Most view articles
2005, 27(2):61-64.
DOI: 10.11835/j.issn.1674-4764.2005.02.014
Abstract:
In view of existing features of activated sludge process without primary sedimentation tank and the requirements on grit removing sedimentation tank,in this paper,two types of grit clarifier-horizontal and whirling one are suggested with consideration of grit removal efficiency for fine particle size during its design.Then,according to the sedimentation theory,the principle of grit removal,control of key technical parameters and type choice of grit discharge equipment are analyzed.It can serve as reference for the design of grit clarifier.
In view of existing features of activated sludge process without primary sedimentation tank and the requirements on grit removing sedimentation tank,in this paper,two types of grit clarifier-horizontal and whirling one are suggested with consideration of grit removal efficiency for fine particle size during its design.Then,according to the sedimentation theory,the principle of grit removal,control of key technical parameters and type choice of grit discharge equipment are analyzed.It can serve as reference for the design of grit clarifier.
1994, 16(3).
DOI: 10.11835/j.issn.1674-4764.1994.03.003
Abstract:
Researches show thatquare- with- gap tube has advantages of better hydraulicconditions, broad adaptability for treatment of various raw waters and high sedimentation efficien-cy. A contrast experiment is carried out between squarewith- gap tube and hexagonal tube. The for-mula of hydraulic character parameter is deducetl for square-with- gap tube provides to theoreticalbaqe for practical application of square-with-gap tube.
Researches show thatquare- with- gap tube has advantages of better hydraulicconditions, broad adaptability for treatment of various raw waters and high sedimentation efficien-cy. A contrast experiment is carried out between squarewith- gap tube and hexagonal tube. The for-mula of hydraulic character parameter is deducetl for square-with- gap tube provides to theoreticalbaqe for practical application of square-with-gap tube.
2009, 31(3):25-28.
DOI: 10.11835/j.issn.1674-4764.2009.03.006
Abstract:
In order to consider the effect of shearing deformation and rotating inertia, an approximate method, which is based on modal perturbation method, is proposed for the free vibration analysis of nonuniform Timoshenko cantilever beams. With the eigenvalues and eigenvectors of uniform Euler beams, a set of partial differential characteristic equations of nonuniform Timoshenko beams is transformed into a set of algebraic equations for solutions of nonuniform Timoshenko beams. The method can solve the dynamic characteristics of beams with complicated crosssection, whether the crosssection variation is continuous or discontinuous. At the end, two types of beams, namely (a) discontinuous variation of thickness and (b) continuous and linear variation, are analyzed and shown that the method is simple, practicable and owns good precision.
In order to consider the effect of shearing deformation and rotating inertia, an approximate method, which is based on modal perturbation method, is proposed for the free vibration analysis of nonuniform Timoshenko cantilever beams. With the eigenvalues and eigenvectors of uniform Euler beams, a set of partial differential characteristic equations of nonuniform Timoshenko beams is transformed into a set of algebraic equations for solutions of nonuniform Timoshenko beams. The method can solve the dynamic characteristics of beams with complicated crosssection, whether the crosssection variation is continuous or discontinuous. At the end, two types of beams, namely (a) discontinuous variation of thickness and (b) continuous and linear variation, are analyzed and shown that the method is simple, practicable and owns good precision.
2009, 31(2):3-7.
DOI: 10.11835/j.issn.1674-4764.2009.02.002
Abstract:
In order to solve the calculation problems of the curved beam, an arbitrary crosssection beam and composite beam, a degenerated 3D fiber beam element is derived based on the degenerated theory. According to the basic assumption of plane section, the 3D displacement field equations of an arbitrary point are discretized in terms of nodal displacements, which take account of shear deformation effect. Furthermore, the tangent stiffness matrix formulation, which takes geometric and material nonlinearity into account, is deduced using Update Lagrange formulation. A finite element method program has been developed, and several typical examples are tested to demonstrate the effectiveness, accuracy and versatility of this beam element.
