Steel box girder bridge structure,which can reduce dead weight and improve construction speed,is widely used in city bridges.Both the transportation of dangerous goods and terrorist attacks are major risk factors to the steel box girder bridge structure operation.As a special and different effect,explosive can generate strong air shock wave in a short time and destroy the key components of bridge structure [1~3].Seriously this effect can cause continuous collapse of bridge structure,highway transportation interruption and secondary disasters.The current domestic bridge design specifications dont contain guideline about explosive effect in China.The foreign bridge specifications also lack the detailed provisions.