Bridge Decks: Mitigation of Cracking and Increased Durability—Phase III

Early-age cracking in concrete decks significantly reduces the service life of bridges. This report discusses the application of various concrete mixtures that include potential early mitigation ingredients. Large-scale (7 ft × 10 ft) experimental bridge prototypes with similar restraint conditions found in actual bridges were poured with different concrete mixtures to investigate mitigation techniques. Portland cement (control), expansive Type K cement, internally cured lightweight aggregate (LWA), shrinkage-reducing admixture (SRA), and gypsum mineral were investigated as mitigating ingredients. Seven concrete mixtures were prepared by using individual ingredients as well as a combination of different ingredients. The idea behind combining different mitigating techniques was to accumulate the combined benefit from individual mitigating materials. The combined Type K cement and LWA mixture showed higher concrete expansion compared with mixtures containing Portland cement, Type K cement, LWA, and SRA in the large-scale experimental deck. Extra water provided by LWA significantly enhanced the performance of Type K cement’s initial expansion as well as caused larger total shrinkage over the drying period. A combination of Type K cement and gypsum mineral showed insignificantly higher expansion compared with the individual Type K mixture. Overall, the experimental deck containing SRA showed the least total shrinkage compared with other mixtures. Finite-element modeling was performed to evaluate and predict concrete stress-strain behavior due to shrinkage in typical bridges. A parametric study using finite-element analysis was conducted by altering the structure of the experimental deck. More restraint from internal reinforcement, less girder spacing, larger girder flange width, and more restrictive support conditions increased the concrete tensile stress and led to potential cracking in the concrete deck.

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Stator Non-Uniform Radial Ventilation Design Methodology for a 15 MW Turbo-Synchronous Generator Based on Single Ventilation Duct Subsystem

Energies ◽

10.3390/en14102760 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2760

Author(s):

Ruiye Li ◽

Peng Cheng ◽

Hai Lan ◽

Weili Li ◽

David Gerada ◽

...

Keyword(s):

Finite Element ◽

Temperature Distribution ◽

Design Methodology ◽

Large Scale ◽

Synchronous Generator ◽

Axial Direction ◽

Scale Model ◽

Element Analysis ◽

Axial Temperature ◽

Ventilation Duct

Within large turboalternators, the excessive local temperatures and spatially distributed temperature differences can accelerate the deterioration of electrical insulation as well as lead to deformation of components, which may cause major machine malfunctions. In order to homogenise the stator axial temperature distribution whilst reducing the maximum stator temperature, this paper presents a novel non-uniform radial ventilation ducts design methodology. To reduce the huge computational costs resulting from the large-scale model, the stator is decomposed into several single ventilation duct subsystems (SVDSs) along the axial direction, with each SVDS connected in series with the medium of the air gap flow rate. The calculation of electromagnetic and thermal performances within SVDS are completed by finite element method (FEM) and computational fluid dynamics (CFD), respectively. To improve the optimization efficiency, the radial basis function neural network (RBFNN) model is employed to approximate the finite element analysis, while the novel isometric sampling method (ISM) is designed to trade off the cost and accuracy of the process. It is found that the proposed methodology can provide optimal design schemes of SVDS with uniform axial temperature distribution, and the needed computation cost is markedly reduced. Finally, results based on a 15 MW turboalternator show that the peak temperature can be reduced by 7.3 ∘C (6.4%). The proposed methodology can be applied for the design and optimisation of electromagnetic-thermal coupling of other electrical machines with long axial dimensions.

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Cord/Rubber Material Properties

Rubber Chemistry and Technology ◽

10.5254/1.3536096 ◽

1985 ◽

Vol 58 (4) ◽

pp. 830-856 ◽

Cited By ~ 20

Author(s):

R. J. Cembrola ◽

T. J. Dudek

Keyword(s):

Finite Element ◽

Material Model ◽

Rubber Composites ◽

Stress Strain ◽

Element Analysis ◽

Rubber Layer ◽

Strain Behavior ◽

Nonlinear Stress ◽

Interlaminar Shear ◽

Mechanics Of Composite Materials

Abstract Recent developments in nonlinear finite element methods (FEM) and mechanics of composite materials have made it possible to handle complex tire mechanics problems involving large deformations and moderate strains. The development of an accurate material model for cord/rubber composites is a necessary requirement for the application of these powerful finite element programs to practical problems but involves numerous complexities. Difficulties associated with the application of classical lamination theory to cord/rubber composites were reviewed. The complexity of the material characterization of cord/rubber composites by experimental means was also discussed. This complexity arises from the highly anisotropic properties of twisted cords and the nonlinear stress—strain behavior of the laminates. Micromechanics theories, which have been successfully applied to hard composites (i.e., graphite—epoxy) have been shown to be inadequate in predicting some of the properties of the calendered fabric ply material from the properties of the cord and rubber. Finite element models which include an interply rubber layer to account for the interlaminar shear have been shown to give a better representation of cord/rubber laminate behavior in tension and bending. The application of finite element analysis to more refined models of complex structures like tires, however, requires the development of a more realistic material model which would account for the nonlinear stress—strain properties of cord/rubber composites.

