Lapping of bars of different quantities

[Jamie112]

Hi,

Say I have 2-span band beams with same width and 1 layer of top reinforcement, 1st span is 15 bars while the other has only 10. Isn’t lapping of the top bars an issue?

 

[ryaneng]

I think a quick sketch would help.

Top bars in a 2 span simple beam? I would only expect top bars to technically be needed over the center support, though maybe I would run them continuous depending on different parameters.

 

[DMac91]

Top bars in a 2 span beam should be lapped mid span where there is no negative (hogging) bending moment. Theoretically the bars wouldn’t need to be lapped, but it is good practice to provide a lap here for minimum beam strength. Lap the 10 bars, the other 5 can just stop.

Alternatively, the 5 bars out of the 15 for the hogging moment could stop a lap length past the point where only 10 bars are required, typically 30% of the span to AS3600