Analyses for Lateral Deflection of Railroad Track Under Quasi-Static Loading

2013 ◽  
Author(s):  
David Y. Jeong
Keyword(s):  
Static Loading ◽  
Fourier Method ◽  
Vertical Plane ◽  
Lateral Force ◽  
Railroad Track ◽  
Lateral Deflection ◽  
Lateral Resistance ◽  
Mathematical Expressions ◽  
Lateral Plane ◽  
Pull Tests

This paper describes analyses to examine the lateral deflection of railroad track subjected to quasi-static loading. Rails are assumed to behave as beams in bending. Movement of the track in the lateral plane is constrained by idealized resistance characteristics, while movement in the vertical plane is resisted by a continuous, linear and elastic foundation. These analyses are based on solving the ordinary differential equations for beam deflections. In certain cases, convenient mathematical expressions may be used to represent idealized lateral resistance characteristics and derive closed-form equations to relate lateral force as a function of track lateral deflection. However, in general, the idealized lateral resistance characteristic may be nonlinear, in which case numerical methods are required to examine the lateral load versus track lateral deflection behavior. In these general cases, a Fourier series technique is used to solve the governing equations numerically. The analysis of track lateral deflection subjected to quasi-static loads may be applied to examine track shift. For example, lateral resistance of track may be measured using Track Lateral Pull Tests (TLPT). The Fourier method is also used to examine the relationship between lateral and vertical wheel loads and track lateral shift.

Structural Systems for Mass Timber Buildings

2019 ◽  
Author(s):  
Tim Gleason ◽  
Gordana Herning ◽  
John Klein
Keyword(s):  
Affordable Housing ◽  
Lateral Force ◽  
Timber Structures ◽  
Braced Frames ◽  
Conventional Concrete ◽  
Composite Systems ◽  
Lateral Resistance ◽  
Mass Timber ◽  
Story Building ◽  
Gravity System

<p>This paper investigates the design of lateral force resisting systems (LFRS) for multi-story mass timber structures in Boston, MA. Structural and environmental tradeoffs of replacing conventional concrete cores or steel braced frames with glue-laminated timber (GLT) braced frames are evaluated through numerical analyses of 8-, 12-, and 18-story building prototypes. Finding an optimal timber gravity system configuration is followed by examining lateral resistance of the prototypes. The resulting designs demonstrate a practical approach to assist designers in selecting a lateral system during the early stages of conceptual design. This research was conducted in parallel with a related study for implementation of mass timber in affordable housing in Boston, enabling a comparison between composite systems and all-timber structures.</p>

On the Effects of the USP on the Lateral Resistance of Ballasted Railway Tracks

2018 ◽  
Author(s):  
Giovanni Pio Pucillo ◽  
Antonio De Iorio ◽  
Stefano Rossi ◽  
Mario Testa
Keyword(s):  
High Speed ◽  
Maintenance Costs ◽  
Speed Reduction ◽  
Track Geometry ◽  
Vertical Stiffness ◽  
Railway Tracks ◽  
Lateral Resistance ◽  
Lateral Plane ◽  
Track Vertical Stiffness ◽  
Proper Values

From the advent of high-speed (HS) railways and with increasing traffic-induced loads transmitted to the superstructure, maintenance costs due to track geometry degradation have become a crucial problem for researchers and railway administrations. Moreover, the operations of ballast renewal, track tamping, and track re-alignment, that are indispensable to guarantee a good track geometry, have dramatic effects on the tie-ballast lateral resistance, which in turn reduce the track flexural strength in the lateral plane and increase the proneness of railway tracks made of continuous welded rails (CWR) to experience either progressive lateral shift of the track panel or thermal track buckling phenomena. To restore proper values of the tie-ballast lateral resistance, railway technicians either impose a speed reduction or compact the ballast bed mechanically by mean of the dynamic track stabilizing machines. Recently, elastic elements in railway tracks are receiving more and more attention due to their ability to reduce track geometry degradation and to attenuate noise and vibrations. Under Tie Pads, or Under Sleeper Pads (USP), guarantee better homogenization of the track vertical stiffness and have received more attention due to their ability to reduce maintenance costs. Most published studies focused their attention to USPs’ attitude to improve track performances in terms of dynamic impact force mitigation and track quality improvement; however, with few exceptions, no available literature exists on lateral resistance of ballasted track with USP, and some question still remains whether or not the lateral resistance is improved by USP. In this study, the experimental results of about 40 lateral resistance tests carried out in situ are reported and discussed. The tests were performed with the Discrete Cut Panel Pull Test (DCPPT) technique on three type of concrete ties, with and without USP; each type of tie and the related track conditions (ballast thickness, subgrade thickness and composition, shoulder width, ballast wall, etc.) were representative of specific track conditions, namely traditional tracks, high-speed lines and gallery. The tests were carried out in loaded and unloaded track conditions, in compacted and just-laid track conditions. In compacted ballast conditions the peak lateral resistance due to USPs can increase up to 20% — depending on the material used — and this variation is almost constant in the bedding modulus range considered in this study, which was quite well representative of typical static bedding modulus values of actual USPs. Even higher advantages seem to be achievable with softer USPs in weak or just-tamped ballast conditions.

