A New Approach to Determine the Stresses in Buried Pipes Under Surface Loading

2016 ◽  
Author(s):  
Fan Zhang ◽  
Nathan Branam ◽  
Benjamin Zand ◽  
Mark Van Auker
Keyword(s):  
Hoop Stress ◽  
Biaxial Stress ◽  
Spring Model ◽  
Longitudinal Stress ◽  
Construction Sites ◽  
Surface Loading ◽  
Buried Pipes ◽  
New Approach ◽  
Cornell University ◽  
Heavy Construction

All buried pipes experience loading from the weight of soil overburden. When pipelines cross railroads, roads, parking lots or construction sites, the pipes also experience live surface loading from vehicles on the ground, including heavy construction equipment in some scenarios. The surface loading results in through-wall bending in pipes, which generates both hoop stress and longitudinal stress. Current standards limit the stresses in buried pipes to maximum values in terms of hoop stress, longitudinal stress and combined biaxial stress. An early approach to estimating stresses and deformations in a pipe subjected to surface loads dates back to Spangler’s work in the 1940s. Many models have been developed since then. API RP 1102 provides guidance for the design of pipeline crossings of railroads and highways following the model developed by Cornell University for the Gas Research Institute (GRI). The Cornell model was developed only based on experiments on bored pipes crossing a railroad or a highway at a near-right angle. The live surface loading distribution is also limited to the wheel-layout typical of railroad cars and highway vehicles. Most other existing models only focus on the hoop stress in the pipe. In this paper, a new approach to determine the stresses in buried pipes under surface loading is introduced. The approach is suitable for assessing pipes beneath any type of vehicle or equipment at any relative position and at any angle to the pipe. First, the pressure on the pipe from surface loading is determined through the Boussinesq theory. Second, both hoop stress and longitudinal stress in the pipe are estimated. The hoop stress is estimated through the modified Spangler stress formula proposed by Warman and his co-workers (2006 and 2009). The longitudinal stress, due to local bending and global bending, is estimated by the theory of beam-on-elastic-foundation. The modulus of foundation can be determined through the soil-spring model developed by ASCE. The hoop stress, longitudinal stress and the resulting combined biaxial stress can then be compared against their respective limits from a pertinent standard to assess the integrity of the pipe and determine the proper remediation approach, if necessary. The performance of the proposed approach is compared in this study with the experimental results in the literature and the predictions from API RP 1102.

The Remaining Strength of Corroded Casing With Combined Hoop and Longitudinal Stress

2010 ◽  
Author(s):  
Robert B. Francini ◽  
Jacob D. Wahl ◽  
Nolan T. Quade
Keyword(s):  
Internal Pressure ◽  
Hoop Stress ◽  
Axial Loading ◽  
Gas Storage ◽  
Metal Loss ◽  
Longitudinal Stress ◽  
Production Well ◽  
Longitudinal Loading ◽  
Corrosion Evaluation

The casings in a gas storage or production well can have large longitudinal loads in addition to the hoop stress resulting from internal pressure. Under certain circumstances these loads need to be taken into account when evaluating the remaining strength of corroded areas. The most commonly used method for corrosion evaluation is based on B31G which does not include longitudinal loads. This paper outlines the range of longitudinal loading where the B31G approach is valid. In addition, it presents a method to evaluate the remaining strength of the corroded area where the B31G approach is not valid. The procedure has been validated by burst tests of casing with real and machined metal loss under axial loading.

Effect of Biaxial Stress on Crack Driving Force

2006 ◽  
Author(s):  
G. Shen ◽  
W. R. Tyson
Keyword(s):  
Internal Pressure ◽  
Driving Force ◽  
Axial Stress ◽  
Axial Strain ◽  
Biaxial Stress ◽  
J Integral ◽  
Longitudinal Stress ◽  
Secondary Stress ◽  
Stress Strain ◽  
Strain Equation

A stress-strain equation of Ramberg-Osgood type is proposed to correlate the longitudinal stress with longitudinal strain of a thin plate when a constant stress is applied transversely. The same approach can be used to correlate the axial stress with axial strain for a thin-walled pipe in axial tension with internal pressure. The proposed stress-strain equation relating the longitudinal stress and strain closely approximates that of deformation theory. The effect of a secondary stress (hoop stress) on the J-integral for a circumferential crack in a pipe under axial load and internal pressure is evaluated by finite element analysis (FEA). The results show that the J-integral decreases with internal pressure at a given axial stress but increases with internal pressure at a given axial strain. It is concluded that while a secondary stress may be safely neglected in a stress-based format because it decreases the driving force at a given applied stress, it should not be neglected in a strain-based format because it significantly increases the driving force at a given applied strain.

Application of a Shell-Spring Model for the Optimization of Radial Tire Contour Using a Genetic Algorithm

2003 ◽  
Vol 31 (1) ◽  
pp. 39-63 ◽  
Author(s):  
G. Unnithan ◽  
R. KrishnaKumar ◽  
A. Prasad
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Optimization Problems ◽  
Optimization Procedure ◽  
Element Model ◽  
Spring Model ◽  
New Approach ◽  
Shell Elements ◽  
Complex Optimization ◽  
Profile Optimization

Abstract Optimization gives a new facet to design and development of tires. A new approach to the tire profile optimization is proposed in this study. The optimization procedure is integrated with a simple shell-spring finite element model for faster evaluation. In the shell-spring model, the shell elements represent the tire carcass, whereas the tread is represented by the spring elements. This is applied for the optimization of the tire contour for better maneuverability. The genetic algorithm, an evolutionary optimization procedure that is robust and efficient in solving complex optimization problems, is chosen. A new tire contour is obtained that improves tire maneuverability by increasing the sidewall belt tension.

