Damage Avoidance Design Steel Beam-Column Moment Connection Using High-Force-to-Volume Dissipators

Abstract

Existing welded steel moment frames are designed to tolerate substantial yielding and plastic rotation under earthquake loads. This sacrificial design approach can lead to permanent, and often irreparable damage when interstory drifts exceed 2%. The experimental seismic performance of a 50% full-scale damage avoidance designed structural steel beam-column connection is presented. The beamcolumn joint region consists of a top flange-hung beam connected to the column by an angle bracket. High-force-to-volume (HF2V) devices are attached from the column to the beam to provide joint rigidity and energy dissipation as the joint opens and closes. The HF2V devices are connected either below the beam flange or concealed above the beam's lower flange. Reversed cyclic lateral load tests are conducted with drift amplitudes up to 4%. No damage is observed in the principal beam and column structural elements. The need for stiff device connections to achieve optimal device performance is demonstrated, and potential design solutions presented. Stable hysteresis and repeatable energy dissipation for a large number of cycles up to the 4% drift level is observed. It is concluded that superior and repeatable energy dissipation without damage can be achieved for every dynamic motion cycle, in contrast to conventional sacrificially designed welded moment frame connections.UCRR http://ir.canterbury.ac.nz/handle/10092/3580

HF2V dissipator effects on the performance of a 3 story moment frame

“…Note that the experimental results in Figure 3 have multiple cycles to 4% drift without any notable stiffness or strength degradation (Mander et al 2009) …”

“…The HF2V joint connection design to be modelled is shown in Figure 2 for an experimental 50% scale steel beam column connection used to investigate device properties and their impact on hysteretic steel connection behaviour (Desombre et al 2011;Mander et al 2009). The beam end is cut at an angle of 0.1 radians to provide space for joint rotational motion to be transmitted to the device.…”

Semi‐explicit rate‐dependent modeling of damage‐avoidance steel connections using HF2V damping devices

“…When a top flange-hung beam-to-column moment connection (of the type shown in Figure 5) opens and closes, different stiffnesses are observed (Mander et al 2009). When the connection is undergoing a loading portion of the response, and the sign of the velocity is the same sign as the force, the vertical leg of the top angle is being subjected to single bending, thus a value of C = 3 is applicable in Equation (24).…”

“…Using this data, a trend-line is fitted to characterize the damper constant, C α , as well as the velocity exponent α. The velocity exponent has been investigated in two different studies, using different HF2V devices (Mander et al 2009;Rodgers et al 2008a). Both studies show the device velocity exponent was typically in the range of α = 0.11 to 0.12.…”

“…These devices have been implemented into several large-scale experiments, using both jointed-precast concrete and steel beam-to-column rigid connections (Mander et al 2009;Rodgers et al 2008b). During these experimental investigations it has become apparent that the influence of connecting elements has a large effect on the connection rigidity and energy dissipation capacity of the damping system.…”