Collapse-based design method for simple seismic design of complex structural systems such as linked column frame system

Abstract

Seismic design of structures is one of the most complex engineering sciences, in addition, the approaches that are currently used for analysis and design increase this complexity. Therefore, in this paper, a new method of seismic analysis and design of structures is presented, which not only eliminates the behavioral complexities of structures, but also increases accuracy. This method, which is called collapse-based design, is simple yet precise, using which even complex structural systems can be designed simply. For this purpose, linked column frame is considered for design as a new dual structural system that has complex, variable, and unclear seismic behavior. This structural system pursues specific target performance objectives and is designed with the aim of simple and quick repair after an earthquake. Currently, there is a lack of a suitable design method for the LCF system that leads to the design of optimal models with sufficient seismic capacity, hence this system is chosen as the prototype model. In the collapse-based design method, the structure is subjected to a seismic intensity equal to its collapse seismic intensity. The stability of the structure at this seismic intensity means sufficient seismic capacity and the maximum capacity of structural members can be used to maintain the stability. The first LCF model designed using this method is 8.5% lighter than a similar moment resisting frame model. The values of ductility and overstrength of this model are 7.56 and 3, and its maximum interstory drift ratio at the DBE and MCE hazard levels are 2% and 2.8%, respectively. Also, its collapse margin ratio is 2.28. But after the implementation of the target performance objectives, the weight of the model increases to 5% heavier than the similar moment resisting frame model, nevertheless, its seismic capacity decreases slightly. Based on this, it’s found that the implementation of the target performance objectives in the LCF system also causes little destructive effects. And as a final conclusion, the results show that the presented methods and approaches are appropriate for the analysis and design of structures and the comprehensive evaluation of designed models.