Determination of Environmental Conditions Relevant for the Ultimate Limit State at an Exposed Aquaculture Location

2017 ◽  
Author(s):  
Pål Takle Bore ◽  
Jørgen Amdahl
Keyword(s):  
Environmental Conditions ◽  
Limit State ◽  
Ultimate Limit State ◽  
Distribution Method ◽  
Wave Data ◽  
Wave Conditions ◽  
One Year ◽  
Ultimate Limit

Methods for determination of environmental conditions relevant for the ultimate limit state at an exposed aquaculture location are proposed. The considered location is in Frohavet, northwest of Trondheim, Norway. Wind, waves and current are considered, but as more severe wave conditions are expected to be the most influential environmental factor when going from sheltered to more exposed locations, particular focus has been given on the description of wave conditions. The estimated long term description of wind and waves are based on 16 year of SWAN hindcast data, where the wave data have been calibrated against one year of in-situ measurements. One month of current measurements were available. The initial distribution method is used to determine the long term distribution of wind and wave conditions. The data fit the applied distributions well, but the sea state characteristics are seen to be highly directional dependent, which is important to take into account. The effect of using only one year of wave data is also investigated, showing that this can lead to significant underestimation of the extreme values. Concepts from the environmental contour line method are applied for determination of sea states corresponding to a given annual probability of exceedance. A deterministic approach from NS 9415 is used to determine the extreme current velocities. Comments on the use of directional criteria for design are also given.

APPLICATION OF UNCERTAINTY ANALYSIS TO STABILITY PROBLEMS OF STEEL-CONCRETE STRUCTURAL MEMBERS

2009 ◽  
Vol 1 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Libor Puklický ◽  
Zdeněk Kala
Keyword(s):  
Epistemic Uncertainty ◽  
Limit State ◽  
Ultimate Limit State ◽  
Load Carrying Capacity ◽  
Structural Members ◽  
Load Carrying ◽  
Steel Sections ◽  
Limit Stress ◽  
Ultimate Limit

The paper deals with the fuzzy analysis of the ultimate limit state of a steel strut with an encased web in compression. The first part of the paper lists presumptions required for the determination of the theoretical load carrying capacity for the column. Stresses in the concrete and steel sections are determined according to the principles of elasticity. The ultimate limit state is given as the limit stress attained in the most stressed section of either the steel or concrete section. A general extended principle, which takes into account the epistemic uncertainty of input parameters, was utilized for the conducted analysis.

scholarly journals ON DESIGN FEATURES OF PROPPED AND UNPROPPED HYPERSTATIC STRUCTURES

2007 ◽  
Vol 13 (2) ◽  
pp. 123-129 ◽  
Author(s):  
Algirdas Kudzys ◽  
Romualdas Kliukas ◽  
Antanas Kudzys
Keyword(s):  
Reinforced Concrete ◽  
Design Methodology ◽  
Extreme Values ◽  
Limit State ◽  
Ultimate Limit State ◽  
Term Survival ◽  
Partial Factor ◽  
Ultimate Limit ◽  
Composite Steel

An effect of structural and technological features on the design methodology of hyperstatic precast reinforced concrete and composite steel‐concrete structures is discussed. Permanent and variable service, snow and wind loads of buildings and their extreme values are analysed. Two loading cases of precast reinforced concrete and composite steel‐concrete continuous and sway frame beams as propped and unpropped members are considered. A redistribution of bending moments for the ultimate limit state of beams is investigated. A limit state verification of hyperstatic beams by the partial factor and probability‐based methods is presented. It is recommended to calculate a long‐term survival probability of beams by the analytical method of transformed conditional probabilities.

