CAST CONNEX® Scorpion™ Yielding Connectors — Full Scale Dynamic Test

Full-Scale, real-time dynamic test demonstration of the Cast ConneX® Scorpion™ Yielding Connectors (SYC) at the University of Toronto. This video shows a steel frame equipped with a SYC in a brace configuration being subjected to the Cyclic Qualification Test for Buckling-Restrained Braces as outlined in AISC 341-10 Chapter K, Section 3. Before this test, this brace assembly had already been subjected to the test protocol applied quasi-statically. In this video, the protocol is applied for a second time, but all within a 30-second duration. Applying the entire protocol within a 30-second duration resulted in displacement periods ranging between 1 second (low amplitude cycles) and 2.5 seconds (high amplitude cycles).

Engineers employing this system select Scorpion Yielding Connectors based on the desired activation load for the brace and then select a conventional W-Shape or HSS brace element based on capacity design requirements and on the desired axial stiffness of the brace assembly. In so doing, the yield force and elastic stiffness of each brace comprising the frame can be independently tuned.

An additional benefit of the system is its unique post-yield response. At large deformations, SYCs exhibit post-yield strengthening and stiffening due to second-order geometric effects. This stiffening behavior allows for a better distribution of yielding in braces over a building’s height at large drift levels. In the event that deformations begin to collect in a single story, the system’s post-yield stiffening and strengthening will cause braces in adjacent stories to be activated, thereby reducing the likelihood of the formation of a “soft-story”. Neither of these advantages are available in systems which exhibit little or no post-yield stiffness.

The combination of high axial stiffness and low activation force also makes SYCs ideal for retrofitting existing seismically deficient reinforced concrete and steel moment-resisting frames. The high elastic stiffness of the system can reduce the drift levels of older buildings while lower activation forces reduce costly remediation of members, connections, and foundations. Furthermore, because all of the inelasticity is confined to the Scorpion Yielding Connectors, engineers using the system have the flexibly to employ a wider range of brace configurations than can be accommodated with other hysteretic brace systems. For example, a single-bay, single-story X configuration can be employed to reduce the number of frames which are lost or obstructed; in the case of retrofit, this configuration can reduce the cost of the removal and replacement of building envelope and finishes.

Post time: Jun-19-2017
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