FWD Apply To Detect Bridge Damage

At present, there are lots of concrete beam bridges of lower grade in our country. These bridges are built early and have worked for a long time. There are many overweight vehicles pass through them now. At the same time, the connection of beam bridges has partially damaged as time passes. The transverse connection has so much as damaged completely, so some a single beam is loaded solely. In order to avoid these phenomena, ensure traffic security and bridge working order, bridge transverse damage need to be detected and repaired. Routine testing instrument sets and measures slowly, and it will intermit traffic several hours. As FWD tests quickly and exactly, it is widely applied to test road surface. This article will apply FWD to detect bridge transverse damages fleetly for the first time.FWD hydraulic pressure system is controlled to heighten and set free one heavy hammer by computer. Heavy hammer load bridge surface by one rigid plate. It is pulse load. The displacement of bridge surface is measured by well-regulated disposal of speed sensors. The shape of pulse load approaches half sine wave. Load size is adjusted by variational hammer weight and height of hammer. Load is measured accurately by pressure sensors. FWD collect time history datum automatically. This kind of load mode simulates vehicle load to bridge surface preferably.In this article, Author disposes measure point along landscape orientation in the middle of bridge, and apply FWD to measure dynamic displacement of actual bridge. He builds limited element model according to bridge, bring FWD pulse load to bear on model, and calculate dynamic displacement of actual measure point. Compare two groups of datum, when they are discrepant, bridge transverse stiffness parameter is amended by system identify method until they are accordant. So model parameter is thought of as actual bridge parameter, and identify damage of bridge transverse stiffness.Theoretic calculation and identify damage effect of actual bridge indicate: the testing result of bridge dynamic displacement by FWD can identify bridge transverse joint damage making use of system identify method.