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Correct lapping zone of Rc Columns in Seismic Areas

Correct lapping zone of Rc Columns in Seismic Areas

Correct lapping zone of Rc Columns in Seismic Areas

I was very surprised today to learn from my new supervisor, a senior civil engineer that the correct lapping zone for RC columns is at mid-height of the column (where bending moments are lowest)and not at the bottom as i knew until today. To be honest, in my country Reinforced Concrete is the traditional way of construction and i have never seen lapping zone at mid-height. I havent been on a lot of projects but all projects i have seen lapping zone was at the bottom.

so what do you think about this and what is the common practise in your country, also what to american standards suggest for this?

RE: Correct lapping zone of Rc Columns in Seismic Areas

For SMRF in Seismic Areas, location of lap splice for columns shall be near midheight. You can refer to ACI 318-14 Section

RE: Correct lapping zone of Rc Columns in Seismic Areas

This is common practice for high seismic zones. Pls look to :https://nvlpubs.nist.gov/nistpubs/gcr/2016/NIST.GC...
Seismic Design of Reinforced Concrete Special Moment Frames.A Guide for Practicing Engineers.

RE: Correct lapping zone of Rc Columns in Seismic Areas

It's a similar requirement in New Zealand. In fact I don't think I can recall any recognised international standard that says otherwise.

It's not just about getting it to a point of low moment. It's more about getting it away from any potential yielding regions, these might extend 2 to 3 times the member depth from the ends of the columns in a typical RC moment frame.

RE: Correct lapping zone of Rc Columns in Seismic Areas

Offcourse we are talking about pure ec8 moment frame (a rare beast imho).
In wall system, splice wherever you want.

RE: Correct lapping zone of Rc Columns in Seismic Areas

Exactly -- it's the balance between:

High seismic zones, where column ductility and shears are critical -- splice at mid-height.

Low seismic zones, to reduce costs by making the splice elevation readily accessible by workers -- splice at the bottom.

just call me Lo.

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