Outriggers are advanced structural systems which are used to design high-rise buildings.

[1] Outriggers are essentially horizontal structural elements which are made up of one or more floors.

[2] These are designed to transfer the lateral forces one stabilizing unit to another unit within the same structure.

[3] When the stability core walls of the structure are stressed & can’t be increased beyond a certain limit, the lateral forces are pushed into an adjacent stabilizing unit at specific floors.

These additional stabilizing unit are gravity column which are generally non lateral load resisting. This enhances the lateral load resisting system at those specific floors.

[4] Outrigger system can be made up of one single or even two floors together. Further outriggers can be placed at multiple locations along the height of the structure.

This enhances the lateral stiffness of the entire structure

[5] Outrigger structural system are discussed in clause 3.12.5 & 3.12.6 of IS 16700 – Criteria of structural safety of tall concrete buildings.

This is a small post on outrigger structural system. Any comments or suggestions are welcomed.