REVIEW OF CURRENT EARTHQUAKE ENGINEERING RESEARCH IN NEW ZEALAND

Research currently being undertaken in Government Departments, Research organisations, and the Civil Engineering Departments in the two University Schools of Engineering is outlined. The reasearch is summarised under the headings of Seismology, Engineering Seismology, Geotechnical Engineering, and Structural Analysis and Design.

These are being used to progressively replace the existing analogue seismographs of the National Network.The Seismological Observatory is developing its own digital recorder to meet the specific needs as no commercially available one meets these needs at an affordable price.Substantial progress has been made, particularly in the area of digital recording of semi-permanent micro-networks (see 2) where only digital seismic traces of earthquakes, identified by their spectral signature, are kept.The detection algorithm is one of the most reliable and least wasteful (fewer false alarms) that has been published.Most of 1. Bulletin Editor, and Department of Civil Engineering, University of Canterbury, Christchurch the software and much of the hardware developed for the micro-network recorders will be adapted to the single National Network stations.
A diversion of effort from the single station to micro-networks was required because of demand for a number of such networks and efficient recording and processing of their data.Within the next few months, new networks will be installed in Hawke's Bay and around the Clyde dam site, and the recording system of the Taupo Network will be upgraded.The Wellington Network, running and producing photographic records since 197 6, changed over to digital recording in 1986 although the analogue recording is to continue for a while until the data processing system is completed.
Although the new networks have been set up principally to perform a monitoring function, it is expected that data from them will lead to the same advances that have resulted from the data from the Wellington Network, which has provided a clear picture of the uppermost 60 km of the earth at Wellington.In addition, attenuative properties of the earth will be mapped for the first time, and other frequency dependent effects of the earthquakes will be reliably measured routinely. 3 Wave Propagation Modelling.A set of Californian accelerograph records are being used to study the influence of the dynamic properties of soils.

MINISTRY OF WORKS AND DEVELOPMENT 1
Bridge Abutments.
In order to obtain a better understanding of the passive earth pressures that develop against bridge abutments built integrally with the superstructure, half size models have been built and tested.The abutments were loaded statically and dynamically by pushing them into sand backfill.The total force and its pressure distribution agreed well with theoretical predictions except at large deformations when the sand was stiffer than predicted.
Further tests are being carried out using dense sands.

2
Pile Foundations.Another aspect of the motivation for the research relates to work that is planned on the lateral load behaviour of piles under earthquake loading.

Research
In this situation the effect of the load cycling on the strength of the clay near the top of the pile is of importance as this affects the maximum displacement and bending moment in a pile during an earthquake.The Seismic Response of Pile Foundations.
This work concerns the calculation of the deformations and bending moments in pile foundations during earthquakes.The results of recent computer studies have lead to methods appearing in the literature for the calculation of pile deformation during strong ground motion.This study will apply these methods to existing foundations and attempt to gauge the the usefulness of the solutions obtained.
The study will also lead to an assessment of the modification of the ground motion by the piles and hence an evaluation of the level of ground motion at the base of the building compared with the free field motion.

STRUCTURAL ANALYSIS AND DESIGN
BUILDING RESEARCH ASSOCIATION OF N.Z.

1
Wall Racking Tests -end restraint conditions.
The standard P21 racking test is used to determine Bracing Ratings for wall units.The test requires the specimen to be cycled in 1mm increments up to 8mm lateral displacement.In order to ensure adequate ductility of the component, the wall is racked to a 4 0mm displacement and cycled +/-4 0mm for four cycles during which the reduction in load is not to exceed 20% of the peak load.

It has been noticeable
from the failure modes of the various wall panels that have been tested to the P21 standard racking test, that a common mode of failure is the separation of the tension chord from the bottom plate.The seismic performance of frame buildings built without the joint shear and confining reinforcement required by current codes is not readily predictable.MWD has embarked on a a series of tests to obtain a better understanding of how these buildings, which form a sizeable proportion of our building stock, will behave in an earthquake.This will permit a rational evaluation of such buildings and an improved assessment of life and property risk.

3
Construction Inovations and Problems.Traditional earth and low-strength masonry construction techniques in various areas are being studied together with their observed seismic behaviour with a view to recommending modifications to improve their seismic performance. 4