Browsing by Author "Terblanche, Jacques Le Febre"

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    Modelling of slotted bolted friction connections as seismic energy dissipaters in braced steel frames
    (Stellenbosch : Stellenbosch University, 2015-12) Terblanche, Jacques Le Febre; Haas, Trevor; Van der Klashorst, Etienne; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: The Slotted Bolted Connection provides additional energy dissipation during seismic loading, which leads to a reduction in structural damage. The effects of past earthquakes have shown that braced steel frames are susceptible to structural damage, particularly in the braces and connections. Although steel structures did not collapse during previous earthquakes, such as the 1994 Northridge earthquake, the numerous brittle failures motivated the development of seismic provisions for enhanced ductility. The improved provisions however still result in significant damage following an earthquake, which was seen after the 2011 Christchurch earthquake. One approach to minimise earthquake damage is by using energy dissipation devices. In contrast to other devices, the Slotted Bolted Connection is simple and economic while energy dissipation is provided by the relative sliding between plates in a friction connection. Slotted Bolted Connections were proposed as brace connections in Concentrically Braced Frames, but the lack of a published design procedure has restricted their use. The absence of a design procedure for Slotted Bolted Connection-braces is attributed to insufficient research conducted on the subject. Previous research concentrated mainly on testing of friction materials for the connection. Literature indicated that there is insufficient understanding of the effect that the configuration of the Slotted Bolted Connection has on its performance. To address this, a Finite Element Analysis study was undertaken. Firstly, a Finite Element model of the Slotted Bolted Connection was calibrated using existing experimental results. The Finite Element model was used to investigate; the effect of bolt-impact with the slot-ends, the differences between Symmetric and Asymmetric Slotted Bolted Connections and the influence of the connection on a braced bay. In addition, a modelling technique was developed to perform a non-linear dynamic analysis of a multi-storey building with Slotted Bolted Connection-braces. The bolt-impact investigation demonstrated that the connection requires suitable detailing to ensure ductility. The analyses indicated that the performance of the Symmetric connection was preferable to that of the Asymmetric connection. Contact between the bolt-shanks and the slot-sides during sliding of the connection in a braced bay affected the hysteresis behaviour, but not detrimentally. Dynamic analysis indicated that the Slotted Bolted Connections successfully decreased brace-damage by providing enhanced lateral drift capacity. The findings have clarified important aspects with regard to the configuration of the connections and have demonstrated the benefits of their introduction to Concentrically Braced Frames. The enhanced understanding contributes to the development of a design procedure for Slotted Bolted Connection-braces.