Net cross-section failure of steel plates at bolt holes:numerical work and statistical assessment of design rules

This paper concentrates on the design rule for net cross-section resistance as one of the design rules relevant for bolted connections. In a previous paper twelve experimental test results were presented of a test program containing 28 specimens in total, with different bolt hole configurations, ranging from one bolt hole to multiple staggered and non-staggered holes. The specimens contain bolts or not, meaning that plates with only bolt holes are tested as well as plates connected by bolts. This paper now summarizes all experimental test results. Subsequently, these experimental test results were used to validate a finite element model. Strain hardening needs to be taken into account in the numerical model. The paper discusses the result for different strain hardening models available in codes. The validated finite element model was then used to create a database of numerical test results. In the database, configurations of plates with and without bolts are included. Bolts M16, M20 and M24 are considered. Both staggered and non-staggered bolt configurations are included with different end and edge distances and pitches. Plate thicknesses range from 8 to 26 mm. Most configurations use steel grade S235 but S460 was also considered. The database was used to perform a statistical assessment of the current design rule for net-section resistance, using the procedure of Annex D of EN 1990 as further developed in the RFCS project Safebrictile together with the statistical distributions for steel properties of Safebrictile. It was found that the current partial factor is over-conservative and can be substantially lowered. Alternatively, the design rule can be modified. The paper concludes with a proposal for a new design rule.