Concentrated Load on Supported One Way Slab
Concentrated Load on Supported One Way Slab
(OP)
I have a need to determine a rational effective width for a supported reinforced concrete slab supporting a concentrated load.
I'm aware of AASTHO having a method and formula but I'm not familiar with AASTHO code nor do I have access to one. I have heard said that it is based on Westergaard's "Computation of Stresses in Bridge Slabs due to Wheel Loads".
Various threads have placed the effective with at about 60% of the clear span. The threads have mentioned Australian and British codes being in close agreement.
My challenge is I need a reference as well as a document to educate myself, a checker, an approver and a client's independent reviewer. If I could get my hand on the Westergaard report, perhaps I would have met my needs.
So, question is, does anyone have a copy of Westergaard's report available, or other reasonable reference, for effective slab width for support of point loads?
Regards,
Boyd
I'm aware of AASTHO having a method and formula but I'm not familiar with AASTHO code nor do I have access to one. I have heard said that it is based on Westergaard's "Computation of Stresses in Bridge Slabs due to Wheel Loads".
Various threads have placed the effective with at about 60% of the clear span. The threads have mentioned Australian and British codes being in close agreement.
My challenge is I need a reference as well as a document to educate myself, a checker, an approver and a client's independent reviewer. If I could get my hand on the Westergaard report, perhaps I would have met my needs.
So, question is, does anyone have a copy of Westergaard's report available, or other reasonable reference, for effective slab width for support of point loads?
Regards,
Boyd






RE: Concentrated Load on Supported One Way Slab
a = "perp dist from the nearest support to section under consideration".
Sorry no Westergaard report.
RE: Concentrated Load on Supported One Way Slab
RE: Concentrated Load on Supported One Way Slab
StructuralEIT, I would be very much interested in your document.
The Australian Code formula is just what I would need, but I can only reference governing codes. I can however, reference published literature and the Westergaard report is regarded by the codes.
It acually is in agreement with the Australian Code at midspan fom what I understand - basically effective slab width = about 60% of the span length.
Westergaard states Beff = 0.58S + 2c, S= Span, c = width of load bearing.
Westergaard is an old document published in 1930. Knowing modern codes essentially agree with it will help bringing the checker to accept it's use.
Another document that would prove to be useful in referencing for this is
Effective Width of Concrete Bridge Slabs Supporting Concentrated Loads, E. F. Kelly, Public Roads,, Vol. 7, NO. 1, March 1926. This is what Westergaard references.
Thanks Again guys.
RE: Concentrated Load on Supported One Way Slab
RE: Concentrated Load on Supported One Way Slab
Thanks, I appreciate your digging this item up. It helps. I would like to know where this formula came from, looks like a professor obtained it fom some text or study.
The great thing about your reference is it also provides direction on a line load across the slab too which is a common challenge.
The formula for the point load is 4/3x + d with x being placement in the span and d with bearing width of the load. It basically becomes 0.67L, L being the span length, which compares to the 0.60L specified by Australian Standard AS 3600-2001.
I'm personally comfortable using 0.58L to 0.67L for point load at midspan. I'm still stuck without a reference though.
It seems strange to me why ACI 318 or other is silent on this, as far as I can tell, when it should be a common load that needs consideration.
Regards,
Boyd
RE: Concentrated Load on Supported One Way Slab
RE: Concentrated Load on Supported One Way Slab
RE: Concentrated Load on Supported One Way Slab
RE: Concentrated Load on Supported One Way Slab
RE: Concentrated Load on Supported One Way Slab
RE: Concentrated Load on Supported One Way Slab
effective width = 0.6L + (width of load)
when load is in centre of a span and L is span
When the load is not central the following formula is used:
2.4x(1-x/L) + (width of load)
where x is distance from centre of point load to centre of support and L is span.
Note that when the point load is near the edge the effective width is reduced.
John
RE: Concentrated Load on Supported One Way Slab
Adam Vakiener