INVESTIGATION OF STRONG COLUMN – WEAK BEAM RATIO IN MULTI-STOREY STRUCTURES

Abstract

It is expected that the engineering constructions should carry the vertical and horizontal loads during the service within thedetermined safety margin. The basic principal of having strong column-weak beam preference is essential for earthquakeresistant structures for all construction types including concrete, steel, wood and prefabricated. The major criteria for havingearthquake resistant structure is to ensure that the columns are stronger and carry the most load than the beam in the nodes.This criterion has been widely adopted in earthquake codes in Europe, USA, Japan and India. It is possible to absorb andconsume the earthquake energy via beam plastic joint hinges if the columns are constructed to be more durable than the beams.For this, it is foreseen that the ratio of the ultimate strength of the upper and lower columns to the right and left beams (β)should be greater than one (β = 1.2) in the beam-column joints as stated in the Turkish Earthquake Code. This coefficient isusually greater than 1.2 in the earthquake codes adopted in the world. It was observed that many structures were damaged orcollapsed due to not meeting the coefficient criteria stated above. This criterion is the most effective one among many to preventthe damage in the structure under seismic action. In this study, the effect of the change in the coefficient on the column andbeam moments is investigated under the Turkish Earthquake Code. Different numerical examples are presents for thecoefficient of 10. The results of the investigation highlighted that irregularity in the strong column-weak beam compositionmay negatively affect the other irregularities in the structure.