		2007 NZSEE Conference
	Abstracts

Keynote Address 1 Defining Acceptable Performance Criteria Planning for Expected Performance / Improving Existing Performance I Improving Existing Performance II Keynote Address 2 Developments Within Design I Developments Within Design II Developments Within Design III / Understanding the Inputs Assessing Existing Performance Poster Papers

Sliding Hinge Joints and Subassemblies for Steel Moment Frames

Charles Clifton, Greg MacRae, Hamish Mackinven, Stefano Pampanin and John Butterworth

The sliding hinge joint (SHJ) has been used in the construction of moment frames because it has a large rotational capacity and almost no damage. One of the innovations of the joint is an assymetric double sliding surface which produces a non-rectangular hysteresis loop. This paper discusses the behaviour of the components influencing the sliding resistance of the joints, the development of a design model, and a comparison with the sliding resistances of joints in component and beam-column subassembly tests.

Paper P19: [Read]

Location of Plastic Hinges in Columns of Steel Frames

Brian Peng, Greg MacRae, Warren Walpole, Peter Moss, Rajesh Dhakal and Charles Clifton

The New Zealand Steel Structures Standard has a seismic provision aiming to ensure that plastic hinges occur at the ends of steel columns rather than along their length. This provision often governs the column sizes in steel frames and concerns have been raised about the need for this requirement and the accuracy of the equation in the provision. This paper describes research carried out to evaluate this equation. Methods were developed from first principles considering second order and residual stress effects. Time history analysis was carried out with RUAUMOKO to examine the likelihood of plastic hinges forming away from the column ends. A computer program was also used to examine the applicability of this equation on different types of steel frame. A new equation is proposed based on the analytical results. It is found that the provision is not applicable to columns in the majority of moment-resisting frames. Columns in eccentrically braced frames, designed in accordance with the capacity design philosophy, often did not yield even at the column base during earthquake excitations. A simple check is proposed to determine whether yielding would occur under a design drift limit which can be used in conjunction with the proposed equation.

Paper P20: [Read]

Advanced Flag-Shaped Systems for High Seismic Performance Including Near-fault Effects

W. Kam, Stefano Pampanin, Athol Carr and Alessandro Palermo

Experience with recent earthquakes near urban centers (Northridge 1994, Kobe 1995, Chi-Chi 1999) highlighted two major challenges in seismic engineering: the hazard and peculiarity of near-fault earthquakes, characterised by low number of cycles and high velocity pulses in its motion and the urgent need for performance-based design and retrofit approaches for buildings in near-fault urban centers such as Wellington City. Meanwhile, the development of high-performance seismic resistant hybrid systems or flag-shape systems, incorporating combination of re-centering elements and hysteretic energy dissipation, have shown to significantly reduce the expected level of damage when compared with traditional (i.e. monolithic) ductile systems. However, traditional hysteretic dissipation is considered inherently inadequate to counteract the near-fault effects. In this paper, the innovative concept of Advanced Flag-shape Systems (AFS) is proposed as an alternative solution for high-seismic performance system in near-fault regions. AFS combines alternative forms of energy dissipation (yielding, friction or viscous damping) in series and/or in parallel together with re-centering elements to achieve high seismic performance for both far-fault and near-fault motions. The concept of AFS is first briefly discussed qualitatively and then numerically investigated using SDOF models subjected to push-pull and time-history analyses under a suit of far field and near fault events. Finally, the enhanced performance of AFS systems is compared and discussed with monolithic solutions or more traditional Flag-shape systems.

Paper P21: [Read]