INVENTING UNIQUE BRIDGE ABUTMENTS IN UTTARAKHAND (Paper 822)
Though traditional bridge abutments are still in common use, an effort has been made to add exceptional features to bridge abutments while going for new bridges on rural roads in the state of Uttarakhand, India. While doing so, some of the key concerns were to achieve economy, improve performance during seismic conditions, reduce bulkiness of traditional abutments, minimize consumption of natural resources and add a little bit of elegance to the scenic hilly surroundings.
Comparisons were made among common type of stone masonry/PCC and RCC abutments while exploring possible ways of achieving the desired features. While proposing the abutment type, attention was also paid to the simplicity of construction as most of the bridges are going to be constructed at remote places.
Based on the exhaustive studies done and comparisons made it was found that U-type abutments with curved shaft (stem) are one which inherit the desired features. The curved abutment shafts behaved like a shell (arch) structure where stress flow predominantly become axial. This helped in achieving least possible thickness of abutment shaft and that also with nominal steel at many places. Reduction in bulkiness of the abutment shaft resulted not only into direct saving but also indirect savings due to reduced seismic forces acting over the abutment. In order to ensure correctness of the design forces, space frame grillage models were made wherever needed.
The paper primarily discusses about the features and design of U-type abutments with curved shafts along with their comparison with other type of commonly used abutments.