Existing Beam Development Lengths

[ChiEngr]

Hello,

I am working on a project in which I need to reinforce an existing concrete spandrel beam for positive moment and shear. Interestingly enough, the amount of negative moment reinforcement is adequate. However, in looking at the bar lengths and bar bend diagrams provided on a typical detail, the existing reinforcement does not have sufficient development length on both sides at a section away from the face of the support. I think I know the answer, but would this mean that technically the beam has to have its capacity reduced due to insufficient development length by modern Code standards?

 

[KootK]

Any chance those top bars are trussed bars (bent down into the bottom of the beam )?

 

[ChiEngr]

KootK,

The condition I have is a 3-span continuous beam. Because the columns are not significantly reinforced, I am analyzing the beams as continuous members over pin-supports. I was able to resolve the top bar development lengths using the excess reinforcement factor. However, my current issue is at the end column - you cannot use the excess reinforcement factor at discontinuous supports. This led to an even more philosophical question of if I had a pinned-pinned beam spanning between columns, how can you ever fully develop the rebar at the ends of the span? I understand that the moment a couple of feet away from the support is very small, but it is still possible that your rebar is not fully developed on both sides at that section.

Apart from my aside, the bottom reinforcement consists of (2) #11 (fy = 40 ksi) in addition to (2) bent #11 bars that bend up toward the end of the beam span as you suggested.

I am a very thorough engineer, so I apologize if these questions may seem over-the-top.

 

[DaveAtkins]

So the (2) #11 which bend up and become negative reinforcement are fully developed from the span side of the beam. Is the development shortfall on the support side?

DaveAtkins