Ruy Pauletti - Academia.edu (original) (raw)

Papers by Ruy Pauletti

Controlling the geometry and forces of a hybrid cable-net and

Newton‟s Method, the most widely used and robust tool for the solution of systems of nonlinear al... more Newton‟s Method, the most widely used and robust tool for the solution of systems of nonlinear algebraic equations, requires successive evaluations of the Jacobian matrix, whose columns can be seen as the directional derivatives of the system‟s residual vector, with respect to each of its degrees of freedom. By their turn, these directional derivatives can be conveniently approximated by finite-difference schemes. However, a naive application of such idea to solve large order nonlinear algebraic equations would easily compromises its practical attractiveness, because the number of required algebraic operations grows with the square of the order of the system. In this paper, we consider problems where the residual vector is define by sub-domains (or „elements‟), allowing the definition of element Jacobian matrices (of much smaller order than the global one), whose columns are again approximated by central-differences. So proceeding, the residual vector becomes locally supported, the ...

This paper presents the results of a three-dimensional model of the one instrumented brazilian co... more This paper presents the results of a three-dimensional model of the one instrumented brazilian concrete dam and foundation. In order to analyze the effects of the concrete expansion due alkali-aggregate reaction, a three-dimensional mathematical models were prepared for simulation purposes using the ANSYS finite element program with APDL language coupling structural-hygrometric to represent a nonlinear behavior. This paper presents the results obtained for the stress evolution in the concrete dams instrumented.

The paper presents a recently developed finite element code for the nonlinear static and dynamic ... more The paper presents a recently developed finite element code for the nonlinear static and dynamic analysis of structures and its application to the analysis of tall buildings. The code is intended for academic purposes (teaching and research). Nevertheless it was used in the nonlinear stability analysis of an inclined tall building in Santos, Brazil, which is near to collapse and will be brought to the right position through the application of hydraulic jacks. This very interesting case is also reported in the paper. The most important features of the system are discussed. The language Fortran 90/95 was chosen in order to allow the reutilization of existing FORTRAN77 routines, to retain numerical efficiency and to take profit of new capabilities of the language, that permitted the development of a very modular and compact code, which is readable, easy to maintain and virtually self-explained. The paper also briefly displays the implemented element and algorithm modules and some speci...

EnglishAlkali-Aggregate Reaction (AAR) in concrete may induce excessive expansion and degradation... more EnglishAlkali-Aggregate Reaction (AAR) in concrete may induce excessive expansion and degradation of mechanical properties due to intensive cracking. This work presents a procedure for the finite element modeling of massive concrete structures affected by AAR. It is also belived that this methodology can bring relevant contributions for the safety's control and rehabilitation of structures affected by AAR. The procedure was implementedin the ANSYS®, Multiphisics finite element code and employed to simulate the structural behavior of a brazilian concrete dam, which is currently presenting advanced degradation due to AAR. Mathematical programming techniques were used to fit the calculated AAR induced swelling deformations to the data collected in field. It is expected that the projection of the evolution of AAR in the dam may thus follow the calibrated mathematical model. portuguesOs problemas estructurais provocados pela Reacao Alacali-Agregado (RAA) estao ligados a expancoes exc...

Lateral buckling load formulation for multi-strut beam string structures

This paper presents the theoretical formulation and the implementation of a class of finite eleme... more This paper presents the theoretical formulation and the implementation of a class of finite elements capable of representing the slippage between border cables and membrane sheaths, without distortion of the cable’s tangent stiffness. After reviewing the 3-node Aufare’s sliding-cable element, new sliding-cable super-element is proposed, which simplifies the mesh generation labor and overcomes some limitations of Aufare’s elements to deal with large amounts of relative sliding between cables and membrane, which arises as long as meshes are refined.

