|
||
Analysis of the effects of alkali aggregate reactionAAR—alkali aggregate reaction—is a phenomenon which can over a period of time cause distortion in large concrete structures. A specialist group within Hatch Energy has set the pace in identifying and managing AAR, and has inspected and evaluated more AAR-affected structures than any other consulting engineering firm. Now the Tennessee Valley Authority, the largest public power company in the USA, has awarded Hatch Energy a multi-year contract to perform finite stress analysis at three hydro facilities affected by AAR. Alkali aggregate reaction (AAR) causes abnormal expansion in large concrete structures. This unwanted "growth" generates stress and, in a hydroelectric facility and can cause various problems such as prevent operation of spillway gates.
|
Tennessee Valley Authority (TVA) has experienced AAR growth at several of the 29 dams within its system, and has engaged Hatch Energy to carry out finite element stress analysis at three affected sites. Hatch Energy has long experience of this kind of work; a specialist group (has developed an analytical tool, GROW3D, which models the future behavior of concrete affected by AAR. GROW3D simulates the gradual expansion of the concrete, and identifies the points at which increased stress will weaken the structure and compromise operations. On this project, the analyses will be carried out using the general purpose finite element system ANSYS. The ANSYS program will be modified to include the special concrete growth analysis features from GROW3D. Hatch Energy's first task is to provide an updated analysis of the Hiwassee Dam in North Carolina. Hiwassee is 1376 feet long, spans the Hiwassee River, and was completed in 1940. Work has already been carried out to limit movement of concrete within the spillway. Here, as in other locations, the prime issue is the overall stability of the dam as AAR progresses. |
|
|
||||