Development of Strain Demand and Capacity Distributions to Use in Limit States Design for Geotechnical Loads

2018 ◽  
Author(s):  
Smitha D. Koduru ◽  
Maher A. Nessim
Keyword(s):  
Design Rule ◽  
Limit States ◽  
Design Rules ◽  
Soil Movement ◽  
Demand Distribution ◽  
Reliability Based Design ◽  
Distribution Parameters ◽  
Applicable Range ◽  
General Guidance ◽  
Demand And Capacity

A limit states design approach for onshore pipelines has been developed as part of a multi-year joint industry project (JIP). As part of this project, reliability-based design rules were developed for geotechnical loads, including landslides, slope creep, seismic loads, frost heave and thaw settlement. In consideration of the modelling complexity of the soil movement mechanisms and pipe-soil interaction, and to allow for flexibility to incorporate future model developments, the design rule formulation is directly based on the distribution parameters of the strain demand and capacity of the pipeline. This paper describes the approach used to develop the strain demand and capacity distributions that are required to apply the design rules, as well as the applicable range of distribution parameters. Slope creep was selected as a basis for demonstrating the proposed process, as this loading mechanism occurs more frequently and the data to characterize the necessary uncertainties is available. General guidance related to the development of the strain demand distribution parameters for other geotechnical loads is also provided.

Limit States Design for Onshore Pipelines: Designing for Hydrostatic Test Pressure and Restrained Thermal Expansion

2014 ◽  
Author(s):  
Riski H. Adianto ◽  
Maher A. Nessim
Keyword(s):  
Thermal Expansion ◽  
Input Parameter ◽  
Local Buckling ◽  
Companion Paper ◽  
Design Rule ◽  
Material Strength ◽  
Safety Factors ◽  
Limit States ◽  
Design Rules ◽  
Test Pressure

Reliability-based design rules have been developed for the key serviceability limit states applicable to onshore pipeline including local buckling due to thermal expansion and excessive plastic deformation under hydrostatic test pressure. The design rules are characterized by three elements: the formulas used to calculate the characteristic demand and capacity; the criteria used to define the characteristic values of the key input parameters to these formulas (such as diameter and material strength); and the safety factors defining the required excess capacity over the demand. The overall methodology used in developing the design rules and the practical implications of applying them are described in a companion paper. This paper describes the process used to calibrate safety factors and characteristic input parameter values that meet the desired reliability levels. The results show that local buckling under restrained thermal expansion is only potentially relevant for a small sub-set of cases and based on this, an explicit design rule was not developed. For excessive deformation under hydrostatic test pressure, two alternate design rules are provided; one stress based and the other strain based. The final design rules are described and an assessment of their accuracy and consistency in meeting the reliability targets is included. Guidance is also provided on the conditions in which each check is used.

Limit States Design for Onshore Pipelines: Design Rules for Operating Pressure and Equipment Impact Loads

2014 ◽  
Author(s):  
Maher A. Nessim ◽  
Riski H. Adianto
Keyword(s):  
Impact Load ◽  
Input Parameter ◽  
Companion Paper ◽  
Material Strength ◽  
Operating Pressure ◽  
Safety Factors ◽  
Limit States ◽  
Design Rules ◽  
Reliability Based Design ◽  
Final Design

Reliability-based design rules have been developed for the key ultimate limit states applicable to onshore pipeline, including burst under operating pressure and failure due to equipment impact. The design rules are characterized by three elements; the formulas used to calculate the characteristic demand and capacity; the criteria used to define the characteristic values of the key input parameters to these formulas (such as diameter, material strength, pressure and impact load); and the safety factors defining the required excess capacity over the demand. The overall methodology used in developing the design rules and the practical implications of applying them are described in a companion paper. This paper describes the process used to calibrate safety factors and characteristic input parameter values that meet the desired reliability levels. The final design rules are described in the paper and an assessment of their accuracy and consistency in meeting the reliability targets is included.

scholarly journals Probabilistic Prediction of Maximum Tensile Loads in Soil Nails

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yongqiang Hu ◽  
Peiyuan Lin
Keyword(s):  
Correction Factor ◽  
Earth Pressure ◽  
Random Variable ◽  
Probabilistic Prediction ◽  
Limit States ◽  
Simple Formulation ◽  
Load Model ◽  
Soil Nail ◽  
Reliability Based Design ◽  
The Difference

