UmarMakhzumi

You should also challenge whats being said in the report by sending RFIs. I do it all the time. In that way all communication and decisions are documented. Thanks.

Mhdhamood, For both cases, the factor with E is 1.0. It wouldn't make any difference. Thanks.

W.s Waqas, Here are some references that can help you get started: 1) ACI 351.3 Foundation For Dynamic Equipment 2) Design of Structures and Foundations for Vibrating Machines by Suresh C. Arya You can get both the documents from google easily. Other than these two there are some discussions in the forum that will provide you some insight about the subject. - http://www.sepakistan.com/topic/1383-pile-design-for-machine-foundation/ - http://www.sepakistan.com/topic/1666-superimposed-beams/ Thanks.

Mhdhamood, The forum already has 2 complete detailed articles with examples that you can follow to confirm your understanding. Here are the links: http://www.sepakistan.com/topic/109-building-drifts-in-etabs/ http://www.sepakistan.com/topic/1341-ubc-seismic-drift-limits/ Thanks.

Uzair, Where I work, it is mandatory that all geotechnical reports to be reviewed and stamped by Professional Geotechnical Engineers before they can be issued for use. Normally, geotech engineer would also visit the site, take the samples and an EIT would assist him make a report. But he is responsible for all engineering content in it. Thanks.

Yeah, make sure you are there before May 24, 2015. I need to tag you in the post on 3 years completion announcement. Thanks.

Good luck. Its a up hill battle. Thanks.

I don't have any experience with them. Sorry.

Weight should stay the same for most cases. Stiffness can be different if structural framing is different. In other words your time period would be different in both directions if structural framing or lateral force resisting system is different in each direction. Thanks.

Is the trench precast Or are you designing it? You can check it using the same way a retaining wall is checked for surcharge loading. Thanks.

What are actuators? Thanks.

Looks legit. However. When designing for shear, make sure that you consider strip cuts(RISA Foundation Terminology) at distance 'd' from the face of support or you may end up over-designing the foundation. Thanks.

Batoul, 1) What is your structural framing- I assume your building is somewhat rectangular and length is significant compared to other direction. Base shears can be different in both direction if your fundamental period is different and so will be the distribution. 2) What is the deflection. The model may have an input error etc. 3) Period depends upon framing and "high" is a relative word. Please state how much? Thanks.

Welcome aboard!

Are you talking about the location of the strip OR width of the strip when you say d/2 ? Thanks.

Good discussion. I will just add that Canadian Code CSA A23.3-09 allows a max distance 'dv' to be considered as part of punching shear perimeter where the slab cantilevers off column/ pile. Thanks.

W.s So the SME says that if there is only compression, the cold joint shouldn't be an issue. But if there is moment in the foundation at cold joint location then reduced stiffness properties shall be considered. I don't know what the foundation framing is? Can you share that- probably a line diagram? Thanks.

Hello Everyone, Don't forget to like us on Facebook. https://www.facebook.com/SEFP.Pakistan Thanks.

Please see: http://www.sepakistan.com/topic/1444-amplification-of-forces-in-etabs/ http://www.sepakistan.com/topic/1504-basement-wall-seismic-drift/?p=3406 http://www.sepakistan.com/topic/1448-location-of-base-for-seismic-design/ http://www.sepakistan.com/topic/1480-diaphragm-flexibility/ Thanks.

R and base shear work quite opposite. Greater the R, the more ductile the system and reduced base shear. Thanks.

Ws. I can see the concern of the Lender's Engineer. For a turbine foundation, with an unintentional cold joint, he may be worried about vibrations and subsequent crack propagation. Well the irony is that you can't really have machine foundation poured in a single unit (unless its a simple small square pad). It has to has construction joints or sometimes unwanted cold joints. Given the nature of problem, a super-imposed beam would not add any value to given problem. This approach shall make sense if you only think inside static design bubble. However, considering the limit states for turbine foundations, the addition of beam may not help. Here are two solutions: 1) Static Design: Your engineers should demonstrate that enough reinforcement is present and crack control is not a problem. I have done huge compressor foundations and have allowed construction joints where required. Joints are inevitable and shouldn't be any problem. The impact of a cold joint on machine foundation is somewhat hard to assess as there are so many factors involved-quality of joint, location of joint, support framing . The above stated solution is an acceptable one if the dynamic loads being produced by turbine are very small- dynamics analysis wouldn't be of any significance. 2) For significant dynamic loads: This solution is applicable if your turbine dynamic loads are significant enough to affect foundation response. Talk to your engineers to see what limit states governed foundation design. If your foundation is table top, re-check the foundation using reduced section properties(since concrete is cracked). Normally, machine foundation design(other than table tops) is based on the assumption of rigid block and no one would consider reduced properties when checking response of foundation against dynamic loads. If your engineer re-checks the foundation based on reduced section properties(If foundation is table top) and amplitudes are still below the maximum limit, and there are no resonance issues, you shouldn't require any modification at all. However, You still need to add the crack control check to ensure that enough rebar has been provided and cracks won't propagate. Don't float this idea to the Client unless someone who designed the foundation has actually done the check. Unless the foundation is excessively over-designed, this condition shall be very hard to meet. I will also discuss this with dynamic analysis subject matter expert and update you on what he thinks. #2 is a conservative way and is just one of many approaches out there. So, adding a beam would do nothing to your wind turbine foundation. If the beam being added is a huge beam, it would add some/ little mass and damping to system but the response of the beam is not related to what your question is about. The question is also about what kind of dynamic loads are present. I have never seen any vendor data of wind turbines and can't say about kind of dynamic loads produced by them. If your dynamic loads are significant and foundation type is table top, see point 2 else point 1. I hope this helps. Keep the updates coming. Thanks. Update: Regarding Point #2, for table top machines, reduced Section properties should be used. For rigid blocks, cold joint will not have any significant affect as foundation will be most likely in compression.

Please see http://www.sepakistan.com/topic/1642-slab-design/ Thanks.

Waqas, Please describe what superimposed beams are. My guess is that you are talking about a new beam that will "bear" on an existing one? Is this understanding correct? Thanks.

I am not sure about what SAFE does but can't you easily check your raft for maximum negative uplift pressure by modelling is at a slab on columns? Thanks.

Cool. Good Stuff Rana.