Limit Analyisis of Frame Structure Based on the Elastic Modulus Reduction Method

2014 ◽  
Vol 578-579 ◽  
pp. 950-953
Author(s):  
Qiu Hua Duan ◽  
Yan Qing Guo ◽  
Dan Dan Zeng ◽  
Yue Jing Luo
Keyword(s):  
Elastic Modulus ◽  
Reduction Method ◽  
Yield Criterion ◽  
Bending Moment ◽  
Limit Load ◽  
Frame Structure ◽  
Structure Damage ◽  
Linear Elastic ◽  
Element Bearing ◽  
Modulus Reduction

An efficient linear elastic iterative finite element method, namely, the elastic modulus reduction method is introduced to calculate limit load of frame structure. The elastic modulus reduction method defines the element bearing ratio on the basis of the generalized yield criterion and the strain energy equilibrium principle. Because the bending moment is the main factor inducing the frame structure damage, the element bearing ratio only considering the bending moment yield is proposed. Numerical examples demonstrate the applicability and precision of the elastic modulus reduction method for limit analysis of frame structures.

Element Bearing Ratio Based Integral Safety Evaluation of Penstocks

2013 ◽  
Vol 671-674 ◽  
pp. 1604-1608
Author(s):  
Jian Wang ◽  
Wei Zhang ◽  
Jin Zhang ◽  
Wen Long Wu
Keyword(s):  
Elastic Modulus ◽  
Limit Analysis ◽  
Safety Assessment ◽  
Reduction Method ◽  
Safety Evaluation ◽  
Limit Load ◽  
Adjustment Procedure ◽  
Pressure Pipe ◽  
Element Bearing ◽  
Modulus Reduction

Though it had been employed for limit analysis and integral safety assessment of pressure pipe and vessel, most of the elastic modulus adjustment procedures were applicable to simple structures because their load multiplier was mainly determined by stress. In this paper, a series of element bearing ratio (EBR) based load multiplier algorithms are given, in which the influence of both stress and material on limit load are included. The EBR based load multiplier algorithms are investigated, and two efficient algorithms are suggested. Then the two algorithms combined with the elastic modulus adjustment procedure of elastic modulus reduction method are applied to limit analysis and integral safety assessment of penstocks.

Safety Evaluation of Branch Pipe in Hydropower Station Using Elastic Modulus Reduction Method

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
LuFeng Yang ◽  
Wei Zhang ◽  
Bo Yu ◽  
LiWen Liu
Keyword(s):  
Elastic Modulus ◽  
Reduction Method ◽  
Yield Criterion ◽  
Branch Pipe ◽  
Safety Evaluation ◽  
Limit Load ◽  
Safety Performance ◽  
Upper And Lower Bounds ◽  
Hydropower Station ◽  
Modulus Reduction

The high pressure branch pipe in hydropower station (BPHS) is usually composed by different materials in different parts and has complicated geometric configurations. The accurate and efficient methods for safety evaluation of the BPHS are still desirable. By introducing the element bearing ratio (EBR), generalized yield criterion as well as the reference volume concept, the elastic modulus reduction method (EMRM) is improved and applied to determine both the upper and lower bounds on limit loads of the BPHS. The global safety factor (GSF) is defined as the ratio of limit load to design load. The safety performance of the BPHS is assessed by comparing the GSF resulted from the EMRM with its allowable value specified in code. The efficiency and precision of the proposed method for safety evaluation of the BPHS are demonstrated through numerical examples in this paper. The results show that the proposed method is more suitable for safety evaluation and design optimization of the BPHS, compared with the elastic stress analysis method (ESAM) based on stress categorization which might underestimate the safety performance of the BPHS.

Study on the Strategy of Elastic Modulus Adjustment of the Elastic Modulus Reduction Method for Limit Analysis of Structures Containing Flaws

2010 ◽  
Vol 163-167 ◽  
pp. 655-663
Author(s):  
Wei Zhang ◽  
Li Wen Liu ◽  
Lu Feng Yang
Keyword(s):  
Elastic Modulus ◽  
Limit Analysis ◽  
High Efficiency ◽  
Reduction Method ◽  
Reference Element ◽  
Reference Stress ◽  
Integral Element ◽  
Element Bearing ◽  
Limit Analysis Method ◽  
Modulus Reduction

As a limit analysis method lately presented, the elastic modulus reduction method (EMRM) has the advantages of simplicity and high efficiency. In this paper, the strategy of elastic modulus adjustment of the EMRM is studied in order to extend the method applicable to the limit analysis of structures containing flaws (SCF). Two new algorithms of the reference element bearing ratio, reference element bearing ratio based on reference stress (REBS) and reference element bearing ratio based on integral element bearing ratio gradient (REBG), are proposed. Numerical examples show that the problems of instability and non-convergence in iterative process of limit analysis of SCF are improved, when the REBS or REBG is used in the strategy of elastic modulus adjustment of the EMRM.

