Design for ductility of building structure


The design must satisfy both strength and ductility. The ductility can be ensured by proper detailing of reinforcement, bar cut-offs, splicing and joint details. The following are the guide lines:

The structural layout should be simple, regular and should avoid any offsets from beams to columns or columns from floor to floor. Stiffness of columns should gradually change from floor to floor.

The tensile steel beam should be restricted and more compression reinforcement should be provided. Compression reinforcement should be enclosed by stirrups to avoid buckling.

The designer should aim to see that the inelasticity is restricted to beams only and columns should remain elastic. To achieve this all beam-column joints should obey the relation below,

? Mcolumn > 1.2 ? Mbeam

The beams should have strong shear strength to avoid non-ductile shear failure by providing sufficient shear reinforcement.

At sections of maximum moment in beams, closed stirrups or spirals will increase the ductility of the members.

The columns should preferably have spiral reinforcement if the axial load exceeds 0.4 times the balanced axial load of columns.

Sufficient splices and bar anchorages must be provided to prevent bond failures.

All the beam-column connection has to be monolithic.


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