Multiple hazard incidents lifecycle cost assessment of structural systems considering state‐dependent repair times and fragility curves

Abstract

Summary The performance and serviceability of structural systems during their lifetime can be significantly affected by the occurrence of extreme events. Despite their low probability, there is a potential for multiple occurrences of such hazards during the relatively long service life of systems. This paper introduces a comprehensive framework for the assessment of lifecycle cost of infrastructures subject to multiple hazard events throughout their decision‐making time horizon. The framework entails the lifecycle costs of maintenance and repair, as well as the salvage value of the structure at the end of the decision‐making time horizon. The primary features of the proposed framework include accounting for the possibility of multiple hazard occurrences, incorporating effects of incomplete repair actions on the accumulated damage through damage state‐dependent repair times, and requiring limited resources in terms of input data and computational costs. A dynamic programming procedure is proposed to calculate the expected damage condition of the structure for each possibility of the number of hazard incidents based on state‐dependent fragility curves. The proposed framework is applied to a moment‐frame building located in a region with high seismicity, and lifecycle costs are evaluated for six retrofit plans. The results displayed variation in the ranking of the retrofit actions with respect to decision‐making time horizon. Furthermore, the sensitivity analyses demonstrated that disregarding repair time in the lifecycle cost analysis can result in false identification of unsafe retrofit actions as optimal and reliable strategies. Copyright © 2016 John Wiley & Sons, Ltd.

A risk‐based life cycle cost strategy for optimal design and evaluation of control methods for nonlinear structures

“…The peak ground acceleration ( PGA ) is a common intensity measure for building structures and is used in this study for LCC analysis. The annual probability of this IM represented by P ( PGA ) is determined as follows: where λ AR ( PGA ) is the mean annual rate of exceedance, which can be determined from probabilistic seismic hazard analysis. ∆λ AR corresponds to the difference between 2 successive values of λ AR ( PGA ) on hazard curve.…”

“…Further details of this design can be found in Gupta and Kunnath . Some cost information for the LCC anaylsis of the building is as follows: Initial construction cost of the building is considered to be 0.91 times the replacement cost of the structure The unit cost of construction is considered to be 1109.33 $/m 2 (103.06 $/ft 2 ) for this concrete bare frame building …”

“…To address these gaps, this paper presents novel control algorithms based on probabilistic assessment of the LCC of structures for seismic hazards. Computation and assessment of LCC in this framework follow the approach established in Fereshtehnejad and Shafieezadeh . The proposed framework has the following characteristics: It models cost as a function of hazard‐induced damages that are defined in terms of interstory drifts. The expected cost of these damages to structural and nonstructural components is determined according to the total probability theorem. The probability of reaching or exceeding a damage state is determined by the outcrossing rate theory, which considers events of crossing upper or lower bounds for responses of interest …”

“…[16][17][18] When a structure is susceptible to multiple hazard occurrences during its lifetime, the risk of these hazards is summed in the LCC framework to compute the LCC of hazard risks. 16,19 In addition to hazard randomness, LCC is capable of incorporating uncertainties in structures, which can have considerable impact on hazard risks. Lifecycle cost, however, has not been incorporated directly into control performance objectives and more generally in the design process of control algorithms.…”

Building service life economic loss assessment under sequential seismic events

“…is the probability that the building would remain in damage state j given the occurrence of i aftershocks and can be calculated as shown in Equation 14.…”