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Experimental dynamic verification of open piled wharf models

University of British Columbia

Designers of wharf structures have historically had little guidance from published standards from which to base their seismic designs. Many of the methods used to develop models for seismic analysis are taken from building or bridge codes, but fundamental differences between the support systems in buildings/bridges and wharves may make these codes unsuitable for analysing wharf structures. Little research has been done to verify the applicability of building and bridge code recommendations for the seismic analysis of open-piled wharves. The aim of this study was to assess the relative importance of different modelling assumptions, taken from guidelines set out by building and bridge codes, to determine the inputs for the dynamic modelling of wharves. In this study, two wharves, a vertical piled wharf and a batter piled wharf, were analysed to determine their dynamic characteristics. The vertical piled wharf was monitored by means of an ambient vibration survey. The ambient vibration measurements provided data from which to calculate the low level vibration characteristics of the wharf. The dynamic characteristics determined from the data were used to calibrate a computer model that was, in turn, used to conduct a parametric study of the major variables used to model wharf structures. The variables that were studied were as follows: non-structural restraints; length to fixity of the piles; structure mass; and stiffness of the framing members. It was found that the first two parameters can make a large difference in the dynamic properties of the structure, while the influence of the last two parameters is relatively insignificant. The batter piled wharf was subjected to strong motion shaking during the 1989 Loma Prieta earthquake. Because of the limited availability of strong motion data for wharves, the data recorded during the earthquake provided a unique opportunity to determine the behaviour of the wharf under strong shaking as well as to evaluate its dynamic characteristics. Analysis showed that the individual sections of the wharf moved independently of one another during the earthquake, although these motions were highly influenced by the ground movements in the free field. Frequency and time domain analyses resulted in the determination of one transverse natural frequency at approximately 3.0 Hz for one of the independent sections of the structure.

Thesis/Dissertation

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2009-02-06

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http://hdl.handle.net/2429/4225

Civil Engineering

University of British Columbia

UBCV

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