Limit State Design of Shallow Footings as Per Eurocode 7 and Its Comparison with is Code WSM

2021 ◽  
pp. 597-603
Author(s):  
Aditi K. Sheth ◽  
K. N. Sheth
Keyword(s):  
Limit State ◽  
Limit State Design ◽  
Eurocode 7

scholarly journals Ultimate Limit State Design of Spread Foundations in The Case of Uplift

2016 ◽  
Author(s):  
Witold Bogusz
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Uplift Capacity ◽  
Limit State Design ◽  
Eurocode 7 ◽  
European Standards ◽  
Lattice Towers ◽  
Overhead Electrical Lines ◽  
Overhead Power Lines ◽  
Ultimate Limit State Design

As vast majority of spread foundations are never subjected to vertical uplift loads, the subject of uplift capacity in such cases is barely covered by current European standards. Although the limit state design due to uplift is a subject of a section 10 of Eurocode 7, it mainly covers the possibility of a hydraulic failure while taking into the account any destabilizing variable actions. However, in the case of separate foundations of lattice towers used as support structures for overhead power lines, the uplift capacity of spread foundations often governs the design. The rules for the design of these structures are included in the informative annex M of EN 50341-1: 2012 Overhead electrical lines exceeding AC 1 kV – Part 1: General requirements – Common specifications. Rules presented in this standard differ significantly from those presented in Eurocode 7. The purpose of this paper is to present the design approaches for the limit state design of spread foundations subjected to uplift, while the differences between design rules and resulting variation of reliability are the primary concerns.

Evaluation of the Effect of Yield to Tensile (Y/T) Ratio on the Structural Integrity of Offshore Pipeline by Limit State Design Approach

2006 ◽  
Author(s):  
Gianluca Mannucci ◽  
Giuliano Malatesta ◽  
Giuseppe Demofonti ◽  
Marco Tivelli ◽  
Hector Quintanilla ◽  
...  
Keyword(s):  
Structural Reliability ◽  
Failure Modes ◽  
Structural Integrity ◽  
Limit State ◽  
Minor Effect ◽  
Offshore Pipelines ◽  
Limit State Design ◽  
A Minor ◽  
Probabilistic Failure Analysis ◽  
Failure Probabilities

Nowadays specifications require strict Yield to Tensile ratio limitation, nevertheless a fully accepted engineering assessment of its influence on pipeline integrity is still lacking. Probabilistic analysis based on structural reliability approach (Limit State Design, LSD) aimed at quantifying the yield to tensile strength ratio (Y/T) influence on failure probabilities of offshore pipelines was made. In particular, Tenaris seamless pipe data were used as input for the probabilistic failure analysis. The LSD approach has been applied to two actual deepwater design cases that have been on purpose selected, and the most relevant failure modes have been considered. Main result of the work is that the quantitative effect of the Y/T ratio on failure probabilities of a deepwater pipeline resulted not so big as expected; it has a minor effect, especially when Y only governs failure modes.

scholarly journals Rational Modeling of Ultimate Pipe Strength Under Bending and External Pressure

2000 ◽  
Author(s):  
André C. Nogueira ◽  
Glenn A. Lanan
Keyword(s):  
Deep Water ◽  
Limit State ◽  
Local Buckling ◽  
External Pressure ◽  
Pressure Effects ◽  
Combined Loading ◽  
Empirical Prediction ◽  
Limit State Design ◽  
Controlled Conditions ◽  
Offshore Pipeline

The capacity of pipelines to resist collapse or local buckling under a combination of external pressure and bending moment is a major aspect of offshore pipeline design. The importance of this loading combination increases as oil and gas projects in ultra deep-water, beyond 2,000-m water depths, are becoming reality. The industry is now accepting, and codes are explicitly incorporating, limit state design concepts such as the distinction between load controlled and displacement controlled conditions. Thus, deep-water pipeline installation and limit state design procedures are increasing the need to understand fundamental principles of offshore pipeline performance. Design codes, such as API 1111 (1999) or DNV (1996, 2000), present equations that quantify pipeline capacities under combined loading in offshore pipelines. However, these equations are based on empirical data fitting, with or without reliability considerations. Palmer (1994) pointed out that “it is surprising to discover that theoretical prediction [of tubular members under combined loading] has lagged behind empirical prediction, and that many of the formula have no real theoretical backup beyond dimensional analysis.” This paper addresses the ultimate strength of pipelines under combined bending and external pressure, especially for diameter-to-thickness ratios, D/t, less than 40, which are typically used for deep water applications. The model is original and has a rational basis. It includes considerations of ovalization, anisotropy (such as those caused by the UOE pipe fabrication process), load controlled, and displaced controlled conditions. First, plastic analysis is reviewed, then pipe local buckling under pure bending is analyzed and used to develop the strength model. Load controlled and displacement controlled conditions are a natural consequence of the formulation, as well as cross section ovalization. Secondly, external pressure effects are addressed. Model predictions compare very favorably to experimental collapse test results.

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