scholarly journals Evaluating additive manufacturing for the production of custom head supports: A comparison against a commercial head support under static loading conditions

2020 ◽  
Vol 234 (5) ◽  
pp. 458-467
Author(s):  
Jonathan D Howard ◽  
Dominic Eggbeer ◽  
Peter Dorrington ◽  
Feras Korkees ◽  
Lorna H Tasker
Keyword(s):  
Additive Manufacturing ◽  
Static Loading ◽  
Computer Aided Design ◽  
Rear Surface ◽  
Cost Effective ◽  
Lateral Force ◽  
Maximum Displacement ◽  
Wheelchair Users ◽  
Continuous Filament ◽  
Aided Design

The provision of wheelchair seating accessories, such as head supports, is often limited to the use of commercial products. Additive manufacturing has the potential to produce custom seating components, but there are very few examples of published work. This article reports a method of utilising 3D scanning, computer-aided design and additive manufacturing for the fabrication of a custom head support for a wheelchair. Three custom head supports, of the same shape, were manufactured in nylon using a continuous filament fabrication machine. The custom head supports were tested against an equivalent and widely used commercial head support using ISO 16840-3:2014. The head supports were statically loaded in two configurations, one modelling a posterior force on the inner rear surface and the other modelling a lateral force on the side. The posterior force resulted in failure of the supporting bracketry before the custom head support. A similar magnitude of forces was applied laterally for the custom and commercial head support. When the load was removed, the custom recovered to its original shape while the commercial sustained plastic deformation. The addition of a joint in the head support increased the maximum displacement, 128.6 mm compared to 71.7 mm, and the use of carbon fibre resulted in the head support sustaining a higher force at larger displacements, increase in 30 N. Based on the deformation and recovery characteristics, the results indicate that additive manufacturing could be an appropriate method to produce lighter weight, highly customised, cost-effective and safe head supports for wheelchair users.

scholarly journals A STUDY FOR CHARACTERISTIC OF LATERAL RESISTANCE OF FOOTING FOUNDATION WITH SHEET PILES BY STATIC LOADING TEST

2008 ◽  
Vol 64 (2) ◽  
pp. 383-402 ◽  
Author(s):  
Hidetoshi NISHIOKA ◽  
Masayuki KODA ◽  
Masaru TATEYAMA ◽  
Naoyuki KITA ◽  
Junichi HIRAO ◽  
...  
Keyword(s):  
Static Loading ◽  
Loading Test ◽  
Lateral Resistance ◽  
Static Loading Test

Lateral resistance and deflection of rigid walls and piles in layered soils

1981 ◽  
Vol 18 (2) ◽  
pp. 159-170 ◽  
Author(s):  
G. G. Meyerhof ◽  
S. K. Mathur ◽  
A. J. Valsangkar
Keyword(s):  
Model Tests ◽  
Horizontal Load ◽  
Layered Soils ◽  
Pile Groups ◽  
Lateral Deflection ◽  
Field Case ◽  
Lateral Resistance ◽  
Vertical Walls ◽  
Rigid Walls

The ultimate lateral resistance and the lateral deflection at working loads of rigid vertical walls and piles with a free head subjected to horizontal load and embedded in two-layered soils of sand and clay have been investigated. Part 1 deals with the behaviour of rigid walls, and the analyses are compared with the results of model wall tests in layered soils. Part 2 treats the behaviour of rigid piles, and the analyses are compared with the results of model tests on piles and pile groups in layered soils and some field case records.

scholarly journals Guidance Law Design for a Class of Dual-Spin Mortars

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Qing-wei Guo ◽  
Wei-dong Song ◽  
Yi Wang ◽  
Zhi-cai Lu
Keyword(s):  
Degrees Of Freedom ◽  
Vertical Plane ◽  
Variable Parameter ◽  
Ease Of Use ◽  
Gps Receiver ◽  
Guidance Law ◽  
Lateral Plane ◽  
The Cost ◽  
Guidance Laws ◽  
Geomagnetic Measurements

