Study On Dynamic Responses And Failure Modes Of RC Piers Under Blast Loads

With the development of economy and the progress of the society,highway becomes more and more important in land transportation.The theme of the world is peace and development,but there is still the possibility of war and the threat of terrorism.Because of the key role of bridge in transportation,striking at bridges has becomes one of the first choice for war and terrorist attacks.Meanwhile,bridge structure could collapse due to accidental explosion.Therefore,the study of dynamic responses and failure modes of bridge structure under blast loads has gradually become a hot issue.The response of the components adjacent to explosive is more violent than than of the whole structure due to the locality and brevity of the blast wave.Pier column is the key component of bridge structure,the whole structure will collapse when piers are damaged.Therefore,it is of great theoretical significance and practical value to study the damage mechanism and failure mode of pier column under blast shock.Columns are simplified based on rigid-plastic and explosion theory in this paper,theoretical analysis and numerical simulation are conducted for cantilever column,one end simply supported and the other end fixed column,and both ends fixed column under blast loads.Moreover,blast resistance and failure mechanism of column are analyzed in this paper.The main contents are as below:(1)Study of plastic hinge and dynamic response of column in large standoff.The time-history curve of overpressure is simplified into the form of triangle load.Besides,horizontal velocity and displacement formula for three kind of columns are derived from theoretical analysis.(2)Comparison between theoretical value and simulation value.Displacement data are extracted from the numerical simulation,moreover,time-history curves are properly handled for calculation in formula.To analyze the rationality of the theoretical analysis,theoretical value and simulation value are compared in different figures and tables.(3)Investigation of anti-blast of columns with different parameters in small standoff.To analyze blast resistance and failure mode of concrete piers,the parameters including horizontal velocity and displacement of pier bottom were investigated with respect to comparison of circular and square piers,reinforcement arrangements and location of detonation.Dynamic response and failure mode of pier columns are studied with the combination of theoretical analysis and numerical simulation in this paper,blast resistance of columns are summarized for the reference of the pier column design in anti-blast.