Survey about Damage, Repair and Safety of Norwegian Concrete Dams

The paper present results and assessments from a survey carried out by SINTEF in 1998. A questionnaire was mailed to all VTA persons in Norway and answers from 287 concrete dams (432 including combination dams), equal to 27% of all main types of concrete dams under public supervision in Norway, were received. 89 dams are so called "large dams" higher than 15 meter. The survey shows that the majority of dam owners follow requirements and recommendation by NVE. Most concrete dams contain few damages of various types without any consequent for the function and safety. However, damages categorized as many occur in up to 5% of the dams, which might influence safety and reliability in a short or long time span. Sur- prisingly many concrete dams were repaired (44%) or will be repaired in the near future (40%) and 10% of existing repair has been repaired more than one time. Large dams are generally more damaged than smaller dams and it looks like dams constructed around 1950 to 1960 are more damaged than other periods.