In order to solve the calculation problems of the curved beam, an arbitrary crosssection beam and composite beam, a degenerated 3D fiber beam element is derived based on the degenerated theory. According to the basic assumption of plane section, the 3D displacement field equations of an arbitrary point are discretized in terms of nodal displacements, which take account of shear deformation effect. Furthermore, the tangent stiffness matrix formulation, which takes geometric and material nonlinearity into account, is deduced using Update Lagrange formulation. A finite element method program has been developed, and several typical examples are tested to demonstrate the effectiveness, accuracy and versatility of this beam element.
2009, 31(2)-7.
DOI: 10.11835/j.issn.1674-4764.2009.02.001
Abstract:
The tubegusset plate connections are widely used in electric transmission towers. However, there is little technical information regarding the behavior of tubegusset plate connections. Thus, a analytical parametric study was conducted to investigate the behavior of tubegusset plate connections. The analytical results were compared with the existing experimental results. It was found that the finite element analysis results were in good agreement with the experimental results. In the parametric study, the effects of geometry, chord load and stiffener on the ultimate strength were considered. Based on the analytical results, a design method for predicting the ultimate strength of tubegusset connections was proposed, and its applicability was verified.
The tubegusset plate connections are widely used in electric transmission towers. However, there is little technical information regarding the behavior of tubegusset plate connections. Thus, a analytical parametric study was conducted to investigate the behavior of tubegusset plate connections. The analytical results were compared with the existing experimental results. It was found that the finite element analysis results were in good agreement with the experimental results. In the parametric study, the effects of geometry, chord load and stiffener on the ultimate strength were considered. Based on the analytical results, a design method for predicting the ultimate strength of tubegusset connections was proposed, and its applicability was verified.
2012, 34(2):69-76.
DOI: 10.11835/j.issn.1674-4764.2012.02.012
Abstract:
Seven specimens were loaded with axial force and horizontal cycle force to analyze the hysteretic performance and the influencing factor as well. The influence of axial compression ratio and aspect ratio on the hysteretic performance was investigated, including the buckling behaviors and the energy dissipation. And the positive role of combined effects on the hysteretic performance of cold-formed specimens was studied emphatically. The experiment reveals that a large axial compression ratio incurs a serious decrease on hysteretic performance, while the combined effects give an increase on it. In addition, the numerical mode is set up. Considering double nonlinearity, the results of experiment and simulation match each other well. Based on the data, it is obtained that local buckling plays a great negative role during the loading course. At last, the characteristics of hysteretic performance of cold-formed steel specimens are concluded and some suggestions are given.
Seven specimens were loaded with axial force and horizontal cycle force to analyze the hysteretic performance and the influencing factor as well. The influence of axial compression ratio and aspect ratio on the hysteretic performance was investigated, including the buckling behaviors and the energy dissipation. And the positive role of combined effects on the hysteretic performance of cold-formed specimens was studied emphatically. The experiment reveals that a large axial compression ratio incurs a serious decrease on hysteretic performance, while the combined effects give an increase on it. In addition, the numerical mode is set up. Considering double nonlinearity, the results of experiment and simulation match each other well. Based on the data, it is obtained that local buckling plays a great negative role during the loading course. At last, the characteristics of hysteretic performance of cold-formed steel specimens are concluded and some suggestions are given.
2009, 31(2):116-120.
DOI: 10.11835/j.issn.1674-4764.2009.02.022
Abstract:
Transit oriented development (TOD) presents a sustainable urban development strategy by creating an efficient integration of land use and public transit. A TOD planning model for the land use of urban rail station area was explored by means of a multiple objective mathematical programming model. Three objectives were considered: encouraging transit system volume, promoting livable communities, and balancing land use. The model can easily be solved by transforming it into a linear multiprogramming problem. The Xujiahui rail rapid transit station area in Shanghai is chosen as case study to illustrate the model application and planning results. The result indicates that the model would be efficient in practice.
Transit oriented development (TOD) presents a sustainable urban development strategy by creating an efficient integration of land use and public transit. A TOD planning model for the land use of urban rail station area was explored by means of a multiple objective mathematical programming model. Three objectives were considered: encouraging transit system volume, promoting livable communities, and balancing land use. The model can easily be solved by transforming it into a linear multiprogramming problem. The Xujiahui rail rapid transit station area in Shanghai is chosen as case study to illustrate the model application and planning results. The result indicates that the model would be efficient in practice.
