One graded approach for the design of nuclear facilities would design high hazard facilities to meet the provisions of ASCE 43 while low hazard facilities would be designed as conventional structures based on the seismic loading and design criteria in ASCE 7. In structures with an intermediate hazard it is not immediately obvious which standard provides a more conservative design. This paper presents a case study that compares the performance of an intermediate hazard structure with ASCE 7 seismic loading and criteria to the target performance goals described in ASCE 43 and DOE-STD-1020.
The purposes of seismic design associated with ASCE 7 are; 1) to provide minimum design criteria for structures appropriate to their primary function and use considering the need to protect the health, safety, and welfare of the general public by minimizing the earthquake-related risk to life, and 2) to improve the capability of essential facilities and structures containing substantial quantities of hazardous materials to function during and after design earthquakes.
Designs developed using the provisions of ASCE 7 are targeted to a collapse prevention limit state probability of 1% in 50 years. The goal of the earthquake provisions in ASCE 43 is to ensure that high hazard nuclear facilities can withstand the effects of earthquakes with desired performance, expressed as probabilistic Target Performance Goals and various limit, or damage, states. These Target Performance Goals range from 1×10−4 to 1×10−5 with limit states ranging from essentially linear response to short of collapse.
There are requirements invoked by ASCE 7 that are different than the requirements of ASCE 43 which prevents a direct computation of performance based on comparing the seismic demand levels required by each standard. These differences include the use of building R values in ASCE 7 compared to component specific Fu values in ASCE 43, the use of different analyses methods, ASCE 7 upper bound limits on seismic forces for some components, the limitations on framing system types, among others. The effect of these differences on the performance achieved between the two standards is evaluated for the design of a reinforced concrete shear wall structure that is representative of the types of structures used in nuclear facilities.