Fire performance of blind-bolted connections to concrete filled tubular columns in tension

Abstract

This paper describes an advanced numerical model to predict the fire behaviour of blind-bolts in the tension area of endplate connections between I-beams and concrete filled tubular (CFT) columns. It is the continuation of a previous research on the thermal response of connections, considering the tension load of a moment-resisting connection. Due to the absence of experiments and data on blind-bolts fire performance the aim was to provide a model for their study. The effect of two main variables was researched, the concrete infill of the columns and the anchored extension of the blind-bolt. The fire resistance rating (FRR), the failure mode and the force-displacement-temperature curve at high temperatures were discussed. Results proved that concrete inside the column enhances the connections response at elevated temperatures in terms of FRR and stiffness. On the other hand, the use of anchored blind-bolts compared with normal blind-bolts provided stiffer connections, but the FRR improvement depended on the plate thickness and steel bolt properties. Finally, the use of fire resistant steel bolts as a method to enhance the fire response was assessed, observing the benefits to these connections when the shank of the blind-bolt governs the failure.Pascual A M, Romero M L, Tizani W. Fire performance of blind-bolted connections to concrete filled tubular columns in tension. Engineering structures 2015;96:111-125. http://dx

Advanced materials for concrete-filled tubular columns and connections

“…The increase of the FRR achieved using FR steel bolts was determined by comparison with normal HSS bolts. FR steel bolts properties were defined following the recommendations from Sakumoto et al [27], while HSS capacity was extracted from Eurocode 3 Part 1.2 Annex D [41] In a previous work from the authors, Pascual et al [9], it was observed that in connections to hollow steel columns in fire, at the failure instant, stresses exceeded the capacity of both, sleeve and shank. Nonetheless, in connections to CFST columns, the sleeve underwent less stresses and the shank was the compromising part for the connection.…”

“…The use of new bolt materials represents a method of enhancement at room and elevated temperatures [9][10]…”

Heat transfer analysis of concrete‐filled steel tubular columns to slim‐floor beam connections subjected to fire

“…Among the different types of blind-bolts, the Hollo-bolt system (Lindapter International, UK) was chosen due to its easy assembly and its feasibility to bear bending moments [10], in particular, a modified version that is anchored into the concrete to increase the connection stiffness [9]. At room temperature the blind-bolt performance has been addressed, but under fire conditions the knowledge is still scarce [7,8]. This research tries to increase the insight by considering an important aspect as it is the effect of the slim-floor.…”

Effect of Concrete Infill and Slenderness on Column-Face Component in Anchored Blind-Bolt Connections

“…They confirmed that the pull-out resistance of the EHB is higher than the tensile capacity of the internal bolt of the EHB and that the behaviour of the EHB is comparable to standard bolt in terms of stiffness, strength and failure mechanism, which makes it suitable for use in moment-resisting connections. Other studies on the EHB included studying its fatigue behaviour (Tizani et al 2014) and its behaviour in fire (Pascual et al 2015).…”