When one of Barr’s long-term clients was planning major maintenance and turbine work at a pumped-storage hydroelectric facility, it turned to Barr for complete detailed structural analyses of the existing powerhouse structure. The overhaul project involved replacing the roof’s existing overhead crane, which was rated for several hundred tons, with two new larger 400-ton rated cranes that could be operated in tandem. The client requested an evaluation of the roof-slab support and supporting beams and columns for the increased crane loads.
Barr developed a finite element analysis (FEA) computer model of the structure and modeled the two 400-ton crane loads moving across the top of the structure. Because of the importance and complexity of the project, Barr developed models using both STAAD and RISA software to provide redundancy in the analyses. Results indicated the structure could support the increased loads for most locations. However, additional shoring was required in two locations. For these, Barr designed new steel columns for beam support and new steel brackets for cantilever support.
The maintenance and overhaul project is ongoing and to date the maximum lifted load has been more than 700 tons with no observed harm to the structures analyzed by Barr.