Reinforcement criteria for mild steel bars of M15 one at each corner for isolated footings for column ties shall be designed to carry in tension as well as in compression, an axial load not less than the earthquake force acting on the heavier of the columns connected is
1
4 bars of 12 mm dia
2
4 bars of 10 mm dia
3
6 bars of 12 mm dia
4
6 bars of 10 mm dia