4 Engenheira Civil GIPAC, Lisboa RESUMO Descreve-se o conjunto de medições da resposta dinâmica e... more 4 Engenheira Civil GIPAC, Lisboa RESUMO Descreve-se o conjunto de medições da resposta dinâmica efectuadas em três pontes ferroviárias balastradas, de um só vão variando entre 19.5 e 23.5 metros, construídas em betão pré-esforçado e existentes num troço da linha Viena-Salzburgo, na Áustria, com vista à caracterização do seu comportamento dinâmico, nomeadamente frequências próprias, modos de vibração e amortecimento. A identificação modal baseou-se na medição de acelerações verticais provocadas pela passagem de comboios bem como na medição de vibrações resultantes de 'ruído branco ambiental'. A investigação permitiu a identificação modal e a validação de modelos numéricos de elementos finitos através da comparação da resposta dinâmica durante a passagem de comboios. Permitiu também obter dados e conclusões relativas à contribuição do balastro para a rigidez e amortecimento modal.
Two major factors contribute to the sustainability of buildings: material efficiency and energy e... more Two major factors contribute to the sustainability of buildings: material efficiency and energy efficiency. Material efficiency relates to the use of environmental-friendly materials and to the minimization of construction waste materials, either during construction and at the end-of-life stage of the building. Energy efficiency is currently understood as the optimization of the energy used during the operation stage of the building. This entails the energy needed for heating, cooling, lighting, etc. Often in order to improve the energy needs of a building, more insulation material is used, thus leading to a trade-off between embodied energy and operational energy. It is the aim of this paper to analyse and discuss the balance between the embodied energy and the operational energy for various levels of insulation, over its life cycle. The operational energy is estimated based on the simplified approach provided by the Portuguese Code of practice. The estimated operational energy is then balanced against the life cycle embodied energy of the system. Finally, the simplified approach for the calculation of the operational energy is confronted to more sophisticated dynamic simulations using the software EnergyPlus.
Steel joints must exhibit sufficient ductility for safe structural behaviour. This is especially ... more Steel joints must exhibit sufficient ductility for safe structural behaviour. This is especially true for partial-strength steel joints, whereby the nonlinear response of the joint plays an important part in the overall response of the structure. Uncertainty in joint response, particularly beyond the elastic limit of the moment-rotation curve, naturally leads to a probabilistic treatment of the ductility of steel joints. It is the objective of the present paper to compare a direct probabilistic approach with simulation techniques using the Monte-Carlo method both at the component and joint level, in the context of the component method, with the aim of establishing safe limits for the ductile behaviour of the steel joints. #
A probabilistic decision-making approach for the sustainable assessment of infrastructures
Expert Systems with Applications, 2012
ABSTRACT Sustainable development is a multidimensional concept that usually implies a simultaneou... more ABSTRACT Sustainable development is a multidimensional concept that usually implies a simultaneous concretization of contradictory aspects. Multi-criteria decision approaches are often used for the management of conflicting perspectives. In life cycle approaches, uncertainties are unavoidable and a decision making approach dealing with life-cycle based criteria cannot disregard the uncertainties associated with the evaluation of criteria. It is the purpose of this paper to introduce a decision-making approach, based on PROMETHEE and AHP, to address both of these important issues. Moreover, the proposed approach aims to address two other types of uncertainties, inherent to the use of PROMETHEE and AHP, which arise from the selection of the generalized criterion functions and the selection of preference values, respectively. The proposed approach enhances the robustness of the decision-making approach and enables decisions to be made on a more reliable base. The approach is applied to a case study: the comparative assessment of alternatives bridges taking into account environmental, economical and social criteria evaluated over the complete life-cycle of the bridges.
4 Engenheira Civil GIPAC, Lisboa RESUMO Descreve-se o conjunto de medições da resposta dinâmica e... more 4 Engenheira Civil GIPAC, Lisboa RESUMO Descreve-se o conjunto de medições da resposta dinâmica efectuadas em três pontes ferroviárias balastradas, de um só vão variando entre 19.5 e 23.5 metros, construídas em betão pré-esforçado e existentes num troço da linha Viena-Salzburgo, na Áustria, com vista à caracterização do seu comportamento dinâmico, nomeadamente frequências próprias, modos de vibração e amortecimento. A identificação modal baseou-se na medição de acelerações verticais provocadas pela passagem de comboios bem como na medição de vibrações resultantes de 'ruído branco ambiental'. A investigação permitiu a identificação modal e a validação de modelos numéricos de elementos finitos através da comparação da resposta dinâmica durante a passagem de comboios. Permitiu também obter dados e conclusões relativas à contribuição do balastro para a rigidez e amortecimento modal.
Two major factors contribute to the sustainability of buildings: material efficiency and energy e... more Two major factors contribute to the sustainability of buildings: material efficiency and energy efficiency. Material efficiency relates to the use of environmental-friendly materials and to the minimization of construction waste materials, either during construction and at the end-of-life stage of the building. Energy efficiency is currently understood as the optimization of the energy used during the operation stage of the building. This entails the energy needed for heating, cooling, lighting, etc. Often in order to improve the energy needs of a building, more insulation material is used, thus leading to a trade-off between embodied energy and operational energy. It is the aim of this paper to analyse and discuss the balance between the embodied energy and the operational energy for various levels of insulation, over its life cycle. The operational energy is estimated based on the simplified approach provided by the Portuguese Code of practice. The estimated operational energy is then balanced against the life cycle embodied energy of the system. Finally, the simplified approach for the calculation of the operational energy is confronted to more sophisticated dynamic simulations using the software EnergyPlus.
Steel joints must exhibit sufficient ductility for safe structural behaviour. This is especially ... more Steel joints must exhibit sufficient ductility for safe structural behaviour. This is especially true for partial-strength steel joints, whereby the nonlinear response of the joint plays an important part in the overall response of the structure. Uncertainty in joint response, particularly beyond the elastic limit of the moment-rotation curve, naturally leads to a probabilistic treatment of the ductility of steel joints. It is the objective of the present paper to compare a direct probabilistic approach with simulation techniques using the Monte-Carlo method both at the component and joint level, in the context of the component method, with the aim of establishing safe limits for the ductile behaviour of the steel joints. #
A probabilistic decision-making approach for the sustainable assessment of infrastructures
Expert Systems with Applications, 2012
ABSTRACT Sustainable development is a multidimensional concept that usually implies a simultaneou... more ABSTRACT Sustainable development is a multidimensional concept that usually implies a simultaneous concretization of contradictory aspects. Multi-criteria decision approaches are often used for the management of conflicting perspectives. In life cycle approaches, uncertainties are unavoidable and a decision making approach dealing with life-cycle based criteria cannot disregard the uncertainties associated with the evaluation of criteria. It is the purpose of this paper to introduce a decision-making approach, based on PROMETHEE and AHP, to address both of these important issues. Moreover, the proposed approach aims to address two other types of uncertainties, inherent to the use of PROMETHEE and AHP, which arise from the selection of the generalized criterion functions and the selection of preference values, respectively. The proposed approach enhances the robustness of the decision-making approach and enables decisions to be made on a more reliable base. The approach is applied to a case study: the comparative assessment of alternatives bridges taking into account environmental, economical and social criteria evaluated over the complete life-cycle of the bridges.
Uploads
Papers by H. Gervásio