A new fuzzy stochastic finite element method based on the fuzzy factor method and random factor method is given and the analysis of structural dynamic characteristic for fuzzy stochastic truss structures is presented....A new fuzzy stochastic finite element method based on the fuzzy factor method and random factor method is given and the analysis of structural dynamic characteristic for fuzzy stochastic truss structures is presented. Considering the fuzzy randomness of the structural physical parameters and geometric dimensions simultaneously, the structural stiffness and mass matrices axe constructed based on the fuzzy factor method and random factor method; from the Rayleigh＇s quotient of structural vibration, the structural fuzzy random dynamic characteristic is obtained by means of the interval arithmetic; the fuzzy numeric characteristics of dynamic characteristic axe then derived by using the random variable＇s moment function method and algebra synthesis method. Two examples axe used to illustrate the validity and rationality of the method given. The advantage of this method is that the effect of the fuzzy randomness of one of the structural parameters on the fuzzy randomness of the dynamic characteristic can be reflected expediently and objectively.展开更多
The finite element method to form Michell truss in three_dimensions is presented.The orthotropic composite with fiber_reinforcement is employed as the material model to simulate Michell truss.The orientation and densi...The finite element method to form Michell truss in three_dimensions is presented.The orthotropic composite with fiber_reinforcement is employed as the material model to simulate Michell truss.The orientation and densities of fibers at nodes are taken as basic design variables.The stresses and strains at nodes are calculated by finite element method.An iteration scheme is suggested to adjust the orientations of fibers to be along the orientations of principal stresses, and the densities of fibers according to the strains in the orientations of fibers.The strain field satisfying Michell criteria and truss_like continuum are achieved after several iterations. Lastly, the Michell truss is showed by continuous lines, which are formed according to the orientations of fibers at nodes. Several examples are used to demonstrate the efficiency of the presented approach.展开更多
This paper presents a simplified numerical simulation tool for the elasto-plastic calculation of plane articulated truss by the finite element method (FEM) in MATLAB. The simplified approach consists of linearizing is...This paper presents a simplified numerical simulation tool for the elasto-plastic calculation of plane articulated truss by the finite element method (FEM) in MATLAB. The simplified approach consists of linearizing isotropic strain-hardening (to obtain a bilinear material law). The numerical implementation is built on the basis of the incremental and iterative FEM algorithms. The numerical resolution technique used is based on the projection methods of the modified Newton-Raphson solution. The MATLAB program is developed for the application of a 3-bar truss under monotonous quasi-static loading. Different values of the approximation error of the convergence criterion are used to study its impact on the quality of the algorithm. Numerical simulations have shown the reliability and quality of our simplified approach regardless of the approximation error.展开更多
Polynomial-basis response surface method has some shortcomings for truss structures in structural optimization,concluding the low fitting accuracy and the great computational effort. Based on the theory of approximati...Polynomial-basis response surface method has some shortcomings for truss structures in structural optimization,concluding the low fitting accuracy and the great computational effort. Based on the theory of approximation, a response surface method based on Multivariate Rational Function basis(MRRSM) is proposed. In order to further reduce the computational workload of MRRSM, focusing on the law between the cross-sectional area and the nodal displacements of truss structure, a conjecture that the determinant of the stiffness matrix and the corresponding elements of adjoint matrix involved in displacement determination are polynomials with the same order as their respective matrices, each term of which is the product of cross-sectional areas, is proposed. The conjecture is proved theoretically for statically determinate truss structure, and is shown corrected by a large number of statically indeterminate truss structures. The theoretical analysis and a large number of numerical examples show that MRRSM has a high fitting accuracy and less computational effort. Efficiency of the structural optimization of truss structures would be enhanced.展开更多
