Metal Culvert
Metal Culvert
(OP)
I have a 7' dia corrugated metal culvert cast into a 20" concrete wall. Is there a method (other than FEM or an involved energy method) of calculating the pull-out capacity of this. It has not been fastened to the concrete wall and the only withdrawal resistance is caused by the corrugations.
Dik
Dik






RE: Metal Culvert
RE: Metal Culvert
RE: Metal Culvert
Anyone??
RE: Metal Culvert
I don't think you need to worry about it retaining its shape before collapsing. If I were worried about it, I'd calculate the pullout capacity on the shear cone of the concrete. Then calculate the tension capacity of the culvert at Fu and compare to the concrete strength. I believe the concrete would break or the culvert would rupture before the metal corrugations buckle in unison.
Chip
RE: Metal Culvert
I could see just a few corrugations failing, adding more load to the others causing them to fail (not necessarily in unison, but many failing as a result of the first few failing).
dik-
I might use a conservative bond stress to account for this.
RE: Metal Culvert
Each corrugation is braced by the opposing corrugation. As it is trying to pull out, the concrete between the corrugations goes into compression, putting pressure on the face of the corrugations resisting the pullout. The backside of these corrugations are acting like columns bracing the top of the corrugations. It's basically a fixed top and bottom as the stiffness coefficient would be the same across all the corrugations. It would take a significant amount of compressive force to buckle the backside of these corrugations. Keep in mind, while these forces are attempting to buckle these corrugations, there is a tensile force attempting to pull out the culvert. So you are going to have fa - ft. So, no, I don't believe the corrugations are going to fail in this loading condition. Put the culvert into compression however, and yes, they would likely buckle before the concrete fails.
One failure mode under pullout may be the concrete shearing across the tops of the corrugations.
RE: Metal Culvert
Dik
RE: Metal Culvert
My gut feeling, unless the pipe is very thin or the corrugations very shallow, is that the concrete would shear near the tops of the corrugations, with some slight flattening of the corrugations, before the pipe would yield.
Do you have an axial force in the pipe resulting from a bend downstream? Is it not possible to put a thrust block at the bend and eliminate the force at the intersecting wall? It seems that a corrugated pipe with an axial force would see some significant axial deflection.
RE: Metal Culvert
Dik
RE: Metal Culvert
RE: Metal Culvert
Thanks, the consultant is concerned about a 'waterhammer' force generated from the flow impacting on the energy dissipater...
Dik
RE: Metal Culvert