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Wave Response Member Force Transfer Functions
Geoff McDonald
Introduction You may have tried to validate stress transfer functions calculated in Fatigue against member end force transfer functions generated in Wave Response and found that the transfer functions do not match. In this post, we will take a look…
over 1 year ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower - Wiki
SACS - Wave loading on plate elements
Adel Hesari
Good day, I have noticed that wave loads generated in SACS are not applied to plates elements. To be more specific, I am modelling a caisson using plate elements. After applying the environmental information to generate and apply wave loading, it…
over 1 year ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
P-delta effects in wave response analysis
Shabad Valiyarambath
Hi, Does the SACS wave response module able to consider the pdelta effects (using PD commands) when generating Base shear transfer function AND also when generating the equivalent static load for accurate stress recovery.
over 2 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
SACS / spectral fatigue analysis
Mohamed Mahmoud
hi all , while generating the seastates (dynamic transfer function) on a cantilever inside the water it was noticed that there is bulb at the early frequency. any ideas why this happens and thanks
over 3 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
Tow Fatigue with SACS
Василий Сивовол
Hi there. I need to perform Fatigue analysis for sea transportation in order to understand this calculation I started studying this guide "Tow Fatigue with SACS". I ran into a problem, if I understood correctly this formulas => have to calculate these…
Answered
over 3 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
DAF random wave for jack up
Xiang Li
Dear friends I am following the SNAME method to estimate the DAF for jack up, based on 3 hours time domain random wave analysis. As per SNAME, the DAF from overturning moment (OTM) should be higher than the DAF from base shear (BS). However, the 2…
over 4 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
DAF Computation - Wave-Current Interaction - SACS - Dynamic Wave Response Analysis
Swarup Selvaraj
Dear All, I understand that only waves cause dynamic effect on offshore jackets and current does not contribute in the dynamic behaviour. I have the following questions regarding to computation of DAF: 1. Is it correct to compute the base shear…
over 4 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
Deep Water Jackets (Water depth > 200m), Dynamic Amplification Factor Computation
Swarup Selvaraj
Dear all, Which would be the best method to compute the Dynamic Amplification Factor (DAF) for dynamically sensitive jackets (water depth > 200m) Method 1: Using equivalent static loads in wave response input file, without using any wave spectrum…
Answered
over 4 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
Selecting modes with mode number higher than 100 for steady state deterministic wave analysis
Eduard Hendriksen
Good day, I am trying to determine the steady state response of a large model loaded by waves and current. Due to the size of the structure and the number of dofs to be considered for dynamic analysis, the number of structural eigenmodes is far…
over 5 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
Extrapolated and Stretched Airy Wave Theory
Kasiphon Kurojjanawong
Dear Sir I am curious about Airy wave theory using in SACS. Refer to 'Seastate manual', AIRY in WAVE card means that kinematic will be calculated at wave crest and trough. AIRC in WAVE card means that kinematic will be calculated at water line…
Answered
over 6 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: Wave response Program
Geoff McDonald
1) The stiffness of the structure does not change. 2) The equivalent static load will include dynamic response of the structure. 3) The soil stiffness is non-linear and is dependent upon the load on the piles. The load used to linearize the piles…
over 6 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: Dynamic Super Element Analysis
Geoff McDonald
Amit, It seems odd that the dynamic superelement data file would be the issue since you are able to run Dynpac without any error. The problem may be with your wave response input. For some reason I can't see the images that you posted so I can't tell…
over 6 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: Wave spreading application
Geoff McDonald
Sanjay, That is not how the wave spreading works in SACS. When you select the wave spreading option, SACS will take the load cases from +- 90 degrees from the fatigue load case direction and factor those load cases using cos^n(theta) so that total equivalent…
over 6 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: SACS - Morison Drag Linearisation for Frequency Domain Analysis
Geoff McDonald
Kasiphon, The nonlinear drag component in spectral wave fatigue analyses is addressed by using constant steepness waves when generating transfer functions. See Section 16.7.2.3 of ISO 19902. Regards, Geoff
over 6 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: Spectral Fatigue Analysis
Geoff McDonald
Quoc, It is possible that the "Use Wave Response Input File" option is set to "No" in your Dynamic Wave Options. Make sure this option is set to "Yes". I would recommend trying to recreate the analysis from scratch to ensure that the runfile options…
over 7 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: Spectral Fatigue Analysis
Geoff McDonald
Quoc, Sometimes analysis options may be available only when certain input is in your input files. It is possible that you are missing some critical input in the wave response input file. Unfortunately, it is difficult to say without looking at your…
over 7 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: Wheeler Stretching
Geoff McDonald
Kasiphon, 1. The 'WH' option is the Wheeler stretching option for random wave analyses. The wave kinematics are calculated for the wave at the water line elevation using the Airy wave exponential decay and then that curve is stretched or compressed…
over 7 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: Spectral Fatigue Analysis
Geoff McDonald
Nalinii, General Wave Response and Deterministic/Transfer Function Generation are both part of the Wave Response module so they are very similar in execution. In fact, the only difference between the two is the input that you provide in you wave response…
over 7 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum
RE: New Wave Theory by Tromans (1991)
Geoff McDonald
Kasiphon, The supported wave theories in SACS are listed in section 4.3 of the Seastate Manual and the New Wave theory is not listed in the list of included theories. I have included the list of supported wave theories below: 1. ‘AIRY’ Airy (or linear…
over 7 years ago
MAXSURF | MOSES | SACS | OpenWindPower
MAXSURF | MOSES | SACS | OpenWindPower Forum