Earthquakes Engineering Essays

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EARTHQUAKE ENGINEERING IN AUSTRALIA BEFORE MECKERING AND AFTER NEWCASTLE by Charles Bubb BE, DIC (Eng. Seis.), FIEAust, CPEng

SUMMARY Earthquake Engineering in Australia, as elsewhere, has been formulated in

the aftermath of damaging earthquakes. The first Australian Code AS2121-1979 was written and published after the 1968 Meckering WA earthquake. The second AS1170.4 1993 was published after the 1989 Newcastle NSW earthquake. Good quality Building Codes are a necessary basis for sound earthquake resistant designs. Both implementation and enforcement of the codes and sound robust construction in the field are essential for the protection of life and infrastructure. Also essential is the preservation and upgrading of the earthquake database. A study to assist the safer operation of emergency services immediately following damaging earthquakes is proposed.

1.

INTRODUCTION

A learned doctor once said " For each man is ill in his own way". So it is with earthquakes. Each new earthquake shakes the ground in its own way, and each type of ground responds differently and every structure reacts differently. I also believe that each society formulates its own reaction to earthquakes and the threat of earthquakes. Here in Australia we have responded in our own way and I want to discuss the various formative events which happened to us in the past and then where we are now and what is yet to come. But when we talk about the past let us always remember this wise counsel:“The past is another country; they do things differently there.” L P Hartley

My own education as an engineer began here in the West. Natural disasters to us in the middle of this century meant flood, fire, drought and above all Cyclones. We all knew about those, and as structural engineers especially cyclones, but I do not recall anyone then mentioning earthquakes in the engineering or design context for Australia. This is perhaps a little surprising because in the late 19th and early part of this century earthquakes were of great interest to the general public. There were often lengthy reports in the local papers of quite small events. This is in marked contrast to the New Zealand situation where in the 1850's it is claimed that local newspapers downplayed the effects of earthquakes, implying that the damage was due to poor building materials and techniques. Grapes and Downes in analysing the great 1855 event (magnitude 8+) (1) wrote:“The reasons were closely linked with important political issues, namely the concern about the effects of the earthquake on immigration, especially to Wellington..." However even in Australia emphasis is often placed on the very poor quality of construction. Let me offer one event picked at random just because it was mentioned in the Canberra Times while I was writing this, that of Dalton-Gunning 1949. I checked out the BMR Isoseismal Atlas and found this "...the walls were built of irregular granite and sandstone blocks the interstices between which had been filled with mortar, wood and even paper." (2) So we had the early (Mechanics Institute) years of general public interest. Then after many years and two World Wars we had the early warning of Adelaide 1954, which largely went unheeded. Then the wake-up call of Meckering 1968 which was heeded only by certain groups. Why was that? 2. PAST VIEWS AND ATTITUDES

The reasons different groups varied so widely in their reactions to these events were because of their widely varying views, attitudes and basic assumptions.

Put very simply they ranged from views that:1) earthquakes posed no threat to any major community in Australia and there was no need for any special precautions in construction. 2) earthquakes posed a limited and graduated threat which could be dealt with by zoning. 3) earthquakes were a threat to all communities in Australia and special precautions were necessary throughout Australia. The first view has been slowly eroded by events such as Meckering and...
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