CARTER LAKE INTAKE TOWER DESIGN: COMPARING AND CONTRASTING DESIGN METHODS

摘要

In the process of designing the intake tower for the Carter Lake Dam No. 1 Outlet Works Addition, URS performed an extensive review of intake tower design guidelines and discovered two different design philosophies for seismic design of intake towers-load factor design (as published by the U.S. Army Corps of Engineers) and working stress design. The review revealed that the two design approaches employ nearly identical methods for developing applied loads on the structures to determine the shear and moment in cross-sections of the tower; however, the two approaches employ different methods to evaluate the nominal strength and stability of the structure. For example, load factor design prescribes large reductions to the applied forces relative to the increase in allowable stresses prescribed by the working stress approach for the earthquake loading conditions. As a result of the differences between the two approaches, the design of the intake tower for the Carter Lake Dam No. 1 varies considerably depending on the approach used. This paper compares and contrasts the two design approaches considered in the design of the intake tower and presents the tower designs resulting from application of the two different methods. This paper also presents a discussion on the differences between the two approaches to moment design and stability evaluation. Specific attention is given to the methods for evaluating the stability of an intake tower.