2010 NZSEE
Conference
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2010 NZSEE Conference |
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Contents |
Keynote Address Tribute to Tom Paulay Session 3 Session 4A Session 4B Session 5A Session 5B Session 6 Session 7A Session 7B Session 8A Session 8B Poster Session Seismic structural displacement measurement using a high-speed line-scan camera: experimental validationM. Nayyerloo, X.-Q. Chen, J.G. Chase, A. Malherbe and G.A. MacRae This paper examines high speed line-scan cameras as a robust and high speed displacement sensor for various seismic monitoring applications. They have the additional benefit of requiring no invasive mechanisms or added processing to provide a high resolution output measure, and do not interfere architecturally. Following the method proposed by Lim et al. for measuring foundation pile movements, multiple displacements and motions of any structure can be determined in real-time at rates over 1 kHz using only one high speed line scan camera and a special pattern. This resolution is more than sufficient for structural monitoring and control problems. Versatility of the proposed measurement technique is examined through both harmonic and random vibration experiments with a suite of different input motions applied to a computer controlled cart. Comparing the input and the measured motions confirms that vision-based structural displacement measurement utilizing a high speed line-scan camera offers a high resolution and low-cost means of measuring structural vibration-displacements. Paper P10: [Read] Building pounding state of the art: Identifying structures vulnerable to pounding damageGregory Cole, Rajesh Dhakal, Athol Carr and Des Bull Due to recent legislation, the past three years has seen a radical increase in the evaluation of potentially Earthquake Prone Buildings (EPBs) in New Zealand. Using the Initial Evaluation Procedure (IEP), EPBs’ vulnerability to seismic pounding must be assessed. Engineers currently have little knowledge of this highly specialised field. This paper aims to assist engineers undertaking either preliminary or in depth assessment of buildings with pounding potential. An international state of the art review is presented with particular emphasis on the loadings caused by pounding. Floor-to-floor collisions are identified as a fundamentally different process to floor-to-column collisions. Current methods of building pounding assessment are reviewed, specifically assessing each method’s applicability and weaknesses. Existing mitigation options are also evaluated in terms of practical application to existing structures. Finally, critical building weaknesses that are vulnerable to pounding are presented. It is intended that this paper will provide a useful contextual background on pounding for all engineers using the IEP or higher order analyses. Paper P11: [Read] Simple methods to evaluate structural irregularities effectsVinod Sadashiva, Gregory MacRae and Bruce Deam Simple analysis methods are available for designing regular structures. For irregular structures, these simple methods are restricted by code regularity limits that lack proper analytical justification. This paper summarises a recent study on structural irregularity effects, involving the quantification of effects of different types, and degrees of, irregularity on structures designed for earthquake using simplified analysis methods. Irregularity types considered include vertical irregularities (e.g. mass, strength-stiffness irregularities), horizontal diaphragm flexibility, and torsional irregularity. Simple design tools describing the change in response due to irregularity are developed. This facilitates designers and plan checkers to rapidly evaluate the likely effect of irregularity on structures. The work was undertaken to provide a rigorous technical basis for new regularity provisions in the New Zealand seismic design Standard, NZS 1170.5. Paper P12: [Read] Development of combined passive and semi-active damping techniques for net-zero base-shear dampingGeoff Rodgers and Geoff Chase The use of passive damping has advantages such as low cost, predictable response, robustness, low complexity and ease of implementation. Recent research into semi-active damping systems has highlighted their highly customisable behaviour. Semi-active damping devices with specific control laws have yielded reductions in displacement and structural force, while simultaneously reducing the total base-shear transmitted to the foundation from both structural column and damping forces. This research combines semi-active resetable devices with high force-to-volume passive energy dissipating devices. This combination can further reduce response if the passive devices are sized not to exceed the semi-active base shear reductions. Results show 40-65% reductions in structural force can be achieved, with no increase in the base-shear using realistically sized dampers. This big response reduction with no in increase in base shear is unique to this combined system, and is not available through other damping techniques. Paper P13: [Read] Keynote Address Tribute to Tom Paulay Session 3 Session 4A Session 4B Session 5A Session 5B Session 6 Session 7A Session 7B Session 8A Session 8B Poster Session |