Proposed design models for the asymmetric friction connection

Abstract

SUMMARYThe Asymmetric Friction Connection (AFC) remains elastic during moderate earthquake shaking but slides and dissipates energy through friction during severe earthquake shaking. The sliding friction forces developed are dependent on the clamping force in the connection which is provided by fully tensioned bolts which pass through slotted holes. During sliding these bolts are subject to moment and shear as well as axial force. Moment-shear-axial force interaction reduces the clamping axial force on the sliding interfaces thereby reducing the sliding shear resistance (V ss ). Two methods to evaluate the moment-shear-axial force interaction have been proposed so that the sliding shear strength can be quantified, but as yet, these methods are not robust. This paper describes the results of 60 tests undertaken to improve the two methods, namely the moment-shear-axial force bolt model and the effective coefficient of friction method, for AFCs with high hardness steel shims. The bolts were M16 to M30 bolts and cleat thicknesses ranged from 12 mm to 25 mm. It is shown that either method may be used in design as the results obtained are similar.

Experimental studies on cyclic performance of column base weak axis aligned asymmetric friction connection

“…The column base uplift displacement, Δ Uplift , is given by Eq. (12), where c Tens is the distance perpendicular to the neutral axis to the extreme fibre of the section on the gapping side as shown in Fig. 9.…”

“…The main objective of these studies was to find materials that can provide a stable performance of friction connection. Chanchí et al [4], Loo et al [19], and Khoo et al [12] tested friction components under low cycle fatigue to many cycles of loading in regard to what they will experience in an earthquake, and no low cycle fatigue was reported. These tests have been for numbers of cycles of loading well in excess of what they have encountered in practice.…”

Dimensional analysis of the slotted bolted connections against impulsive earthquake ground motions

“…The ductile performance of the SBC is remarkable, dissipating significant amount of seismic energy [23,24]. FitzGerald et al [15] concluded two states of the SBC performance, where the first state was the friction state with no strength hardening and the second state included the strength hardening at a larger deformation level.…”

Comprehending the ductile behavior of slotted bolted connections

“…Loo et al proposed a type of symmetric slip–friction connector where the expensive brass shims were eliminated. Extensive researches on SBCs were done at University of Auckland by Butterworth, Clifton, and their co‐workers, who developed the semi‐rigid sliding hinge joint and its friction damper, namely the asymmetric friction connection. In addition to the rotational SBCs, the shear SBCs, which are applied to the center of the beam, have been proposed recently to improve the shear force resistance for generalized lateral load‐resisting systems, where the shear SBCs act as a mechanical shear fuse demonstrating reliable seismic behaviors.…”

“…In terms of the seismic performance, experimental studies have demonstrated that SBC components are able to dissipate significant amounts of energy . Existing studies found that a typical SBC usually demonstrate force pinching phenomena due to contact phenomena and plastic deformation .…”