural analysis of gravity dams considering non-linear behavior in the dam-foundation interface - Development of a 3DFE code using MATLAB: DamSlide3D
http://repositorio.lnec.pt:8080/jspui/handle/123456789/1011530
Title: Structural analysis of gravity dams considering non-linear behavior in the dam-foundation interface - Development of a 3DFE code using MATLAB: DamSlide3D
Authors: Rodrigues, M.; Oliveira, S.
Abstract: The main objective of this work is the development and presentation of a three-dimensional finite element program, DamSlide3D, to study the behavior of gravity dams for scenarios of sliding through the dam-foundation interface. The DamSlide3D, developed using MATLAB, includes cube-type finite elements with 20 nodal points ("serendipity") and finite interface elements with 16 nodal points (joint elements). Initially, we present the fundamental equations of Solid Mechanics, referring to the main simplified hypotheses considered in the computationally implemented formulation, which is presented mathematically as a problem of boundary values using a displacement formulation. For the structure body and for the foundation, the hypothesis of isotropic materials with linear elastic behavior is assumed and for the interfaces the hypothesis of non-linear behavior is considered using the Mohr- Coulomb criterion. The DamSlide3D input data is provided in an excel file and includes structure geometry data, material properties, support conditions and load parameters. As output, the program graphically displays the stress field (principal stresses) and the displacement field (deformed structure). The program was verified throughout three numerical tests with known theoretical solutions. In these tests a simple structure was used, composed by a column discretized in 3DFE. At the contact surface between the column and the base (horizontal surface) it was considered an interface discretized using joint finite elements. A plane surface that crosses the column with a given slope is also considered, discretized using the same type of joint finite elements. In the first test, the field of elastic stresses at the base, due to self-weight (SW) and hydrostatic pressure (HP), was compared with the theoretical results. In the second test the nonlinear column response was studied for different values of the
friction angle at the inclined interface (in this test the structure is only submitted to SW). In the third test, for the main SW + HP loads, the stability of the column is studied for a variation of the friction angle, and for a variation of the water level. In these three numerical tests the results were always consistent with the theoretical solutions. Finally, as an example of application, a gravity dam structural behavior was analyzed considering the non-linear behavior in the dam-foundation interface. The dam was subjected to self-weight and hydrostatic pressure. A parametric study was developed in order to study the dam stability for different
values of water level and friction angle.Mon, 01 Apr 2019 00:00:00 GMThttp://repositorio.lnec.pt:8080/jspui/handle/123456789/10115302019-04-01T00:00:00Z