Robustness of beam-to-column end-plate moment connections with stainless steel bolts subjected to high rates of loading

This paper presents an experimental investigation into end-plate beam column connections for buildings. The work demonstrates that a fourfold increase in the energy absorbed to failure can be achieved by replacing carbon steel bolts with their stainless steel counterparts. Experimental tests were carried out under load control, and these provided the opportunity to observe the time required for connection fracture. Under quasi-static loading, connections tested with stainless steel bolts showed clearly visible signs of distress prior to failure, whereas the carbon-steel-bolted equivalents provided no warning of failure prior to brittle fracture. Experimental tests were carried out on bolts, and these showed strain rate–induced strength enhancements. End-plate connections were also tested under high strain rates. Loading rate was not observed to significantly affect the performance of stainless steel–bolted connections. However, carbon-steel–bolted connections were observed to weaken under high-strain rates; therefore, dynamically increased material properties did not always translate into increase connection strength. The design strengths predicted using Eurocode 3 were found to be in good agreement with the experimentally observed values under quasi-static loading for both bolt types. Under high-strain-rate conditions, the Eurocode 3 method was also found to provide a good prediction for stainless steel-bolted connections but was found to over predict for carbon-steel connections. The simple modification of replacing carbon-steel bolts with their stainless steel equivalents is shown to be an effective way of improving the performance of industry standard connections. This modification is of relevance to the design of buildings and other structures in which the ductility is of high importance; for example, in structures which may need to resist transient loads from blast or impact

Structural design of elliptical hollow sections : a review

Tubular construction is synonymous with modern architecture. The familiar range of tubular sections square, rectangular and circular hollow sections - has been recently extended to include elliptical hollow sections (EHSs). Due to differing flexural rigidities about the two principal axes, these new sections combine the elegance of circular hollow sections with the improved structural efficiency in bending of rectangular hollow sections. Following the introduction of structural steel EHSs, a number of investigations into their structural response have been carried out. This paper presents a state-of-the-art review of recent research on EHSs together with a sample of practical applications. The paper addresses fundamental research on elastic local buckling and post-buckling, cross-section classification, response in shear, member instabilities, connections and the behaviour of concrete-filled EHSs. Details of full-scale testing and numerical modelling studies are described, and the generation of statistically validated structural design rules, suitable for incorporation into international design codes, is outlined