Low-Volume Road Bridge Alternative

2000 ◽  
Vol 1696 (1) ◽  
pp. 178-186
Author(s):  
B. M. Phares ◽  
F. W. Klaiber ◽  
T. J. Wipf
Keyword(s):  
Finite Element ◽  
Design Methodology ◽  
Structural Engineering ◽  
Element Model ◽  
Analytical Investigation ◽  
Bridge Engineering ◽  
Scale Model ◽  
Small Scale ◽  
Steel Beams ◽  
Concrete Deck

Recent reports indicate that a significant number of the nation’s bridges are either structurally deficient or functionally obsolete. A large number of these bridges are on the secondary road system and fall under the jurisdiction of county engineers with limited budgets and engineering staff. In response to this problem, a bridge replacement system was developed for simple span bridges with minimal to no skew that county engineers can design and build with limited resources. The bridge system involves fabrication of precast units consisting of two steel beams connected with a thin reinforced concrete deck. The precast deck thickness is limited to reduce the weight of the units so that they can be fabricated at one site and then easily transported to the bridge site. Multiple units are then connected on site to give the desired width of bridge, after which a reinforced cast-in-place concrete deck is placed over the entire bridge. Development of the design methodology for the steel beam precast unit bridge consisted of four phases. During the initial phase, small-scale bridge components and a full-scale model bridge were constructed and tested in the Iowa State University Structural Engineering Laboratory. These specimens were tested under a variety of loading configurations under service and ultimate loads. After completion of the laboratory testing, finite-element models of the laboratory bridge were developed and validated with data collected during the first phase. The validated finite-element model was then used to extrapolate analyses of common bridge configurations. The results of the analytical investigation were then combined with classic bridge engineering principles into a design methodology that is easy to use and understand. Although it is not discussed in detail, a demonstration project in which this concept was used has recently been completed and tested.

Dynamic Behavior of Nagawado Arch Dam in the Event of 1984 Naganoken Seibu Earthquake

1987 ◽  
Vol 3 (2) ◽  
pp. 347-364 ◽  
Author(s):  
T. Fujii ◽  
K. Egawa ◽  
I. Katayama
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Arch Dam ◽  
Scale Model ◽  
Small Scale ◽  
Vibration Modes ◽  
Band Pass ◽  
Small Scale Model ◽  
Good Agreement ◽  
Foundation Rock

Nagawado dam, a slender arch dam of 155 m height and 355.5 m chord length, recorded maximum accelerations of 193 and 242 gal at the crown and the 1/4 point of the crest arch, respectively, in the September 14, 1984 Naganoken Seibu earthquake of magnitude 6.8. The maximum accelerations in the foundation rock were in the range of 21 to 31 gal. Fourier analysis and band-pass filtering of corrected accelerograms, and spatial and temporal diagrams of the computed displacements of the dam and the foundation indicate the significant structural modes of peak frequencies 3.3, 3.6, 4.7, and 5.5 Hz. These frequencies correspond to the antisymmetric first, the symmetric first, the symmetric second, and the antisymmetric second modes of the dam. The first three peak frequencies were in good agreement with the values of corresponding vibration modes obtained by a small-scale model test. The derived frequencies and vibration modes were found also compatible with the results of eigenvalue analysis of a preliminary 3-D finite-element model as a whole. Orthogonal sets of accelerograms recorded at the points across a treated fracture zone in the foundation rock did not record any significant relative motions.

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

Energies ◽  
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.

