PT Loss Into Columns?

[haynewp]

Any of you that are doing PT consider loss into the typical columns due to restraint? It seems to be the industry standard in my area to ignore any loss of stressing to the columns and assume that it all gets into the floor beam.

I am somewhat concerned at first floor elevated floor stressing cases where the floor to floor height is short. Also, I have noticed that Adapt also does not consider any loss into the columns when they are modeled into the program.

 

[rapt]

Tunacan,

The restraint effect should be considered if it is significant.

Just because a commercial computer program does not consider it does not mean that you should ignore it. Adapt also ignores other areas of design that you need to consider.

And it is not just restraint to PT you need to consider, it is restraint to all shortening caused by shrinkage, creep and temperature change. These also occur in RC structures.

 

[hokie66]

Another related issue is cracking of the columns due to the shortening of the floor. The shorter the columns, the more likely this is to occur. For instance, watch out for the trap of casting stubby columns on top of a basement wall.

 

[haynewp]

Anyway, I have found for myself that loss of force during stressing due to column restraint does not make much difference for a typical case of a parking deck on 24" square columns. I found that 98% of the force still got into my floor beam.