Eccentric Loading on Concrete Beam 1

[pioneer09]

Have a project we are working on for a concrete batching plant. The design utilizes steel hoppers that sit on concrete beams that also support the divider walls for the different hoppers. See the attached rough sketch. Where I hope to get some input is with respect to the eccentricity that is developed due to the uneven height of steel hopper ledges. The ledges are approximately 4' apart and as a result there is approximately 20% in load difference from one side to the other. My first though was that the lighter load travels axially through the concrete until in reaches the H x W concrete beam that supports all of the load. Eccentricity would develop due to the uneven loading, but my thought was to provide steel embed plates at the ledges that the steel hoppers could be welded to alleviate any possible torsion action on the concrete beam; essentially like a diaphragm/deck. Secondly, I would think the horizontal and vertical bars that tie the divider walls to the concrete walls making up the other two side of each hopper would also eliminate torsion from occurring. Any thoughts or insight would be appreciated.

 

[WARose]

I don't see how torsion (or more accurately: a flexural force in the wall) could be avoided in that set up. You are going to have a net/unequal force going to those divider walls.....which will have a horizontal and vertical component eccentric to the members shown.

 

[pioneer09]

WARose,

Not avoided but restrained/resisted I guess is a better way of putting it. I realize that a net component both horizontally and vertically will be present. Worst case will be with only one side loaded as in the following attachment. My opinion is that the "horizontal component" restraint provided by the flexural steel reinforcement members that terminate at a 90 degree bend in the cross-wall along with the steel hopper bin elements that are welded to the ledge is a potential approach to resist this horizontal force. Additionally, these tall divider walls (10' up to 20' in height above the ledge bearing surfaces) would provide a vertical element of restraint; the wall would seem to act like a deep vertical beam in addition to the horizontal beam member. With this restraint provided, I would think the true "vertical component" at the ledger bearing surfaces could be designed/resisted by the "true" beam element directly under the ledge bearing surface.

Thoughts?

 

[WARose]

My opinion is that the "horizontal component" restraint provided by the flexural steel reinforcement members that terminate at a 90 degree bend in the cross-wall along with the steel hopper bin elements that are welded to the ledge is a potential approach to resist this horizontal force. Additionally, these tall divider walls (10' up to 20' in height above the ledge bearing surfaces) would provide a vertical element of restraint; the wall would seem to act like a deep vertical beam in addition to the horizontal beam member. With this restraint provided, I would think the true "vertical component" at the ledger bearing surfaces could be designed/resisted by the "true" beam element directly under the ledge bearing surface.

It would certainly restrain it to some degree......analysis will tell you how much.