Problem

The calculation of the punching carrying capacity of connection elements with direct fastening for acceptance in building authority approval Z-14.4-407 is made analog to the proceeding for acceptance to approval Z-14.1-4 by tests on stirrup samples according to Klee/Seege. As in a calculation according to_________ a reduction of the tension carrying capacity has to be made depending on the distance of the connection member to the webs which stiffen the building parts that are to be fastened, does not happen in a calculation according to Klee/Seege, although it can be assumed that stiffening webs are not existing in this case. According to this, the results from punching tests on sandwich elements show lesser punching carrying capacities than tests on stirrup samples by Z-14.1-4. Until noe it was assumed that the missing webs were compensated by the supporting effect of the foam core. Although, a simple transfer to of the reduction factors by Z-14.1-4 is not possible, because a reduction factor of “0” would be the result for planar elements, meaning that there is no arithmetical tension carrying capacity.
This problem becomes more important in coherence with decreasing (nominal) densities of polyurethane foam cores, because a reduction of the supporting effect has to be assumed.
So the goal is to determine reduction factors for sandwich elements to allow a safe/secure design with the existing, calculated with stirrup samples, carrying values, without the necessity of new tests for these connection members. The reduction factors shall be determined with negligence of the material’s influence, so that these values will be applicable for sandwich elements with polyurethane or polystyrene cores as well as mineral cotton. The same will be done with the element’s thickness.
The distance’s influence on non-stiffened rims is to be examined too.

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