Flats slabs became a common solution for buildings because they are easy and fast to build. In the last few years, some building that constructed using flat slab system required strengthening for column to slab junction due to either some imperfections during design, construction or due to increase of the design load in case of change of the building function. The common strengthen methods against punching shear (column heads, drop panels) leave an obvious trace which in most cases conflicts with some extensions parts and may reduce the height of the story considered, thus it can’t be applied in such cases. A relatively new technique was studied, it consists of high tensile steel bolts installed vertically through the slabs by drilling and bonding with high-performance epoxy adhesive and mechanically anchored to the slab surface. Many studies validated the efficiency of the technique in strengthen against punching shear and also in enhancing the ductility of the slab-column connection and the results shows that the method can be applied in practice. In this paper, the post-installed bolts technique is presented and applied in a practical case study. The capacity of the slab enhanced by 53% and it was easy to design and construct. Also, it took not more than few hours for its application. In addition, the building extension utilities (Heating ventilation and air conditioning, communications...etc.) was not harmed because the slab surface remains clear. Those advantages make the technique a favorable option for owners and engineers when strengthening against punching shear.
A Comparison of Punching Shear Strengthening of RC Flat Plates with FRP Bars and Steel Bolts