The expressions of the internal forces of the webs under the vertical loads of the simply supported beam type trusses with vertical and horizontal webs and without vertical webs are studied through the mathematical fo...The expressions of the internal forces of the webs under the vertical loads of the simply supported beam type trusses with vertical and horizontal webs and without vertical webs are studied through the mathematical formula method. The variations of internal forces under different angles and spacings of the webs are simulated. The law of the optimal arrangement of the webs of the parallel-string simple-beam truss is obtained: under the condition that the rigidity of the rod is allowed, the form of no vertical web-type truss and reducing the span distance and inclination of the side span are advisable, which can save materials and reduce the weight as well. This method can be applied to the calculation of internal forces for arbitrary loads and truss forms.展开更多
Purpose of present work is to develop a reliable and simple method for structural analysis of RC Shear Walls. The shear wall is simulated by a truss model as the bar of a truss is the simplest finite element. An itera...Purpose of present work is to develop a reliable and simple method for structural analysis of RC Shear Walls. The shear wall is simulated by a truss model as the bar of a truss is the simplest finite element. An iterative method is used. Initially, there are only concrete bars. Repeated structural analyses are performed. After each structural analysis, every concrete bar exceeding tensile strength is replaced by a steel bar. For every concrete bar exceeding compressive strength, first its section area is increased. If this is not enough, a steel bar is placed at the side of it. For every steel bar exceeding tensile or compressive strength, its section area is increased. After the end of every structural analysis, if all concrete and steel bars fall within tensile and compressive strengths, the output data are written and the analysis is terminated. Otherwise, the structural analysis is repeated. As all the necessary conditions (static, elastic, linearized geometric) are satisfied and the stresses of ALL concrete and steel bars fall within the tensile and compressive strengths, the results are acceptable. Usually, the proposed method exhibits a fast convergence in 4 - 5 repeats of structural analysis of the RC Shear Wall.展开更多
Steel truss bridges are frequently used in bridge engineering because of their good ability of spanning capacity, construction and light self-weight. Main trusses are the critical component of steel truss bridge and t...Steel truss bridges are frequently used in bridge engineering because of their good ability of spanning capacity, construction and light self-weight. Main trusses are the critical component of steel truss bridge and the main truss are made of truss members linked by integral joints. This paper presents the mechanic performance of key joints, and the codified design of joints in steel truss girders according to the latest European norms. The results showed that the fatigue resistance of welded joints evaluation is necessary to predict, detect, and repair the crack in time for the safety service life of the bridge. The stresses of integral joint are greater than that of truss members;the stresses in the center area of the integral joint are greater than the stress at the edge.展开更多
基金Project supported by the Natural Science Foundation of Shaanxi Province of China (No,A200214)
文摘A new fuzzy stochastic finite element method based on the fuzzy factor method and random factor method is given and the analysis of structural dynamic characteristic for fuzzy stochastic truss structures is presented. Considering the fuzzy randomness of the structural physical parameters and geometric dimensions simultaneously, the structural stiffness and mass matrices axe constructed based on the fuzzy factor method and random factor method; from the Rayleigh＇s quotient of structural vibration, the structural fuzzy random dynamic characteristic is obtained by means of the interval arithmetic; the fuzzy numeric characteristics of dynamic characteristic axe then derived by using the random variable＇s moment function method and algebra synthesis method. Two examples axe used to illustrate the validity and rationality of the method given. The advantage of this method is that the effect of the fuzzy randomness of one of the structural parameters on the fuzzy randomness of the dynamic characteristic can be reflected expediently and objectively.
文摘The finite element method to form Michell truss in three_dimensions is presented.The orthotropic composite with fiber_reinforcement is employed as the material model to simulate Michell truss.The orientation and densities of fibers at nodes are taken as basic design variables.The stresses and strains at nodes are calculated by finite element method.An iteration scheme is suggested to adjust the orientations of fibers to be along the orientations of principal stresses, and the densities of fibers according to the strains in the orientations of fibers.The strain field satisfying Michell criteria and truss_like continuum are achieved after several iterations. Lastly, the Michell truss is showed by continuous lines, which are formed according to the orientations of fibers at nodes. Several examples are used to demonstrate the efficiency of the presented approach.
