Recent content by malbek

dhengr, I don't know if AISC has guidance on this, however I have now done a STAAD time history analysis of this which confirmed that vibrations were within the required limits. With my original query I was looking to see if there were any "rules of thumb" which could be used to say if a motor...

Thanks for that WARose. The motor sits on a skid frame which will be bolted on to the deck of an oil platform. I have already done frequency analysis of this, however that doesn't really tell me enough as it doesn't take any account of the magnitude of the forcing function. I will now be doing a...

Thanks for your comments folks. The pump itself is not a cause for concern as it operates at a frequency sufficiently lower than the first mode of the supporting structure. The electric motor is the issue here as this runs close to the structure frequency. However as I said above, the rotor is...

Thanks Swearingen. What you say regarding the rotor mass relative to the beam mass sounds like a good starting point. I am currently looking at a pump package weighing 3600kg, critical operating frequency is that of the electric motor rotor which is about 90kg. The whole package is supported on...

Hi All, I have recently been looking at some jobs involving pumps and electric motors supported on structural steelwork. With regard to vibration of the structure, I know the general requirement is to try to ensure that the fundamental frequency of the structure is not too close to the...

I am currently looking at the effects of quarry blasting on a nearby buried pipeline. The limited info I have on this (based on work by Esparaza) gives pipe stress increases for a given charge size, type and standoff distance, and looks at "deep" and "shallow" cases. However it takes no account...

Thanx prex, I'll check these out.

Hi All, I have an unusual problem which I am trying to get some guidance on. I have a composite section which is being used in bending. The section comprises a glass fibre and mineral wool filled core with thin steel plates bonded either side. I am trying to establish how much buckling...

Hi All, I am soon going to be working on the design of some steel cabin type structures, some are blast resistant cabins and some are marine cargo containers. Normal construction for both of these seems to usually comprise a rectangular box type frame with corrugated steel panels forming the...

Hi All I'm currently trying to do a preliminary design for a steel framed shed which is to take blast loading. I can get an estimate of max displacement ok from the ASCE "Design of Blast Resistant Buildings in petrochemical facilities" book however for element forces this only gives a method...

Hi All I'm currently trying to calculate the horizontal fundamental frequency of a diesel tank base. To simplify things I want to treat it as a shear beam with the centre of gravity of the mass at a height 'h' above underside of base. The base will not be fixed as it is just sitting on the...

Thanks for the replies folks. Found a good old book on the slideruleera site & spreadsheet will also be useful.

Can anyone advise me of a calculation method for getting cable tension forces and end reactions for a catenary carrying a point load on the span?