Effect of Cushion Layers on Mechanical Characteristics of Spiral Case Structure in Hydropower Station

2013 ◽  
Vol 351-352 ◽  
pp. 897-900
Author(s):  
Bo Liu ◽  
Jian Hua Liu ◽  
Zhe Wang
Keyword(s):  
Mechanical Characteristics ◽  
Poisson Ratio ◽  
Water Pressure ◽  
Deformation Modulus ◽  
Hydropower Station ◽  
Finite Element Program ◽  
Load Bearing ◽  
Spiral Case ◽  
Element Program ◽  
Cushion Layer

The effects of deformation modulus, thickness and range of cushion layer on mechanical characteristics of spiral case in hydropower station has been analyzed using the finite element program ANSYS and nonlinear contact theory. The result shows that when cushion layer scope and poisson ratio is fixed, as the elastic modulus of cushion layer decreases, the deformation and stress of spiral case increases, surrounding concrete load-bearing ratio of water pressure reduces. If the cushion layer deformation modulus is fixed and the range of cushion layer extends to 10 degree site bellow the waist of spiral case, the steel spiral case stress decrease, the radial stress transferred from the spiral case to surrounding concrete increase by about from 0.01MPa to 0.03MPa, and load-bearing ratio of concrete increase, when the cushion layer Poisson ratio increases from 0.25 to 0.35.

Study on Friction Coefficient of Spiral Case with Cushion Layer in Large-Scale Hydropower Plant

2011 ◽  
Vol 71-78 ◽  
pp. 4248-4251
Author(s):  
Jian Wei Zhang ◽  
Yi Na Zhang ◽  
Shu Fang Yuan
Keyword(s):  
Coefficient Of Friction ◽  
Large Scale ◽  
Water Pressure ◽  
Structural Type ◽  
Hydropower Plant ◽  
Finite Element Program ◽  
Spiral Case ◽  
Element Program ◽  
Cushion Layer ◽  
Elastic Cushion

Elastic cushion layer between the steel spiral case and surrounding concrete is often used as a structural type in large-scale hydropower plant in China. In view of the uncertainty of the optimal elastic coefficient of friction and the transfer mechanism of internal water pressure to the surrounding concrete, Spiral case with cushion layer of large-scale hydropower plant is simulated with ANSYS nonlinear finite element program, considering the slip contact characteristics between steel spiral case and the surrounding concrete, the more reasonable coefficient of friction between the steel spiral case and concrete is studied. This provides reliable theoretical analysis for the design of large-scale hydropower plants.

Study on Optimization under Internal Water Pressure of Spiral Case of Hydropower Station

2013 ◽  
Vol 438-439 ◽  
pp. 834-838
Author(s):  
Xin Yong Xu ◽  
Ying Bin Kang ◽  
Di Zhang
Keyword(s):  
Numerical Model ◽  
Working Conditions ◽  
Mechanical Characteristics ◽  
Simulation Analysis ◽  
Water Pressure ◽  
Hydropower Station ◽  
Internal Water ◽  
Nonlinear Contact ◽  
Spiral Case ◽  
Case Structure

Based on the ANSYS program, a numerical model of spiral case structure of hydropower station is built. The nonlinear contact characteristics are introduced in this model. For the working conditions under the different internal water pressure, structural simulation analysis is conducted. The effect of the internal water pressure on the structure, and the mechanical characteristics and stress of reinforcement are analyzed. The evolution process of concrete cracks, from microscopic period to macroscopic period is exhibited. The reasonable scheme of optimization under internal water pressure is attained.

Predicting the behaviour of storage cells in early Condeep structures

2016 ◽  
Vol 43 (7) ◽  
pp. 643-656 ◽  
Author(s):  
Amr I.I. Helmy ◽  
Michael P. Collins
Keyword(s):  
Cell Wall ◽  
Size Effect ◽  
Shear Failure ◽  
Water Pressure ◽  
Scale Model ◽  
Finite Element Program ◽  
3 Dimensional ◽  
Stress Strain Relation ◽  
Element Program ◽  
Storage Cells

RASP, also now called VecTor6, is a nonlinear finite element program for the analysis of reinforced concrete structures that uses 3-dimensional stress–strain relation of cracked concrete based on the modified compression field theory. RASP was used to predict the behavior of a 3-dimensional 1:13 scale model of a typical upper dome-cell wall junction of a storage cell in an early Condeep structure. It predicted a flexure-shear failure at the top of the cell wall when it was subjected to a pressure differential equivalent to 129–134 m head of water. Yet, there was deviation between the theoretical and the observed response of the model since the analysis ignored the detrimental effect of water pressure in the cracks. Before applying the results of the pressure test on the scale model to the prototype structure the size effect in shear was examined. It was concluded that because the failure was triggered by flexural yielding the size effect in shear was not significant for this case.

