Horizontal shear at the section between flange and web for T beam

[kww2008]

Please share your experience/view on the matter discussed below. I am interested in the requirements of the Australian Standard AS1500.5. I am also interested in the requirements of other standards realting to this.

I am load rating a T beam bridge, and am not sure whether I need to consider the longitudinal shear at the section between the flange and web for non-composite T sections.

My interpretion of AS5100.5 is that horizontal shear has to be considered for sections through flanges only for sections cast monolithically.

I have posted a similar query on the "AS/NZS Code Issues" forum for broader coverage . Please do not post the same response to both.

 

[bridgebuster]

I'm unfamiliar with Australian standars, however, I've never check for longitudinal (horizontal) shear in a concrete T beam rating.

AASHTO Bridge Evaluation Manual (2nd Ed.) indicates this check is only necessary with a superstructure.

 

[graybeach]

I agree with bridgebuster. Also, why would you consider the longitudinal shear between the flange and web for non-composite T sections? If non-composite, you should not be counting on any composite action. No?

 

[hokie66]

I think the longitudinal shear at the web to flange of normally dimensioned sections is never critical, and that is why we don't check it, but that doesn't mean that shear is not present.

graybeach, the OP never said anything about composite or otherwise, but the flange and web of monolithically cast sections do act compositely.

 

[graybeach]

"section between the flange and web for non-composite T sections"? But what does that mean anyway?

I agree with Hokie66. We recently did a load rating for prestressed girders that are composite with the deck slab. The section (concrete plus shear reinforcement plus prestressing effects) was rated for vertical shear, but we did not include the horizontal shear at the interface in the rating.

 

[kww2008]

Sorry for the confusion. "Non-composite" refers to the entire T section built together (monolithically), not the web and the flange formed separately. I used the term "section" to differentiate this from "interface" where one part is built first and the other added on later.

 

[hokie66]

graybeach, with prestressed girders composite with a cast in place deck slab, the horizontal shear at the junction needs to be considered.

 

[graybeach]

hokie66, I'm sure this was considered in the original design fifty years ago. For the recent load rating we had done, our consultant did not calculate a rating factor for horizontal shear.