摘要: |
Post-tensioned concrete bridges, which were pioneered in France, but soon taken up by the engineers in other advanced countries, have proven to be increasingly popular as an economically competitive and safe form of construction. With the introduction of many innovative techniques within a relatively short period, it was perhaps inevitable that quite a few problems would be encountered subsequently. A number of grouted-duct bridges have collapsed in service and others have shown potentially dangerous defects. Failure of a prestressed bridge can be particularly risky as this type of bridge contains high levels of strain energy and hence failure can be catastrophic. It is of great credit to the overseeing government departments, the national laboratories in many countries, and the industry itself, that these problems have been diligently dealt with as they have occurred, and the excellent record of the functionality and safety of these bridges has been maintained. |