scholarly journals PLASTIC CAPACITY OF BOLTED RHS FLANGE-PLATE JOINTS UNDER AXIAL TENSION

2016 ◽  
Vol 8 (3) ◽  
pp. 85-93
Author(s):  
Andrej Mudrov ◽  
Gintas Šaučiuvėnas ◽  
Antanas Sapalas ◽  
Ivar Talvik
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Finite Element Program ◽  
Load Bearing ◽  
Axial Tension ◽  
Flange Thickness ◽  
Element Program ◽  
Two Sides ◽  
Ansys Workbench

This article considers the calculation of load-bearing capacity of flange-plate joints with bolts along two sides of rectangular hollow sections (RHS) under axial tension. It provides a review and comparison of various calculation methodologies for establishing the load-bearing capacity of RHS flange-plate joints, such as suggested in EN 1993-1-8:2005 and STR 2.05.08:2005 as well as those proposed in different countries and by other authors. Common design principles and derived results for load-bearing capacity of flange-plate joints have been analysed and compared. Following the numerical modelling, which has been done using ANSYS Workbench finite element program, the derived results for load-bearing capacity have been compared with analytical load-bearing capacity results for flange-plate joints of the same structure. The analysis has focused on one type of flange-plate joints with bolts – both preloaded and non-preloaded – along two opposite sides of the tube, with the flange thickness of 15 mm and 25 mm.

scholarly journals A numerical parametric study on the efficiency of prestressed geogrid reinforced soil

2020 ◽  
Vol 205 ◽  
pp. 12004
Author(s):  
Soukat Kumar Das ◽  
N. K. Samadhiya
Keyword(s):  
Energy Requirement ◽  
Reinforced Soil ◽  
Shallow Foundation ◽  
Finite Element Program ◽  
Load Bearing ◽  
Total Input ◽  
Ground Conditions ◽  
Element Program ◽  
Numerical Parametric Study ◽  
The Impact

Prestressing geosynthetics offers a rapid and safe method of improving the poor ground conditions. This paper aims to find out the effect of prestressing the geogrid layer on load bearing and settlement performance. This study also takes into account the impact of the size, depth of placement and the adjacency of footing, for unreinforced (UR), geogrid reinforced (GR) and prestressed geogrid reinforced (PGR) soil on the load-bearing and the settlement characteristics by using the finite element program Plaxis 3D. Based on numerical simulation, it appears that PGR soil can enhance the bearing pressure of the UR soil by almost 500% and reduced the settlement by nearly 88 % by reducing the energy consumption. The footing placed at higher depths for PGR soil gives better performance as compared to GR soil. Moreover, placing two adjacent square footing increases the interference zone of PGR soil by 67% as compared to UR soil. This method can be instrumental in reducing the total input energy requirement to achieve a certain settlement during placement of shallow foundation for various important structures while being economic simultaneously.

Research on Optimizing Precast Water Head on Preloading Filling Spiral Case of a Large-Scale Hydropower Station

2011 ◽  
Vol 243-249 ◽  
pp. 6183-6187
Author(s):  
Hai Lin Wu ◽  
Shi He Qin ◽  
Yao Li ◽  
Xiao Fan Du
Keyword(s):  
Finite Element Method ◽  
Large Scale ◽  
Mechanical Characteristics ◽  
Nonlinear Finite Element ◽  
Hydropower Station ◽  
Nonlinear Finite Element Method ◽  
Contact State ◽  
Water Head ◽  
Spiral Case ◽  
Pumped Storage

In combination with the practice of a pumped storage hydropower station, a 3-D nonlinear finite element method on the preloading filling spiral case is carried out to compare and analyze stresses of the steel spiral case and hoop reinforcement, the stress and bearing ratio of the surrounding concrete, the contact state between the spiral case and concrete in different precast water head. The results indicate that the stress of the surrounding concrete will get better with the increasing of precast water head. But there is a distance between the spiral case and the surrounding concrete when the water head is excessive, which is unhelpful for operating of the unit. When the precast water head of the spiral case is 439m or so, it can play a greater degree of mechanical characteristics of steel and concrete under the premise of operating stably of the unit.

