Turbine Generator Foundations—State-of-Practice Review

Steam-turbine-generator (STG) and combustion-turbine-generator (CTG), are at the “hearts” of power generations. They are heavy, yet very precisely-manufactured, rotational vibrating machineries, running either at 50 or 60 Hz (25 or 30 Hz for nuclear power plants). Normal operations of such equipment demand minimum dynamic amplification effects from supporting foundations, to avoid long-term deteriorations of critical mechanical components (bearings, shafts, rotors etc.). The foundations, often called turbine pedestals due to their massive appearances, must be designed to withstand all applicable load scenarios, including stringent stiffness and vibration criteria, stipulated by machine manufacturer and industrial standards, under cyclic, dynamic unbalance forces. In practice, structural engineers follow manufacturer's foundation requirement documents and applicable codes or standards to perform the design. However, manufacturer requirements do vary, and code or standard provisions are often subjected to interpretations when applied to such foundations. Thus, many practitioners have developed their own “proprietary” or "customized" approaches, based on own experiences and preferences, some of which are conflicting. The ASCE Energy Division recognized the need for a report that can provide practitioners with clearer instructions, guidelines, and recommendations for TG foundation design. To this end, the task committee for “Turbine Generator Foundations” was formed in April 2014, whose work is now published in Task Committee for Turbine Generator Foundations (2018). This paper summarizes the work of the task committee. Note: All figures in this paper are from Task Committee for Turbine Generator Foundations (2018).