column mechanical splice coupler?

[pattontom]

How much maximum percentage of steel do you use in columns? It is said when it goes above 3%. One must use mechanical splice coupler.. any experience with this? Have you designed percentage of column steel that goes 4% and just using ordinary splicing at mid point of column?

 

[rjenyoy12]

As per 10.9.1 of ACI 318-05 (which I have of this time), percentage of steel is from 1% to 8%. At R10.9.1 it says "The percentage of reinforcement in columns should usually not exceed 4 percent if the column bars are required to be lapped splice." Thus, if you will have a 100% lap splice you will have a maximum reinforcement of 8%. But if you will exceed this requirement, then you will need mechanical splices.