Estimate of Deflections

Abstract

In most structures, the primary concern is that the structure should have adequate strength. Deflections are mostly of secondary concern. The calculations of deflections are important, however, because excessive deflections may hinder the operation of moving parts or the closing of doors or they may cause the cracking of a plaster-finished ceiling. Also, deflection control is needed to limit the lateral deflection (drift) of tall buildings. In fact, the simple plastic theory is valid only when the deflections at the collapse load (P-Δ effect) are small.