Multihazard resilience and economic loss evaluation method for cable-stayed bridges under the combined effects of scour and earthquakes

Abstract

Cable-stayed bridges (CSBs) commonly experience scour-induced foundation issues during their service life, impacting both structural seismic resilience and economic losses. Nonetheless, these aspects remain inadequately addressed in existing seismic codes. This paper presents a comprehensive probabilistic multihazard fragility, resilience, and economic loss evaluation method for CSBs influenced by scour and earthquakes. Numerical models with various scour depths considering epistemic uncertainties in loads, structural properties, and soil conditions are first established using the Latin-hypercube sampling (LHS) method. Incremental dynamic analyses (IDAs) are then conducted on these models in cases with near-fault and far-field bidirectional ground motions, yielding probabilistic multihazard demand models and component- and system-level multihazard fragility surfaces for diverse limit states. Subsequently, resilience and economic losses are comparatively evaluated by integrating damage probabilities with corresponding uncertain functional recovery functions. Eventually, a rapid bridge traffic capacity evaluation method based on the critical traffic capacity surface concept is devised to effectively assess CSB open patterns under various peak ground accelerations (PGAs), scour depths, and repair times. The numerical results show apparent shifts in the nonmonotonic seismic fragility, resilience, and economic loss of the case CSB due to scour effects, with the rates of change reaching 31.4 %, 34 %, and 24.8 %, respectively, associated with a critical scour depth of 12 m at IM = 0.8 g. The developed analysis framework provides a reference for the life-cycle design and maintenance of CSBs affected by multihazard scour and earthquakes.