Summary of the behaviour of bridges and culverts made of HAMCO-MultiPlate during the centennial floods August 2002

Subject of this investigation are MultiPlate structures within the area of the Weißeritz, originator of the first flood wave in Dresden as well as in the area of the Mulde, origi-nator of the disastrous damages in Döbeln, Grimma and Bitterfeld as well as further neighbouring places and local flooded area in Middle Saxony. 15 palces with 17 ob-jects were visited. Due to the high flow velocity and/or high water level an inspection of the front sides could only be made. 15 out of 17 culverts as bottom pipe construction endured the floods undamaged in spite of water damming up to height of street and/or total flooding. The corrosion protection of two forest culverts was considerably damaged or partly removed from heavy bed-load transport. Two MultiPlate structures were completely washed out, caused by a total collapse of the front and rear quay and/or insufficient compaction and protection of embankment in front of the culvert. If the structures were to be restored is not to be determined any more.		Altogether it can be judged that embedded, corrugated steel pipes are structures, which are resistant to extreme loads from floods as long as the river bank areas are not damaged to an extent where point of attack arise to wash away the bedding areas of the pipe. Careful pavement of the embankment slope with natural stones on sub-concrete plays an important role to avoid points of attack of the pressure head of the water at the edges of the slope. In the first 1 to 2 years culverts are endangered after backfilling as despite careful compaction the backfill is internally not suffiently compacted and a protective matting of grass with depp couch-grass has not grown yet. The good hydraulic flow behaviour of corrugated steel pipes is proven. There are no indications that the hydraulic behaviour of corrugated steel pipe is different from that of other bridges with a comparable flow cross-section. It may be assumed that the coefficient of roughness in accordance with Kauder are unfavourable, i.e. the flow velocities are too moderate. For a confirmation of this assumption, however, measure-ments would have to be carried out. The complete report including photos is only available in German! [PDF, German]