Analysis Of Interior Slab-column Connections Under Unbalanced Moment

The reinforced concrete flat plate structure has become more and more popular in our daily life due to its advantages such as it is easy to build and generates greater flexibility in the disposition of rooms. One prominent feature of flat plate structure is that slabs of the structure directly support on columns. That the stresses near the slab-column connection is very complex and the structure is sensitive to punching failure has caused special attention of the researchers.Under combined vertical load and horizontal load, the slab-column Connecticut has not only to bear shear caused by vertical load but also to transfer unbalanced moment by horizontal load. Generally when designing a structure, we don’t use flat plate structure as lateral force resisting system(LFRS) alone. But when suffering earthquake or wind load, flat plate structure has to deform compatibly with LFRS such as shear walls. The flat plate structure must have enough deformation ability under horizontal load to guarantee the carrying capacity under vertical load. So, we must pay special attention on the deformation of the flat plate structure. But the existing analytical models such as equivalent frame method, equivalent beam method and eccentric shear stress model etc. cannot calculate the deformation of slab-column structure. In this paper, Based on the critical shear crack theory and the finite element software, the following work have been done :① For slab-column connections without shear reinforcement, experiments under combined vertical load and unbalanced moment tested by researchers at home and aboard have been collected; the punching capacity calculated according to the specifications of GBJ50010-2010、ACI318-11、BS 8110-97 and CEB-FIP MC90 have been analyzed comparatively. In addition to CEB-FIP code, results calculated according to these specifications disperse widely, especially the ACI318 code whose calculation results are the worst.② Derived the equivalent method for non-standard members based on the critical shear crack theory; proposed calculation method of punching shear capacity and deformation of flat plate structure under combined gravity loads and unbalanced moment and prepare a flow chart and programming the calculation procedure of Python. the proposed method is feasible which is verified by compare calculated results to the experimental results;③ By using finite element software, established a grid model for the slab- column connections under combined vertical force and unbalanced moment and discussed the value of parameter used in the model; by comparing the simulated load-displacement curve to the test curve, verified and validated the accuracy of grid model.