Concrete beam design for Gantry Cranes

[samaaamal]

Hi All,

Could any1 provide guidelines/ advice on designing RC Footing /Foundation supporting a RC Beam @ every 6m. The RC Beam will in-turn support the Rails for the Gantry Crane (8 Ton and 10 Ton).

Am new to concrete designing this is the first time i will be involved in any of RC related design.

Thanks

 

[Ron]

Hopefully you have someone locally who can guide you through this. Gantry cranes have high loads and high performance expectations, including low tolerance for settlement in general and differential settlement in particular.

This subject is not one that a forum can give the kind of guidance you'll need.

 

[samaaamal]

Thanks Ron,

but i require the guidelines for estimation purpose only to get approximate size of the footing and the Beam.

Final design would be by a civil contractor.

 

[hokie66]

As Ron advised, this is not the place to look for the kind of guidance you need. And for the final design, you need a structural engineer, not a "civil contractor".

 

[msquared48]

For "estimation only", the maximum reaction to the footing, if this is railed, twin beam gantry with a traversing hoist, will be with the twin rails centered over the column and the hoist to the side of the column/footing, fully loaded. Add impact as required.

For the beam, the maximum positive moment will be with the CG of the twin beam gantry system at the center of the beam and the hoist as near to the beam as possible, again fully loaded, with impact.

Fot =r the maximum shear in the beam, put one of the wheels of the gantry at a distance "d" from the column, and let the other wheel be on the same span, again with the hoist as near to the beam as possible, fully loaded, with impact.

You really do need to get a licensed Structural Engineer involved here, not just a Civil, as this is pretty specialized structure - preferably one who has done this type of structure before.

This gets more complicated if there are two gantrys, as you havde suggested, working in close proximity as their loads can become additive to certain members. In addition, certain gantry systems have a maximum deflection, which can get difficult to calculate.


Mike McCann
MMC Engineering

 

[samaaamal]

Thank You So Vry Much Msquared48.

Actually I my self am a structural designer (Structural Steel) so have limited knowledge about Structural Concrete (only academic course).

My Boss had asked me about getting approximate sizes of footings and the beam jus to get an idea, finally this job will going to be designed (Steel part if any, by us) and Concrete part (substructure) by a civil contractor who in turn will assign a Structural (concrete) engineer for the work.

The idea is like.. there will be a continuous RC beam of about 70m, with footings at every 6m. this entire assembly will support the Rails of gantry over which two 8Tons cranes will run, (bridge span is 15m).

In past I have had designed Steel beams rested on Steel Columns (for industrial shed, factories etc) for overhead cranes using staad, but again the foundation work was out of our scope.

This is the first time I came across gantry cranes running on ground rails (so the sub structure be RC design).

I have modeled 1 RC beam (with ends as fixed) of 6m in Staad, applied Moving loads (took the critical location for max. BM and max. Shear) and then applied static load at these locations for max BM and Shear. (this is how we do for Steel beams and then the steel beams are designed)

But for RC design I don know whether it should be designed for static load or like roads/bridges where moving loads are of concern giving warping stresses and all..

This is where am finding it difficult.

While for Footing, I guess the maximum reactions from the 6m beam is to be considered for the design.
Or should I model in Staad Two 6m beams with 3 footings and design.

Advice would b appreciated.