Investigation on Mechanical Behavior of Hydrological Tower

2011 ◽  
Vol 243-249 ◽  
pp. 4524-4527
Author(s):  
Hui Xiong ◽  
Zheng Liang Li ◽  
Nuan Deng
Keyword(s):  
Finite Element ◽  
Composite Structure ◽  
Mechanical Characteristics ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Element Model ◽  
Finite Element Program ◽  
Safety And Reliability ◽  
Element Program ◽  
Static Performance

The safety and reliability of hydrological tower play an important role in the security and accuracy of the hydrological measurement. In order to simulate the space mechanical characteristics of the composite structure of tower with guy lines accurately, the finite element program is used to establish a precise three dimensional space finite element model. The structural strength and stability was also analyzed. Meanwhile, the static performance and vibration characteristics of the tower with guy lines was compared with the ones of the tower with none guy lines. The results show that the mechanical characteristics of composite structure are similar to the ones of continuous beams with lateral bearing spring. The guy lines rationalize the force distribution on structures, enhance the structural bearing capacity, and increase the structural stiffness. In addition, the paper can be a reference for the analysis of hydrological towers in aspects of numerical analysis, design methods and data.

Analysis of Ultimate Load-Bearing Capacity of Long-Span CFST Arch Bridges

2011 ◽  
Vol 90-93 ◽  
pp. 1149-1156 ◽  
Author(s):  
Yang Liu ◽  
Da Wang ◽  
Yi Zhou Zhu
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Ultimate Load ◽  
Elastic Buckling ◽  
Load Bearing Capacity ◽  
Finite Element Program ◽  
Load Bearing ◽  
Linear Elastic ◽  
Long Span ◽  
Element Program

In order to study the ultimate load-bearing capacity of the long-span concrete-filled steel tubular (CFST) arch bridge with fly-bird-type, the ANSYS finite element program was used to establish its special model, and to study ultimate load-bearing capacity of this bridge with three different methods. The constitutive relation factors of concrete-filled steel tubular was taken into consideration including confining effect ultimate load coefficients, failure modes, and load-displacement curves of this bridge under different cases. The result indicate that the ultimate load-bearing capacity of the bridge can meet the requirement, all of its failure modes is out-plane, the two methods, linear elastic buckling analysis and only geometric nonlinearity analysis, will over high estimate ultimate load-bearing capacity of this bridge, and linear elastic buckling method cannot reflect real failure mode of this structure. In order to correctly estimate the ultimate load-bearing capacity of the bridge structure, the effect of geometric and material double nonlinearity couldn’t be neglected.

Sensitivity Analysis of Large Unit Spiral Case for Different Reinforcement Arrangement

2011 ◽  
Vol 474-476 ◽  
pp. 1855-1858
Author(s):  
Xin Yong Xu ◽  
Jian Wei Wang ◽  
Zhen Yue Ma
Keyword(s):  
Sensitivity Analysis ◽  
Numerical Model ◽  
Mechanical Characteristics ◽  
Reinforcement Ratio ◽  
Hydropower Station ◽  
Large Unit ◽  
Steel Bar ◽  
Spiral Case ◽  
The Impact ◽  
Ratio Range

A numerical model for spiral case of hydropower station is built. The contact is considered and the sensitivity analysis for different reinforcement ratio is analyzed. The impact of different ratios on structure is studied. The stress and mechanical characteristics of steel bar is analyzed. The contact status is taken. The rational reinforcement ratio range, the process and evolution regularity of concrete cracks from microcosmic aspect to macroscopic aspect are obtained.

scholarly journals Influence of Tunneling in Cohesionless Soil for Different Tunnel Geometry and Volume Loss under Greenfield Condition

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Raja Kanagaraju ◽  
Premalatha Krishnamurthy
Keyword(s):  
Free Field ◽  
Deformation Modulus ◽  
Cohesionless Soil ◽  
Support Pressure ◽  
Measuring Instruments ◽  
Volume Loss ◽  
Tunnel Face ◽  
Finite Element Program ◽  
Element Program ◽  
Tunnel Size

This paper presents the numerical analysis of settlement to profile the vulnerable zone or influence zone due to tunneling activities in cohesionless deposits for free field or Greenfield conditions. The analysis considers the factors like saturated density (γsat), unsaturated density (γunsat), angle of shearing resistance (φ), deformation modulus (ES), volume loss (VL), and the support pressure of the shield head at the tunnel face. The obtained results using a finite element program (FEM) PLAXIS 3D are compared with measured and predicted surface settlement using field measuring instruments, and analytical and empirical solution show a reasonable agreement and are found to be conservative. From literature, for Greenfield condition the ground settlement equal to 10 mm is taken as the minimum value to map the influencing zone considering the fact that the structure which lies beyond this zone would undergo negligible settlement. Settlement trough and 10 mm settlement contour characteristics are presented for different tunnel sizes placed at the same depth and the same tunnel size placed at different depths, respectively. Various influencing zones are arrived for the sandy grounds of different denseness based on the parametrical studies involving parameters such as tunnel size “D,” tunnel axis depth “z,” and volume loss “VL.”

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