Author(s): Y. M. Chiew

Linked Author(s): Yee Meng Chiew

Keywords: Bridge-pier scour; Bed degradation; Total scour depth; Site-specific scour

Abstract: Amongst all scour research, bridge-pier scour is by far the oldest. A reason for the need to investigate this type of scour problem is because building a bridge to span waterways have been in existence since medieval days. Our forefathers found that putting a column (or pier) in the waterway to reduce the bending moments and forces acting on the bridge deck often led to the formation of a pier-scour hole, which could undermine the foundation of the bridge. Modern pier-scour research started in the mid-1950s in Europe, followed by works done in the USA. Later an extensive pier-scour research program was undertaken in New Zealand in the 1970s. Those early works are now continued worldwide, and pier-scour research persists to the present era. A casual scrutiny of all the published works todate reveals a very fascinating trend in that pier-scour research often are undertaken separately in that simple local pier-scour experiments, either experimentally or numerically, are conducted on its own and is assumed to be independent from the other type of scour that can occurred in the field. Nature, however, is much more complex than this and failure of bridges often are not just related to pier-scour alone. The other types of scour or erosion that occur in rivers can and do contribute to the total scour depth that leads to the eventual failure. An example is the failure of Houfeng Bridge in Taiwan province. Hong et al. (2012) conducted an analysis on the contribution to the total scour depth around the failed bridge pier to show that local scour only contributed to 38% of the overall total depth. The other 62% are related to bed degradation, contraction, bend and jet scour. Clearly these latter types of scour or erosion are very site specific and are very difficult to be studied in laboratories generally. Some of these types of scour can be very important in one bridge but completely irrelevant in another. Because of the complexities, it is not surprising that pier-scour research continues to be an area of doctoral research world-wide despite modern pier-scour research have started more than seven decades ago. This talk does not offer opinions on whether new researchers in this area should continue to work on local pier-scour on its own or if the need to explore all possible types of scour in combination exists. The site-specificity probably is a large deterrence against the latter approach.

DOI:

Year: 2024