Analytical and computer calculations carried out by researches of Physics Institute - University ... more Analytical and computer calculations carried out by researches of Physics Institute - University of Sao Paulo (IFUSP), for defining the engineering project and constructing the TBR-II tokamak are presented. Parameters were determined for magnetic confinement of the plasma. The computer code was developed using magnetohydrodynamics (MHD) equations which involve plasma interactions, magnetic field and electrical current circulating in more than 20 coils distributed around toroidal vase of the plasma. The electromagnetic, thermal and mechanical couplings are also presented. The TBR-II will be feed by two turbo-generators with 15 MW each one.

Revista Internacional De Metodos Numericos Para Calculo Y Diseno En Ingenieria, 1995

O trabalho apresenta a formulacao geometricamente exata e a implementacao computacional de um ele... more O trabalho apresenta a formulacao geometricamente exata e a implementacao computacional de um elemento finito de cabo que permite o escorregamento em presenca de atrito. O novo elemento fornece procedimentos naturais para simular o processo de montagem e a resposta aos carregamentos de estruturas de cabos em geral, alem de ter campos promissores de aplicacao no modelamento de estruturas de concreto protendido e no estudo de oscilacoes auto-excitaveis. Resultados de exemplos elementares sao discutidos.

Curved and Layered Structures, 2021

The new paradigms of parametric modelling have been proving promising on the advance of systems f... more The new paradigms of parametric modelling have been proving promising on the advance of systems for analysis and design of taut (or tensile) structures. With this premise, the presented work consist on the development with a form-finding tool for Computer Aided Design(CAE) and Computer Aided Engineering (CAE) integration using VPL (Visual Programming Language), in the context of parametric modelling. The methods used in the implementation are the Force Density Method (FDM) and the Natural Force Density Method (NFDM), taking advantage of the linear solution approach provided, suitable for fast form-finding computational procedures. The program is implemented as a Grasshopper plug-in and it is named BATS (Basic Analysis of Taut Structures), which enables parametric definition of boundary conditions for the form-finding. The program structure and benchmarks with other available Grasshopper plug-ins for taut structures form-finding are presented, showing considerably superior performanc...

Controlling the geometry and forces of a hybrid cable-net and

Newton‟s Method, the most widely used and robust tool for the solution of systems of nonlinear al... more Newton‟s Method, the most widely used and robust tool for the solution of systems of nonlinear algebraic equations, requires successive evaluations of the Jacobian matrix, whose columns can be seen as the directional derivatives of the system‟s residual vector, with respect to each of its degrees of freedom. By their turn, these directional derivatives can be conveniently approximated by finite-difference schemes. However, a naive application of such idea to solve large order nonlinear algebraic equations would easily compromises its practical attractiveness, because the number of required algebraic operations grows with the square of the order of the system. In this paper, we consider problems where the residual vector is define by sub-domains (or „elements‟), allowing the definition of element Jacobian matrices (of much smaller order than the global one), whose columns are again approximated by central-differences. So proceeding, the residual vector becomes locally supported, the ...

This paper presents the results of a three-dimensional model of the one instrumented brazilian co... more This paper presents the results of a three-dimensional model of the one instrumented brazilian concrete dam and foundation. In order to analyze the effects of the concrete expansion due alkali-aggregate reaction, a three-dimensional mathematical models were prepared for simulation purposes using the ANSYS finite element program with APDL language coupling structural-hygrometric to represent a nonlinear behavior. This paper presents the results obtained for the stress evolution in the concrete dams instrumented.

The paper presents a recently developed finite element code for the nonlinear static and dynamic ... more The paper presents a recently developed finite element code for the nonlinear static and dynamic analysis of structures and its application to the analysis of tall buildings. The code is intended for academic purposes (teaching and research). Nevertheless it was used in the nonlinear stability analysis of an inclined tall building in Santos, Brazil, which is near to collapse and will be brought to the right position through the application of hydraulic jacks. This very interesting case is also reported in the paper. The most important features of the system are discussed. The language Fortran 90/95 was chosen in order to allow the reutilization of existing FORTRAN77 routines, to retain numerical efficiency and to take profit of new capabilities of the language, that permitted the development of a very modular and compact code, which is readable, easy to maintain and virtually self-explained. The paper also briefly displays the implemented element and algorithm modules and some speci...

