Introduction to Skeleton Bridge Abutment

Abstract

Abutment in a bridge structure is a vital component, defined as the first and the last support to the bridge deck. Most commonly used bridge abutment type is the wall type abutment. Bridge abutment is subjected to horizontal and vertical forces. Horizontal forces are due to braking of vehicles on the bridge deck and the force due to soil fill behind the abutment. Vertically transferred force on to the abutment from bridge deck is constant for a particular live load combination, but the horizontal force varies with the height of the abutment. Tall abutments are subjected to massive earth pressure force. For shorter height of the abutment, the dominating force would be the vertical force and when the abutment height increases the dominating force changes from vertical to horizontal. In order to avoid the massive earth pressure of the embankment, the skeleton bridge abutment could be used effectively. Skeleton abutment supports the bridge superstructure and it does not effectively support the horizontal force due to earth pressure. This paper describes the basic concept of skeleton bridge abutment, its behaviour, advantages and disadvantages, limitations in practice and its practical application in 'Mahaweli Raja Mawatha' from Adikarigama to Mapakada in Sri Lanka.