This paper presents the development of a simplified model for estimation of maximum nail loads during or at completion of construction of soil nail walls. The developed simplified nail load model consists of two multiplicative components: the theoretical nail load and the correction factor. The theoretical nail load is computed as the product of lateral active Earth pressure at nail depth and the nail tributary area. The correction factor is introduced to account for the difference between the theoretical and the measured nail loads. A total of 85 measured nail load data were collected from the literature; out of which, 74 were used to develop a simple formulation for the correction factor, whereas the remaining 11 were used for validation. After the validation, the model was updated using all 85 data. The updated simplified nail load model was demonstrated to be accurate on average (mean of model factor equal to 1), and the spread in prediction quantified as the coefficient of variation of the model factor was about 40%. Here, model factor is the ratio of measured to estimated nail load. The randomness of the model factor was also verified. Finally, the model factor was demonstrated to be a lognormal random variable. The proposed simplified nail load model is beneficial due to its simplicity and quantified model uncertainty; thus it is practically valuable to both direct reliability-based design and load and resistance factor design of soil nail wall internal limit states.

scholarly journals Hardware Design Rule Checker Using a CAM Architecture

VLSI Design ◽  
1996 ◽  
Vol 4 (2) ◽  
pp. 141-147
Author(s):  
Seokjin Kim ◽  
Ramalingam Sridhar
Keyword(s):  
Pattern Matching ◽  
Input Data ◽  
Hardware Implementation ◽  
Low Cost ◽  
Design Rule ◽  
Design Rules ◽  
One Dimensional ◽  
Content Addressable Memory ◽  
Logic Operations ◽  
Geometric Designs

This paper presents a hardware implementation of design rule checker using a specialized Content Addressable Memory(CAM) for the Manhattan geometric designs. Two dimensional relationships between rectangular objects in a design are checked with one dimensional design rules. The input data is processed by the pixel pre-processor in such a way that direct comparison between the input data and the stored rules in the CAM is possible. The comparison by the CAM reduces the number of memory references and logic operations of pattern matching and the simple architecture of the system enables a low cost implementation.

Reliability-based design criteria for timber bridges in Ontario

1986 ◽  
Vol 13 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Andrzej S. Nowak ◽  
Raymond J. Taylor
Keyword(s):  
Reliability Index ◽  
Structural Reliability ◽  
Structural Safety ◽  
Design Code ◽  
Bridge Design ◽  
Limit States ◽  
Acceptance Criterion ◽  
Reliability Based Design ◽  
Load And Resistance Factor ◽  
Timber Bridges

The new Ontario Highway Bridge Design Code (OHBDC) is based on limit states theory and therefore uses a load and resistance factor format. This paper deals with the development of the basis for the timber bridge design provisions (OHBDC). Three structural systems are considered: sawn timber stringers, laminated nailed decks, and prestressed laminated decks. The latter system has been successfully used in Ontario for the last 7 years.The acceptance criterion in calculation of load and resistance factors is structural reliability. It is required that bridges designed using the new code must have a reliability equal to or greater than a preselected target value. Reliability is measured in terms of the reliability index. The safety analysis is performed for a structural system rather than for individual members. The live load model was developed on the basis of available truck survey data. Material properties are based on extensive in-grade test results. Numerical examples are included to demonstrate the presented approach. Key words: bridge deck, design code, prestressed timber, reliability, reliability index, stringers, structural safety, timber bridges.

Reliability-Based Design and Heuristic Optimization MPSO-SA of Structures

2011 ◽  
Vol 274 ◽  
pp. 91-100
Author(s):  
Norelislam Elhami ◽  
Mhamed Itmi ◽  
Rachid Ellaia
Keyword(s):  
High Performance ◽  
Simulated Annealing Algorithm ◽  
Optimization Problems ◽  
Structural Parameters ◽  
Dominant Role ◽  
Limit States ◽  
Reliability Indices ◽  
Modified Particle Swarm Optimization ◽  
Reliability Based Design ◽  
Research Fields

In this paper, we present a probability study about spring of clutch structure. In the structure problems, the randomness and the uncertainties of the distribution of the structural parameters are a crucial problem. In the case of Reliability Based Design Optimization (RBDO), it is the objective is to play a dominant role in the structural optimization problem introducing the reliability concept. The RBDO problem is often formulated as a minimization of the initial structural cost under constraints imposed on the values of elemental reliability indices corresponding to various limit states. This paper proposes a new method for a modified particle swarm optimization algorithm (MPSO) combined with a simulated annealing algorithm (SA) and RBDO. MPSO is known as an efficient approach with a high performance of solving optimization problems in many research fields. It is a population intelligence algorithm inspired by social behavior simulations of bird flocking. Numerical results show the robustness of the MPSO-SA algorithm and RBDO.