1991, 13(4).
DOI: 10.11835/j.issn.1674-4764.1991.04.008
Abstract:
McHarg,a noted American landscape architect,hasbecome well known around the world as one of first group of ecologicalplanners since 1960s;As a pioneer of applying subjectively ecologicalprinciples to urban and regional landscape planning,he created a scienti-fical ecological planning method which has a far-reaching affect to mo-dern planning and design science in the world.This paper introducesMcHarg's philosophic idea and his ecological planning method,clarifiesthe perspective of applying the method to landscape planning and designin China.
McHarg,a noted American landscape architect,hasbecome well known around the world as one of first group of ecologicalplanners since 1960s;As a pioneer of applying subjectively ecologicalprinciples to urban and regional landscape planning,he created a scienti-fical ecological planning method which has a far-reaching affect to mo-dern planning and design science in the world.This paper introducesMcHarg's philosophic idea and his ecological planning method,clarifiesthe perspective of applying the method to landscape planning and designin China.
2012, 34(Z1):116-119.
Abstract:
For multilayer concrete structure, the seismic ability of the ground floor column is very poor, improving the seismic fortification intensity of structure is adopted in this paper, the axial force, shear and moment of beam and column are calculated and analyzed in seven degree and eight degree seismic fortification intensity. Numerical results show that with improving the fortification intensity of the structure, the axial force, shear and moment of beam and column increase and the change of the ground floor is the most prominent. In earthquake the destruction of the structure mainly happens in the ground floor column, so this problem is solved fundamentally with increasing fortification intensity in architectural design.
For multilayer concrete structure, the seismic ability of the ground floor column is very poor, improving the seismic fortification intensity of structure is adopted in this paper, the axial force, shear and moment of beam and column are calculated and analyzed in seven degree and eight degree seismic fortification intensity. Numerical results show that with improving the fortification intensity of the structure, the axial force, shear and moment of beam and column increase and the change of the ground floor is the most prominent. In earthquake the destruction of the structure mainly happens in the ground floor column, so this problem is solved fundamentally with increasing fortification intensity in architectural design.
2015, 37(Z1):133-138.
Abstract:
The healing garden is a new landscape type emerging in recent years, which takes rehabilitation and health function as the design theme of landscape. The horticultural therapy of healing gardens has achieved good results in the rehabilitation of chronic disease, thinking dysfunction, etc, as shown by practices. In order to use the plant landscape effect of healing gardens more effectively, we need to establish a compound plant perception system based on five sense of vision, hearing, smell, taste, and touch. Multiple plants gardening system with the themes for children and the elderly were designed for different service groups. The plant space experience systems, merged as a suitable combination of different spatial scales, were created with the core of rehabilitation people. Optimizations in three aspects of the plant use were adopted in the rehabilitation landscape. Combinations of the plant’s color, smell, shape together with the construction of landscape’s whole environment were adopted to satisfy the physiological and psychological needs of different vulnerable groups including the old, young, sick, disabled and so on.
The healing garden is a new landscape type emerging in recent years, which takes rehabilitation and health function as the design theme of landscape. The horticultural therapy of healing gardens has achieved good results in the rehabilitation of chronic disease, thinking dysfunction, etc, as shown by practices. In order to use the plant landscape effect of healing gardens more effectively, we need to establish a compound plant perception system based on five sense of vision, hearing, smell, taste, and touch. Multiple plants gardening system with the themes for children and the elderly were designed for different service groups. The plant space experience systems, merged as a suitable combination of different spatial scales, were created with the core of rehabilitation people. Optimizations in three aspects of the plant use were adopted in the rehabilitation landscape. Combinations of the plant’s color, smell, shape together with the construction of landscape’s whole environment were adopted to satisfy the physiological and psychological needs of different vulnerable groups including the old, young, sick, disabled and so on.
2010, 32(1):12-17.
