1994 Vol. 11 No. 3
1994, 11(3): 1-11.
Abstract：
Based on the authors earlier work entitled "A virtual boundary elementcollocation method for solvinhg problems of elasticity" published in the journal of Computational Structural Mechanics and its Applications, 8(1), 1991, in this paper the least square method is used to formulate the boundary integral equations satisfying the boundary conditons of the problem of elasticity and these integral equations are discretized by linear virtual boundary element. And then the analytical characteristics of these equations are studied. The Raita's (paИTa) criterion of error analysis is introduced for judgying the level of solution's error and an ideal effect is obtained. A VBELSM microcomputer programm is coded in which the Gaussion integral scheme is adopted and the symmetric conditions are considered to simplify calculation. The method can treat not only the smooth boundary but also the rough ones. The numerical examples show that this method has higher accuracy, the computer programm is reable and the algorithm is stable when the virtual boundary is selected suitably.
Based on the authors earlier work entitled "A virtual boundary elementcollocation method for solvinhg problems of elasticity" published in the journal of Computational Structural Mechanics and its Applications, 8(1), 1991, in this paper the least square method is used to formulate the boundary integral equations satisfying the boundary conditons of the problem of elasticity and these integral equations are discretized by linear virtual boundary element. And then the analytical characteristics of these equations are studied. The Raita's (paИTa) criterion of error analysis is introduced for judgying the level of solution's error and an ideal effect is obtained. A VBELSM microcomputer programm is coded in which the Gaussion integral scheme is adopted and the symmetric conditions are considered to simplify calculation. The method can treat not only the smooth boundary but also the rough ones. The numerical examples show that this method has higher accuracy, the computer programm is reable and the algorithm is stable when the virtual boundary is selected suitably.
1994, 11(3): 12-17.
Abstract：
The procedtires for the general buckling analysis 0f ring-stiffened cylindrical shells under hydrostatic presstlre by finite strip method are formulated. The stiffened shell is treated as a bare shell with orthotropic properties. The elasticity matrix of the strip is worked out. The buckling load of a simply supported ring-stiffened cylindrical shell by FSM compares favorably with the analytical solntion. It is shown that the finite strip method is an effective method for the buckling analysis of ringstiffened cylindrical shells with closely spaced stiffeners.
The procedtires for the general buckling analysis 0f ring-stiffened cylindrical shells under hydrostatic presstlre by finite strip method are formulated. The stiffened shell is treated as a bare shell with orthotropic properties. The elasticity matrix of the strip is worked out. The buckling load of a simply supported ring-stiffened cylindrical shell by FSM compares favorably with the analytical solntion. It is shown that the finite strip method is an effective method for the buckling analysis of ringstiffened cylindrical shells with closely spaced stiffeners.
Abstract：
The authors investigated systematically the BSI PD6493 advanced assessment method and EPRI engineering method based on ductile tearing.By the notion of maintainning equilibrium between driven and resistance forces under stable crack growth, established an optimization method for failure assessment.It possesses the characteristics of simplicity and clarification. Therefore, it eliminates the complexity and undeterminacy of various assessment diagram methods.The revised PD6493 advanced assessment method (1991) and EPRI engineering method possess similar precision probably, then their assessment results by ductile tearing may be trusted in the full senses.
The authors investigated systematically the BSI PD6493 advanced assessment method and EPRI engineering method based on ductile tearing.By the notion of maintainning equilibrium between driven and resistance forces under stable crack growth, established an optimization method for failure assessment.It possesses the characteristics of simplicity and clarification. Therefore, it eliminates the complexity and undeterminacy of various assessment diagram methods.The revised PD6493 advanced assessment method (1991) and EPRI engineering method possess similar precision probably, then their assessment results by ductile tearing may be trusted in the full senses.
1994, 11(3): 28-37.
Abstract：
A finite element model for simulating the opening and closing of joints in jointed structures is presented in this paper. The initial pressure and resistance to the tensile strengh at the interface are considered. It can be formed easily and used widely.Some nonlinear finite element formulas are carried out, and corresponding nonlinear finite element programme is compiled. A contact problem of two contact blocks and nonlinear dynamic response of a plane arch are calculated, different jointed parameters, initial pressure and whether having joints or not between the structure and foundation are considered, Some conclusions are given.
