• SACS - Wave loading on plate elements

    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…
  • Why does wave response need pile linearization?

    Hi All, I don't understand why pile linearization is required in Wave Response as shown in the following figure? what purpose? What is the difference of the pile linearization used between in PSI and in Wave Response? If the pile is re-linearized…
  • P-delta effects in wave response analysis

    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.
  • SACS / spectral fatigue analysis

    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
  • Tow Fatigue with SACS

    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…
  • DAF random wave for jack up

    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…
  • DAF Computation - Wave-Current Interaction - SACS - Dynamic Wave Response Analysis

    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…
  • Deep Water Jackets (Water depth > 200m), Dynamic Amplification Factor Computation

    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…
  • Wave Response - Stress Recovery Method

    Dear Sir, I am curious about Stress Recovery option in Wave Response Module. 3 Methods i.e. Equivalent static, Enhanced Modal and Modal Acceleration method are mentioned in Wave response manual. However, I do not see any option and command in SACS…
  • Damping

    When running a wave response analysis, what exactly is the damping value that should be input in the wvrinp file? Is it the damping ratio ξ (actual damping/critical damping) or the total damping 2*ξ ? And so, if we say that a structure has 7% damping…
  • Selecting modes with mode number higher than 100 for steady state deterministic wave analysis

    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…
  • Extrapolated and Stretched Airy Wave Theory

    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…
  • RE: Wave response Program

    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…
  • RE: Dynamic Super Element Analysis

    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…
  • RE: Wave spreading application

    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…
  • Spectral Fatigue Analysis

    For a (particular) fixed offshore platform, If I need to reduce the time taken for a wave response run, what are the main inputs that I should be changing? For eg. is it number of selected frequencies or number of joints where we lump the mass or…
  • RE: SACS - Morison Drag Linearisation for Frequency Domain Analysis

    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
  • RE: Spectral Fatigue Analysis

    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…
  • RE: Spectral Fatigue Analysis

    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…
  • RE: Wheeler Stretching

    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…
  • RE: Spectral Fatigue Analysis

    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…
  • RE: New Wave Theory by Tromans (1991)

    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…