How spacing of shear link is calculated for gravity column as per IS13920:2016 code?
In the column detail drawing generated no specific confinement zone is being recommended , rather it is prescribing 'Full Height of the Column' as confinement zone and prescribing same closely spaced column laterals throughout the column length resulting in extra consumption of steel. Please explain.
When we are designing columns in RCDC using IS13920:2016 code there are several frame type options available to use in the design. One of them is gravity. If user choose frame type as gravity then column gets designed as per section 11 of IS13920:2016 code. As per clause 11.1.1 the spacing of links along the FULL HEIGHT shall not exceed 6 times diameter of smallest longitudinal bar or 150mm. So, if we have used 12mm dia rebar in column maximum permissible spacing is 72mm and for 16mm dia longitudinal rebar the spacing is 96mm and so on.
For this clause we end up getting closely spaced stirrups for columns all over the length. If we change the frame type to lateral then this clause is not activated and closely spaced stirrups are placed in a confined zone as mentioned in code as per chapter 7 and Fig 12.