Investigation on the shaft voltage generation of large synchronous turboalternators

2020 ◽  
Vol 39 (5) ◽  
pp. 1145-1156
Author(s):  
Kevin Darques ◽  
Abdelmounaïm Tounzi ◽  
Yvonnick Le-menach ◽  
Karim Beddek
Keyword(s):  
Finite Element ◽  
Design Methodology ◽  
Short Circuit ◽  
Element Model ◽  
Stator Winding ◽  
Content Type ◽  
Voltage Generation ◽  
The Impact ◽  
Investigation Process ◽  
Circulating Currents

Purpose This paper aims to go deeper on the analysis of the shaft voltage of large turbogenerators. The main interest of this study is the investigation process developed. Design/methodology/approach The analysis of the shaft voltage because of several defects is based on a two-dimensional (2D) finite element modeling. This 2D finite element model is used to determine the shaft voltage because of eccentricities or rotor short-circuit. Findings Dynamic eccentricities and rotor short circuit do not have an inherent impact on the shaft voltage. Circulating currents in the stator winding because of defects impact the shaft voltage. Originality/value The original value of this paper is the investigation process developed. This study proposes to quantify the impact of a smooth stator and then to explore the contribution of the real stator winding on the shaft voltage.

scholarly journals A Buckling Flexure-Based Force-Limiting Mechanism

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Jonathan Slocum ◽  
Kenneth Kamrin ◽  
Alexander Slocum
Keyword(s):  
Finite Element ◽  
Design Methodology ◽  
Structural Model ◽  
Cost Effective ◽  
Element Model ◽  
Single Shot ◽  
Excessive Force ◽  
Molding Machine ◽  
Preliminary Model ◽  
Wide Range

A force-limiting buckling flexure has been created which can be used in a wide range of applications where excessive force from an implement can cause harm or damage. The buckling flexure is monolithic, contains no electronics, and can be manufactured using a single shot in an injection molding machine, making it cost effective. In this paper, the design of the flexure is applied to a force-limiting toothbrush as a design study to show its application in a real-world technology. An overview of the buckling flexure is presented, and a structural model is presented to predict when the flexure will elastically buckle. Flexures of different geometries were tested and buckled. The data show that the model can predict buckling of the flexure with an error of 20.84%. A finite element model was also performed which predicts buckling of the flexure within an error of 25.35%. Furthermore, a preliminary model is presented which enables the design of the buckling beam’s displacement, such that the total breakaway deformation can be maximized, making sensing the sudden deformation easier to detect. As part of the application of the buckling flexure, an ergonomic, injection moldable toothbrush was created with the flexure built into the neck of the brush. When the user applies too much force while brushing, the flexure gives way and alerts the user when they have applied too much force; when the user lets off the force, the brush snaps back to its original shape. This design methodology is generalized and can be utilized in other force limited applications where an injection-moldable, pre-set force, and purely mechanical breakaway device is desired.

scholarly journals Numerical analysis of castellated beams with oval openings

2018 ◽  
Vol 195 ◽  
pp. 02008
Author(s):  
Yanuar Setiawan ◽  
Ay Lie Han ◽  
Buntara Sthenly Gan ◽  
Junaedi Utomo
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Main Idea ◽  
Element Model ◽  
Steel Beams ◽  
Good Representation ◽  
Actual Behavior ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
The Web

The use of castellated beams has become more popular in the last two decades. The main idea for the use of these types of steel beams is to reduce their self-weight by providing openings in the web of wide flange (WF) or I sections. Numerous research on castellated beams has been conducted, the majority of the studies aimed to optimize the opening size and the shape configuration of the openings. A numerical analysis of castellated beams with oval openings was performed in this study. The sections under investigation had variations in the height-to-length ratios of the beam. The Do to D and b to Do ratios were kept at a constant. The D value was defined as the height of the beam, while Do is the height of the opening, and b is the width of the opening. The numerical analysis was performed by the finite element analysis using the STRAND7 software. The numerical model was further validated to the experimental data. The results showed that the developed finite element model resulted in a very good representation to the actual behavior of the sections.

