| Civil Engineering structures could suffer from various extreme loads during their service life,such as earthquakes,tsunamis,fires,impacts and blasts.The structure subjected to extreme loads may be seriously damaged,resulting in a great threat to the security of lives and property.Amongst several types of extreme loads,impact loads have enjoyed special attention.Especially in recent years,due to the fast construction of traffic infrastructure and the increasing number of motor vehicles,there is a growing threaten of collisions between engineering structures and vehicles,and a higher demand should be proposed for the impact resistance of structures.So far,RC structures have been widely used in the fields of Engineering Structure,and it is of significant importance and of great engineering value to study and improve the collision resistance of these structures.Accordingly,the research on impact resistance of RC elements is one of the important issues.This thesis is to study the performance of RC elements subjected to lateral impact loads.The main contents are as follows.Firstly,a literature review on related fields was provided,including the dynamic mechanical performance of steel and concrete material,and the impact resistance of RC column.The review indicates that there is limited experimental studies on shear behavior of the RC elements under impact loads.And some important issues have not been resolved,such as the failure mechanism of RC columns under impact loads.Secondly,circular section RC column was tested under lateral impact loads using a large-scale horizontal collision facility.The variables of the experiment included impact velocity,spacing of hoops and boundary conditions.The detailed results of tests were obtained,such as the final damage of specimens,the development of cracks,time history of the impact force(and reaction force),the relationship between impact force and displacement,and lateral deformation of the column.What’s more,the experimental results were discussed,and the influent of impact velocity,spacing of hoops and boundary conditions on the behavior of RC column under impact loads was also analyzed.Finally,concrete and steel material models commonly used in LS-DYNA software were briefly reviewed,and the different modeling approaches of RC elements were compared and analyzed.In this thesis,a three-dimension circular section RC column under impact load was established using ANSYS/LS-DYNA finite element software.Based on this numerical model,the nonlinear dynamic analysis of RC cantilever columns was conducted,and the results of impact force,vehicle displacement,column deformation and final damage were obtained.In summary,the impact behavior of RC columns was analyzed with two methods:FE simulation and experimental study.The deformation,impact force and final damage were emphatically discussed. |
