scholarly journals Reliability Analysis of Flexible Pavement Using First Order Method

2020 ◽  
pp. 38-54
Author(s):  
Sameh S. Abd El- Fattah ◽  
Ahmed E. Abu El- Maaty ◽  
Ibrahim H. Hashim
Keyword(s):  
Design Methodology ◽  
Flexible Pavement ◽  
Pavement Design ◽  
Design Parameters ◽  
Army Corps ◽  
First Order ◽  
Failure Patterns ◽  
Reliability Method ◽  
Current Design ◽  
The Impact

Flexible pavement design is influenced by many design parameters such as (traffic characterization, pavement depths, structure materials and environmental conditions). To study the impact of variations in design parameters on pavement performance, several attempts have been achieved to add reliability concept to the mechanistic-empirical (M-E) design of pavements. In (M-E) design of pavements, the pavement life depends on subgrade rutting and fatigue cracking, considering them as independent failure patterns. The current design methodology used in many countries such as Egypt is ignoring the impact of temperature variation (despite its importance) on the pavement design. This research aimed to predict the pavement reliability due to variation in pavement design parameters especially temperature using the first-order reliability method (FORM) considering rutting and fatigue failures. Moreover, a comparison was performed between regressions models represented from different pavement agencies to recommend the most efficient one for Egyptian temperature. The results obtained that, considering design parameters variations (without temperature); the reliability based on US Army Corps method (91.64%) was the nearest one to the current design methodology in Egypt (91.0%). After adding temperature variations, the reliability was clearly affected where the regression model of Shell Research agency was the most appropriate one for all Egyptian temperature zones as it achieved the lowest error mean (-0.03) and the lowest error standard deviation (0.0011). Moreover, the air temperature of 28ºC was considered as the inflection point for pavement reliability-temperature curve in Egypt.

Reliability of Buried Pipeline Using a Theory of Probability of Failure

2006 ◽  
Vol 110 ◽  
pp. 221-230 ◽  
Author(s):  
Ouk Sub Lee ◽  
Dong Hyeok Kim ◽  
Seon Soon Choi
Keyword(s):  
Failure Probability ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Reliability Estimation ◽  
Design Parameters ◽  
Buried Pipeline ◽  
Safety Level ◽  
First Order ◽  
Reliability Method ◽  
Corrosion Defects

The reliability estimation of buried pipeline with corrosion defects is presented. The reliability of corroded pipeline has been estimated by using a theory of probability of failure. And the reliability has been analyzed in accordance with a target safety level. The probability of failure is calculated using the FORM (first order reliability method). The changes in probability of failure corresponding to three corrosion models and eight failure pressure models are systematically investigated in detail. It is highly suggested that the plant designer should select appropriate operating conditions and design parameters and analyze the reliability of buried pipeline with corrosion defects according to the probability of failure and a required target safety level. The normalized margin is defined and estimated accordingly. Furthermore, the normalized margin is used to predict the failure probability using the fitting lines between failure probability and normalized margin.

Assessment of Equivalent Thickness Design Principles for Geosynthetic Reinforced Pavements by Way of Accelerated Testing

2018 ◽  
Vol 2672 (40) ◽  
pp. 132-142 ◽  
Author(s):  
W. Jeremy Robinson ◽  
Jeb. S. Tingle ◽  
Gregory J. Norwood ◽  
Isaac L. Howard
Keyword(s):  
Design Methodology ◽  
Full Scale ◽  
Pavement Design ◽  
Army Corps ◽  
Army Corps Of Engineers ◽  
Original Design ◽  
Equivalent Thickness ◽  
Simplifying Assumptions ◽  
Pavement Construction ◽  
Conservative Result

The Engineer Research and Development Center (ERDC) of the U.S. Army Corps of Engineers has performed multiple laboratory and full-scale evaluations of geosynthetic reinforced pavements. One result from early geosynthetic reinforced pavement evaluations was a pavement design methodology implemented in ETL 1110-1-189: Use of Geogrids in Pavement Construction. Since that time, the evaluations have been primarily focused on comparing performance between varying types of geosynthetic products. While the studies have independently compared the discrete performance of single geosynthetic reinforced sections to unreinforced sections, a comprehensive analysis of available data has not been performed to validate or refine the implemented design methodology. The objective of this effort was to assemble available data from laboratory and full-scale testing conducted at ERDC for the primary purpose of assessing the flexible pavement design methodology presented in ETL 1110-1-189. Simplifying assumptions were made to allow comparison of varying loading and pavement structure conditions. This assessment found that the combined dataset supports the original design curve produced with the equivalent thickness methodology described in ETL 1110-1-189. The updated dataset would reduce the equivalent reinforced thickness by approximately 1.0-inches (25.4 mm) at unreinforced thicknesses less than 14 inches (356 mm), providing a slightly more conservative result. The adjusted data converged with the original equivalency chart at an unreinforced thickness of approximately 16 inches (406 mm).

