2009 NZSEE
Conference
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2009 NZSEE Conference |
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Contents |
Keynote Address Session 1 Session 2 Session 3A Session 3B Session 4A Session 4B Session 5A Session 5B Session 6 Session 7 Poster Session Centrifuge Tests of Rocking Shallow Bridge FoundationsTom Algie, Lijun Deng and Bruce Kutter The effects of rocking bridge foundations were investigated by a series of highly instrumented centrifuge tests at the University of California, Davis. Slow cyclic tests on shallow foundations supporting rigid elastic columns were performed to capture the nonlinear moment-rotation behaviour of foundations. Relatively small zones of improved soil were strategically located in some slow cyclic tests to study ways in which to reduce settlement associated with rocking foundations. Dynamic shaking tests were performed on lollipop type bridge structures with variable footing dimensions supporting yielding columns. Results show that plastic rotation demand on the column decreases consistently with a decrease in the foundation moment capacity and a rocking footing can reduce ductility demand and permanent drift, improving bridge system behaviour. Numerical analyses were implemented in OpenSees, an open source finite element platform, to validate the experimental results by using a nonlinear spring bed model. Numerical analysis is shown to be able to capture the experimental results satisfactory. Paper P06: [Read] [Presentation] Steel Frame Lateral System Concept Utilizing Replaceable LinksPeter Dusicka, Jeffrey Berman and Rupa Purasinghe The loss of occupancy and the difficulty associated with repairing a conventional structure following an earthquake can economically burden owners as well as occupants. This paper outlines a concept of a linked column steel framing system utilizing replaceable components that are strategically placed to protect the gravity load carrying system. The nonbraced lateral system relies on the inelastic behaviour of bolted shear links. Non-linear pushover analyses were used to investigate the performance of a three-story building and demonstrated ductile behaviour with the potential for rapid return to occupancy. Practical connection details for the link components were proposed in an effort to provide elastic connections that shift plastic strains away from critical welds, thereby avoiding some of the failures observed in past tests on similarly detailed link-to-column eccentrically braced frames. Link end details were investigated using detailed non-linear finite element analyses and showed the viability of the shear link component to provide inelastic energy dissipation while limiting plastic strains at the bolted connection. In general, the linked column framing system is thought to be viable under seismic loading, offering a ductile structural system with the ability to rapidly return to occupancy. Paper P07: [Read] [Presentation] Probabilistic Seismic Performance Assessment of a Bridge-Foundation-Soil SystemBrendon Bradley, Misko Cubrinovski, Rajesh Dhakal and Gregory MacRae This paper presents the probabilistic seismic performance assessment of an actual bridge-foundation-soil system, the Fitzgerald Avenue twin bridges. A two-dimensional plane strain finite element model of the longitudinal direction of the bridge-foundation-soil system is modelled using advanced soil and structural constitutive models. Ground motions are selected based on the seismic hazard deaggregation at the site, which is dominated by both fault and distributed seismicity. Based on rigorous examination of several deterministic analyses, engineering demand parameters (EDP’s) are determined which capture the global and local demand and damage to the bridge and foundation, and multiple ground motions at various intensity levels are used to conduct seismic response analyses of the system. It was found that the non-horizontal layering of the sedimentary soils has a pronounced effect on the seismic demand distribution to the bridge components, of which the north abutment piles and central pier are critical in the systems seismic performance. Paper P08: [Read] [Presentation] Estimating seismic impacts on lifelines: an international review for RiskScapeSonia Giovinazzi and Andrew King In this paper an international overview is provided about the main methods and computational tools available for the development of seismic damage scenarios and for the assessment of the ensuing loss of functionality of selected geographically distributed lifelines, namely transportation networks, electric power systems and potable water systems. The final objective of the study is to provide the Regional RiskScape programme in New Zealand with an engineering basis upon which the losses incurred by lifeline systems can be assessed under the action of different natural hazards. To this aim reliable and worldwide implemented methods have been investigated in order to understand: 1) the parameters adopted for the representation of the ground shaking; 2) the classification system and the asset attributes considered for the implementation of the exposure analysis; 3) the assumed spatial data representation; 4) the technical basis upon which vulnerability, fragility curves, loss and restoration have been developed. The feasibility of implementing the models presented for the seismic performance assessment of lifelines in New Zealand is finally discussed with reference to a study-case. Paper P09: [Read] [Presentation] Special Presentation: NZSEE Reconnaissance to WenchuanPathmanathan Brabhaharan, Stuart Read, Jiashun Yu, Philip Yong and Meng Fong
Special Presentation: Hollow-core Floors - Guidelines for Design, Assessment and RetrofitDavid Hopkins [Presentation] [Guidelines for Comment]
Keynote Address Session 1 Session 2 Session 3A Session 3B Session 4A Session 4B Session 5A Session 5B Session 6 Session 7 Poster Session |