Fatigue life of an anchored blind-bolt loaded in tension

This paper investigates and reports on the fatigue behaviour of a novel blind-bolt system termed the Extended Hollo-bolt (EHB). The new blind-bolt is a modified version of the standard Lindapter Hollo-bolt, and its application relates to the construction of bolted, moment-resisting connections between open profile beams and concrete-filled tubular columns. The fatigue behaviour of the system is studied on the basis of constant amplitude loading tests, with a total of 56 experiments being reported. The specimens were subjected to tensile loading for various stress ranges, with the repeated load being selected relative to the design yield stress of the blind-bolt's internal shank. The influence of testing frequency and strength of concrete infill is also examined. An analysis of the results indicates that an increase in the concrete strength can increase the fatigue life of the EHB system. Within the tested range, the failure mode of the EHB under repeated loading was found to be due to internal bolt shank fracture, a mode which is consistent with its monotonic behaviour and also comparable with standard bolt–nut–washer system behaviour. The experimental results (S–N data) were further compared with the Eurocode 3 Part 1-9 guidelines. The fatigue design strength of the anchored EHB blind-bolt is found to be adequately represented by the current specification detail Category 50 that is provided for standard bolting systems

Static and fatigue performance of resin injected bolts for a slip and fatigue resistant connection in FRP bridge engineering

This paper presents test results to evaluate the slip and fatigue performance of Resin Injected Bolted Joints (RIBJs) for pultruded Fibre Reinforced Polymer (FRP) material. The objective of the test series is to provide a robust method of connection for structural engineering that is both fatigue and slip resistant. Forty-six joints (using 23 specimens) were subjected to either static or combined static/cyclic loading at ambient room temperature. Ten specimens (five batches of two) had bolted connections without injected resin and were included to provide baseline static joint strengths. Sikadur®-30 and RenGel®-SW404 were the two cold-curing epoxy based resins used to fabricate the 13 RIBJ specimens. Testing was conducted with double lap-shear joints in accordance with modified guidance from Annex G and Annex K in standard BS EN 1090-2:2008. The specimen’s geometry was established using this British Standard and an American Society of Civil Engineers pre-standard for pultruded thin-walled structures. Rectangular plates for the lap joints were cut from either a wide flange section of size 254×254×9.53 mm or a flat sheet of 6.35 mm thickness. Bolting was with either M16 or M20 steel threaded bolts of Grade 8.8. Sixteen specimens, for eight batches of two specimens were failed in a short duration for static strength. Four RIBJ specimens had static load cycling to an assumed service load level. Three specimens out of 23 were subjected to staged static and cyclic fatigue loadings to determine stiffness changes, life-time ‘slip’ load and residual joint strength. The reported results are evaluated for slip and fatigue performance and the main finding is that resin injection shows much promise as a mechanical method of connection in pultruded FRP structures

Experimental seismic performance evaluation of modular lightweight steel buildings within the ELISSA project

Lightweight steel buildings made up by cold‐formed steel (CFS) members as main structural components are growing in popularity in the most industrialized countries. Cold‐formed steel buildings start to be adopted also in seismic regions thanks to their efficient fabrication, reduced site work, short time of construction, and good structural performance. However, the dynamic properties and full seismic performance of CFS buildings completed with finishing is an open question. This paper attempts to provide a contribution to this research question, by a full experimental campaign aiming at investigating the dynamic properties of a modular building developed within the “Energy efficient LIghtweight Sustainable SAfe steel construction” (ELISSA) research project. The work shows the results of an international collaboration between universities and industrial partners aimed at developing a CFS prefabricated dry construction system with improved antiseismic properties and energy performance. This work will discuss the design of the modular building named ELISSA house, the experimental investigation going from small‐scale tests of components, to static tests of shear walls, up to shake table tests of a 2‐storey mock‐up building. It will analyze the dynamic properties of the structural system compared to the building completed with all the finishing, focusing on fundamental period of vibration, damping ratio, building drift, and observed damage

Flexural Wrinkling Strength of Lightly Profiled Sandwich Panels with Transverse Joints in the Foam Core

In Australia, sandwich panels are commonly made of flat or lightly profiled steel faces and expanded polystyrene foam cores, and are increasingly used as roof and wall claddings in industrial and commercial buildings. Flexural wrinkling is often the governing criterion in the design of these panels. The use of lightly profiled faces is expected to increase the flexural wrinkling stress considerably whereas the presence of joints between the polystyrene foam slabs in the transverse direction introduces a reduction to the flexural wrinkling stress. Therefore a series of full scale experiments and finite element analyses were conducted to evaluate the effects of lightly profiled faces and transverse joints on the flexural wrinkling stress of panels subjected to a lateral pressure loading. The results showed that properly designed lightly profiled panels provided considerable improvement to flexural wrinkling strength over flat panels whereas the presence of transverse joints caused a significant reduction to wrinkling strength. This paper presents the details of this investigation, the results and comparison with available theoretical and design solutions

Research on Self-Drilling Screwed Lap Connections in Steel Diaphragms and the Design Models

In this paper, the results of a research on thin-plate single-lap connections are presented. Such type of connections is popular in steel roofs made of trapezoidal plates and other thin-walled elements. In case of a building safety it is necessary to ensure that materials with proper durability and ductility are used. Connections are one of the most important components in such structures, particularly when in-plane strength of a roof is taken into account. So far, in many existing regulations, only general calculations of such connections are conducted. However recently, discrete and computational methods can be used to build new, expanded mathematical design models, such as those presented here. Such models could be useful in an advanced design where a static analysis is combined with the safety assessment of the connections in a structural system. This is difficult when sheeting is utilized as a structural in-plane shear diaphragm. These require to take into consideration the important interactions of structure with covering and covering with another covering elements. The research is an effect of authors works on practical design approaches. Such methods can be effectively used for structural designs of buildings where the stressed skin diaphragm action is involved. Finally, practical input values about connections can be acquired from the presented data