Sensitivity and Robustness of Hydrodynamic Mooring Models

2002 ◽  
Vol 124 (4) ◽  
pp. 179-189 ◽  
Author(s):  
Joa˜o Paulo J. Matsuura ◽  
Michael M. Bernitsas ◽  
Luis O. Garza-Rios ◽  
Kazuo Nishimoto
Keyword(s):  
Design Methodology ◽  
Higher Order ◽  
Systematic Change ◽  
Mooring System ◽  
University Of Michigan ◽  
First Order ◽  
Global Properties ◽  
Higher Order Terms ◽  
The University ◽  
The Impact

Various hydrodynamic maneuvering models are available for modeling the slow motion horizontal plane dynamics of mooring and towing systems. In previous work, we compared four representative and widely used maneuvering models and assessed them based on the design methodology for mooring systems developed at the University of Michigan. In this paper, we study the impact of experimental uncertainties in the maneuvering coefficients on mooring system dynamic analysis. Uncertainties in higher order coefficients may even result in sign change as measured by different experimental facilities. This may indicate lack of robustness in maneuvering modeling. In our recent work, maneuvering models were classified in two schools of thought, each having a different set of coefficients subject to uncertainties. The first school is represented by the Abkowitz (A-M) and the Takashina (T-M) models, and the second by the Obokata (O-M) and the Short Wing (SW-M) models. The design methodology developed at the University of Michigan uses time independent global properties of mooring system dynamics to compare the maneuvering models, and assess their sensitivity and robustness. Equilibria, bifurcation sequences and associated morphogeneses, singularities of bifurcations, and secondary equilibrium paths are such global properties. Systematic change of important coefficients in each model shows that, for both schools of thought, sensitivity to first order terms is high while sensitivity to higher order terms is low. Accuracy in measurement of first order terms is high while accuracy in measurement of higher order terms is low. These two tendencies reduce each other’s impact, providing acceptable robustness.

Cost of Pavement Damage Due to Heavier Loads on Louisiana Highways: Preliminary Assessment

2000 ◽  
Vol 1732 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Freddy L. Roberts ◽  
Ludfi Djakfar
Keyword(s):  
Pavement Design ◽  
Design Parameters ◽  
Preliminary Assessment ◽  
Design Data ◽  
Present Worth ◽  
Gross Vehicle Weight ◽  
Pavement Damage ◽  
The Cost ◽  
Government Statistics ◽  
The Impact

A preliminary assessment is made of the impact of increasing the gross vehicle weight (GVW) from current legal limits to 100,000 lb (45 400 kg) on vehicles hauling sugarcane, rice, timber, and cotton. Sections of road were chosen in each area of Louisiana where commodities are produced, the amount of each commodity hauled was estimated, and the effects of increasing the GVW were evaluated for each section using pavement design models. Design data were secured from the Louisiana Department of Transportation and Development computer database and project files to determine the pavement design parameters and traffic estimates for each road. The number of vehicles hauling the 1998 harvest payload was estimated, a projected increase in the production of each commodity was estimated on the basis of government statistics, and rehabilitations were designed with the use of the 1986 AASHTO Design Guide for a 20-year analysis period. Present worth (PW) was calculated for each GVW scenario for each roadway. Comparisons of PW between the weight scenarios showed that increases in GVW have more effect on state and U.S. highways than they do on Interstate highways. Any increase in GVW over current limits increases the cost of overlays and decreases the length of time before an overlay is required. The cost increase due to increasing the GVW is substantial. Fee structures should be modified by the legislature so that these costs are paid for either through the current registration and overweight permit fee structure or through some new tax, such as a ton-mile tax.

Sensitivity Analysis on Dynamic Properties of Large Span Concrete-Filled Steel Tube Arch Bridge

2012 ◽  
Vol 204-208 ◽  
pp. 1976-1979
Author(s):  
Hang Sun ◽  
Xiao Jian Han ◽  
Xiu Yun Gao
Keyword(s):  
Dynamic Properties ◽  
Steel Tube ◽  
Design Parameters ◽  
Arch Bridge ◽  
Concrete Filled Steel Tube ◽  
Space Model ◽  
Long Span ◽  
Current Design ◽  
Arch Bridges ◽  
The Impact

The calculation formula of the vertical fundamental frequency of arch bridge has been given in current design codes, in which the rise-span ratio is the only variable on condition that the structure mass and stiffness are known. However, the dynamic properties of long-span concrete filled steel tube arch bridges have their own characteristics, which are influenced by a series of factors. Thus this article establishes a space model of a concrete-filled steel tube arch bridge. By analyzing the main design parameters’ influence on the structure dynamic properties, including rise-span ratios, arch-axis coefficient and wide-span ratios, some of conclusions has been made, which can be used for further research of the impact effect and earthquake dynamic response, and provide the necessary basis for the dynamic design of bridges of this kind

