共查询到20条相似文献，搜索用时 15 毫秒
1.
Equivalent linear system method is the main method of nonlinear structural system random response analysis. While it would generate big error when the results of equivalent linear system method are used to analyze the structural dynamic reliability. Through minimum mean square error principle, general nonlinear system was converted to equivalent Duffing nonlinear system, based on which the structural dynamic reliability was analyzed. The accurate steady state analytic solution of Duffing nonlinear system can be worked out by FPK equation, so it is not only convenient but also accurate to analyze structural dynamic reliability by using the equivalent nonlinear system method. It is also shown that the analysis results of equivalent nonlinear system method presented here is reliable and the calculation accuracy is higher than equivalent linear system method apparently through the example analysis. 相似文献
2.
Based on Melan's theorem, the symmetric Galerkin boundary element method (SGBEM) is used to discretize two dimensional structures and a computational formulation of structural limit analysis is established. The self equilibrium stress field is constructed by linear combination of several basic vectors, which are the stress differences between different iteration steps at the same increment using the traditional elastoplastic incremental method. Then the complex method is used to solve the nonlinear programming directly, so that the lower bound load multiplier of two dimensional structures is obtained. The validation of the present method has been confirmed by some numerical examples. 相似文献
3.
Super-tall building structures have the features of complex structural systems, diverse structural functions, long service life, massive investment and fixed owners. The life-cycle cost of super-tall building structures mainly contains initial cost, maintenance cost, failure cost caused by hazard and demolition cost. In order to achieve the minimization of the life-cycle cost of the super-tall building structure, a multi-dimensional life cycle economic cost assessment method is proposed in this study. The proposed method considers alternative design schemes, structural components and cost items. The overall cost management and optimization will be done at the initial phase of the structural project if this method can be employed. The proposed method is applied to a super tall building to illustrate its effectiveness and applicability. 相似文献
4.
As a new kind of supporting member, a prestress self balanced cable truss has been widely applied in point supported glass curtain walls. The free and forced vibration behaviors were analysed. Taking the temperature effect and geometric nonlinearity into consideration, the nonlinear vibration equation was derived with continua theory for prestress self balanced cable truss support system in point supported glass curtain wall. By the Galerkin method, the partial differential equation was transformed into ordinary differential equation and then solved with L P method and KBM method. With the case study, the effects of temperature, amplitude, and exterior excitation on the nonlinear vibration were discussed. And it was found that the frequency would decrease with increase of temperature and the nonlinear vibration showed the characteristics of hard spring. 相似文献
5.
In this paper, a constitutive function in form of integration is presented for a nonlinear analysis of structures of linear elements. With applications of a constitutive function, the truss and frame elements material nonlinear stiffness equations are derived. The results shows the convenience in numerical analysis and the ability to solve some difficult problems in tn the structural behavior study both in loading and unloading process by use of the presented constitutive function. 相似文献
6.
The national structural codes GB50010-2002 and GB 50011-2001 have been modified in many aspects compared with the old ones. To verify the effectiveness of structural capacity design provisions in the new codes, firstly, two typical RC frame structures of Grade 2 in intensity-category 8 and Grade 1 in intensity-category 9 are designed according to the new codes. Then, nonlinear dynamic analyses of the two structures are carried out under excitations of several ground motions with the fortification and rare intensity levels. With the analysis results the availability of strong column weak beam is checked carefully, which is desirable with capacity design measures of RC frame in Chinese new structural design code. The conclusions drawn from the analysis are helpful to structural design and local modification of the codes. 相似文献
7.
The improvement of research on simulation of structural seismic responses based on neural networks(NN) is reviewed in this paper.Three key problems to simulate linear structures,selection of NN model,determination of NN structure and control of simulating precision,are discussed and the method to deal with the problems are suggested.Main problems of the research on simulating nonlinear structures under the action of earthquake ground motions based on NN are presented. 相似文献
8.
