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.

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.

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.

On the Carrying Capacity of Plates of Arbitrary Shape and Variable Fixity Under a Concentrated Load

1958 ◽  
Vol 25 (4) ◽  
pp. 598-602
Author(s):  
M. Zaid
Keyword(s):  
Carrying Capacity ◽  
Arbitrary Shape ◽  
Plastic Material ◽  
Yield Criterion ◽  
Limit Load ◽  
Upper And Lower Bounds ◽  
General Shape ◽  
Concentrated Load ◽  
Load Location ◽  
Unit Yield

Abstract The previously known limit-load solution for a circular plate, with a centrally concentrated load, is extended to include a plate of general shape and fixity with arbitrary load location. Considering an ideally plastic material that obeys the Tresca yield criterion, this limit load is equal to 2π times the unit yield moment (M0). The techniques of this paper can be used to establish upper and lower bounds to the limit load for plates under other loading conditions.

Sign in / Sign up

Export Citation Format

Share Document