DNV-OS-C502 Offshore Concrete Structures

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DNV-OS-C502 Offshore Concrete Structures

App.A: Environmental Loading (Guidelines)

A: General

A100: Environmental Loads

App.A
A 100 Environmental Loads

App.A A
101 Wind, wave, tide and current are important sources of environmental loads (E) on many structures located offshore. In addition, depending on location, seismic or ice loads or both can be significant environmental loads.

App.A A
102 Loads from wind, wave and current occur by various mechanisms. The most important sources of load are:

—	viscous or drag effects, generally of most importance for relatively slender bodies
—	inviscid effects due to inertia and wave diffraction. These are generally of most importance in terms of global effects for relatively large volume bodies.

App.A A
103   For fixed concrete structures, static analyses can be adequate. The possibility that dynamic analysis is required on local components or on the global platform shall be investigated. In the specific case of wave loading, the possibility that non-linear effects can lead to loads at frequencies either above or below the frequency range in the wave spectrum both during temporary floating conditions and at the permanent location shall be investigated. Potential dynamic effects on local or global loads from wave, wind and current sources shall also be investigated.

App.A A
104   The influence of the structure on the instantaneous water surface elevation shall be investigated. Possible direct impact of green-water on a deck or shafts shall also be investigated. Total water surface elevation depends on storm surge and tide, the crest height of incident waves, and the interaction of the incident waves with the structure or other adjacent structures.

App.A A
105   Environmental loads due to wind, wave and current relate particularly to the ultimate limit state requirements. In addition, these loads can contribute to the fatigue, serviceability, and accidental limit states. Environmental loads due to wind, wave and current shall also be considered in temporary configurations of the structure during construction, tow, and installation.

App.A A
106   The estimation of loads due to wind, wave and current requires an appropriate description of the physical environment in the form of seastate magnitude and direction, associated wind magnitude and direction, and relevant current descriptions in terms of current velocity profiles through the depth and associated directional information. The derivation of wind, wave and current combinations required for calculation of loads is described in DNV-OS-101 Sec.3.

App.A A
107   Procedures for the estimation of seismic loads are provided in DNV-OS-C101 Sec.3.

App.A A
108   The computation of ice loads is highly specialized and location dependent and is not covered in detailed by this Standard. There is an extensive relevant body of literature available for the computation of ice loads that should be consulted for guidance. Ice loads shall be computed by skilled personnel with appropriate knowledge in the physical ice environment in the location under consideration and with appropriate experience in developing loads based on this environment and the load return periods in accordance with DNV-OS-C101 Sec.3.

DNV-OS-C502 Offshore Concrete Structures

App.AA 100 Environmental Loads

App.A
A 100 Environmental Loads