caison steel 1

[bridgeman5858]

i resently poured a caison can for a hammer head. we realized that our hoops were short by one run the contractor would like us to chip out the concrete and lap the splice and then continue. they want a 52 inch splice for a number 5 bar .being the concrete is at grade wouldntit be the same thing if i drilled and epoxyed the rebar and continue the lap for the caison

 

[JAE]

It depends on if you are resisting shear or tension forces at the top of the pier.

To get proper shear across the top of the pier, you need to fully develop reinforcement across the joint (to fy of the bars) to ensure shear friction bond between the two pours. I think some anchors can get you there.

To get proper tension capacity across the top of the pier you need to transfer the tension in the vertical hammerhead pier reinforcement down to the vertical reinforcement in the pier. To do this you need to either:
1. Lap the reinforcement the required tension lap for Class B lap., or

2. Use a mechanical coupler between bars.

Simply drilling in a 6" deep epoxy anchor won't transfer that tension as you haven't developed the tension into the pier reinforcement below.

 

[bridgeman5858]

if my caison is poured and i dont have enough lap bar on the cage
can i drill next to the rebar at 2ft deep and epoxy in a rebar to continue my missing lap this is for a single bridge caison

 

[JAE]

I think so... but that is a lot of drilling. At some point just chipping down the top portion of the pier might be better - both structurally, cost-wise and time-wise.

 

[Zambo]

bridgeman5858

the answer depends on your specfication and the designer.

Let's say your rebar diameter is 25mm and the specification is for a lap of 40 x diam. That gives a lap length of 1,000mm. If the existing height of the rebar above the cut-off level is 400mm then drilling 600mm (approx 2ft) should be acceptable.

Another option would be to use mechanical couplers. In your case you could cut 50% of the bars alternately to 200mm height to at least get some stagger in the couplers.

As suggested by JAE the alternative of breaking down 600mm and recasting the upper section could be the quicker option.