A new method for post-installed punching shear reinforcement


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Title: A new method for post-installed punching shear reinforcement

Author(s): Rupert Walkner, Mathias Spiegl, Jürgen Feix

Publication: Special Publication

Volume: 315


Appears on pages(s): 337-351

Keywords: Punching shear reinforcement, strengthening, concrete screws, post-installed shear reinforcement, punching tests

Date: 4/1/2017

The assessment of existing flat slabs and bridges often shows insufficient punching shear resistance in the area of the support regions. The reasons for this are modified requirements of use or more restrictive design rules. There are many different methods to increase the punching shear resistance, but most of them are expensive and require access to the upper surface of the structure. Thus the construction work is only possible under restricted operation. In addition, difficult detail issues arise with regard to the rearrangement of the structure sealing. This paper deals with a new strengthening system using concrete screws, which are installed vertically into pre-drilled holes from the soffit of the slab. The results of two test series with a total of nine specimens are presented in this paper. It turns out that this strengthening method leads to a significant increase in the shear punching capacity and to a less brittle failure mode.