Input Parameters for the Mechanistic-Empirical Design of Full-Depth Reclamation Projects

2021 ◽  
pp. 036119812110179
Author(s):  
Vishwa V. Beesam ◽  
Cristina Torres-Machi
Keyword(s):  
Pavement Design ◽  
Design Parameters ◽  
Future Research ◽  
Limited Information ◽  
Full Depth Reclamation ◽  
Input Parameters ◽  
Current Design ◽  
Long Term Performance ◽  
Term Performance

Cold recycling technologies such as full-depth reclamation (FDR) are sustainable and cost-effective techniques for pavement rehabilitation that reduce environmental impacts and construction costs and time. The limited information available on the material properties of FDR mixtures and their characterization in mechanistic-empirical (M-E) pavement design hinders the full deployment of FDR. Previous research has found current M-E default values to be non-representative and overly conservative, leading to an underestimation of the true performance capabilities of FDR materials. To address this gap, this paper analyzes the performance of 11 FDR sites constructed throughout Colorado, U.S., and compares their long-term performance with M-E predictions. The objective of this paper is to recommend input values for the M-E design of FDR base materials that result in reliable predictions of FDR long-term performance. The analysis includes both non-stabilized and emulsion-stabilized FDR projects. Both initial International Roughness Index (IRI) and resilient modulus were found to have a significant impact on M-E predictions and were calibrated in a two-step process. The proposed input parameters lead to a conservative design of FDR projects and result in improved IRI predictions compared with the ones derived from current design criteria. With the current design parameters, IRI predictions were, on average, overestimated by 51 in./mi, whereas the proposed input parameters make it possible to reduce this difference to 17 in./mi. Future research is needed to improve current models in M-E pavement design software to adequately model cold in-place recycled layers such as FDR.

Space Hardware Advanced Manufacturing Engineering: SHAME to miss out on a potential game changer?

2018 ◽  
Vol 26 (1) ◽  
pp. 117-126
Author(s):  
Laurent Pambaguian ◽  
Eleonie van Schreven ◽  
Ilaria Roma
Keyword(s):  
Systems Engineering ◽  
Design Methodology ◽  
European Space Agency ◽  
Systems Design ◽  
Design Parameters ◽  
Concurrent Design ◽  
Potential Game ◽  
Advanced Manufacturing ◽  
Design Environment ◽  
The Impact

Advanced Manufacturing is widely used with features and applications playing a game changing role in our daily life. The European Space Agency has initiated in April 2016 a multi-disciplinary approach exploring the impact of infusing Advanced Manufacturing into space practices. A Concurrent Design Facility study was performed investigating potential design methodology amendments produced by introducing Advanced Manufacturing techniques into the design space. Innovative materials and processes were added to the conventional design parameters usually populating the systems design trade-spaces. This enabled multifunctional solutions, previously inconceivable, with a redefinition of interfaces and related requirements, shifted from ‘discipline’ boundaries to ‘units’ or ‘assembly’ boundaries. The Concurrent Design Facility Study identified the core domains of expertise required in a ‘Design for Advanced Manufacturing’ frame, governed by a flexible, open-minded systems engineering coordination. Early involvement of material and process engineers in the design proved to be an essential ingredient of the ‘Design for Advanced Manufacturing’ recipe. The design freedom brought by Advanced Manufacturing calls for unconventional design solutions, creativity becomes a need and infusion from non-space is invaluable. Biomimicry and architecture principles enriched the concurrent design environment, which proved to be very well suited with the needs and objectives of the new design methodology. This article reports the Concurrent Design Facility study conduct, as first attempt to understand Advanced Manufacturing impact on design methodology, the study cases selected for analysis, the observations on the methodology and on the interactions among the specialists in the team. The study outcome is reported, including an overview of benefits, disadvantages and points for further investigation in relation to the study cases assessed. In addition, the paper proposes recommendations for injecting Advanced Manufacturing into the project life cycle, from early design up to procurement phases and ultimately to the assembly, integration and verification phases, indicating required modelling tools, technologies and redefined engineering roles and expertise.

