Study On The Vulnerability Of Single-pylon Cable-stayed Bridge Under Vehicle Bomb Explosion On The Deck

Bridges are important nodes of road traffic.They have important effect and status in road traffic transport system.During the whole life cycle of bridges,they may be attacked by guide missiles,bloodcurdling explosions,occasional bursts and so on.cable-stayed bridges which work as one main bridge type of long span cable-stayed bridges have high risk to be attacked by terrorist attacks.This paper uses theoretical analysis and numerical analysis to study single-pylon cable-stayed bridges' vulnerability based on vehicle bomb exploded on the deck.The simplified analysis method of “analyse of structure vulnerability—Simulation of local crevasses—Safety assessment” is constructed.The main contents are as follows:(1)Study of single-pylon cable-stayed bridges' vulnerability.In allusion to cablestayed bridges' features,this paper created one method to analysis plane combination structures.The paper established a calculation procedure by MATLAB to analysis one single-pylon cable-stayed bridge's collapse patterns and key components.The result showed that: Sections of tower pier disconnect-type cable-stayed bridges' main beams that near near-end supports are not only key components,but also weak links.Their breakages are the easiest to cause bridges to completely collapsed.(2)Study of steel-box girders' crevasses by vehicle bomb exploded on the deck.This paper used ALE multi-material fluid-structure coupling computation by ANSYS/LS-DYNA to simulate steel-box girders' crevasses by minivan bomb exploded on the deck,analyzed its failure modes and obtained sizes of the crevasses.The result showed that: When equivalent of 500 to 1000 kg minivan bomb blasted in the middle and the ends of the bridge,there were crevasses in the steel-box girders' bottom plates and top plates and large deformation in the web plates and diaphragm plates.The crevasses' radius were determined by explosive equivalent and scaled-distance.Parallel crevasses' radius of the top plates was larger than horizontal crevasses' radius.When the explosion was occurred in the end of the bridge,the crevasses' radius was larger.(3)Analysis of steel-box girders' broken sections' residual bearing capacity.In this paper,computational formula of steel-box girders' broken sections' residual bearing capacity was established.N-M curve of broken sections' residual bearing capacity was drawn.girders' permanent load internal force was calculated and compared with broken sections' residual bearing capacity.Security of the steel-box girders was also analyzed.The result showed that: The larger was the broken sections' size,the smaller was the residual bearing capacity.the broken sections had relatively large spare capacity under the effect of constant load When minivan bomb blasted in the bridge floor.