Development of the rotational bolted active links

Abstract

Eccentrically Braced Frames (EBFs) are one of the most commonly used systems for resisting seismic loading. While buildings with conventionally designed EBFs performed well in terms of life safety and collapse prevention in the 2010/2011 Christchurch Earthquake series, the extensive inspection time and repair cost has led to economic losses due to direct cost of rehabilitation and delays in reoccupying the buildings.

In recent years, low damage design systems for building structures have gained interest from researchers and society in response to the adverse economic effects of earthquake events. It allows buildings to be rapidly repaired or immediately occupied following a major earthquake event by limiting and reducing the damage sustained by buildings. Slip friction connectors have been developed and implemented in steel moment resisting frames (MRFs) for the low damage design application. These connections dissipate seismic energy through friction sliding between bolted steel plates.

In this research, a suitable friction sliding system for EBFs was developed. The friction sliding connectors developed in this research is referred to as the Rotational Bolted Active Link (RBAL). The RBAL confines any inelastic action and deformation thus protecting the structure from irreversible inelastic deformation. It also allows damage to be quickly inspected and repaired by replacing bolts in the connectors. The performance of the RBAL has been investigated through full scale component testing. The experimental results show the RBAL is considered as an effective low damage alternative to the conventionally designed EBFs.

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Technical Abstract

Friction connections are an effective way to dissipate energy in seismic resisting systems. In this research, a new type of friction connector referred to as the Rotational Bolted Active Link (RBAL) has been developed for the application of active links in Eccentrically Braced Frames (EBFs). The inelastic deformation and energy dissipation of the RBAL is achieved through rotational sliding of symmetric friction connection.

Experimental studies of the full-scale RBAL specimens have been conducted using mild steel and abrasion resisting steel capping plates. The shear friction resistance constantly increased during reverse cyclic loading when mild steel capping plates were used. This is due to material wear, which increased the bolted clamping length and bolt tension. The application of abrasion resisting steel capping plates reduced material wears, and produced stable and reliable hysteresis behavior while maintain strength and stiffness over large cycles up to 0.09 rad link rotation. The experimental results show the RBAL can achieve high ductility is capable to dissipating large amount of energy during friction sliding. The RBAL is con is considered as an effective low damage alternative to the conventionally designed EBFs.