I have received suggestions from engineers to take up the discussion on irregularities as per table no. 5 &6 of IS 1893 (Part 1) : 2016.
It is a well established fact that the regular building perform better than the irregular buildings during seismic event. In IS 1893 (Part 1) : 2016, plan and vertical irregularities are defined in Table no. 5 & 6 of the code. The building is said to be irregular if any one of the irregularity is present in the building. It is mentioned in the code that all the efforts shall be made to eliminate irregularities by modifying architectural planning and structural configurations.
For each irregularity, mathematical limits are defined in the code as well as further action is detailed out whenever the irregularity exceeds the defined limits.
Table no. 5 – Plan irregularities :
- Torsional irregularity
- Re-entrant corners
- Floor slabs having excessive cut-outs or opening
- Out-of-plane offsets in vertical elements
- Non-parallel lateral force system
Table no. 6 – Vertical irregularities :
- Stiffness irregularity (Soft storey)
- Mass irregularity
- Vertical geometric irregularity
- In-plane discontinuity in Vertical elements resisting lateral force
- Strength irregularity (Weak storey)
- Floating or stub columns
- Irregular modes of oscillation in two principal plan directions
We will discuss each irregularity in detail during live technical discussion. The participants will also share their experiences related to the table no. 5 & 6 of the code.
You may share the specific queries / discussion point which may be taken up during live technical discussion.
Join us on next Sunday (25-Oct-20) for live technical discussion on different irregularities as per table no. 5 and 6 of IS 1893 (Part 1) : 2016. Please share discussion points for the same in the comment box. You may also circulate this message with the interested engineers in your circle.