文摘This paper presents a simplified numerical simulation tool for the elasto-plastic calculation of plane articulated truss by the finite element method (FEM) in MATLAB. The simplified approach consists of linearizing isotropic strain-hardening (to obtain a bilinear material law). The numerical implementation is built on the basis of the incremental and iterative FEM algorithms. The numerical resolution technique used is based on the projection methods of the modified Newton-Raphson solution. The MATLAB program is developed for the application of a 3-bar truss under monotonous quasi-static loading. Different values of the approximation error of the convergence criterion are used to study its impact on the quality of the algorithm. Numerical simulations have shown the reliability and quality of our simplified approach regardless of the approximation error.
基金Supported by National Natural Science Foundation of China (Grant No.5150261)Shandong Provincial Natural Science Foundation of China (Grant No.ZR2015AM013)
文摘Polynomial-basis response surface method has some shortcomings for truss structures in structural optimization,concluding the low fitting accuracy and the great computational effort. Based on the theory of approximation, a response surface method based on Multivariate Rational Function basis(MRRSM) is proposed. In order to further reduce the computational workload of MRRSM, focusing on the law between the cross-sectional area and the nodal displacements of truss structure, a conjecture that the determinant of the stiffness matrix and the corresponding elements of adjoint matrix involved in displacement determination are polynomials with the same order as their respective matrices, each term of which is the product of cross-sectional areas, is proposed. The conjecture is proved theoretically for statically determinate truss structure, and is shown corrected by a large number of statically indeterminate truss structures. The theoretical analysis and a large number of numerical examples show that MRRSM has a high fitting accuracy and less computational effort. Efficiency of the structural optimization of truss structures would be enhanced.
文摘The expressions of the internal forces of the webs under the vertical loads of the simply supported beam type trusses with vertical and horizontal webs and without vertical webs are studied through the mathematical formula method. The variations of internal forces under different angles and spacings of the webs are simulated. The law of the optimal arrangement of the webs of the parallel-string simple-beam truss is obtained: under the condition that the rigidity of the rod is allowed, the form of no vertical web-type truss and reducing the span distance and inclination of the side span are advisable, which can save materials and reduce the weight as well. This method can be applied to the calculation of internal forces for arbitrary loads and truss forms.
文摘Purpose of present work is to develop a reliable and simple method for structural analysis of RC Shear Walls. The shear wall is simulated by a truss model as the bar of a truss is the simplest finite element. An iterative method is used. Initially, there are only concrete bars. Repeated structural analyses are performed. After each structural analysis, every concrete bar exceeding tensile strength is replaced by a steel bar. For every concrete bar exceeding compressive strength, first its section area is increased. If this is not enough, a steel bar is placed at the side of it. For every steel bar exceeding tensile or compressive strength, its section area is increased. After the end of every structural analysis, if all concrete and steel bars fall within tensile and compressive strengths, the output data are written and the analysis is terminated. Otherwise, the structural analysis is repeated. As all the necessary conditions (static, elastic, linearized geometric) are satisfied and the stresses of ALL concrete and steel bars fall within the tensile and compressive strengths, the results are acceptable. Usually, the proposed method exhibits a fast convergence in 4 - 5 repeats of structural analysis of the RC Shear Wall.
文摘Steel truss bridges are frequently used in bridge engineering because of their good ability of spanning capacity, construction and light self-weight. Main trusses are the critical component of steel truss bridge and the main truss are made of truss members linked by integral joints. This paper presents the mechanic performance of key joints, and the codified design of joints in steel truss girders according to the latest European norms. The results showed that the fatigue resistance of welded joints evaluation is necessary to predict, detect, and repair the crack in time for the safety service life of the bridge. The stresses of integral joint are greater than that of truss members;the stresses in the center area of the integral joint are greater than the stress at the edge.
