Rotation of Steel Lintels Supporting Brick Veneer

[neffers]

I have several questions regarding steel lintels w/ bottom plates that support masonry with a brick veneer.

1. Could someone please tell me how to calculate the angle of rotation for W-flange sections and Tube sections that are loaded torsionally?

2. What is an acceptable amount of vertical movement of the plate supporting the brick due to rotation, say at the centerline of the brick veneer? Do you use L/600? Is the vertical deflection due to normal flexural loading additive with the deflection due to the torsional rotation and the deflection of the plate itself due to bending. Does this total need to be less than L/600?

Any help would be greatly appreciated.

 

[Lutfi]

Get a copy of the AISC design guide No. 9 which deals with the design of open sections for torsion. It addresses all kinds of issues regarding torsion in beams and how to calculate it and how to negate effects of torsion. Remember, the best way to deal with torsion is not to let it happen, knowing that this is impossible all the time.

You will need to define end boundary conditions torsionally. You have only three end conditions to consider, free (flange and web are free to warp and rotate), fixed flange and web are prevented from rotating) and last pinned (web is prevented from rotating and the flanges are free to warp)


Good luck

 

[haynewp]

Torsion of W shapes can be a real pain to analyze correctly, all depending on your assumptions of the actual restraints etc. I try to avoid them or else be conservative by adding welded rods to the top of the beam in grouted cells.

 

[DaveAtkins]

Refer to the post named "Torsion in Masonry Lintels" on this website. DaveAtkins

 

[leebelsh]

I would not consider using an open section, unless the lintel span is very short, and go for a rectangular hollow section.
As for the deflection limit, I would suggest that you should consider the visual appearence of the facing brick wall, in our projects the mortar joins in facing brick walls are usually 10mm, therefore if the supporting plate & lintel deflects considerably more than this, from a distance you will notice the facing brick wall bowing even at relativley small deflections of say 25mm.