Research On Bearing Capacity Of Punching And Behavior Of RC Slab-column Connection Under Shear And Unbalanced Moment

Slab-Column structure is a kind of structure that the floor is directly supported on the column,which has good economic advantage.It could effectively reduce building height,further take full use of the clear height.Most research has been conducted about the punching failure of slab-column connection under vertical load,however,If slab-column connection subjected the earthquake load in which the additiaonal unbalanced moment may occur,the mechanisim of which is more complex.At present,international and domestic codes are not perfect for the calculation method of slab-column connection subjecting shear and unbalanced moment.And the effect of shear reinforcement on the bearing capacity of punching and unbalanced moment of slab-column connection is not clear.Therefore the bearing capacity of punching and behavior of RC slab-column connections under shear and unbalanced moment is one of the hot issues in current research.The paper studied the bearing capacity of punching and behavior of RC slab-column connection by three aspects,including the study of typical calculation methods,the comparison of codes and elastoplastic FE analysis respectively.Starting from the calculation method of China's stardards,introduced and compared four kinds of typical calculation methods with the experimental data.Through the correction of the shear transfer coefficient k,it could be concluded the revised Committee 326 method was more consistent with the experimental data and conform to the actual situation.Meanwhile,through the comporison of the calculation method of punching bearing capacity form diffetent countries,such as China,Europe,American and so on,and comparison between test results and theoretical values from different national codes,the study discussed the influence of the factors such as the selection of parameters,the equivalent method of unbalanced moment and the ratio of reinforcement to the punching shear capacity.In which,the results obtained by the EC2 were relatively ideal.On contrast,the calculation method for China was still weak and need improvement.ABAQUS was used to simulate the mechanic behavior of reinforced-concrete slab-column connection,through comparing the simulated results with experimental results,the validity of the FE model was verified and the influence of shear steel bars on shear and unbalanced moment were further studied.The result showed that the shear steel bars was not fully utilized in slab-column connection with shear reinforcement,and the force of the bending reinforcement increased.Meanwhile the effective width of slab that resisted the actual unbalanced moment widen.On the basis of the above researches,the width amplification factor of the slab under unbalanced moment transmitted by bending was proposed.