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…
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…
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.
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
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…
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…
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…
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…
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…
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…
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…
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…
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…
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
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…
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…
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…
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…
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…