DOI: 10.11835/j.issn.1674-4764.2010.01.004
Abstract:
A coupling modeling method with MIDAS/GTSFLAC3D was put forward aiming at the technical difficulties and deficiencies in preprocessing for complex geologic body and structural engineering with FLAC3D. The coupling procedure was that, firstly, the threedimension geometry model was built with MIDAS/GTS and the model meshes were divided. And Secondly, the element and node data of the completed model built in MIDAS/GTS were exported. After data was transformed by using the interface program in MATLAB, the information was imported into FLAC3D. Thus the threedimension FLAC3D model for complex engineering was generated coupling with MIDAS/GTS. With coupling method, the complex threedimension model was built for Fanshuigou bridgeShipogou tunnel engineering above minedout region, and the results verified the feasibility and effectiveness of the proposed method.
A coupling modeling method with MIDAS/GTSFLAC3D was put forward aiming at the technical difficulties and deficiencies in preprocessing for complex geologic body and structural engineering with FLAC3D. The coupling procedure was that, firstly, the threedimension geometry model was built with MIDAS/GTS and the model meshes were divided. And Secondly, the element and node data of the completed model built in MIDAS/GTS were exported. After data was transformed by using the interface program in MATLAB, the information was imported into FLAC3D. Thus the threedimension FLAC3D model for complex engineering was generated coupling with MIDAS/GTS. With coupling method, the complex threedimension model was built for Fanshuigou bridgeShipogou tunnel engineering above minedout region, and the results verified the feasibility and effectiveness of the proposed method.
2009, 31(6):71-80.
DOI: 10.11835/j.issn.1674-4764.2009.06.013
Abstract:
Wind hazard damage estimation was addressed for light steel industrial buildings which were the typical wind vulnerable structures in southeast coastal cities. With parametric analysis of wind damage and the structural failure features, the envelop elements and the connecting elements were determined as the pivots of the damage analysis. Upon the consideration of the coeffect of exterior wind pressure, windinduced internal pressure and windborne debris damage, a typhoon load model was proposed. And with the calculation method of the element resistance from the regulation, the procedure of the damage estimation was described and the damage classification of industrial buildings was specified with detailed indicators. Finally, the proposed method was approved with the actual data of typhoon CHANCHU (0601).
Wind hazard damage estimation was addressed for light steel industrial buildings which were the typical wind vulnerable structures in southeast coastal cities. With parametric analysis of wind damage and the structural failure features, the envelop elements and the connecting elements were determined as the pivots of the damage analysis. Upon the consideration of the coeffect of exterior wind pressure, windinduced internal pressure and windborne debris damage, a typhoon load model was proposed. And with the calculation method of the element resistance from the regulation, the procedure of the damage estimation was described and the damage classification of industrial buildings was specified with detailed indicators. Finally, the proposed method was approved with the actual data of typhoon CHANCHU (0601).
2010, 32(1):61-65.
DOI: 10.11835/j.issn.1674-4764.2010.01.012
Abstract:
“Macro model” in OPENSEES is an ideal and effective method for simulating RC beamcolumn joint. Some disadvantages, however, exist in both the modified compression field theory (MCFT) and diagonal compression strut model, with which they are commonly used to obtain the shear stressstrain relation of joint core. A new method by means of strutandtie model (STM), which reflected three mechanisms in joint well, was proposed to simulate the shear stressstrain response of joint core. The deformation compatibility and equilibrium condition of the model were deduced thereafter. It was indicated that the result of STM method was in good agreement with that of test data. And it could simulate more accurately the shear stressstrain response of joint core with a wide range of stirrup ratio.
“Macro model” in OPENSEES is an ideal and effective method for simulating RC beamcolumn joint. Some disadvantages, however, exist in both the modified compression field theory (MCFT) and diagonal compression strut model, with which they are commonly used to obtain the shear stressstrain relation of joint core. A new method by means of strutandtie model (STM), which reflected three mechanisms in joint well, was proposed to simulate the shear stressstrain response of joint core. The deformation compatibility and equilibrium condition of the model were deduced thereafter. It was indicated that the result of STM method was in good agreement with that of test data. And it could simulate more accurately the shear stressstrain response of joint core with a wide range of stirrup ratio.