采用4种数学模型(直角双曲线模型、非直角双曲线模型、修正直角双曲线模型、指数模型)对白及组培幼苗不同生长时期叶片光合光响应过程进行拟合分析,以期筛选出与白及幼苗期相适宜的光响应模型。结果表明:1)4种拟合模型精度以修正非直角双曲线模型最佳。2)光合参数的拟合效果拥有不同的表现。在4种拟合模型中初始量子效率(α)与表观量子效率(AQE)拟合值均在合理范围内,修正直角双曲线模型对白及幼苗最大净光合速率(Pnmax)、光饱和点(LSP)与光补偿点(LCP)的拟合较为准确,而暗呼吸速率(Rd)的拟合采用直角双曲线模型较为合理。3)光合有效辐射(PAR)对植物净光合速率(Pn)、气孔导度(Cond)及蒸腾作用(Trmmol)存在良好的正向线性关系,与胞间二氧化碳浓度(Ci)存在一定的负向线性关系。 相似文献
9.
10.
A forward algorithm for prestressed construction process of large-span suspendome based on the equivalent pre-tension 
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下载免费PDF全文 To accurately simulate prestressed construction process of large-span suspendome, the initial state of construction process according to practical construction sequence is established, and the construction mechanical analysis for prestressed construction process is especially studied. Features of prestressed construction process of large-span suspendome are summarized, and the insufficiencies of the application of state variable superposition method, back analysis method, birth and death element method are analyzed. Combined with nonlinear finite element analysis method, forward algorithm for prestressed construction process based on the equivalent pre-tension is proposed, and the specific application method and procedure are given. Changzhou stadium steel roof engineering is taken as an example to verify the practicability and applicability of forward algorithm for prestressed construction process. The conclusion is that, using forward algorithm for prestressed construction process based on the equivalent pre-tension, the structure state of each construction phase can be accurately tracked, and the nonlinear contact of strut and rigid framework, interactive impact of cable force, conversion of temporary structure system, and structural geometric nonlinearity can be comprehensively considered. 相似文献
11.
Traditional structural design emphasizes checking whether a loaded structure satisfies design requirements without considering the construction process. There is a great difference in structures between the states in construction processes and design, however. To solve the above problems, a method of nonlinear time varying mechanics was adopted to analyze the construction process of a structure. The structural characteristics in each construction stage were analyzed by time varying mechanics and the variations of internal force and displacements obtained. We conclude that designs will not be safe if the time varying effect in the construction process analysis is not considered. We offer advice on the design and construction of large span structures. 相似文献
12.
The Cuplock Template supports system joint initial rigidity and bowl buckle tightening torque was closely linked, with MATLAB applications for the two order and three order numerical fitting between them, found that three order fitting accuracy was higher than two order fitting results. Using ANSYS finite element software to establish the corresponding with the entity model, the changes in simulated nodes hinged, rigid and different initial stiffness condition for supporting system, and the simulation results were compared with the actual bearing capacity of the frame body stability. Find node is hinged and rigid connection simulation results state and actual frame difference. When the simulation results between node tightening torque of the 35N.m~50N.m and the actual time the frame carrying capacity is close, the node for the semi-rigid connection state. In order to show that the semi-rigid joint model can simulate accurately with the actual capacity of the Cuplock Template supports system. 相似文献
13.
The Non-Linear Finite Element Analysis of Cable Structures Based on Four-Node Isoparametric Curved Element 总被引：1，自引：0，他引：1
In this paper,based on the geometric nonlinear behavior of cable structures,a finite element method with four-node isoparametric element was presented,the third order polynomial was used as displacement functions and initial curve of the element.By means of the principle of virtual work and the updated Lagrangian method,the authors derived the finite element equations,and solved them by Newton-Raphson method.The proposed model leads to high precision and can meet the engineering requirements.The model presented in this paper can be applied in the analysis of long-span tension structures,such as cable structures,cable domes and so forth. 相似文献
14.
Wang Zhijun Liu Nanke 《保鲜与加工》1998,(4):14-20
Based on the extensive study of various iterative methods, a simple but practical way of the iterative route search and acceleration is introduced into the normal displacement and arc-length methods to fit the nonlinear full-range analysis of concrete structures, by which the convergence of iteration is much improved. 相似文献
15.
