advice Needed - Joints in a Concrete Seawall 1

[bridgebuster]

I'm reviewing the final plans for the replacement of a bulkhead. Here are the particulars:

Existing gravity wall of unknown dimensions. The top 4-feet will be completely demolished. On the remaining portion an 11" layer of concrete will be removed from the front face of the wall, down to about 3' below the mudline.

A pseudo-soldier pile and lagging wall will then beconstructed. I use pseudo because the lagging will be cast in place concrete. See attached plan view. Total height of new wall is about 11'. MHW is 4' below top of wall. MLW is actually below the mudline.

Soldier piles (W18x234 at 7'-6") will be installed in 30" diameter holes drilled through the wall, and then socketed into rock. The piles are about 30' long.

The "lagging" will be cast against the old wall and also encase the soldier piles. 11" minimum thickness of concrete, which is a marine grade concrete - low shrinkage, self-consolodating. The rebar is stainless steel.

The plans call for expansion joints at 120'. They use a standard retaining wall detail with waterstop and joint filler. The designer also calls for dummy joints every 30'- that's giving me grief! My gut feeling is that cracks will form at each soldier pile. In front of each pile the wall is only be 5 1/2".

Any thoughts would be appreciated.

 

[DaveAtkins]

If you provide horizontal reinforcing with an area equal to 0.5 percent of the wall area, the wall can be any length desired, without control joints. If you provide this reinforcing, the wall may crack in front of the steel soldier piles, but the cracks will be held tight.

DaveAtkins

 

[hokie66]

Yep. Cracks will form at each pile.

 

[paddingtongreen]

The expansion joint is clearly useless, the soldier piles will insist on any expansion or contraction being evenly spread along the section. I don't see if you are backfilling behind the wall, if you are, if it is subject to outward pressure, I would consider punching holes in the webs and running the rebar through them. Last, I would place the splices in the front face between the piles rather than in front of them, to allow better concrete flow past the piles, it would also take them away from the maximum tension area in the case of high seas.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[bridgebuster]

Thanks for the replies.

The horizontal rebar does exceed .5%

The expansion joints do seem useless. The wall is going to be cast against the existing wall