Abstract
The P-△ effect is caused by the weight and lateral deformation of the structure and can not be neglected in the case where the structure is not stiff and develops considerable amount of lateral deformation as is the case of multi-story steel frames subjected to severe earthquakes. The energy absorption capacity of a structure is partly consumed by P-△ effect and its remainder becomes the substantial resistance of the structure. Through vast amount of numerical response analyses the energy consumption due to P-△ effect is evaluated and expressed by a simple formula.