Examination of the Transferability of CTOA From Small-Scale DWTT to Full-Scale Pipe Geometries Using a Cohesive Zone Model

2020 ◽  
Author(s):  
Chris Bassindale ◽  
Xin Wang ◽  
William R. Tyson ◽  
Su Xu
Keyword(s):  
Finite Element ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Element Model ◽  
Full Scale ◽  
Opening Angle ◽  
Small Scale ◽  
Zone Model ◽  
Pipe Model ◽  
Good Agreement

Abstract In this work, the cohesive zone model (CZM) was used to examine the transferability of the crack tip opening angle (CTOA) from small-scale to full-scale geometries. The pipe steel STPG370 was modeled. A drop-weight tear test (DWTT) model and pipe model were studied using the finite element code ABAQUS 2017x. The cohesive zone model was used to simulate crack propagation in 3D. The CZM parameters were calibrated based on matching the surface CTOA measured from a DWTT finite element model to the surface CTOA measured from the experimental DWTT specimen. The mid-thickness CTOA of the DWTT model was in good agreement with the experimental value determined from E3039 and the University of Tokyo group’s load-displacement data. The CZM parameters were then applied to the pipe model. The internal pressure distribution and decay during the pipe fracture process was modeled using the experimental data and implemented through a user-subroutine (VDLOAD). The mid-thickness CTOA from the DWTT model was similar to the mid-thickness CTOA from the pipe model. The average surface CTOA of the pipe model was in good agreement with the average experimental value. The results give confidence in the transferability of the CTOA between small-scale specimens and full-scale pipe.

Effects of Diameter to Thickness Ratio and External Pressure on the Velocity of Dynamic Buckle Propagation in Offshore Pipelines

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Z. Omrani ◽  
K. Abedi ◽  
A. R. Mostafa Gharabaghi
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Element Model ◽  
External Pressure ◽  
Thickness Ratio ◽  
Small Scale ◽  
Element Analysis ◽  
Models Comparison ◽  
Buckle Propagation ◽  
Exerted Pressure

In this paper, a numerical study of the dynamic buckle propagation, initiated in long pipes under external pressure, is presented. For a long pipe, due to the high exerted pressure, local instability is likely to occur; therefore, the prevention of its occurrence and propagation are very important subjects in the design of pipelines. The 3D finite element modeling of the buckle propagation is presented by considering the inertia of the pipeline and the nonlinearity introduced by the contact between its collapsing walls. The buckling and collapse are assumed to take place in the vacuum. The numerical results of the nonlinear finite element analysis are compared with the experimental results obtained by Kyriakides and Netto (2000, “On the Dynamics of Propagating Buckle in Pipelines,” Int. J. Solids Struct., 37, pp. 6843–6878) from a study on the small-scale models. Comparison shows that the finite element results have very close agreement with those of the experimental study. Therefore, it is concluded that the finite element model is reliable enough to be used for nonlinear collapse analysis of the dynamic buckle propagation in the pipelines. In this study, the effects of external pressure on the velocity of dynamic buckle propagation for different diameter to thickness ratios are investigated. In addition, the mathematical relations, based on the initiation pressure, are derived for the velocity of buckle propagation considering the diameter to thickness ratio of the pipeline. Finally, a relation for the buckle velocity as a function of the pressure and diameter to thickness ratio is presented.

Simulation of Behaviors of a One-Third Scale Containment Model Test

2017 ◽  
Author(s):  
Guopeng Ren ◽  
Rong Pan ◽  
Feng Sun
Keyword(s):  
Finite Element ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Nuclear Power ◽  
Element Model ◽  
Scale Model ◽  
Prestress Losses ◽  
The Finite Element Model

