Author : Ghanim Abbas AL-Khafaji, Ali
journal of kerbala university,
Volume 10, Issue 4, Pages 247-269
This study presents the theoretical study of the nonlinear behavior of reinforced concrete slabs subjected to impact loads .
The nonlinear finite element analysis adopted by ANSYS software were used in this study. Concrete was simulated by eight-node isoparametric brick elements ( SOLID 65 ) since this element is capable to model cracking and crushing of concrete while steel reinforcing bars were modeled by a three dimensional spar element ( LINK 8 ) which has two nodes with three degrees of freedom identical to those of the ( SOLID 65 ).
The effect of reinforcement ratio, dimensions of slabs and support conditions of the slab were studied too. In dynamic analysis, load-time history , deflection-time relation , and stress-time relation were investigated. Crack patterns were also explained. The central deflections of the slabs under impact were found to become smaller as the tensile reinforcing steel ratio increases, but the rate of the decreases in the deflection is less for high steel reinforcement ratio (1.77 %). Also, those deflections were found to be oscillatory in nature but not in-phase with the applied load. However clamping edges of the slabs results in larger oscillation frequencies as compared to the case of simple supports.
Finally , this study showed that, the maximum central deflection of the slabs becomes larger by ( 20 – 45 % ) as the span of the slab increases by ( 60 – 125 % ) .