To minimize the cost and maximize the ease of use, a class of dual-spin mortars is designed which only rely on GPS receiver and geomagnetic measurements. However, there are some problems to be solved when the range is small, such as low correction authority and trajectory bending. Guidance law design for this mortar is detailed. Different guidance laws were designed for the ascending and descending segments, respectively. By taking variable parameter guidance law in the vertical plane and using compensation in the lateral plane, the problems mentioned above were resolved. Roll angle resolving algorithms with geomagnetic measurements were demonstrated and the experiment results proved to be effective. In order to verify the effectiveness, Seven-Degrees-of-Freedom (7-DOF) rigid ballistic model were established and hardware in the loop simulation was introduced. After the transform function of the actuator was obtained, the control model of the shell was improved. The results of the Monte Carlo simulation demonstrate that the guidance law is suitable and the mortar can be effectively controlled.

Installation and Lateral Resistance of Model Suction Caissons in Sandy Ground

2014 ◽  
Vol 1030-1032 ◽  
pp. 790-797
Author(s):  
Yasuyuki Nabeshima
Keyword(s):  
Wind Turbines ◽  
Failure Surface ◽  
Lateral Force ◽  
Offshore Wind ◽  
Suction Caisson ◽  
Offshore Wind Turbines ◽  
Lateral Resistance ◽  
Sandy Ground ◽  
Suction Caissons

Suction caissons attract the attention as the foundation of offshore wind turbines. Installation and resistance behaviors of the suction caisson are important factors for the design of foundation. An installation behavior into sandy seafloor was discussed by using a model suction caisson and the failure surfaces in the aluminum rod mass, as the model ground, subjected to lateral force were compared. Consequently, the installation of model suction caisson into sandy sea depended on the permeability of sandy seafloor and lateral resistance of suction caisson depended on the dimension of suction caisson which affected on the shape of failure surface in the ground.

Correlation between Static and Dynamic Response of Model Masonry Structures

1990 ◽  
Vol 6 (3) ◽  
pp. 573-591 ◽  
Author(s):  
T. J. Paulson ◽  
D. P. Abrams
Keyword(s):  
Energy Dissipation ◽  
Static Loading ◽  
Lateral Force ◽  
Test Method ◽  
Shaking Table ◽  
Masonry Structures ◽  
Structural System ◽  
Lateral Forces ◽  
Scale Test ◽  
Computer Controlled

The paper presents correlations between response of the same structural system subjected to either dynamic shaking or static lateral forces. Two one-quarter scale test structures were constructed with identical designs and were tested in the laboratory using two different methods. The first structure was subjected to simulated earthquake motions on a shaking table while the second structure was forced to displace through the same history at static rates using computer controlled servohydraulic actuators. Characteristics of dynamic lateral force distributions are examined first and followed by a description of techniques used for the static loading experiment. Correlations are made between observed response of the statically and dynamically tested twin structures to suggest differences in strength, stiffness and energy dissipation that may arise with each test method.

Influence of Track Maintenance on Lateral Resistance of Concrete-Tie Track

2003 ◽  
Vol 1825 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Theodore Sussmann ◽  
Andrew Kish ◽  
Michael Trosino
Keyword(s):  
Critical Level ◽  
Track Structure ◽  
Lateral Stability ◽  
Test Results ◽  
Railroad Track ◽  
Thermal Compression ◽  
Mechanical Stabilization ◽  
Track Maintenance ◽  
Lateral Resistance ◽  
Subsequent Stabilization

Adequate lateral resistance is required to provide the stable track structure necessary for safe rail operations on passenger and freight railroad track. Insufficient lateral resistance, coupled with a large thermal compression force in the rail from high rail temperature, can buckle the track structure. Railroads typically use mechanical stabilization, slow orders, or both, following maintenance operations that disturb the ballast section, such as track surfacing and alignment. Tests were conducted to improve the understanding of lateral resistance variations on concretetie track caused by surfacing and subsequent stabilization or compaction. Factors influencing track stability are summarized, maintenance procedures are described, the single-tie push test is described, and test results are presented. Tests were conducted to evaluate the changes in lateral resistance, from the trafficked, well-consolidated track structure before surfacing and alignment through the laterally weak track structure after surfacing. The influence of stabilization on the lateral resistance of the track structure was evaluated. The tests results indicate that surfacing significantly reduces the lateral stability of the track to a potentially critical level. Mechanical stabilization following surfacing significantly increased the lateral stability of all sections tested.

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