Reactor containment of a nuclear power plant is a structure to ensure the safety of nuclear power plant. It acts as the last barrier to prevent the release of radioactive materials from NPP during accidents. Finite element models were established to simulate a 1/3 scale model of a reactor containment building under leakage test pressure. General finite element software ANSYS were applied. The nonlinear behavior of containment materials, geometric were taken into account in the analysis. The reliability of the finite element model was verified through the comparison of theoretical analysis results with experimental results. In the ANSYS finite element model, the concrete, steel bars and prestress tendons were separated and the prestress tendons were considered by the method of cooling method on the prestress tendon elements. The mechanical properties of the finite element model in the prestress tension process and the absolute internal pressure of 0.52MPa were analyzed. Transient and time dependent losses were taken into account at the same time during the calculation of prestress of tendons, so as to calculate effective prestress at different locations of tendons. Calculation results of prestress losses show that the prestress losses at the hole of equipment hatch are larger than the other areas. The results show that, the deformation of over-all structure of the containment is shrink inward under the action of prestress. And the simulation can achieve the consistent deformation effect between tendons and concrete. The maximum radial displacement of the whole containment structure is located at of 10 ° ∼ 20 °area on the right of the hole of the gate. The effect of expansion deformation of the containment caused by design internal pressure is insufficient to offset the inward shrink effect generated by tendons, and the over-all structure of the concrete containment scale model is mainly under compressive stress. The containment test model is still with a large safety margin under the action of design internal pressure. The largest tensile stress is on the up and down areas of the internal sides of the equipment hatch, dome area close to ring beam, and bottom of perimeter wall close to the base slab. There is possibility of cracking on the concrete in limited local zones. This benchmark can provide a reference for engineering design of containment.

Thermal Effects on the Anchoring of Flexible Pipe Tensile Armors

2015 ◽  
Author(s):  
Olaf O. Otte Filho ◽  
Rafael L. Tanaka ◽  
Rafael G. Morini ◽  
Rafael N. Torres ◽  
Thamise S. V. Vilela
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Effects ◽  
Current Model ◽  
Element Model ◽  
Small Scale ◽  
Flexible Pipe ◽  
System A ◽  
Flexible Pipes ◽  
Better Than

In the design of flexible pipes, predict the anchoring behavior on end fittings is always challenging. In this sense, Prysmian Surflex has developed a finite element model, which should help the end fitting design as well the prediction of the structural behavior and the acceptable maximum loads. The current model considers that the contact between armor-resin is purely cohesive and has been suitable for the design of end fittings [1] and [2]. But tests and new studies [3] and [4] indicate that only cohesive assumption would not be the best approach. Experimental data from prototype tests also show that the current model would not predict acceptable results for loads higher than those used in previous projects. This document will describe a study developed considering the friction and thermal contraction, instead of the cohesive phenomenon in the anchoring behavior analysis. Small scale tests were conducted in order to understand the anchoring relation between the resin and the wire used in the tensile armor. For this purpose, a special test device was developed to simulate an enclosure system. A parametric study was also performed to identify the cooling temperatures, coefficients of friction and contact properties parameters taken from small scale tests. The finite element model considers the thermal effects during exothermic curing. Using the new parameters obtained, a second model was developed. This model consists of only one real shaped bended wire inside an end fitting cavity. To validate the model, samples were tested on laboratory according anchoring design. The results of this round of tests were studied and corroborate the argument that use friction and thermal effects is better than use only the cohesive condition.

Stress Concentration Factors of Dented Pipelines

2006 ◽  
Author(s):  
Bianca de Carvalho Pinheiro ◽  
Ilson Paranhos Pasqualino ◽  
Se´rgio Barros da Cunha
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Numerical Model ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Element Model ◽  
Small Strain ◽  
Small Scale ◽  
Concentration Factors ◽  
Stress Concentration Factors

A nonlinear finite element model was developed to assess stress concentration factors induced by plain dents on steel pipelines subjected to cyclic internal pressure. The numerical model comprised small strain plasticity and large rotations. Six small-scale experimental tests were carried out to determine the strain behavior of steel pipe models during denting simulation followed by the application of cyclic internal pressure. The finite element model developed was validated through a correlation between numerical and experimental results. A parametric study was accomplished, with the aid of the numerical model, to evaluate stress concentration factors as function of the pipe and dent geometries. Finally, an analytical formulation to estimate stress concentration factors of dented pipelines under internal pressure was proposed. These stress concentration factors can be used in a high cycle fatigue evaluation through S-N curves.

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