2013, 35(2):66-72.
DOI: 10.3969/j.issn.1674-4764.2013.02.011
Abstract:
The heat conduction characteristic of glass curtain wall was investigated. Based on one dimensional steady heat conduction theory, the numerical calculation model of glass system thermal transmittance was set up by using insulating glass as an example. Based on two dimensional steady heat conduction theory and finite element method, both the thermal transfer matrix and temperature load array of 3 DOFs triangular element were derived. Then the revised formulas about the heat transfer matrix and temperature load array under the boundary conditions of constant heat flux, heat convective, radiation and coupled of them were also derived. Then the numerical calculation models of glass curtain wall frame and linear thermal transmittance were set up. The program TJCW based on the Visual C++ and ObjectARX was developed for calculating the thermal transmittance of glass curtain wall and was validated by contrast with the results calculated by thermal software LBNL. Finally, TJCW program was used to calculate and check the thermal transmittance of glass curtain wall in a practical project. The results indicate that the thermal transmittance of glass curtain wall can be calculated correctly by adopting the presented model, and the program based on this model can be used in energy conservation calculation and analysis in the actual projects.
The heat conduction characteristic of glass curtain wall was investigated. Based on one dimensional steady heat conduction theory, the numerical calculation model of glass system thermal transmittance was set up by using insulating glass as an example. Based on two dimensional steady heat conduction theory and finite element method, both the thermal transfer matrix and temperature load array of 3 DOFs triangular element were derived. Then the revised formulas about the heat transfer matrix and temperature load array under the boundary conditions of constant heat flux, heat convective, radiation and coupled of them were also derived. Then the numerical calculation models of glass curtain wall frame and linear thermal transmittance were set up. The program TJCW based on the Visual C++ and ObjectARX was developed for calculating the thermal transmittance of glass curtain wall and was validated by contrast with the results calculated by thermal software LBNL. Finally, TJCW program was used to calculate and check the thermal transmittance of glass curtain wall in a practical project. The results indicate that the thermal transmittance of glass curtain wall can be calculated correctly by adopting the presented model, and the program based on this model can be used in energy conservation calculation and analysis in the actual projects.
2012, 34(2):27-31.
DOI: 10.11835/j.issn.1674-4764.2012.02.005
Abstract:
In order to find out the current basic wind pressure in China, the parameters were estimated based on Gumbel distribution by statistically analyzing the annual maximum values of wind speed of 159 typical cities in China between 1951 and 2008. The basic wind pressure values for 10-year, 50-year and 100-year return periods were calculated based on moment method and Gumbel method, respectively. The distribution function was tested by the Kolmogorov criterion. Finally, the calculation results were compared with those in current design codes and the results of the correlative literature. The results show that basic wind pressure values worked out by Gumbel method are better than those by moment method in most cases when the statistic of the annual maximum values of wind speed is conducted and analyzed by Gumbel distribution. There are significant differences between the basic wind pressure values for 10-year, 50-year and 100-year return periods in Loading Code for Design of Building Structures and the results calculated with the annual maximum values of wind speed in recent decades, which shows that the sample data in Loading Code for Design of Building Structures are relatively insufficient and cannot reflect the present true condition in China. Therefore, basic wind pressure value should be revised accordingly.
In order to find out the current basic wind pressure in China, the parameters were estimated based on Gumbel distribution by statistically analyzing the annual maximum values of wind speed of 159 typical cities in China between 1951 and 2008. The basic wind pressure values for 10-year, 50-year and 100-year return periods were calculated based on moment method and Gumbel method, respectively. The distribution function was tested by the Kolmogorov criterion. Finally, the calculation results were compared with those in current design codes and the results of the correlative literature. The results show that basic wind pressure values worked out by Gumbel method are better than those by moment method in most cases when the statistic of the annual maximum values of wind speed is conducted and analyzed by Gumbel distribution. There are significant differences between the basic wind pressure values for 10-year, 50-year and 100-year return periods in Loading Code for Design of Building Structures and the results calculated with the annual maximum values of wind speed in recent decades, which shows that the sample data in Loading Code for Design of Building Structures are relatively insufficient and cannot reflect the present true condition in China. Therefore, basic wind pressure value should be revised accordingly.