Evaluation of Uncertainties in Loadings on Offshore Structures due to Extreme Environmental Conditions

1993 ◽  
Vol 115 (4) ◽  
pp. 237-245 ◽  
Author(s):  
R. G. Bea
Keyword(s):  
Environmental Conditions ◽  
Epistemic Uncertainty ◽  
Limit State ◽  
Offshore Structures ◽  
Ultimate Limit State ◽  
Mackenzie Delta ◽  
Loading Effects ◽  
Load Effects ◽  
Available Information ◽  
Ultimate Limit

This paper summarizes results from a Canadian Standards Association (CSA) sponsored study of the uncertainties associated with extreme (1000 to 10,000-yr return periods) environmental loadings acting on offshore structures (Bea, 1991). The evaluations of the loadings addressed loading effects that resulted from dynamic and nonlinear interactions of the structures. Loading uncertainties were organized and characterized in two categories: 1) inherent randomness (aleatory uncertainty), and 2) analytical variability (epistemic uncertainty). The study addressed the global ultimate limit state performance of three structures designed according to the provisions of the draft CSA guidelines (1989a, 1989b) for offshore structures: 1) a concrete Gravity Base Structure (GBS) located off the East coast of Canada (Hibernia), 2) a steel pile template located on the Scotian Shelf off Sable Island, and 3) a caisson retained island located in the Mackenzie Delta area of the Beaufort Sea (Amuligak). The results of this study indicate that, based on presently available information and data, it is often not possible to develop unambiguous characterizations of uncertainties. The different technical communities that background environmental conditions and forces (storms, earthquakes, ice) recognize and integrate these uncertainties into loading characterizations in different ways. In many cases, major sources of uncertainty are not included in probabilistic characterizations. Because of the needs for design code information sensitivity and consistency in demonstrating compliance with target reliability goals, there is a need for well-organized and definitive evaluations of uncertainties in extreme environmental loadings and load effects (Bitner-Gregersen et al., 1993).

scholarly journals RELIABILITY ANALYSIS OF THE LATERAL TORSIONAL BUCKLING RESISTANCE AND THE ULTIMATE LIMIT STATE OF STEEL BEAMS WITH RANDOM IMPERFECTIONS

2015 ◽  
Vol 21 (7) ◽  
pp. 902-911 ◽  
Author(s):  
Zdeněk Kala
Keyword(s):  
Failure Probability ◽  
Limit State ◽  
Ultimate Limit State ◽  
Safety Factors ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Random Variability ◽  
Partial Safety Factors ◽  
Ultimate Limit

The paper deals with the analysis of reliability of a hot-rolled steel IPE-beam designed according to Eurocodes. A beam at its ultimate limit state is considered. The load acting on the beam consists of permanent and long-term single variation actions. The beam is loaded with end bending moments about the major principal axis. The beam is susceptible to lateral torsional buckling between the end supports. Reliability of the beam is assessed using probabilistic analysis based on the Monte Carlo method. Failure probability is a function of the random variability of the loadcarrying capacity and the random variability of load effects. The variability of the load-carrying capacity is influenced by the variability of initial imperfections. Imperfections are considered according to experimental research. Numerical studies showed that the failure probability is significantly misaligned. High values of failure probability were obtained for slender beams, for beams loaded only by permanent load action, and for beams loaded only by long-term single variation load. In further studies the values of partial safety factors of load and resistance were calibrated so that the failure probability had a target value of 7.2E–5. Relatively high values of partial safety factors were obtained especially for beams with high slenderness.

scholarly journals Determination of the ULS, for columns with small dimensions, under biaxial bending and symmetrical fire conditions

2017 ◽  
Vol 10 (2) ◽  
pp. 451-476
Author(s):  
M. CHEREM ◽  
V. PIGNATTA SILVA
Keyword(s):  
Ambient Temperature ◽  
Cross Sections ◽  
Load Capacity ◽  
Limit State ◽  
Ultimate Limit State ◽  
Biaxial Bending ◽  
Structural Engineers ◽  
In Fire ◽  
Ultimate Limit

Abstract Obtaining internal load capacity, in reinforced concrete sections, at ambient temperature, under biaxial bending, is one of the most common tasks done by structural engineers, but not so common when the member is in fire situation. The intention of this paper is to show that is possible to correlate the ultimate limit state (ULS), in fire situation, with ULS at ambient temperature, for square cross sections under fire from all faces. To reach the purpose and give support to the numerical analysis of this article, a computer program, in Delphi language, called COL FIRE, is being developed by the authors.

Sign in / Sign up

Export Citation Format

Share Document