A finite element model for simulating the opening and closing of joints in jointed structures is presented in this paper. The initial pressure and resistance to the tensile strengh at the interface are considered. It can be formed easily and used widely.Some nonlinear finite element formulas are carried out, and corresponding nonlinear finite element programme is compiled. A contact problem of two contact blocks and nonlinear dynamic response of a plane arch are calculated, different jointed parameters, initial pressure and whether having joints or not between the structure and foundation are considered, Some conclusions are given.
Abstract：
This paper studies the problem of free transverse vibration of circular plates with an arbitrary number of the concentric elastic ring supports, a new analytical solution is presented. The analytical solution of dynamic response of the circular plate is obtained by regarding the reaction forces of the elastic ring supports as the unknown external forces acted on the plate. The integral constants of the solution are decided by the boundary conditions of the plate. The reaction forces of elastic ring supports are decided by the linear relationship of the reaction forces and the displacements at supports. The frequency equation is described by a determinant whose order is equal to the number of the elastic ring supports. The eigen-frequencies can be given by the searching root method of determinant. The mode shape functions are described by an analytical representation. Finally, an example is given and the numerical results are compareed with those obtained.
This paper studies the problem of free transverse vibration of circular plates with an arbitrary number of the concentric elastic ring supports, a new analytical solution is presented. The analytical solution of dynamic response of the circular plate is obtained by regarding the reaction forces of the elastic ring supports as the unknown external forces acted on the plate. The integral constants of the solution are decided by the boundary conditions of the plate. The reaction forces of elastic ring supports are decided by the linear relationship of the reaction forces and the displacements at supports. The frequency equation is described by a determinant whose order is equal to the number of the elastic ring supports. The eigen-frequencies can be given by the searching root method of determinant. The mode shape functions are described by an analytical representation. Finally, an example is given and the numerical results are compareed with those obtained.
1994, 11(3): 47-54.
Abstract：
This paper describes a new model for the prediction of contact fatigue life controlled by stresses. Mieses equivalent stress is chosed as a stress-related fatigue criterion. A non-zero contact fatigue limit is used. Depended on defect mechanics, relation between fatigue limit and material or inclusion is analysed. Two failure forms initiated in the subsurface or surface are considered, and prediction of contact fatigue life to the two failure forms is combined to a formula. A cofficient f(Λ) related to oil film cofficient Λ is used to express lubrication's influence upon contact fatigue life. The model is used to predict smme experimential contact fatigue lives. Predicted results fit experimental results well.
This paper describes a new model for the prediction of contact fatigue life controlled by stresses. Mieses equivalent stress is chosed as a stress-related fatigue criterion. A non-zero contact fatigue limit is used. Depended on defect mechanics, relation between fatigue limit and material or inclusion is analysed. Two failure forms initiated in the subsurface or surface are considered, and prediction of contact fatigue life to the two failure forms is combined to a formula. A cofficient f(Λ) related to oil film cofficient Λ is used to express lubrication's influence upon contact fatigue life. The model is used to predict smme experimential contact fatigue lives. Predicted results fit experimental results well.
1994, 11(3): 55-79.
Abstract：
in this paper,concentration of stresses near circular hole of an axisymmetrical spherical shell with stiffening ring are discussed. The calculating formulas for three stress resultants (radial bending moment,radial and hoop normal forces)under normal distributed load and ring load are derived. The numerical tables of them for poison's ratio ν=0 and different geometrical parameters are given for directly use in engineering design.
in this paper,concentration of stresses near circular hole of an axisymmetrical spherical shell with stiffening ring are discussed. The calculating formulas for three stress resultants (radial bending moment,radial and hoop normal forces)under normal distributed load and ring load are derived. The numerical tables of them for poison's ratio ν=0 and different geometrical parameters are given for directly use in engineering design.
1994, 11(3): 80-86.