2009, 31(6):132-136.
DOI: 10.11835/j.issn.1674-4764.2009.06.024
Abstract:
In order to improve the hydraulic permeability of wastewater infiltration system, two installations were designed with two with layers of red soil and cinder. At the load of 10 cm3/(cm2·d), the average removal efficiency of COD, TP, NH+4-N were different fillers for treating domestic wastewater at laboratory.1 installation was filled with layers of red soil and sand, while 2 obtained 91.1%, 97.6%, 48.7% and 80.1%,respectively by 1 installation; and 94.9%,98.3% and 89.0%,respectively by 2. The average effluent concentrations of nitric and nitrite were 54.7mg/L and 0.09mg/L by 1 installation; and 60.3mg/L and 0.15mg/L by 2. It was found that the removal efficiency of COD,TP and NH4+-N by 2 installation were better than those of 1, whilst 1 installation was more favourable for the removal of nitric and nitrite. The results further implied that layeredfilling can make good use of its filling performance. The hydraulic permeability of wastewater infiltration system and the removal of pollutants can also be effectively improved.
In order to improve the hydraulic permeability of wastewater infiltration system, two installations were designed with two with layers of red soil and cinder. At the load of 10 cm3/(cm2·d), the average removal efficiency of COD, TP, NH+4-N were different fillers for treating domestic wastewater at laboratory.1 installation was filled with layers of red soil and sand, while 2 obtained 91.1%, 97.6%, 48.7% and 80.1%,respectively by 1 installation; and 94.9%,98.3% and 89.0%,respectively by 2. The average effluent concentrations of nitric and nitrite were 54.7mg/L and 0.09mg/L by 1 installation; and 60.3mg/L and 0.15mg/L by 2. It was found that the removal efficiency of COD,TP and NH4+-N by 2 installation were better than those of 1, whilst 1 installation was more favourable for the removal of nitric and nitrite. The results further implied that layeredfilling can make good use of its filling performance. The hydraulic permeability of wastewater infiltration system and the removal of pollutants can also be effectively improved.
1988, 10(4).
DOI: 10.11835/j.issn.1674-4764.1988.04.012
Abstract:
This paper proves some properties of homogeneous function. Mainly, it proves that a sufficient condition of a parahomogeneous function is a subhomogeneous function. From which the relations of homogeneous function and partial derivatives of its respective variables are obtained. By these properties, this paper finally solves spcial first order total differential equations and obtains the quadrature of total differential of some function with n-variables. The obtained method of solution is simpler than usual one.
This paper proves some properties of homogeneous function. Mainly, it proves that a sufficient condition of a parahomogeneous function is a subhomogeneous function. From which the relations of homogeneous function and partial derivatives of its respective variables are obtained. By these properties, this paper finally solves spcial first order total differential equations and obtains the quadrature of total differential of some function with n-variables. The obtained method of solution is simpler than usual one.
2009, 31(2):29-32.
DOI: 10.11835/j.issn.1674-4764.2009.02.007
Abstract:
To set up a mechanical model of threepoint loading for the intellectual measuring equipment of cable tension, the cases for elastic support with two ends of hinged support and those of fixed support with consideration of the influence of the cable were systematically studied. The equations for the upper and lower limits of the cable tension T as well as those for the real measured values have been obtained. A more rational equation for online measuring the cable tension by “Threepoint Bending Method” has been derived through secondary measurement.
To set up a mechanical model of threepoint loading for the intellectual measuring equipment of cable tension, the cases for elastic support with two ends of hinged support and those of fixed support with consideration of the influence of the cable were systematically studied. The equations for the upper and lower limits of the cable tension T as well as those for the real measured values have been obtained. A more rational equation for online measuring the cable tension by “Threepoint Bending Method” has been derived through secondary measurement.
