Design recommendations for multi-bolted staggered connections of PFRP structural members

Towards the wider applicability of the Pultruded fibre-reinforced polymer (PFRP) structures, this study focused on developing an optimum connection geometry. PFRP multi-bolt staggered connection behaviour is investigated in this study. A total of sixty connection tests were carried out by varying the design parameters, such as the angle of loading, thickness of the PFRP plate, diameter of the bolts, and different patterns of staggered alignments. The test results are comprehensively analysed to determine the optimum connection geometry for achieving the bearing failure with progressive deformation. The appropriateness of the existing design standards for determining the bearing and shear-out strength of the bolted connections is verified. Based on the observations from the experimental results, minimum required bolt connection geometry dimensions are proposed. The comparison of test and design results shows that the strength predictions by design specifications CNR 2008, ASCE Pre-standard 2010, EU 2016, CEN/TC 19101, and FprCEN/TS 19101 are largely conservative but still not accurate. Therefore, suggestions to improve the design equations are proposed.