Damage Mechanism Of Reinforced Concrete Column And Wall Subjected To The Synergistic Effects Of Adjacent Blast And Fragments

In recent years,the research about destruction of building structure under blast shock wave has achieved some results both at home and abroad.But these studies tended to ignore the damage produced by explosion fragments.Study on damage of civil construction subjected to both the explosion shock wave and fragment,which was very important to promote the protective design of civil buildings,was almost blank now.To solve this problem,the finite element analysis software ANSYS/LS-DYNA was used in this paper to analyse damage process of reinforced concrete column and wall subjected to combined action of shock wave and fragment by numerical simulation.The main research work and results are as follows:(1)The coupling models of air-fragments-explosive-column/wall were built,and constitutive model and coupling algorithm were selected.The selected material constitutive and fluid-solid coupling algorithm in this paper were proved to be applicable by comparing the simulation results with the test data.(2)The failure processes of reinforced concrete column and wall subjected to the synergistic effects of the close-in explosion and fragment were analysed,and the failure mechanisms of column and wall are that under the adjacent explosion,blast waves come to the column or wall before fragments,and a bending failure caused by impact effect of blast waves and erosions of fragments occurs on the column with a certain initial damage,while a local failure caused by impact effect of blast wave and erosions of fragments occurs on the wall with a certain initial damage.(3)The dynamic responses of reinforced concrete column under blast wave alone,fragments alone,and the combined action of them were compared.The results show that the synergistic effects of fragments and blast wave on the column are more serious than the separate effect of either of them on the column,and these are more serious than the effects of linear superposition of them on the column;damages of the column casued by fragment cluster are far worse than that caused by blast wave;the time of the column's peak displacement response is controlled mainly by the fragment effect.(4)The dynamic responses of reinforced concrete column with different parameters under the adjacent explosion shock wave and fragment were analysed.The results show that the increase of the ratio of column longitudinal reinforcement can cut down the column's horizontal peak displacement;improving the strength of concrete blindly may be adverse for enhancing the protective ability of the column under synergistic effects;the explosive initiation mode has great influence on the dynamic response of the column;the damage degrees of reinforced concrete column with the same quantity of explosive at a different height are different;the displacement response of column increases exponentially with the increase of fragment size.(5)The dynamic responses of reinforced concrete shear wall under blast wave alone,fragments alone,and the combined action of them were compared.The results show that the synergistic effects of fragments and blast wave on the wall are more serious than separate effects of either of them on the wall,and these are more serious than the effects of linear superposition of them on the wall.(6)The dynamic responses of reinforced concrete shear wall with different parameters under the adjacent explosion shock wave and fragment were analysed.The results show that increasing the thickness of shear wall and reducing the distance between the distribution bars can reduce the horizontal peak displacement;the smaller the explosive proportional distance is,the more serious the damage of shear wall is.