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  • Users: sgdon
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  1. sgdon

    Vibration of Dance Floor

    Hi 271828 Your effort in response is definitely appreciated and definitely not gone unnoticed. Thanks also to the rest who are willing to share your knowledge and experience in this tread, or others in the Forum. I am not able to get hold of DG11 or Design Guide 11 in my office. But i am able...
  2. sgdon

    Vibration of Dance Floor

    Thanks all for the valuable inputs to this tread. I think to put it simply, the inclusion of a certain percentage of Live Load is to assume that these group of people are not atationary while the rest which are dancing will cause the excitation frequecy. We should then avoid the resonnace of...
  3. sgdon

    Vibration of Dance Floor

    Thanks prsconsultant. At least, now i know what i see is a valid design procedure. But What is the rationale? By adding live loads to the mass of the structure, are we not artificially altering the true natural frequency of the structures?
  4. sgdon

    Vibration of Dance Floor

    I have seen people adding some percentages of live and superimposed dead loads to the mass of the floor. The model is then run (in Etabs) to obain the eigenvalue, i.e. natural frequency. As we know natural frequency is not a function of external loads, what is the rationale of considering the...
  5. sgdon

    Etotal?

    Hi users Anyone can explain the term Etotal in ABAQUS for checking purposes. I u derstand it is a energy check but what if Etotal grows with Internal Energy and its magnitude is comparable with the Internal Energy as well? Does this mean the model is wrong -possibly due to rigid body motion...
  6. sgdon

    Zero Displacement

    Thanks. THe material definition is correct. Im really not too sure what the cause but manage to complate the analysis without using riks.
  7. sgdon

    Zero Displacement

    Dear all I wonder have any of you encouter such error: ***ERROR: A ZERO DISPLACEMENT SOLUTION WAS FOUND IN THE FIRST ITERATION OF A RIKS STEP. THE ANALYSIS CANNOT PROCEED. THE MOST LIKELY CAUSE IS THAT ALL DISPLACEMENT DEGREES-OF-FREEDOM ARE CONSTRAINED TO BE ZERO...
  8. sgdon

    Submerged Density/Density of Composite Pipes

    Thanks all. I have use directly the load/m length to replace the submerged density. This is compared with the use of the submerged density derived from the steel area only. Both results are extremely close to each other. This shows that the FE is using the submerged density and multiply it by...
  9. sgdon

    Submerged Density/Density of Composite Pipes

    Dear all From a survey report of a subsea pipeline, i am managed to read off the weight of the pipe in per metre run (say X). This weight has taken account of the various components of the composite pipes (i.e. concrete, steel and anti corrosion coating etc) and the buoyancy. However, i need...
  10. sgdon

    Subsea HP/HT Pipeline Analysis

    Thanks gwolf. Sorry for not being specific as my intention is just to tap the experience and views from anyone who have done such analysis. I have not met any problems currently in the planning stage but it is expected there will be difficulties associated with plotting the 3-D seabed profile...
  11. sgdon

    Subsea HP/HT Pipeline Analysis

    Dear all I wonder if any of you have done any such analysis using abaqus or some other softwares? I understand it is extremely difficult to model the subsea condition. Care to share your experience? Rgds sgdon
  12. sgdon

    von mises stress vs maximum shear stress

    Thanks johnhors. Silly me!
  13. sgdon

    Design of concrete foundation for impact load?

    Also, in stuctural design, engineers always like to use a factor of two to take account of dynamic effect whenever there is an impact load . I wonder if this is conservative here. I would however need to point out that the aplication of the dynamic factors require the consideration of the whole...
  14. sgdon

    von mises stress vs maximum shear stress

    Tresca and von Mises agree at 6 points in a planar failure surface in terms of priniciple stresses. In pure torsion, tresca will predict 0.5fy and Mises 0.577fy.
  15. sgdon

    Flexure/Shear test data processing

    Ha..you are also trying to test my limits huh?! For 4 pt and still assuming elastic, one can work out to be Stress=Moment/Elastic modulus (For rectangular section, elastic modulus=bd^2/6) Moment = (P/2)*l/3 (assume total load on the beam is P) i.e. Stress=Pl/(b*d*d) Having, i did come across...
  16. sgdon

    Flexure/Shear test data processing

    Hi phoenix221 Apologise for the mistake here. Yes, you were right, the flexure stress factor should be 1.5. For 4-pt test, you can similarly derive from 1st priciple, i.e. obtain moment from the triangular stress block and equate to the moment obtained from the free body diagram. Thanks
  17. sgdon

    Flexure/Shear test data processing

    Hi, assuming elastic regime, Stress (flexure) = (0.75*L*P)/(b*d*d) Stress (shear) = (0.75*P)/(b*d) where P is the load of the 3-point test. Regards sgdon
  18. sgdon

    Carbon fiber in FEA

    Thanks Erik. The explanation is very helpful! sgdon
  19. sgdon

    Carbon fiber in FEA

    Thanks Erik, I totally agree with you. The point we trying to understand now is why G12 has no relationship with E1 and E2 and v12, all in principle material direction with no regards to XY coordinates. For the sake of discussion again, if we have a lamina with all fibres running in every...
  20. sgdon

    Carbon fiber in FEA

    Hi Eap2n Thanks you so much for the explanation and i apologise for the error in the given equation. The difficult part to is to understand why G12 has no relationship with E1/E2 and v12. Thanks for reminding me about the Herakovich's bk. I tried to search for additional explanation and it is...

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