Block tearing of S700 high strength steel bolted connections: Testing, numerical modelling and design

The block tearing behaviour and resistance of S700 high strength steel (HSS) bolted connections in tension have been investigated through tests and numerical simulations and reported in this paper. The experiments were performed on sixteen S700 high strength steel bolted connections, including seven 2-bolt connections (with each comprising two bolts arranged perpendicular to the loading direction) and nine 4-bolt connections (with each comprising four bolts arranged in two rows). All specimens were carefully designed, with a series of geometric parameters, including the end and edge distances as well as the longitudinal and transverse pitches, varied and studied. The experimental setup and procedures, together with the key observed results, including the failure loads, the load-elongation curves and the block tearing failure modes, are fully reported and discussed. The experiments were supplemented by numerical simulations; finite element models were firstly developed to replicate the experimental behaviour and then employed to perform parametric studies to generate further numerical data on S700 high strength steel bolted connections susceptible to block tearing over a wide range of geometric dimensions. On the basis of the test and numerical data, the existing design methods for high strength steel bolted connections susceptible to block tearing, as given in the European code, American Specification and Australian Standard, were evaluated. The evaluation results revealed that all three considered design codes lead to consistent and safe-sided but conservative predictions of the failure loads, due principally to the lack of appropriate consideration of the location and area of the shear failure plane. The proposals of Teh and Uz [1], developed for normal strength steel bolted connections, were then investigated and shown to result in substantial improvements of block tearing resistance predictions, although some of the resistances are unsafe. Finally, the reliability of the proposal of Teh and Uz [1] when used for S700 high strength steel bolted connections was demonstrated by means of statistical analyses.

Automated summary

This study investigates the block tearing behavior and resistance of S700 high strength steel bolted connections under tension through experiments and numerical simulations. The existing design methods for high strength steel bolted connections susceptible to block tearing were found to provide conservative predictions of failure loads due to insufficient consideration of shear failure plane location and area. The proposals of Teh and Uz showed improvements in block tearing resistance predictions, but some resistances remained unsafe when applied to S700 high strength steel bolted connections, as demonstrated through statistical analyses.