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Abstract(s)
Durante a vida útil de uma estrutura, suas necessidades de utilização podem ser alteradas passando a ser necessário resistir a novos carregamentos. Juntamente, torna-‐se necessário atender ao controle da deformação, que, no caso das estruturas de madeira, assume particular relevo por conta de o seu módulo de elasticidade ser inferior à generalidade dos demais materiais de construção e estarem sujeitas a deformações diferidas por fluência. Diante dessas situações, uma intervenção estrutural pode ser necessária para prover, novamente, níveis de segurança e funcionalidade adequados na estrutura.
Este trabalho tem como objetivo incrementar a capacidade de carga das vigas de madeira aliado a menores níveis de deformação a partir da implementação de sistemas de reforço utilizando pré-‐esforço. Para isso foram testados experimentalmente três soluções diferentes de reforço com aplicação de pré-‐esforço, sendo eles com chapa de aço, varão de aço e cabos de aço. Todos os sistemas foram submetidos previamente a análise numérica computacional, com objetivo de dimensionamento dos elementos de reforço e obtenção das forças de pré-‐esforço até a tensão admissível das vigas.
Atendendo ao objetivo inicial, os sistemas de reforço tiveram um excelente desempenho, conferindo às vigas um aumento de capacidade de carga de até 114 % para o reforço com chapa de aço, 106 % para o reforço com varão de aço e 286 % para o sistema reforçado com cabos de aço. Quanto ao desempenho na redução dos deslocamentos, o nível de carga obtida ao atingir o valor limite de flecha instantânea teve um acréscimo de até 210 % com o reforço por meio de chapa de aço, 529 % com o reforço do varão e 886% com o reforço por meio de cabos. De modo geral os sistemas adotados para reforço estrutural de vigas à flexão atenderam a todos os objetivos, conferindo ainda modos de rotura menos frágeis para as vigas de madeira.
During the life cycle of a structure, your requirement use can be changed needing to resit a new loads. At the same time, it is necessary to attend the deformation limits, in the case of timber structures it is requires more care because the reduced elasticity modulus compared to the other comum construction materials, in addition to be subject to deformation by creep. Faced with these situations, a structural intervention may be necessary to provide again security and appropriate functionality to the structure. This work aims to increase the load capacity of timber beams with lower levels of deformation with Implementation of strengthening systems using prestress. For that purpose, three different strengthening solutions were experimentally tested with the application of prestress and making use of steel plates, steel rebars and steel cables. All systems were previously submitted to a finite element analysis, with the objective of simulating the experiments, designing the elements to use and obtaining the prestress forces, taking into account allowable stress levels in the wood. Attending to the initial goal, the strengthening systems had an excellent performance, giving an increasing up to 114% of load capacity for strengthening with steel plate, 106% for reinforcement with steel rebar and 286% for the strengthening system with steel cables. As the performance in the reduction of displacements, the load level obtained upon reaching the limit instant displacement had increased by up to 210% with the strengthening with steel plate, 529% with the rebar strengthening and 886% with the strengthening system with steel cables. Altogether, the structural strengthening systems proposed to timber beams in bending attended to all objectives, conferring less fragile failure modes to the timber beams.
During the life cycle of a structure, your requirement use can be changed needing to resit a new loads. At the same time, it is necessary to attend the deformation limits, in the case of timber structures it is requires more care because the reduced elasticity modulus compared to the other comum construction materials, in addition to be subject to deformation by creep. Faced with these situations, a structural intervention may be necessary to provide again security and appropriate functionality to the structure. This work aims to increase the load capacity of timber beams with lower levels of deformation with Implementation of strengthening systems using prestress. For that purpose, three different strengthening solutions were experimentally tested with the application of prestress and making use of steel plates, steel rebars and steel cables. All systems were previously submitted to a finite element analysis, with the objective of simulating the experiments, designing the elements to use and obtaining the prestress forces, taking into account allowable stress levels in the wood. Attending to the initial goal, the strengthening systems had an excellent performance, giving an increasing up to 114% of load capacity for strengthening with steel plate, 106% for reinforcement with steel rebar and 286% for the strengthening system with steel cables. As the performance in the reduction of displacements, the load level obtained upon reaching the limit instant displacement had increased by up to 210% with the strengthening with steel plate, 529% with the rebar strengthening and 886% with the strengthening system with steel cables. Altogether, the structural strengthening systems proposed to timber beams in bending attended to all objectives, conferring less fragile failure modes to the timber beams.
Description
Keywords
Estruturas de madeira Reforço estrutural Pré-esforço Análise por Elementos Finitos Timber structures Structural strengthening Prestress Finite element analysis (FEA)