Abstract
Eccentrically Braced Frames (EBFs) are widely used seismic-resisting systems, as they allow both strength and stiffness to be optimised while providing good ductility capacity. However, in theory they have a low damage threshold in severe earthquakes and post-earthquake repair of conventional EBFs will be difficult and expensive.
 This paper presents the Numerical Integration Time-History (NITH) analysis of two ten storey EBF buildings; one with a conventional active link and the other with a new form of low damage active link based on rotational sliding bolted plates. The low damage active link can be designed to allow rotation only, or to allow both rotation and axial extension. The conventional active link response in terms of displacement, rotation and inelastic demand was well within the range of the rotational active links under the records considered. The analysis shows that average maximum displacement of the building and rotation of the link for both the rotational and the rotational+extension active links was almost identical. The extension of the rotational active link permitting axial extension was less than 1.5 mm. Axial load demands on the collector beams and braces were similar in the case all three active links.
 It can be concluded from the analysis that the rotational active link with extension is not required, as the lateral extensions can be accommodated within the rotational plates with nominal clearances in the bolt holes to accommodate the lateral extension.
Highlights
The Eccentrically Braced Frames (EBFs) is a steel-framed earthquake resisting system for multi-storey buildings which are designed for the highest level of ductile demand.It is one of the most widely used multi-storey steel seismicresisting systems in New Zealand and many other first world seismically active countries, as it allows for both strength and stiffness to be optimised in a system that delivers dependable inelastic response and takes up little building useable space in plan or elevation
The analysis shows that the maximum average horizontal displacement of the ten storey building with three different types of link is similar as shown in Figure 6 and within design lateral displacement; the displacement in the case of conventional active link is slightly lower than rotational active link
This paper describes the concept behind a low damage form of active link for eccentrically braced frames and analytical analyses on a ten storey building with built in conventional and rotational active link to undertake initial proof of concept
Summary
Braced Frames (EBFs) are widely used seismic-resisting systems, as they allow both strength and stiffness to be optimised while providing good ductility capacity. In theory they have a low damage threshold in severe earthquakes and post-earthquake repair of conventional EBFs will be difficult and expensive. Axial load demands on the collector beams and braces were similar in the case all three active links It can be concluded from the analysis that the rotational active link with extension is not required, as the lateral extensions can be accommodated within the rotational plates with nominal clearances in the bolt holes to accommodate the lateral extension
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