Limit Bearing Capacity Analysis of Structure System with Different Types of Element Using Elastic Modulus Reduction Method

2011 ◽  
Vol 189-193 ◽  
pp. 2335-2340
Author(s):  
Wei Zhang ◽  
Lu Feng Yang ◽  
Li Wen Liu
Keyword(s):  
Elastic Modulus ◽  
Bearing Capacity ◽  
Reduction Method ◽  
Capacity Analysis ◽  
Governing Parameter ◽  
Structure System ◽  
Different Types ◽  
Plastic Limit Analysis ◽  
Element Bearing ◽  
Modulus Reduction

Limit bearing capacity analysis of structure system with different types of element (SSDE) is difficult to elastic modulus adjustment procedures. In this paper, elastic modulus reduction method (EMRM) is introduced for evaluation of the limit bearing capacity of SSDE, using the element bearing ratio (EBR) as the governing parameter. As a dimensionless quantity, the EBR can be used to measure the bearing state of every element, and the scheme of reducing elastic modulus can be expressed using a uniform equation for different types of element. When the structure system destroys, all elements will tend to reach their own strength. The algorithm is then extended to the plastic limit analysis of SSDE. Numerical examples are employed to demonstrate the applicability, accuracy and efficiency of the method.

Limit Load Solutions of the Orthotropic Thick-Walled Pipe Subjected to Internal Pressure, Bending Moment and Torsion Moment

2019 ◽  
Author(s):  
Min Xu ◽  
Yujie Zhao ◽  
Binbin Zhou ◽  
Xiaohua He ◽  
Changyu Zhou
Keyword(s):  
Analytical Solution ◽  
Yield Strength ◽  
Internal Pressure ◽  
Yield Criterion ◽  
Bending Moment ◽  
Limit Load ◽  
Pure Bending ◽  
Pure Torsion ◽  
Torsion Moment ◽  
The Difference

Abstract Based on the Hill yield criterion, the analytical solutions of the limit load of orthotropic thick-walled pipes under pure internal pressure, bending moment and torsion are given respectively. The simplified Mises analytical solution and finite element results of limit load for isotropic thick-walled pipe are obtained. The solution verifies the reliability of the analytical solution. The paper discusses the difference of limit load of isotropic and orthotropic pipes under the conditions of pure internal pressure, pure bending moment and pure torsion moment. It is concluded that the influence of material anisotropy on the limit load is significant. The limit load of pipe under pure internal pressure is mainly determined by circumferential yield strength, pure bending is only related to axial yield strength and pure torsion moment is related to the yield strength in the 45° direction and radial yield strength.

scholarly journals A Limit Load Solution for Anisotropic Welded Cracked Plates in Pure Bending

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1764
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Alexander Pirumov ◽  
Dinh Kien Nguyen
Keyword(s):  
Numerical Method ◽  
Yield Criterion ◽  
Plastic Anisotropy ◽  
Bending Moment ◽  
Limit Load ◽  
Vertical Axis ◽  
Pure Bending ◽  
Cracked Plates ◽  
Base Materials ◽  
Assessment Procedures

The present paper’s main objective is to derive a simple upper bound solution for a welded plate in pure bending. The plate contains a crack located in the weld. Both the weld and base materials are orthotropic. Hill’s quadratic yield criterion is adopted. The solution is semi-analytic. A numerical method is only required for minimizing a function of two independent variables. Six independent dimensionless parameters classify the structure. Therefore, the complete parametric analysis of the solution is not feasible. However, for a given set of parameters, the numerical solution is straightforward, and the numerical method is fast. A numerical example emphasizes the effect of plastic anisotropy and the crack’s location on the bending moment at plastic collapse. In particular, the bending moment for the specimen having a vertical axis of symmetry is compared with that of the asymmetric specimen. It is shown that the latter is smaller for all considered cases. The solution found can be used in conjunction with flaw assessment procedures.

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