Walter Pohl, The Avars: A Steppe Empire in Central Europe, 567–822. Ithaca, NY, and London: Cornell University Press, 2018, xxiii, 636 pp., 4 maps.

Mediaevistik ◽  
2020 ◽  
Vol 32 (1) ◽  
pp. 381-382
Author(s):  
Albrecht Classen
Keyword(s):  
English Translation ◽  
The Political ◽  
Early Medieval ◽  
The West ◽  
New Approach ◽  
Cornell University ◽  
The North ◽  
Medieval Europe ◽  
Nomadic People ◽  
Military Structure

Even though this is not a new publication, Pohl’s study on the Avars deserves particular attention, now in its first English translation. While not identified on the cover page, Pohl’s book was superbly translated into English by Will Sayers, who is briefly mentioned in the preface. Pohl had published his book originally in German in 1988, and it appeared in its third edition in 2015. Only in the last few decades has our awareness and understanding of the Avars grown and changed, particularly because intensive archaeological evidence has vastly changed our concept of that Steppe people who lived in the Carpathian Basin long before the Magyars settled there. Consequently, Pohl has made great efforts to reflect on the new insights and rewrote the respective sections of this book. In short, although here we hold in our hands ‘only’ the English translation of the third edition, The Avars represents, after all, a new approach and a thorough update of the current research on that people that had significant influence on the Byzantines, the Germanic peoples to the west and southwest, and to the north and east. They were the first to introduce into Europe the stirrup, but they left practically no written sources. They were Nomadic people, and yet not simply barbarians, as later chroniclers liked to call them. Hence, Pohl’s study on this early medieval people sheds important light on the political and military structure of early medieval Europe in an area where the Byzantine sphere of interest ended and where the Carolingians endeavored to place their stakes.

The Ruins of Baalbek

2021 ◽  
Author(s):  
Robert Wood
Keyword(s):  
North America ◽  
Present State ◽  
18Th Century ◽  
Great Influence ◽  
Human Geography ◽  
Archaeological Sites ◽  
New Approach ◽  
Cornell University ◽  
Classical Architecture ◽  
Architectural Features

First published in the 1750s, The Ruins of Palmyra and The Ruins of Baalbek are a remarkable record of an expedition to the Levant by three antiquarians - Robert Wood, John Bouverie and James Dawkins - along with a draftsman, Giovanni Battista Borra. With over 100 engravings of the classical architecture of the two ancient cities of Palmyra and Baalbek, the volumes represent the earliest-known examples of monographs on archaeological sites. They were unique in providing systematic discussion of the sites’ physical and human geography alongside two kinds of pictorial evidence: views of the ancient sites in their then-present state and detailed plans, with measurements, of architectural features. This new approach was immediately copied by antiquarians in the later 18th century and also had great influence upon Neoclassical architecture in Britain, Europe and North America. This new edition features reproductions of all the engravings from the original publications and includes a new introduction by noted scholar, Benjamin Anderson (Cornell University, USA).

3D-Based Crane Evaluation System for Mobile Crane Operation Selection on Modular-Based Heavy Construction Sites

2017 ◽  
Vol 143 (9) ◽  
pp. 04017060 ◽  
Author(s):  
SangHyeok Han ◽  
Ahmed Bouferguene ◽  
Mohamed Al-Hussein ◽  
Ulrich (Rick) Hermann
Keyword(s):  
Evaluation System ◽  
Construction Sites ◽  
Mobile Crane ◽  
Heavy Construction

scholarly journals Stress Analysis for Cylinder Made of FGM and Subjected to Thermo-Mechanical Loadings

Metals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 4 ◽  
Author(s):  
El-Sayed Habib ◽  
Medhat Awad El-Hadek ◽  
Abla El-Megharbel
Keyword(s):  
Finite Element Analysis ◽  
Stress Analysis ◽  
Radial Stress ◽  
Hoop Stress ◽  
Thermal Loading ◽  
Functionally Graded ◽  
Longitudinal Stress ◽  
Ansys Software ◽  
Element Analysis ◽  
Graded Materials

Functionally-graded materials (FGM) have recently been widely used. Furthermore, FGM are widely recommended in cylinder design. This study represents a mathematical analysis of the stresses and strains of an FGM cylinder. The paper is interested in introducing a stress analysis to an FGM cylinder where its properties vary exponentially in the r-direction. Firstly, a benchwork has been done and compared with recent works in the same field. The radial stress, the hoop stress, and the longitudinal stress on a cylinder under mechanical and thermal loading have been theoretically derived. In addition, a finite element analysis has been investigated through ANSYS software. Finally, the values of stresses obtained from the derived equations and the corresponding values of stresses obtained from ANSYS have been compared. The obtained results established the efficiency of the proposed stress distribution and the optimization model in this research, which would be helpful for understanding well the technical design of FGM vessels or related constructions.

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