To prevent scouring-related damage in flood condition, bridge pier structures
are inspected to judge whether repair or remolding is required. For this
purpose, scouring-apprehended bridge piers are selected by engineers
in the field, meaning that not all candidate piers are necessarily extracted.
This requires the establishment of a technique to extract scouring-apprehended
bridge piers correctly and efficiently.
Accordingly, the RTRI has created two scoring tables as a means of selecting
bridge piers for repair or remodeling. One is for primary extraction
used in general inspection (Table 1) and the other is for secondary extraction
in detailed inspection of individual bridge piers extracted in the general
inspection. The RTRI has also prepared an application manual in relation
to the tables. In general inspection, bridge piers are evaluated in 10
categories including river/structure conditions mainly through visual
inspection based on the scoring table, without relying on high-level
expertise on rivers. Those scoring less than 110 points according to
judgment by expert engineers are classified as being susceptible to scouring
damage (Fig. 1). In detailed inspection of the damage-apprehended bridge
piers extracted in general inspection, scouring and riverbed degradationing
speeds are estimated based on detailed information relating to bridge
structure/river conditions and deluge history (Table 2). Through this
process, the stability of bridge pier foundations is evaluated into the
future.
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