This is an upright frame, usually made in wrought iron or steel strutted by diagonal thrust beams against the engine-house wall or other solid abutments, the height to the bearings of the guide pulleys being from 80 to 1 00 ft.
The substructure consists of (a) the piers and end piers or abutments, the former sustaining a vertical load, and the latter having to resist, in addition, the oblique thrust of an arch, the pull of a suspension chain, or the thrust of an embankment; and (b) the foundations below the ground level, which are often difficult and costly parts of the structure, because the position of a'bridge may be fixed by considerations which preclude the selection of a site naturally adapted for carrying a heavy structure.
On the other hand, a girder imposes only a vertical load on its piers and abutments, and not a horizontal thrust, as in the case of an arch or suspension chain.
Brunel constructed the towers and abutments for a suspension bridge of 702 ft.
Two main towers in the river and two towers on the shore abutments carry the suspension chains.
Eads, the engineer, determined to establish the piers and abutments on rock at a depth for the east pier and east abutment of 136 ft.
Road to pass between the springings and ensured the transmission of the wind stresses to the abutments without interrupting the crossbracing.
The bridge when closed is supported on abutments at each end.
The substructure of a bridge comprises the piers, abutments and foundations.
When girders form the superstructure, the resultant pressure on the piers or abutments is vertical, and the dimensions of these are simply regulated by the sufficiency to bear this vertical load.
Piers and abutments are of masonry, brickwork, or cast or wrought iron.
(4) Some types of bridge can be built out from the abutments, the completed part forming an erecting stage on which lifting appliances are fixed.
The reactions at the abutments are R 1 = Wm/1 and R2 = W (l - m)/l.
Behind the gateway is another vestibule leading to another portal which gives entra ice to the building, the lateral walls and abutments of the portal being also decorated with reliefs much worn.
For foundations and abutments where settlements may occur.
A / / is wl; the reactions at abutments, R I = R2 = 2w/.
The cost of abutments and bridge flooring is practically independent of the length of span adopted.