Abstract：
A method to predict the ultimate loads for short concrete-filled steel columns with rectangular section is proposed. The behavior of steel tubes is assumed as plane stress states and the filled concrete is divided into biaxial and triaxial compression regions based on stress analysis by using finite element method. Therefore,the axial load of the column can be represented as a function of hoop tensile streess in the steel tube.The stresses of the steel tube are evaluated by Mises's yield condition and the strength of filled concrete are estimated by Kupfer's envelope for biaxial regions and Richart's criterion for triaxial regions. Based on the lower bound formula in the theory of limit analysis, the maximum value of axial loads,which is regarded as the ultimate load,can be determined by using stationary conditions. Inaddition,twelve specimens were studied by this model and very good results have been gaven.
A method to predict the ultimate loads for short concrete-filled steel columns with rectangular section is proposed. The behavior of steel tubes is assumed as plane stress states and the filled concrete is divided into biaxial and triaxial compression regions based on stress analysis by using finite element method. Therefore,the axial load of the column can be represented as a function of hoop tensile streess in the steel tube.The stresses of the steel tube are evaluated by Mises's yield condition and the strength of filled concrete are estimated by Kupfer's envelope for biaxial regions and Richart's criterion for triaxial regions. Based on the lower bound formula in the theory of limit analysis, the maximum value of axial loads,which is regarded as the ultimate load,can be determined by using stationary conditions. Inaddition,twelve specimens were studied by this model and very good results have been gaven.
1994, 11(3): 87-90.
Abstract：
KIc of marble was measured with method of three-point bending. The effect of loading velocity, crack length and its shape on the value of KIc is studied.
KIc of marble was measured with method of three-point bending. The effect of loading velocity, crack length and its shape on the value of KIc is studied.
1994, 11(3): 91-98.
Abstract：
Under the action of earthquake, the large span transmission lines with supporting towers is a complicated system of spatial coupling vibration. It is necessary to determine the reasonable computation scheme of this system for engineering design.The conventional methods will never be valid to calculate the seismic responses of the large span transmission lines and their supporting towers under the condition of unknown rigidity distribution. In this paper, an approach with noverl idea is presented.The upper bound seismic responses can be determined by putting the product function specially defined in this paper in extrema. Only two modes which have contributions to the responses need to be considered in design. as all the other high modes have strictly no contributions.In thd paper, the mechanical model of tower-line coupling vibrstion is given in X-Y plane. We compare the unknown rigidity distribution with known rigidity distribution in 2-degrees-of-freedom(DOF). We find the upper bound seismic loads in unknown rigidity distribution are always greater than the seismic loads in known rigidity distribution.
Under the action of earthquake, the large span transmission lines with supporting towers is a complicated system of spatial coupling vibration. It is necessary to determine the reasonable computation scheme of this system for engineering design.The conventional methods will never be valid to calculate the seismic responses of the large span transmission lines and their supporting towers under the condition of unknown rigidity distribution. In this paper, an approach with noverl idea is presented.The upper bound seismic responses can be determined by putting the product function specially defined in this paper in extrema. Only two modes which have contributions to the responses need to be considered in design. as all the other high modes have strictly no contributions.In thd paper, the mechanical model of tower-line coupling vibrstion is given in X-Y plane. We compare the unknown rigidity distribution with known rigidity distribution in 2-degrees-of-freedom(DOF). We find the upper bound seismic loads in unknown rigidity distribution are always greater than the seismic loads in known rigidity distribution.
1994, 11(3): 99-108.
Abstract：
This paper develops a new dynamic particular solution boundary element method to solve the dynamic interactions of damreservoir-foundation system inthetim edomain,studies the influences of elasticity of foundation.fluid of reservoir and damping of system to dynamic characteristic、hydrodynamic pressure and dynamic amplify factor,and calculats the earthquake response of system by using Wilson-θ method. The results show that the method proposed in this paper can treat conveniently the coupling problems of the system,reduces a lot of computing work and has a good precision.
This paper develops a new dynamic particular solution boundary element method to solve the dynamic interactions of damreservoir-foundation system inthetim edomain,studies the influences of elasticity of foundation.fluid of reservoir and damping of system to dynamic characteristic、hydrodynamic pressure and dynamic amplify factor,and calculats the earthquake response of system by using Wilson-θ method. The results show that the method proposed in this paper can treat conveniently the coupling problems of the system,reduces a lot of computing work and has a good precision.