New Common Design Rules for U-Tube Heat Exchangers in ASME, CODAP and UPV Codes

2002 ◽  
Author(s):  
F. Osweiller
Keyword(s):  
Heat Exchangers ◽  
Pressure Vessels ◽  
Design Rule ◽  
Technical Approach ◽  
Design Rules ◽  
Asme Code ◽  
European Code ◽  
Section Viii ◽  
Technical Basis ◽  
Year 2000

In year 2000, ASME Code (Section VIII – Div. 1), CODAP (French Code) and UPV (European Code for Unfired Pressure Vessels) have adopted the same rules for the design of U-tube tubesheet heat exchangers. Three different rules are proposed, based on different technical basis, to cover: • Tubesheet gasketed with shell and channel. • Tubesheet integral with shell and channel. • Tubesheet integral with shell and gasketed with channel or the reverse. At the initiative of the author, a more refined technical approach has been developed, to cover all tubesheet configurations. The paper explains the rationale for this new design rule which is being incorporated in ASME, CODAP and UPV in 2002. This is substantiated with comparisons to TEMA Standards and a benchmark of numerical comparisons.

Dependability-Based Design Optimization of Degrading Engineering Systems

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Gordon J. Savage ◽  
Young Kap Son
Keyword(s):  
Design Optimization ◽  
Lifetime Cost ◽  
Limit State ◽  
Value Theory ◽  
Cumulative Distribution ◽  
Reliability Based Design ◽  
Design Variables ◽  
Reliability Method ◽  
Distribution Parameters ◽  
Present Worth

In this paper, we present a methodology that helps select the distribution parameters in degrading multiresponse systems to improve dependability at the lowest lifetime cost. The dependability measures include both quality (soft failures) and reliability (hard failures). Associated costs of scrap, rework, and warrantee work are included. The key to the approach is the fast and efficient creation of the system cumulative distribution function through a series of time-variant limit-state functions. Probabilities are evaluated by Monte Carlo simulation although the first-order reliability method is a viable alternative. The cost objective function that is common in reliability-based design optimization is expanded to include a lifetime loss of performance cost, herein based on present worth theory (also called present value theory). An optimum design in terms of distribution parameters of the design variables is found via a methodology that involves minimizing cost under performance policy constraints over the lifetime as the system degrades. A case study of an over-run clutch provides the insights and potential of the proposed methodology.

scholarly journals Limit States Design—A Probabilistic Study

1975 ◽  
Vol 2 (1) ◽  
pp. 36-49 ◽  
Author(s):  
D. E. Allen
Keyword(s):  
Structural Steel ◽  
Composite Structures ◽  
Human Error ◽  
Residential Buildings ◽  
Building Structures ◽  
Limit States ◽  
Design Rules ◽  
Performance Factors ◽  
Importance Factor ◽  
Probabilistic Study

Canadian structural standards for buildings are moving toward a unified limit states philosophy with common safety and serviceability criteria for all materials and types of construction. Structural steel and cold formed steel will have limit states design rules by 1975 and concrete, masonry, and wood will follow later.This paper compares the new rules with existing NBC/CSA requirements on the basis of probability of failure calculated by simplified theory. The main emphasis is on load combinations of dead, floor, and wind loads for office and residential buildings where failure occurs by yielding of steel. Other aspects of the new limit states design rules—column formula for structural steel, performance factors for composite structures, the importance factor which reflects the seriousness of failure, and safety factors during construction, are also considered.The results indicate that the new rules provide more consistent safety than existing rules for different combinations of loads and materials; and that simple rules are sufficiently accurate, keeping in mind the predominating influence of human error on failures and the simplifications used in analyzing complex building structures.

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