Blind-bolted shear connections for axially compressed RHS columns strengthened with open sections

Abstract

The process of implementing principles of sustainable development in building for existing structures is much more challenging than for new designs. This issue is particularly acute when it comes to improving the stability of an axially compressed bar elements made of rectangular hollow section (RHS). This paper presents the results of experimental and analytical studies that address the question whether blind bolts BOM may be an effective alternative to bolted fasteners in one-sided lap connections between strengthened bar and strengthening branches. The results of shear tests of single lap connections with blind BOM-R16-4 bolts prove that the structural properties of the tested joints are similar to the structural properties of connections with M16-8.8 grade bolts. Results of the parametric analysis carried out for a perfectly straight axially compressed RHS columns, symmetrically strengthened by two U-shaped branches indicate the special potential of BOM fasteners in applications for joining the walls of strengthened tubular bar and strengthening branches of open cross-section. The analytical results demonstrate that the lack of the main slip in the lap bearing connections of branches with BOM fasteners gains efficiency in strengthening of the axially compressed column in comparison with solutions using bolts. The results obtained provide the basis for the development of an efficient method of strengthening bar elements with closed cross-sections that is characterized by low energy expenditure, in accordance with the principles of sustainable building.