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An Efficient 3D-to-2D Reduction Technique for Frequency-Domain Layered Finite Element Analysis of Large-Scale High-Frequency Integrated Circuits

2007 IEEE Electrical Performance of Electronic Packaging ◽

10.1109/epep.2007.4387185 ◽

2007 ◽

Cited By ~ 4

Author(s):

Feng Sheng ◽

Sourav Chakravarty ◽

Dan Jiao

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Integrated Circuits ◽

Frequency Domain ◽

High Frequency ◽

Large Scale ◽

Reduction Technique ◽

Element Analysis

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The Finite Element Analysis of the Large-Scale Converter Transformer Valve Side of the Electric Field

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.325-326.476 ◽

2013 ◽

Vol 325-326 ◽

pp. 476-479 ◽

Cited By ~ 1

Author(s):

Lin Suo Zeng ◽

Zhe Wu

Keyword(s):

Finite Element ◽

Electric Field ◽

Large Scale ◽

Calculation Model ◽

Simulation Software ◽

Field Calculation ◽

Element Analysis ◽

Ansys Simulation ◽

The Finite Element Analysis ◽

Electric Field Calculation

This article is based on finite element theory and use ANSYS simulation software to establish electric field calculation model of converter transformer for a ±800kV and make electric field calculation and analysis for valve winding. Converter transformer valve winding contour distribution of electric field have completed in the AC, DC and polarity reversal voltage.

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Experimental Study on Mechanical Property of Stiffening-ribbed-hollowpipe Reinforced Concrete Girderless Floor with Four Clamped Edges Supported

The Open Civil Engineering Journal ◽

10.2174/1874149501307010170 ◽

2013 ◽

Vol 7 (1) ◽

pp. 170-178 ◽

Cited By ~ 3

Author(s):

Weijun Yang ◽

Yongda Yang ◽

Jihua Yin ◽

Yushuang Ni

Keyword(s):

Mechanical Property ◽

Finite Element Analysis ◽

Finite Element ◽

Reinforced Concrete ◽

Large Scale ◽

Load Test ◽

Static Load Test ◽

Loading Test ◽

Element Analysis ◽

Clamped Edges

In order to study the basic mechanical property of cast-in-place stiffening-ribbed-hollow-pipe reinforced concrete girderless floor, and similarities and differences of the structural performance compared with traditional floor, we carried out the destructive stage loading test on the short-term load test of floor model with four clamped edges supported in large scale, and conducted the long-term static load test. Also, the thesis conducted finite element analysis in virtue of ANSYS software for solid slab floor, stiffening-ribbed-hollow-pipe floor and tubular floor. The experiment indicates that the developing process of cracks, distribution and failure mode in stiffening-ribbed-hollow-pipe floor are similar to that of solid girderless floor, and that this kind of floor has higher bearing capacity and better plastic deformation capacity. The finite element analysis manifests that, compared with solid slab floor, the deadweight of stiffening-ribbed-hollow-pipe floor decreases on greater level while deformation increases little, and that compared with tubular floor, this floor has higher rigidity. So stiffening-ribbed-hollow-pipe reinforced concrete girderless floor is particularly suitable for long-span and large-bay building structure.

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Dynamic Analysis of Large-Scale Power House

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.446-449.837 ◽

2012 ◽

Vol 446-449 ◽

pp. 837-840

Author(s):

Yu Zhao ◽

Shu Fang Yuan ◽

Jian Wei Zhang

Keyword(s):

Finite Element ◽

Dynamic Characteristics ◽

Large Scale ◽

Three Dimensional ◽

Dynamic Responses ◽

Dynamic Loads ◽

Element Analysis ◽

Power House ◽

Dimensional Finite Element ◽

Three Dimensional Finite Element

The underwater structure of power house is major structure under the dynamic loads of unit. The vibration problem is very common in operation. So the structures should have sufficient stiffness to resist dynamic loads of unit. This paper establishes three-dimensional finite element models with finite element analysis software—ANSYS. Dynamic characteristics of the power house and dynamic responses of structure under earthquake are analyzed. The results of the computation show that fluid-solid coupling may be ignored when studying dynamic characteristics of structures of the underground power house.

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