The structural engineering design of not conventional typologies imposes a complex path that begins evaluating procedures of a preliminary design and ends with complex procedures to validate the analysis response. Any...The structural engineering design of not conventional typologies imposes a complex path that begins evaluating procedures of a preliminary design and ends with complex procedures to validate the analysis response. Any guide lines to follow are often available. About complex shapes, in particular, any details are presented in the codes to evaluate wind action and so wind tunnel experiments are necessary to valuate this. The evaluation of wind tunnel data is a complex process that often needs new and specific subroutines programmed by researchers. The difficult increases when the objective is to study a not specific building but general aspects as for examples the dependence of a generic phenomenon by a geometric sample;in this case it is necessary to design and to program numerical subroutines before and then the wind tunnel experiments. Often, these subroutines are left detached and are non-generalizable process. Purpose of this paper is to describe a complete procedure to pre- and post-process wind tunnel data with the objective to design a not convectional structure as a tensile structure. In this particular case the research aim is a parametrization of the aerodynamic behavior of Hyperbolic Paraboloid roofs, shape used for cables net. The reason of the experiments is the absence in the international codes of the pressure coefficients for these geometries. The paper describes the numerical procedure evaluated to choose a sufficient representative geometric sample, the numerical procedure evaluated to design and to construct the wind tunnel models and FE models, the numerical procedure to evaluate and to use for FEM analyses of the wind tunnel data, the numerical procedure to calculate nonlinear structural analysis, and, finally some applications. All these numerical procedures use basic theory derived for example by the cable theory, the fluid mechanic, the nonlinear geometric analysis and other. However specific codes were necessary and were programmed to apply the theories on the specific case of study;the co展开更多
In the context of ongoing densification of cities and aging urban populations,public spaces are a crucial infrastructure to support the physical and mental wellbeing of urban residents.The design of public space furni...In the context of ongoing densification of cities and aging urban populations,public spaces are a crucial infrastructure to support the physical and mental wellbeing of urban residents.The design of public space furniture elements is often standardised,and not considered in relation to environmental conditions and mechanisms of social interaction.This article presents a digital workflow to generate site-specific designs for shaded public seating,considering the relationships of local public places to their surroundings.A strategy for customised and site-specific design is developed through the use of multiple software tools,employing evolutionary algorithms and multi-objective optimisation.The method is applied to a small public space canopy prototype installed within a public housing estate in Hong Kong,incorporating additional criteria to achieve a low-cost and light-weight structure.Through multiple stages of refinement and optimisation,a material,structural and social performance-driven outcome was achieved that creates a shaded space for public seating,people watching and social interaction.As part of a larger research agenda exploring architectural form-finding and environmental psychology,the project represents potential new applications in the emerging field of socially driven computational design.展开更多
Fiber reinforced polymer (FRP) reinforcing bars for concrete structure has been extensively investigated for last two decades and a number of FRP bars are commercially available. However, one of shortcomings of the ex...Fiber reinforced polymer (FRP) reinforcing bars for concrete structure has been extensively investigated for last two decades and a number of FRP bars are commercially available. However, one of shortcomings of the existing FRP bars is its low elastic modulus, if glass fibers are used (i.e., GFRP). The main objective of this study using the concept of material hybridization is to develop a viable hybrid FRP bar for concrete structures, especially for marine and port con- crete structures. The purposes of hybridization are to increase the elastic modulus of GFRP bar with acceptable tensile strength. Two types of hybrid GFRP bar were considered in the development: GFRP crust with steel core and GFRP bar with steel wires dispersed over the cross-section. Using E-glass fibers and unsaturated polyester resins, the hybrid GFRP bar samples of 13 mm in diameter were pultruded and tested for tensile properties. The effect of hybridization on tensile properties of GFRP bars was evaluated by comparing the results of tensile test with those of non-hybrid GFRP bars. The results of this study indicated that the elastic modulus of the hybrid GFRP bar was increased by up to 270 percent by the material hybridization. The results of the test and the future recommendations are summarized in this paper. To ensure long-term durability of the hybrid GFRP bars in waterfront structure applications, the individual and combined effects of environmental conditions on hybrid GFRP rebar itself as well as on the interface between rebar and concrete should be accessed.展开更多
The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation i...The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation is normally coupled with the kinematic mechanism movement. Firstly, the basic equations of prestress developing by moving boundary joint are derived from the total potential energy equation. Secondly, the presumed initial tension is proposed to impose into the elements and avoid the singularity of global stiffness matrix. And the self-stress mode which is calculated from the equilibrium matrix with singular vMue decomposition is employed as basically presumed initial tension. By applying boundary movement increment, an iterative computation is developed to calculate the updating geometric configuration and tension evolution. Finally, the MATLAB program is coded from the presented method, and numerical examples indicate that this computational method is effective and has theoretical significance and valuable guide to design and construction of tensile cable-net structure.展开更多
