A methodology for value based seismic design of structures by the endurance time method

Abstract

A new design methodology based on the total value of structures is introduced. This methodology, namely Value Based Design of structures (VBD), uses the advantages of Endurance Time (ET) method. While prescriptive and earlier generations of performance based design approaches commonly try to find structures with the least initial cost, a design approach to directly incorporate the concept of value in design procedure has been formulated here. Reduced computational effort in ET analysis provides the prerequisites to practical use of optimization algorithms in seismic design. A genetic algorithm is used with the objective of minimizing total cost of the building during its lifespan. ET method is used to estimate the structural responses of each candidate design to probable earthquakes and the expected costs of earthquake consequences are calculated using Life Cycle Cost Analysis (LCCA). A prototype steel frame is optimally designed according to a prescriptive, performance based and the proposed value based design method. Then, their seismic performance and expected cost components are investigated. The results provide a pathway towards practical value based design and show that conformance to design code requirements or performance objectives does not assure achieving the best design regarding the overall design values.