Study On Failure Modes And Story Drift Ratio Of Interior Slab-Column Connection

Being a structural system, the reinforced concrete flat plate is simple in form and able to reduce the height of buildings. It could also be constructed easily. However, its seismic behavior is worse than frame structure. It is required by"Code for Seismic Design of Buildings"(GB50011-2010) that spandrel beam should be set around the slab-column system. Compared with exterior slab-column connections with spandrel beam, the interior connection is more likely to suffer from brittle punching failure under vertical load and unbalance moment, which is the key factor of effecting seismic behavior of the slab-column system. In this dissertation, the failure modes and story drift ratio of interior slab-column connection are further studied and discussed. The main contents are as following.1. The relation between punching shear capacity and flexural strength is set up by equivalent concentrated force. And the effect of gravity shear ratio and reinforcement ratio on the failure modes of interior slab-column is discussed. Interior connections with low gravity shear ratio may suffer from flexure failure or punching failure, which is mainly due to reinforcement ratio. When gravity shear ratio is high, interior connections are prone to punching failure.2. Based on the reported test results at home and abroad, the analysis of failure modes of interior slab-column connections with stud-shear reinforcement shows that the calculation formula of punching shear capacity of slab-column connection with stirrup reinforcement recommended by"Code for Design of Concrete Structures"is also suitable for the connections with stud-shear reinforcement. Construction measures of interior slab-column connections with stud-shear reinforcement are recommended.3. The statistics and analysis of the collected experimental results of the slab-column connections without shear reinforcement under low cyclic loads show that the gravity shear ratio is the major factor of effecting story drift ratio when the connection suffers from punching failure. The story drift ratio will decrease with the gravity shear ratio increasing. However, there is no direct effect when flexure failure occurs. A double-linear model for the relationship of story drift ratio and gravity shear ratio is recommended.