EnglishAlkali-Aggregate Reaction (AAR) in concrete may induce excessive expansion and degradation... more EnglishAlkali-Aggregate Reaction (AAR) in concrete may induce excessive expansion and degradation of mechanical properties due to intensive cracking. This work presents a procedure for the finite element modeling of massive concrete structures affected by AAR. It is also belived that this methodology can bring relevant contributions for the safety's control and rehabilitation of structures affected by AAR. The procedure was implementedin the ANSYS®, Multiphisics finite element code and employed to simulate the structural behavior of a brazilian concrete dam, which is currently presenting advanced degradation due to AAR. Mathematical programming techniques were used to fit the calculated AAR induced swelling deformations to the data collected in field. It is expected that the projection of the evolution of AAR in the dam may thus follow the calibrated mathematical model. portuguesOs problemas estructurais provocados pela Reacao Alacali-Agregado (RAA) estao ligados a expancoes exc...

Lateral buckling load formulation for multi-strut beam string structures

This paper presents the theoretical formulation and the implementation of a class of finite eleme... more This paper presents the theoretical formulation and the implementation of a class of finite elements capable of representing the slippage between border cables and membrane sheaths, without distortion of the cable’s tangent stiffness. After reviewing the 3-node Aufare’s sliding-cable element, new sliding-cable super-element is proposed, which simplifies the mesh generation labor and overcomes some limitations of Aufare’s elements to deal with large amounts of relative sliding between cables and membrane, which arises as long as meshes are refined.

Analytical and computer calculations carried out by researches of Physics Institute - University ... more Analytical and computer calculations carried out by researches of Physics Institute - University of Sao Paulo (IFUSP), for defining the engineering project and constructing the TBR-II tokamak are presented. Parameters were determined for magnetic confinement of the plasma. The computer code was developed using magnetohydrodynamics (MHD) equations which involve plasma interactions, magnetic field and electrical current circulating in more than 20 coils distributed around toroidal vase of the plasma. The electromagnetic, thermal and mechanical couplings are also presented. The TBR-II will be feed by two turbo-generators with 15 MW each one.

Revista Internacional De Metodos Numericos Para Calculo Y Diseno En Ingenieria, 1995

O trabalho apresenta a formulacao geometricamente exata e a implementacao computacional de um ele... more O trabalho apresenta a formulacao geometricamente exata e a implementacao computacional de um elemento finito de cabo que permite o escorregamento em presenca de atrito. O novo elemento fornece procedimentos naturais para simular o processo de montagem e a resposta aos carregamentos de estruturas de cabos em geral, alem de ter campos promissores de aplicacao no modelamento de estruturas de concreto protendido e no estudo de oscilacoes auto-excitaveis. Resultados de exemplos elementares sao discutidos.

Curved and Layered Structures, 2021

The new paradigms of parametric modelling have been proving promising on the advance of systems f... more The new paradigms of parametric modelling have been proving promising on the advance of systems for analysis and design of taut (or tensile) structures. With this premise, the presented work consist on the development with a form-finding tool for Computer Aided Design(CAE) and Computer Aided Engineering (CAE) integration using VPL (Visual Programming Language), in the context of parametric modelling. The methods used in the implementation are the Force Density Method (FDM) and the Natural Force Density Method (NFDM), taking advantage of the linear solution approach provided, suitable for fast form-finding computational procedures. The program is implemented as a Grasshopper plug-in and it is named BATS (Basic Analysis of Taut Structures), which enables parametric definition of boundary conditions for the form-finding. The program structure and benchmarks with other available Grasshopper plug-ins for taut structures form-finding are presented, showing considerably superior performanc...