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A network of eight M02 strong-motion accelerographs was established in the Hutt Valley between the years 1966-70 with a view to determining the effect of the local geology on earthquake attack on structures. The location of the instruments is shown in Fig. 1 and a typical cross-section of
the Valley in Fig. 2. The instruments
are all owned by the Physics and Engineering Laboratory (PEL), DSIR, apart from the one at the Haywards Substation, which is owned by NZED but serviced by PEL.
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In the September 1982 Bulletin the Research Recommendations developed at the December 1981 Wairakei Workshop on the Design of Seismic Resistant Highway Bridges were presented. At the time of publication the assessment of research priorities as found from the Applied Technology Council (ATC) postal survey of the Workshop participants was not available and these are now presented.
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Advice was received from the Seis-mological Observatory in the afternoon of Thursday, October 14, 1982 that the earthquake swarm felt in Wanganui over
the previous few days was the strongest activity in the area for many years and that it would be worthwhile to have strong-motion instrumentation in the area. The only PEL instrument in Wanganui at that time was a scratch-plate in the basement
of the Post Office, with the nearest film-recording MO2 accelerographs 25 kilometres from Wanganui in the four-instrument array at Atene on the Wanganui River. There were, however, two six-component Solid State Equipment (SSE)
Ltd digital accelerographs located in an office building in Wanganui. No earthquakes had been recorded on a SEE accelerograph previously. It was therefore decided to install a MO2 in Wanganui and another at some suitable site to be determined after discussion with the Seismological Observatory team monitoring the swarm.
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An accelerogram recorded at the Turangi telephone exchange during the earthquake centred just southwest of Lake Taupo on
5 March 1984, at 1407 NZST has been digitised and processed by computer to produce corrected records of ground vibration.
The earthquake that generated the accelerogram had a Richter local magnitude of 5.6, and a hypocentral location 12 kilometres (±4 kilometres) NNW of Turangi at a depth of 12 kilometres (see Figure 1). Minor damage was reported in the township of Turangi, with the intensity level being estimated at MM VI. Significant damage was reported for sensitive equipment at the Tokaanu power station some 3.5 kilometres closer to the epicentre (Figures 6 and 7); a report of this damage will be published elsewhere by Electricity Division. It is hoped that an examination of the Turangi accelerogram may lead to some insights into the seismic excitation characteristics at Tokaanu.
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A study group of the New Zealand National Society for Earthquake Engineering has recently completed recommendations for the seismic design of storage tanks in a form suitable for use as a code.
A knowledge of site response is an integral part of seismic analysis, unfortunately providing guidelines on assigning relevant soil parameters (shear modulus and damping in particular) cannot easily be resolved in a code format. However, as shear modulus (Gs) is referred to directly in the recommendations, it was decided to provide this technical note to enable some guidelines for its assessment to be given. It is an involved problem which requires a great deal of judgment on the designer's behalf if a realistic value of Gs is to be attained.
Most available data on Gs has been developed for either sands or saturated clays although there has been a limited amount of work done on gravelly soils. Because most soils have curvilinear stress-strain relationships, it will be appreciated that the shear modulus is not constant but is usually expressed as the secant modulus determined for a specific value of shear strain.
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There is reason to be cautious about predicting intense shaking zones for large shallow New Zealand earthquakes.
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In April 2011, 27 processed seismic acceleration records at 27 seismic stations whose epicental distances were less than 50 km in Feb. 22 Christchurch, New Zealand earthquake (Mw6.3), were collected from GeoNet strong motion data centre. Applying Sun-Yuan liquefaction detection method on the selected records, 9 liquefied sites and 18 non-liquefied sites were blindly identified thereof in May 2011, prior to the real liquefaction reports (papers) been published. Up to present, liquefaction detection results of 11 sites, i.e., 8 liquefied sites CBGS, CCCC, CHHC, CMHS, HPSC, PRPC, REHS and SHLC and 3 non-liquefied sites PPHS, HVSC and LPCC, were confirmed by publications which were consistent with the detections. New approaches and proof (or evidence) need to be pursued to demonstrate the detected results on other sites, i.e., liquefied site LINC and 15 non-liquefied sites.
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This paper provides a comparison of four different seismic performance metrics which relate to the determination of design seismic demands from seismic response history analyses. The considered metrics include those implemented in New Zealand and international codes of practice, as well as emerging metrics which are well established in related research and state-of-the-art practice, but have yet to find their way into conventional guidelines. The metrics are directly compared and contrasted based on a central example. It is illustrated that the use of the “maximum demand” metric in the NZ loadings standard, and the “mean demand” in international codes of practice are notably conservative and unconservative, respectively. Either of the two emerging metrics provide a significant improvement, and given that they require the same information from an analyst’s perspective, are recommended as replacements.
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The Tauroa residential subdivision is situated in the hills of southern Havelock North in Hawke’s Bay, New Zealand. The development proposal includes removal of a moderately deep (<10 m) landslide and its replacement with an engineered fill slope. A simplified “screening analysis” method was utilised to develop reduced equivalent horizontal seismic loads for use in a pseudo-static slope stability assessment of the proposed remedial engineered fill slope. This risk-based method allows limited slope deformations to occur as a result of the design seismic event, with the magnitudes of the allowable slope deformations set in accordance with the tolerance level of the proposed development.
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An extensive experimental testing programme named JETBIS project (Joint Experimental Testing of Base Isolation Systems) was developed within the RELUIS II project (Task 2.3.2) and RELUIS III project (Line 6) involving partners from different Italian universities. This paper describes the seismic tests performed by the research unit of University of Basilicata (UNIBAS) on an isolation system based on Double Concave Friction Pendulum (DCFP) bearings. The DCFP bearing contains two separate concave sliding surfaces and exhibits different hysteretic properties at different stages of displacement response. The main objective of this work is to evaluate the horizontal response of the DCFP isolators by means of controlled-displacement tests and shaking table tests. The experimental model was a 1/3 scaled steel framed structure with one storey and one bay in both directions. Four DCFP bearings with equal properties of the sliding surfaces were considered. In this work, three different sliding surface conditions (with and without lubrication) have been studied. The isolated base model was subjected to 8 natural earthquakes of increasing seismic intensities and considering two mass configurations (with both symmetrical and eccentric masses). The reliability of the design procedure considered for the isolation system was verified also when relevant residual displacements occurred due to previous earthquakes. In this paper, the comparisons between the experimental outcomes and the numerical results of nonlinear time-history analyses using SAP2000 are shown.
