Extreme Response Prediction of Guiding Beam Employed for Incremental Launching Construction of a Continuous Bridge Under Non-Synoptic Storm Winds

Abstract

The southeast coastal region of China frequently encounters non-synoptic storm winds, such as tornadoes and downbursts, which pose significant risks to bridges under construction owing to their sudden onset. Despite this, few studies have examined the structural reliability of bridges exposed to such conditions. This paper analyzes a continuous steel box bridge constructed using the incremental launching method, aiming to improve wind-resistant design and enhance reliability assessment during construction under tornado and downburst events. Key parameters characterizing tornado and downburst wind fields and their impacts on the extreme deformation of the guiding beam are investigated. Response surfaces and a 4D (four dimensions) color map are developed to analyze the sensitivity of extreme displacement in the guiding beam. To capture the stochastic nature of non-synoptic storms, a Type III extreme value distribution model for tornado wind speeds and a Gaussian model for downburst turbulence are applied. The virtual process method (VPM) is then used to predict the extreme value distribution (EVD) of guiding beam deformation. The study reveals that for tornadoes, the sensitivity of extreme transverse and rotational (RotX) displacements is highest for maximum tangential wind speed (U_max), followed by approach angle (ψ) and vortex core radius (R_max). In downbursts, extreme displacement ζ_i shows high sensitivity to maximum horizontal wind speed (um) and downburst jet diameter (D_j) but is minimally affected by approach angle (ψ). Additionally, lateral extreme values owing to downburst turbulence exhibit wide variation, strongly influenced by um and largely independent of D_j and ψ.