Earthquake Recorders For New City Building

Press, Volume CI, Issue 29871, 11 July 1962, Page 21

Earthquake Recorders For New City Building

A major building to be put up wui.ton the next two to tnree years in Christchurch will have special instrumesits to observe the effects of earthquakes, Mr R. I. Skinner. head of the engineering seismology section, Dominion Physical Laboratory, Department of Scientific and Industrial Research, Gracefield, said yesterday. Two new buildings in Wellington and one in Auckland would also be equipped. This was in addition to the 10-siorcy block of fla.s equipped in Wellington. Six accelerometers would be set in each building—two in the base, two in the top. and two at intermediate levels, said Mr Skinner. These together with another an the ground at a distance from the building sufficient for the building itself to have no influence, would be linked to a single recorder. The accelerometer would show the extent of the forces to which building members had been subjected during an earthquake. The buildings in Wellington would also have strainsensing elements to measure the strain in various members, Mr Skinner said. This would probably not be convenient in Christchurch or Auckland, however, as the

elements had to be built into the concrete as it was being poured, which required the presence of officers of the section at critical times during cons .ruction.

The exact position of the equipped buildings would be checked very carefully, so that any displacement auring an earthquake could be observed and measured. The result of lite instrumentation should be a more realistic earthquake building code, giving more value for money spent on trying to obtain an earthquake-resistant design, Mr Skinner added. This information would only be available, however, after a moderate or severe earthquake had occurred in an area where there was a fully-instrumented building. The building-code revision now under way would, of course, proceed, as the occurrence of an earthquake was unpredictable. . The engineering seismology section was interested in finding the size and frequency of shocks in different areas, and the effect of various types of subsoil on which buildings were erected, as well as the behaviour of the buildings themselves. Tne work was complementary to that of tlie Seismological Observatory, the observatory differing from the section in being interested in earthquakes as such, rather than in their effect on buildings.