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The high peak accelerations recorded at Karakyr Point during the Ms = 7.2 May 17, 1976 Gazli, U.S.S.R. earthquake have caused considerable interest amongst earthquake engineers particularly in this country where aseismic design of structures is currently based on the N-S component of the Mg = 7.1 May 18, 1940 El Centro, California accelerogram with much lower peak accelerations. Information about the Gazli earthquake is quite scanty. However, because of the interest it has generated it is felt that in spite of the limited information available a preliminary discussion of the record would be useful.
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As an aftermath to the 1971 San Fernando earthquake in southern California two existing levelling routes were relevelled in order to assess the amount of earth shift that triggered this earthquake. Comparison of
the new and old data revealed two important points:
(a) the 1971 earthshift resulted in a maximum uplift of 2 m on the upthrown (Transverse Ranges) side and a maximum subsidence of 110 mm on the downthrown (Los Angeles basin complex) side.
(b) prior to the 1971 earthshift the area was deforming for at least 10 years, reaching over the period 1968-69 the maximum of about 80 mm uplift in the future epicentral area.
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The writer attended the second Microzonation Conference at San Francisco in December, 1978. The Conference lasted five days and papers were
delivered on a wide variety of subjects. Discussion here is limited to topics where new developments appear to the writer to be of general interest, These notes therefore hardly constitute a review of the conference, but they may assist earthquake engineers not directly involved in engineering seismology or in microzoning studies to keep aware of current developments.
Papers are referred to by page number and a list of proceedings is appended. The proceedings (in three Volumes) will shortly be available from the Ministry of Works and Development and University libraries. Copies can also be obtained from the Conference Organiser: Professor Mehmet A. Sherif at the University of Washington, Seattle.
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This is a summary report of recent testing of a haunched reinforced concrete beam at the Ministry of Works and Development Central Laboratories. The testing will shortly be reported in greater depth in Ministry of Works and Development Central Laboratories Report No. 5-79/2.
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The writer attended a short course entitled "Advances in Earthquake Engineering" from 16 to 20 June 1980 at the University of Californis, Berkeley. The course was organised by "Continuing Education in Engineering, University Extension, and the College of Engineering" UC Berkeley. The course is run every few years, and as the title implies is an attempt to bring together in the form of
a series of lectures all recent developments in the fields of engineering seismology, seismic resistant design of civil and building structures, and seismic analysis. Approximately 250 attended this course, the majority being from the USA and in particular California, but with several participants from Canada, Central and South America, a few from Japan, Europe, Australia and two from New Zealand.
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A testing program has been carried out by MWD with the aim of comparing imported hot-rolled and New Zealand-made cold-rolled RHS with welded connections at location of maximum bending. A full description of the experiments is found in Ministry of Works and Development Central Laboratories Report No. 5-80/3. This is available from the Ministry of Works and Development Head Office Library.
The size of section compared was 102 x 51 x 4.9 mm corresponding to the largest size manufactured by New Zealand Steel Limited. Lengths of RHS of respective types were fabricated into 1.83 m long simply supported beams with a fillet-welded dividing plate through the midspan location. Two such beams of the cold-rolled and hot-rolled RHS were loaded monotonically through application of load at the dividing plate.
The cold-rolled beams failed at a rather low maximum deflection ductility of 7.3 and in a manner which indicated a lowered yield stress in the vicinity of the weld of the dividing plate. On the other hand, the hot-rolled beams continued to strain harden to the limit of the test rig, equivalent to a deflection ductility of 29.
While hysteretic testing is needed to draw firm conclusions
on the reliability of cold-rolled RHS in energy-absorbing systems, the test series does permit the observation that the material would be inadmissible in a situation where moderate to large member ductility demands were anticipated near welds.
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The Engineering Seismology section of the Physics and Engineering Laboratory, DSIR, has recently published the above volume presenting the results of computer analyses of twenty, three-component, accelerograms recorded by the New Zealand Strong-Motion Network. It contains a brief introduction, three tables summarising the accelerogram characteristics, site information and earthquake information, and the results of the computer analyses. The results presented for each accelerogram begin with a heading page, followed by computer plots of acceleration, velocity and displacement histories, acceleration response spectra and Fourier amplitude spectra. The spectral values are also tabulated.
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To study fatigue of defective welds, beam-column joints were cyclically loaded at MWD Central Laboratories. However, local buckling occurred in the beam
flanges during the first few cycles at displacement ductilities 2.25-2.6. Despite the buckling, the peak resisted load had a maximum of 15% reduction after 10 cycles at these ductilities, and the hysteresis loops showed little change
in shape. Nevertheless, because steel frame structures can be expected to sustain a ductility demand of about 4/SM or 6, there is clearly some doubt as to whether the strength of a system already buckling at a DF < 3 would be maintained under
the design earthquake. The 310 UB 40 beam tested complied with the current NZ Steel Code, which required no stiffeners in this case.
