Shear and the distance d

[connect2]

Regardless of reinforced masonry or concrete the shear requirement from the face of the support to a distance of d from the support is the shear at the distance d for a flexural member. Several conditions one of which is, no CONCENTRATED load can be within the distance d. Fine. If you are designing a lintel or header over an opening in a wall and you have a concentrated point load above at the top of the wall, say a reaction from an OWSJ, the general procedure is to distribute this point load at an angle of 60 degrees until a prescribed maximum width is reached thus converting the concentrated point load into a uniformly distributed load. And lets say in this case an OWSJ reaction is with in the distance d from the edge of the lintel/beam or opening. Question is, is this a concentrated load? Does the requirement of utilizing the shear value at a distance d apply or not? Thanks.

 

[rapt]

It is a concentrated load. The only debate is if it is sufficiently large copmpared to the other loading to require checking at the face of the support.

Depending on which code you are using, this is not necessarily onerous. For the Australian code AS3600 and British code BS8110, there is a factor that increases shear capacity in this zone anyway so you are not being disadvantaged.

The only other option would be strut-tie analysis and design.

 

[JAE]

We usually run lines up diagonally from the opening corners to form a triangular wedge of loading on the lintel. If this triangle is interrupted by the top of wall level (joist bearing level) then the joists are treated as individual concentrated loads instead of spread-out uniform loads. In that case we'd then possibly have a concentrated load within d from the support.

If not, the loads are considered to be spread out enough such that the reduced shear can be used.

 

[UcfSE]

I agree with JAE. I do it that way also.