Analysis of wind-induced vibration and collapse failure of prestressed truss string structures under thunderstorm downbursts

Abstract

A deterministic-stochastic hybrid model is employed to simulate the thunderstorm downburst wind field on prestressed truss string structures (PTSS). Subsequently, machine learning techniques are utilized to predict the wind pressure coefficients (WPCs) of the structure under such downbursts, which indicate that the XGBoost model demonstrates superior predictive performance, achieving the R² of 0.9921. Based on the wind field simulations and WPC predictions, the wind-induced vibration response of the PTSS is analyzed. The results show that yielding of diagonal web members leads to significant residual deformation, while cables experience tension relaxation, with up to 56 % loss. Subsequent incremental dynamic analysis (IDA) quantitatively investigated the progressive deformation patterns and the wind-driven collapse mechanism. As the downburst wind speed approaches its peak, stress conditions of the top and bottom chords undergo a sudden change. Notably, significant mid-span deformation occurs in the bottom chord on the windward side, leading to bulging and sinking areas. The stress conditions of diagonal web members undergo a secondary abrupt change leading to buckling, increasing buckling degrees among related members. Such changes cause substantial rotations within one-third span of truss on the windward side, culminating in dynamic structural collapse, which indicates the high sensitivity of PTSS under thunderstorm downbursts.