Safety Assessment of Cables of Suspension Bridge under Blast Load
Atta E. Mustafa, Ali Javed, Khawaja Ali
Abstract
This paper presents a simplified approach to assess the safety of main cable and suspenders of long-span suspension bridges under blast loads, whereby a two-layer solution is adopted to solve the blast-bridge interaction problem: (1) blast aspect is modelled as nodal load by simulating the area of blast pressure contour on the deck surface; and (2) bridge is simulated as a 3D fishbone skeleton FE model. The detailed implicit dynamic analysis is performed under small to large sized blasts detonated at different locations to evaluate the redundancy of main cable and suspenders in a parametric manner. The analysis results show the sufficient and insufficient redundancy of main cable and suspenders under small to medium sized blasts, respectively, whereas a large sized blast can lead to the progressive collapse of entire bridge. At last, the first-order reliability analysis method is also applied to assess the safety of main cable and suspenders under large sized blasts, which concludes that a minimum safety factor of 3 is indispensable for main cable to achieve the target reliability index of 3.5, whereas the shorter suspenders carrying large axial stresses are more vulnerable to the blasts than longer ones and suffer the largest blast damage.