A framework for the lifecycle cost assessment of structures considering multiple mainshock-aftershock sequences

Structures in an earthquake-prone region have the potential to experience multiple mainshock-aftershock (MSAS) sequences during their lifetime. The multiple aftershocks of a given mainshock would further aggravate the damage extent of the mainshock-damaged structure, and meanwhile extend its recovery time. This manuscript proposes a probabilistic framework for lifecycle cost assessment of the structure under multiple MSAS sequences. This framework comprehensively considers the effects of repair status (i.e, finished repair or not) and uncertainties related to multiple MSAS sequences and damage state of the structure. Then this framework is applied to six 4-story reinforced concrete moment frames (i.e., one original structure and five retrofitted scenarios). The results indicate that ignoring repair status would underestimate the lifecycle cost by maximum level of 20%. Multiple aftershocks would increase the lifecycle cost of structures, and such an increment varies from 6% to 137% for different retrofitted scenarios. FRP wrapping is the best retrofit method while Shear wall is the worst one from the perspective of lifecycle cost.