Crane Loading

[ivanga7]

Hi, I'm designing the footings for a metal building (designed by others) that will house a 50 ton crane. The metal building designer has provided me with the reactions at each frame. One of those reactions is the crane load which accounts for the crane moving. I am having a difficult time figuring out how to incorporate that load into my load combinations. Should I just treat it as a live load?

 

[BAretired]

Yes.

BA

 

[chicopee]

BAretired, what happened if the live load becomes stationary for a few hours such as during a power shortage? Is the load still considered live?

 

[SwinnyGG]

Yes.

If you want to get into the semantics, every gantry design I've ever seen is capable of being moved without power.

 

[sputnikcdn]

Yes you need to include your load combinations, if the building designer hasn't already.

You should also make sure any impact factors have already been applied and that the crane load you've been given is a maximum. Look at the AIST Technical Report No. 13 for details.

And don't forget the lateral loads for your shear.

 

[structuralsteelhead]

ivanga7,...I would agree with BAretired. A live load. Chicopee,...no stress increase for live load or stress decrease for dead in concrete design as in wood materials. Only Load Factoring. ivanga7, since the building manufacturer is supplying the loads, you should use his loads. I would always do some reasonable quick check of live and dead loads including horizontal portal frame loads. With regards to crane loads, depends on how many questions you want to ask him as to how he derived his loading, may not be in your company's budget to chase this rabit all the way down the hole as just reading my long post is eating away at your profit margin . Used to design foundations for the same type of buildings that were so fast tracked, we designed the foundations and had a foundation permit before the PEMB drawings and calculations were done, hoping our conservative foundation assumptions we tabled on the foundation drawings were greater than the eventual loadings of the PEMB engineer. Short form of questioning you 'might' ask,...1)Have you separated the dead load and Live Load components of the crane loading (most likely yes and the crane loading is the crane live load) 2) Does the crane loading include a minimum impact loading per code and crane type (see ASCE-7 for minimums)(most likely does) 3) Trolley beam starting/stopping forces - Do the main frames include a lateral crane shear load for the motorized trolley and perpendicular force on the building crane rail/beam, (if yes, this is still a live load) 4) Trolley or end truck starting/stopping forces - Do the sidewall frames include a longitudinal load on the building crane rail (see ASCE-7 for minimums)). These are minimum loads, if you want to get deeper into it,....loads from the manufacturer/supplier should be listed in within the respective product data. 5) You can ask the PEMB manufacturer is he has included loads as per code or by manufacturer or by a PEMB company standard for a 50 ton crane building crane, you could ask for him to forward the load data for the system being purchase by the client but most likely they do not have this information yet either.

This advice is based upon the fact that you do not have the crane specification in your contract with the building owner and are not the EOR for the entire project which would include the specification of the serviceability requirements of the PEMB. Best to have some type of clarification as to who is responsible for this specification. Typically, if you are the EOR for the entire project you would be specifying all the governing codes and minimum live loads, including crane loading for the project. Most likely, you'll be the EOR for foundations only, and the PEMB is designed and built per MBMA code and you will not the EOR for the building, but some reasonable checks on the column/footing/anchorage design would be assumed which is sounds like you are doing. Hope this helps,...lots of other information here (Eng-tips) on the PEMB/EOR issue, may find some similar posts if you look.