文摘The structural engineering design of not conventional typologies imposes a complex path that begins evaluating procedures of a preliminary design and ends with complex procedures to validate the analysis response. Any guide lines to follow are often available. About complex shapes, in particular, any details are presented in the codes to evaluate wind action and so wind tunnel experiments are necessary to valuate this. The evaluation of wind tunnel data is a complex process that often needs new and specific subroutines programmed by researchers. The difficult increases when the objective is to study a not specific building but general aspects as for examples the dependence of a generic phenomenon by a geometric sample;in this case it is necessary to design and to program numerical subroutines before and then the wind tunnel experiments. Often, these subroutines are left detached and are non-generalizable process. Purpose of this paper is to describe a complete procedure to pre- and post-process wind tunnel data with the objective to design a not convectional structure as a tensile structure. In this particular case the research aim is a parametrization of the aerodynamic behavior of Hyperbolic Paraboloid roofs, shape used for cables net. The reason of the experiments is the absence in the international codes of the pressure coefficients for these geometries. The paper describes the numerical procedure evaluated to choose a sufficient representative geometric sample, the numerical procedure evaluated to design and to construct the wind tunnel models and FE models, the numerical procedure to evaluate and to use for FEM analyses of the wind tunnel data, the numerical procedure to calculate nonlinear structural analysis, and, finally some applications. All these numerical procedures use basic theory derived for example by the cable theory, the fluid mechanic, the nonlinear geometric analysis and other. However specific codes were necessary and were programmed to apply the theories on the specific case of study;the co
基金supported by a grant from Design Trust,Hong Kong.
文摘In the context of ongoing densification of cities and aging urban populations,public spaces are a crucial infrastructure to support the physical and mental wellbeing of urban residents.The design of public space furniture elements is often standardised,and not considered in relation to environmental conditions and mechanisms of social interaction.This article presents a digital workflow to generate site-specific designs for shaded public seating,considering the relationships of local public places to their surroundings.A strategy for customised and site-specific design is developed through the use of multiple software tools,employing evolutionary algorithms and multi-objective optimisation.The method is applied to a small public space canopy prototype installed within a public housing estate in Hong Kong,incorporating additional criteria to achieve a low-cost and light-weight structure.Through multiple stages of refinement and optimisation,a material,structural and social performance-driven outcome was achieved that creates a shaded space for public seating,people watching and social interaction.As part of a larger research agenda exploring architectural form-finding and environmental psychology,the project represents potential new applications in the emerging field of socially driven computational design.
文摘Fiber reinforced polymer (FRP) reinforcing bars for concrete structure has been extensively investigated for last two decades and a number of FRP bars are commercially available. However, one of shortcomings of the existing FRP bars is its low elastic modulus, if glass fibers are used (i.e., GFRP). The main objective of this study using the concept of material hybridization is to develop a viable hybrid FRP bar for concrete structures, especially for marine and port con- crete structures. The purposes of hybridization are to increase the elastic modulus of GFRP bar with acceptable tensile strength. Two types of hybrid GFRP bar were considered in the development: GFRP crust with steel core and GFRP bar with steel wires dispersed over the cross-section. Using E-glass fibers and unsaturated polyester resins, the hybrid GFRP bar samples of 13 mm in diameter were pultruded and tested for tensile properties. The effect of hybridization on tensile properties of GFRP bars was evaluated by comparing the results of tensile test with those of non-hybrid GFRP bars. The results of this study indicated that the elastic modulus of the hybrid GFRP bar was increased by up to 270 percent by the material hybridization. The results of the test and the future recommendations are summarized in this paper. To ensure long-term durability of the hybrid GFRP bars in waterfront structure applications, the individual and combined effects of environmental conditions on hybrid GFRP rebar itself as well as on the interface between rebar and concrete should be accessed.
基金the National Natural Science Foundation of China (Nos. 50878128 and 51278299)
文摘The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation is normally coupled with the kinematic mechanism movement. Firstly, the basic equations of prestress developing by moving boundary joint are derived from the total potential energy equation. Secondly, the presumed initial tension is proposed to impose into the elements and avoid the singularity of global stiffness matrix. And the self-stress mode which is calculated from the equilibrium matrix with singular vMue decomposition is employed as basically presumed initial tension. By applying boundary movement increment, an iterative computation is developed to calculate the updating geometric configuration and tension evolution. Finally, the MATLAB program is coded from the presented method, and numerical examples indicate that this computational method is effective and has theoretical significance and valuable guide to design and construction of tensile cable-net structure.
