Concrete column parameters

[eit09]

Concrete Column Bending Reinforcement.

1. Please explain the column labeled span.Where do you set the # of spans? Some times my models show 1 span and other times multiple spans are displayed.

2. When multiple spans are shown the bending reinf displayed is only provided for one span. Does Risa take worst cast per span and provide reqired bending reinf?

3. For the shear reinforcment I have same question for the span & region columns.

 

[JoshPlumSE]

EIT09 -

I'm not sure I understand the questions completely. But, will try to answer them. If my answers don't make sense, then you might consider e-mail your questions (with the attached model) to the RISA technical support group.

1) If you've got a continuous column which spans mulitple floors. Then each "span" is defined as the distance between one floor (where the column is laterally supported by beam members) and the next floor. Make sense?

2) RISA will try to provide reinforcement based on the design rules you assigned to the column. Then it will do a code check on the column for each location in that span. If any location fails, then the program will try to increase the capacity of the section by increasing bar size or increasing the number of bars.

We do this for each span. The program does try to establish some form of bar continuity between spans. However, it is possible to have different reinforcement at the lowest level compared to the level above it.

3) Shear design is done based on the envelope shear diagrams. The shear tie spacing could technically vary along the span. But, that doesn't usually happen with columns. The worst case shear demand controls the shear tie spacing for that span. Each span is checked independently .