In addition to what Harold has said; the summary and conclusions of this
report were as follows:
1. no cap plates required. This increases quality of concrete compaction
around pile head
2. minimum pile embedment of 6" and min. edge distance (center of pile to
face of cap) of 12" to 21" depending on design capacities of piles
working load (tons) min. edge dist. (")
<110 - 12
110 to 140 - 16
>140 - 21
3. with this embedment and edge distance ultimate bearing of 8 * f'c. With
supplementary pile cap reinf. around the piles and ultimate of 10 * f'c can
4. ensure adequate development of lengths and design caps as deep beams/slabs.
5. If tension on cap exists then straight or hooked rebar welded to piles
and adequately embedded with be your best bet.
BTW I got this info and three other publications on steel piles from Tom
Dismuke who was chairman of Bethlehem Steel when the report Harold
mentioned was prepared. I got the first clue from Harold and several phone
calls later I got Mr. Dismuke at home where he is now retired. At first he
wondered who the hell I was calling him out of the blue. This quickliy
turned into a very insightful discussion on this matter. This was my first
insight into the power of this list.
At 02:16 PM 3/13/00 -0600, you wrote:
>This was researched and tested several years ago by Lehigh and GAI
>Consultants. Reference "The Steel Pile Pile Cap Connection", 1982,
>published by AISI. Basically, leave the cap plates off. The only time a
>connection plate may be required is for uplift. I know the bearing stresses
>get high, but the concrete is confined. The same holds true under the head
>of anchor rods, tests by the Texas DOT and TVA (for ACI 349 appendix B) show
>that the high local bearing stresses are not a problem.
>The confined bearing strength of concrete was quantified for the first time
>in "Strength Design of Anchorage to Concrete", by Cook, 1999, PCA. You will
>see the strength can go to 8.0 * f'c.
>> -----Original Message-----
>> From: Olive, Harry [SMTP:HOlive(--nospam--at)ngl.ca]
>> Sent: Monday, March 13, 2000 1:14 PM
>> To: 'seaint(--nospam--at)seaint.org'
>> Subject: H-Piles Cap Plates
>> I was wondering what the concensus is on the use of pile cap plates (or
>> cover plates) to the transfer of the load in the pile cap to the steel
>> H-piles. I always use pile cap plates to transfer the loads because the
>> stress in the piles (9 ksi or higher) is usually much greater than the
>> bearing strength of the concrete. Lately, I have had several piling
>> contractors ask why I specify the use of cap plates. I am not adverse to
>> changing my ways, but first I would like to find some "good" articles on
>> subject. The CRSI manual touches lightly on the lack of cap plates
>> ("increase pile embedment to 6 inches to avoid use of cover plates"), and
>> assume the "prevent vertical edge splitting" clause is a phenomena
>> associated with lack of cover plates due to the high bearing stresse in
>> concrete over the exterior flange of the outer piles. Does anyone know
>> where I might find some "good" articles which will shed some light on this
>> Harry Olive, P.Eng., P.E.
>> Neill and Gunter
David Handy, P.Eng.
The Thompson Rosemount Group, Cornwall, Ont. Canada
Opinions expressed are personal only.