1994, 11(3): 109-114.
Abstract：
This paper studies 3-D sensitivity analysis in arch dam shape optimization based on FEM with the Improved Semianalytical Method (ISM). Some analytical formulations related to sensitivity calculation are derived. The correspondent programs have been developed. Examples show that ISM has an advantage in accuracy and stability, and is efficient in arch dam shape optimization based on 3-D FEM.
This paper studies 3-D sensitivity analysis in arch dam shape optimization based on FEM with the Improved Semianalytical Method (ISM). Some analytical formulations related to sensitivity calculation are derived. The correspondent programs have been developed. Examples show that ISM has an advantage in accuracy and stability, and is efficient in arch dam shape optimization based on 3-D FEM.
1994, 11(3): 115-120.
Abstract：
The plastic limit loads of circular silos has been studied in this paper.The loads on the silo's wall are calculated according to Janssen formula. Three plastic collapse mechanisms are analyzed, and curves of limit load versus silo parameters are gaven in non-dimensional form.
The plastic limit loads of circular silos has been studied in this paper.The loads on the silo's wall are calculated according to Janssen formula. Three plastic collapse mechanisms are analyzed, and curves of limit load versus silo parameters are gaven in non-dimensional form.
1994, 11(3): 121-128.
Abstract：
A general solution on Suhir's interfacial stresses differential equation is given and used in solving for the interfacial stresses problem of bimaterial strips structure subjected to external loading on its two ends. For example, famous Goland-Reissner interfacial stresses problem is solved (here two layer laminated strips respectively have thicknesses h1 and h2, elastic modulus E1 and E2). Finally, we obtain the intefacial stresses solution for a special case (h1=h2, E1=E2), and compare this solution with the results of other works.
A general solution on Suhir's interfacial stresses differential equation is given and used in solving for the interfacial stresses problem of bimaterial strips structure subjected to external loading on its two ends. For example, famous Goland-Reissner interfacial stresses problem is solved (here two layer laminated strips respectively have thicknesses h1 and h2, elastic modulus E1 and E2). Finally, we obtain the intefacial stresses solution for a special case (h1=h2, E1=E2), and compare this solution with the results of other works.
1994, 11(3): 129-136.
Abstract：
Based on disasters due to earthquake, two model-beam-type dynamic instability and Shell-type dynamic instability for two types of dynamic instability of buried pipelines in axial direction are put forward,and equation for the dynamic instability of buried pipelines are established. The models regards the pipeline as long beam and circular cylindrical thin shell buried in elastic half-space. The soil-pipeline interaction is obtained by combining the dynamic plane strain solution with the static Mindlin solution. Taking buried gas pipelines in city and long oil-pipelines in our country as examples, parametric studies are carried out,and some conclusions are obtained, and reasons for disasters are explained.
Based on disasters due to earthquake, two model-beam-type dynamic instability and Shell-type dynamic instability for two types of dynamic instability of buried pipelines in axial direction are put forward,and equation for the dynamic instability of buried pipelines are established. The models regards the pipeline as long beam and circular cylindrical thin shell buried in elastic half-space. The soil-pipeline interaction is obtained by combining the dynamic plane strain solution with the static Mindlin solution. Taking buried gas pipelines in city and long oil-pipelines in our country as examples, parametric studies are carried out,and some conclusions are obtained, and reasons for disasters are explained.
1994, 11(3): 137-143.
Abstract：
Using the method of coupling infinite BE and FE, the authors have calculated the thin plate based on elastic half space. The elastic thin plate is treated by FE,the elastic half space treated by BE, and the infinite BE is used to treat the infinite boundary. We get the comprehensive matrix equations considing the compatible conditions on the surface of the plate and the foundation. The results show that the method has many advantages and is very suited for pavement and other foundation engineerings.
Using the method of coupling infinite BE and FE, the authors have calculated the thin plate based on elastic half space. The elastic thin plate is treated by FE,the elastic half space treated by BE, and the infinite BE is used to treat the infinite boundary. We get the comprehensive matrix equations considing the compatible conditions on the surface of the plate and the foundation. The results show that the method has many advantages and is very suited for pavement and other foundation engineerings.
