13-05-2013, 04:12 PM
RCC BRIDGES
RCC BRIDGES.pptx (Size: 41.03 KB / Downloads: 92)
INTRODUCTION
A bridge is a structure providing passage over an obstacle without closing the way beneath.
The required passage may be for a road, a railway, pedestrians, a canal or a pipeline. The obstacle to be crossed may be a river, a road, railway or a valley.
The primary function of bridges is to carry pedestrians, bicycles, and/or vehicles over various types of transportation facilities or natural features. Bridges come in a wide variety of configurations and structure types.
COMPONENTS OF BRIDGES
1. Superstructure or Decking
This includes slab, girder, truss, etc. This bears the load passing over it and transmits the forces caused by the same to the substructures.
2. Bearings
The bearings transmit the load received from the decking on to the substructure and are provided for distribution of the load evenly over the substructure material which may not have sufficient bearing strength to bear the superstructure load directly.
3. Substructure
This comprises piers and abutments, wing walls or returns and their foundation.
Piers and Abutments
These are vertical structures supporting deck/bearing provided for transmitting the load down to the bed/earth through foundation.
B. Wing walls and Returns
These are provided as extension of the abutments to retain the earth of approach bank which otherwise has a natural angle of repose.
SELECTION TYPE OF BRIDGES
In the selection of the proper type of concrete bridge for any particular case, cost is usually the determining factor.
Occasionally, however, the problem is complicated by special requirements, such as appearance, restricted headroom, difficult foundations, limited time of construction, or difficulties in formwork caused either by the required height of supports or by the fact that it is necessary to maintain traffic under the bridge during construction.