Suitable Bridge Pier Section for a Bridge over a Natural River

G A P Gampathi

doi:10.4038/engineer.v43i3.6973

Abstract

Estimation of maximum scour depth at the bridge pier is necessary for the safety and economy of the bridge design. Therefore, the phenomenon of scour around bridge piers was extensively studied from the literature to find the effect of pier shapes and inclined flow on scour depth at bridge piers. It was found from the analysis that scour depth increases with the increase of the flow angle relative to the pier axis, but for a cylindrical pier, maximum scour depth does not change with flow angle. When the flow angle is at 300, the scour depth for the cylindrical pier is smaller than other pier shapes; hence circular pier shape is more suitable for natural rivers which have possibility of changing flow direction.

Highlights

Scour is the local lowering of stream bed elevation which takes place in the vicinity or round a structure constructed in flowing water
It can be seen from the table 6 that maximum scour depth varies with the pier shape eventhough the flow and sediment conditions are equal
It can be stated that maximum scour depth occurs when the pier shape is cylindrical

Summary

Introduction

Scour is the local lowering of stream bed elevation which takes place in the vicinity or round a structure constructed in flowing water. Scour take placed around bridge piers, abutments, around spur, jetties and breakwaters due to modification of flow pattern in such a way as to cause increase in local shear stress. This in turn dislodges the material on the stream bed resulting in local scour. Hurber [1] has stated that since 1950 over 500 bridges in USA have failed and that the majority of the failures were related to the scour of foundation material Such data are not available for the PNG (Papua New Guinea) bridges. The concern about safety of bridges is primarily due to three reasons which are: 1).inadequate knowledge about scour phenomenon when the bridges were constructed; 2). inadequate data on which the design flood was chosen and 3). increase in the loading on the bridges due to increase in size of trucks and other vehicles and their frequency of operation

Methods

Results

Conclusion