2 results for Ang, Beng Ghee

  • Seismic shear strength of circular bridge piers.

    Ang, Beng Ghee (1985)

    Doctoral thesis
    University of Canterbury Library

    The project was carried out with the intention to study the shear strength of circular reinforced concrete bridge piers under seismic loading. Two series of tests were conducted. Initially, twenty-five column units were tested by subjecting them to static incremental reversed cyclic loading, to investigate the influence of some main parameters. The columns were loaded into the inelastic range to controlled displacement ductility levels. The second stage of experimental work involved dynamic testing of bridge piers, which were half scale models of the static test units on a shake-table. Altogether eight single pier models and two twin-pier models were tested. The single pier models were subjected to sinusoidal excitation while the twin-pier models were tested using scaled earthquake accelerograms. The performance of the test units was gauged mainly in terms of shear strength and displacement ductility capacity. Four failure modes were identified according to the displacement ductility level at which significant degradation occurred. The static test results indicated that existing code provisions for shear strength were conservative and suggested that the level of shear strength and the displacement ductility might be related. The behaviour of single pier models in the dynamic tests was compatible with that of the static test units. The behaviour of the twin-pier models was less predictable, especially when axial tension was acting. The dynamic magnification effect on material strength due to higher strain rate was not significant in the tests. A design method was proposed as an outcome of the static tests. The proposal allows the shear strength and the displacement ductility capacity to be determined, and has been incorporated into an integral flexure/shear design approach in which the provision of transverse reinforcement is considered for confinement as well as shear resistance. Some theoretical study was also conducted using 'Diagonal Compression Field Theory'. The theory was adapted using a stress strain relationship developed for confined concrete. The agreement between the predicted and the experimental behaviour in terms of load displacement response was reasonable.

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  • Ductility of reinforced concrete bridge piers under seismic loading.

    Ang, Beng Ghee (1981)

    Masters thesis
    University of Canterbury Library

    A continuation of the extensive research project undertaken in the University of Canterbury on ductility of bridge piers is reported. The testing described herein covers an experimental investigation into the post-elastic ductile behaviour of reinforced concrete bridge piers, particularly into the influence of aspect ratio on such behaviour. The test units, two octagonal and two square sections, were designed according to the Second Draft of the Concrete Design Code DZ 3101, for different axial load levels. The testing included slow static incremental loading followed by fast dynamic cyclic loadings. The results are presented in the form of load-displacement hysteresis curves, curvature profiles and transverse steel strain distribution. Discussion of results deals with the comparison of ultimate moment capacities, measured ductilities, equivalent plastic hinge lengths, maximum concrete compression strains, the ultimate shear forces, the enhancement of concrete strength by confinement and the idealized stress-strain curves for confined concrete. Some comparisons with previous projects are made and conclusions drawn from the entire analysis.

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