Multidisciplinary Design of a Low-Noise Propeller: Part II — Efficient Aero-Acoustic-Mechanical Design Methodology Exploiting Surrogate Models in an Adaptive Design Space

2020 ◽  
Author(s):  
Lieven Baert ◽  
Chloé Dumont ◽  
Charlotte Beauthier ◽  
Caroline Sainvitu ◽  
Ingrid Lepot ◽  
...  
Keyword(s):  
Design Methodology ◽  
Adaptive Design ◽  
Design Space ◽  
New Technologies ◽  
Mechanical Design ◽  
Low Noise ◽  
Machine Learning Techniques ◽  
Design Parameters ◽  
Industrial Leadership ◽  
The Impact

Abstract The regional aircraft segment plays a crucial role in achieving the EU Flightpath 2050 objectives (increase connectivity through Europe, enforce Europe’s industrial leadership, and significantly reduce the environmental impact of aviation). Despite an outdated perception by the general public, turboprop aircraft are typically less expensive to operate than regional jets. The impact of new technologies is therefore even more evident. Achieving a significant reduction in perceived noise levels remains however a challenge for the success of further turboprop deployment. This twofold paper discusses the design of an innovative low-noise propeller in the framework of the Clean Sky 2 Regional Aircraft IADP, with a focus on the design methodology itself in this second part. The design is inherently multidisciplinary — aerodynamic, acoustic, mechanical — with multiple flight conditions and a wind tunnel condition to be considered. In order to limit the number of expensive high-fidelity computations, an online surrogate-based optimisation (SBO) approach has been deployed. A high-dimensional design space has been considered to enable to identify disruptive low-noise concepts. By exploiting the results of low-fidelity tools (see the first part of the paper), combined with efficient machine learning techniques and data mining capabilities, a gradual increment of the design space from 57 to 111 design parameters has been considered. A significant noise reduction of about 6.5 dB has been achieved without major degradation of the aerodynamic efficiency — fully aligned with the objectives for the Regional Aircraft IADP.

scholarly journals Quantifying the Impact of Climate Change on Flexible Pavement Performance and Lifetime in the United States

2019 ◽  
Vol 2673 (1) ◽  
pp. 110-122 ◽  
Author(s):  
Anne M. K. Stoner ◽  
Jo Sias Daniel ◽  
Jennifer M. Jacobs ◽  
Katharine Hayhoe ◽  
Ian Scott-Fleming
Keyword(s):  
Climate Change ◽  
United States ◽  
Global Climate Model ◽  
Flexible Pavement ◽  
The United States ◽  
Pavement Design ◽  
Pavement Performance ◽  
Climate Projections ◽  
Impact Of Climate Change ◽  
The Impact

Flexible pavement design requires considering a variety of factors including the materials used, variations in water tables, traffic levels, and the climatic conditions the road will experience over its lifetime. Most pavement designs are based on historical climate variables such as temperature and precipitation that are already changing across much of the United States, and do not reflect projected trends. As pavements are typically designed to last 20 years or more, designs that do not account for current and future trends can result in reduced performance. However, incorporating climate projections into pavement design is not a trivial exercise. Significant mismatches in both spatial and temporal scale challenge the integration of the latest global climate model simulations into pavement models. This study provides a national-level overview of what the impact of climate change to flexible pavement could look like, and where regional focus should be placed. It also demonstrates a new approach to developing high-resolution spatial and temporal projections that generates hourly information at the scale of individual weather stations, and applies this as input to the AASHTOWare Pavement ME Design™ model. The impact of three different future climates on pavement performance and time to reach failure thresholds in 24 locations across the United States are quantified. Changes to projected pavement performance differ by location, but nearly all result in decreased performance under current design standards. The largest increases in distress are observed for permanent deformation measures, especially toward the end of the century under greater increases in temperature.

First-Order Reliability Analysis of Vehicle Safety in Highway Horizontal Curves

2013 ◽  
Author(s):  
Jaekwan Shin ◽  
Ikjin Lee
Keyword(s):  
Reliability Analysis ◽  
Failure Modes ◽  
Design Method ◽  
First Order ◽  
Horizontal Curves ◽  
State Highway ◽  
Reliability Method ◽  
Current Design ◽  
Margin Of Safety ◽  
Analytic Models

This study presents a reliability analysis of vehicle sideslip and rollover in highway horizontal curves, mainly focusing on exit ramps and interchanges. To accurately describe failure modes of a ground vehicle, analytic models for sideslip and rollover are derived considering nonlinear characteristics of vehicle behavior using the commercial software, TruckSim®, with high fidelity. Then, the probability of accident is evaluated using the First-Order Reliability Method (FORM). Furthermore, sensitivity functions of each failure mode are analytically derived to apply FORM. Numerical studies are conducted using a single-unit truck model. The results show that a truck is more likely to rollover than to slip at dry load. To propose practical application of the study, the reliability analysis for the minimum radius recommended by American Association of State Highway and Transportation Officials (AASHTO) at various speeds and bank angles is conducted. The reliability analysis of current design method shows that the method cannot provide the sufficient margin of safety against both of rollover and sideslip when there are deviations from assumed conditions, especially at low speed of vehicles.

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