Mechanical behavior of concrete slab of large-span through tied-arch composite bridge was investigated by finite element analysis (FEA). Improved methods to decrease concrete stresses were discussed based on compariso...Mechanical behavior of concrete slab of large-span through tied-arch composite bridge was investigated by finite element analysis (FEA). Improved methods to decrease concrete stresses were discussed based on comparisons of different deck schemes, construction sequences and measures, and ratios of reinforcement. The results show that the mechanical behavior of concrete slab gets worse with the increase of composite regions between steel beams and concrete slab. The deck scheme with the minimum composite region is recommended on condition that both strength and stiffness of the bridge meet design demands under service loads. Adopting in-situ-place construction method, concrete is suggested to be cast after removing the full-supported frameworks under the bridge. Thus, the axial tensile force of concrete slab caused by the first stage dead load is eliminated. Preloading the bridge before concrete casting and removing the load after the concrete reaching its design strength, the stresses of concrete slab caused by the second stage dead load and live load are further reduced or even eliminated. At last, with a high ratio of reinforcement more than 3%, the concrete stresses decrease obviously.展开更多
In order to receive a licence to produce, poultry farmers have to take into account societal demands, among others： animal welfare, healthy working conditions for the workers and landscape quality. A way to reach a c...In order to receive a licence to produce, poultry farmers have to take into account societal demands, among others： animal welfare, healthy working conditions for the workers and landscape quality. A way to reach a combination of these goals is to create a design for the poultry house and outdoor run. We propose a methodology based on five steps, which enables us to create a design that takes into consideration societal demands and that can be tested on its effects. These five steps are： 1. Giving a theoretical background on the societal demands （hen ethology, farm management and landscape quality） and based on this; 2. Giving a set of design criteria. 3. Describing the cttrrent state of the farm, in order to know its current qualities, 4. Making a design of the farm using the sets of criteria as guiding principle. 5. Reflecting on the design, to show whether the different criteria can be combined and where compromises are needed. A case study on an organic farm in the centre of the Netherlands showed that hen welfare, farm management and landscape quality can be improved together, although some measures do not add to all design criteria. Especially the effect on landscape quality and farm management is variable： the latter is also depending on the personal motivation of the farmer.展开更多
Consciousness is the main quality one can ask architecture students. Consciousness means the ability to recognize that the design process is a ＂problem solving＂ activity and not an exercise of uncontrolled imaginati...Consciousness is the main quality one can ask architecture students. Consciousness means the ability to recognize that the design process is a ＂problem solving＂ activity and not an exercise of uncontrolled imagination. In architectural education, small structures are a common subject in American and European universities where the inductive teaching is practiced routinely. This teaching experiment is developed within a design studio course in the second year of an architecture degree course and regards design and construction of a small bridge l：l scale. The exercises focus on the role of structural behaviour within architectural design. The teaching method contributes to the perception of the great complexity of the design process, to the acquisition of an attitude of prudence in design choices and to attention to detail in the development of creativity.展开更多
基金Project(2005k002-c-2) supported by the Science and Technology Development Program of Railways Department, China
文摘Mechanical behavior of concrete slab of large-span through tied-arch composite bridge was investigated by finite element analysis (FEA). Improved methods to decrease concrete stresses were discussed based on comparisons of different deck schemes, construction sequences and measures, and ratios of reinforcement. The results show that the mechanical behavior of concrete slab gets worse with the increase of composite regions between steel beams and concrete slab. The deck scheme with the minimum composite region is recommended on condition that both strength and stiffness of the bridge meet design demands under service loads. Adopting in-situ-place construction method, concrete is suggested to be cast after removing the full-supported frameworks under the bridge. Thus, the axial tensile force of concrete slab caused by the first stage dead load is eliminated. Preloading the bridge before concrete casting and removing the load after the concrete reaching its design strength, the stresses of concrete slab caused by the second stage dead load and live load are further reduced or even eliminated. At last, with a high ratio of reinforcement more than 3%, the concrete stresses decrease obviously.
文摘In order to receive a licence to produce, poultry farmers have to take into account societal demands, among others： animal welfare, healthy working conditions for the workers and landscape quality. A way to reach a combination of these goals is to create a design for the poultry house and outdoor run. We propose a methodology based on five steps, which enables us to create a design that takes into consideration societal demands and that can be tested on its effects. These five steps are： 1. Giving a theoretical background on the societal demands （hen ethology, farm management and landscape quality） and based on this; 2. Giving a set of design criteria. 3. Describing the cttrrent state of the farm, in order to know its current qualities, 4. Making a design of the farm using the sets of criteria as guiding principle. 5. Reflecting on the design, to show whether the different criteria can be combined and where compromises are needed. A case study on an organic farm in the centre of the Netherlands showed that hen welfare, farm management and landscape quality can be improved together, although some measures do not add to all design criteria. Especially the effect on landscape quality and farm management is variable： the latter is also depending on the personal motivation of the farmer.
文摘Consciousness is the main quality one can ask architecture students. Consciousness means the ability to recognize that the design process is a ＂problem solving＂ activity and not an exercise of uncontrolled imagination. In architectural education, small structures are a common subject in American and European universities where the inductive teaching is practiced routinely. This teaching experiment is developed within a design studio course in the second year of an architecture degree course and regards design and construction of a small bridge l：l scale. The exercises focus on the role of structural behaviour within architectural design. The teaching method contributes to the perception of the great complexity of the design process, to the acquisition of an attitude of prudence in design choices and to attention to detail in the development of creativity.