传统边坡可靠度分析往往在岩土参数服从线性Mohr-Coulomb（简称线性M-C）破坏准则的假设条件下进行,并且常常采用极限平衡法或有限元法计算安全系数。然而,岩土介质破坏准则具有一定的非线性。为能更加实际地描述岩土破坏机理和得到严格精确的解,基于非线性Mohr-Coulomb（简称非线性M-C）破坏准则,结合极限分析上限法和蒙特卡洛法,进行边坡可靠度上限分析。当非线性参数m=1时,与等效的线性M-C破坏准则进行对比计算,验证了方法的可行性。同时,将初始粘聚力、内摩擦角arctan（c0/σt）和非线性参数作为随机变量且服从截断正态分布,进行了参数变异性和敏感性影响分析。研究表明：非线性M-C破坏准则下,边坡可靠度随初始粘聚力、内摩擦角arctan（c0/σt）和非线性参数变异性的增大而减小;边坡可靠度随初始粘聚力和内摩擦角arctan（c0/σt）的增大而增大,随非线性参数的增大而减小。 相似文献
16.
GONG Xian sheng 《保鲜与加工》1999,(3):15-23
A method which is used for calculating steady vibration response of shipping propulsion shafting connecting with a coupling with nonlinear hysteresis characteristics are studied. On condition that the nonlinear dynamic stiffness and hysteresis damping of the coupling be considered, on the basis of GLM(Galerki Levenberg Marquard) method, a method called SSGILM(Separate System Galerkin and Improved Levenberg-Marquardt)to be used for calculating steady vibration response of propulsion shafting with local nonlinear dynamic stiffness and hysteresis damping, is proposed. A simple example is given out and the analyses show that it is effective to calculate steady vibration response of the shafting with local nonlinear dynamic stiffness and hysteresis damping by SSGILM method. From initial response values given arbitrarily, the automatic search algorithm in SSGILM method can converge the given initial response values to the response values accorded with required accuracy quickly; nonlinear dynamic stiffness and hysteresis damping of the coupling have different effect on vibration response of the shafting at different range of frequency. At the area of close nature frequency of the shafting ,displacement amplitude of the shafting is bigger. Beyond the range, the characteristics of the coupling have restraint effect on vibration of the shafting. 相似文献
17.
YANG Zhi-ping~ 《保鲜与加工》2004,(9):40-44
The load changed of motor affects normal run. If it is not adjusted, the state of motor will become poor, while it affects steady of the system. This paper presents an efficient method for the motor speed controlling, it applies Tacagi-Sugeno's method that each linear submodels are connected for fuzzy algorithm, an algorithm of the fuzzy model identifying and fuzzy control is fulfilled through whole nonlinear model which are replaced with local linear models. It makes speed of motor to maintain steady, and variable structure control is applied to guarantee performance of dynamic flowing for process controlled, the design of stability and robustness is proposed in the scheme. Practice running results show that it is efficient that uncertain dynamic processes are controlled. 相似文献
18.
农村金融生态环境关键影响因素的辨识与分析 总被引：1，自引：0，他引：1
农村金融生态环境受到系统内外许多因素制约,确定影响农村金融生态环境的关键影响因素成为农村金融生态环境改善的重要环节。利用DEMATEL方法,从各因素之间的相互影响关系出发,建立直接影响矩阵并求出综合影响矩阵,通过计算各因素的影响度、被影响度、中心度,考察因素综合影响关系,确定了农村金融生态环境的关键影响因素并对其进行系统分析,提出了改善农村金融生态环境的建议。 相似文献
19.
Based on the second method of Lyapunov stability theory, the stability of non-equilibrium state for multiphase system is analysed. The results show that the dV/dt is always less than zero ff the V-function, which is defined as the entropy generation of the system, is greater than zero for the non-equilibrium state in linear zone, and the system is absolutely stable. On the other hand, the stability of the system in non-linear zone is determined with the symbol of dV/dt. 相似文献
20.
Liao Xiaoyun Lei Wenyu 《保鲜与加工》1999,(1):18-23
A new analysis method for machining surface profile error is presented in this paper.The linear regression and nonlinear regression are first applied respectively,and then the Weierstrass Mandebrot fractal function is used to obtain the fractal parameters of machining profiles.A minimal parameter set which depicts the machining surface geometric precision is set up,and the surface profile can be reconstructed using these parameters,and an analysis method for part performance and its tolerance structure is proposed.Examples are provided to illustrate the method is feasible and effective. 相似文献