R. G. Tyler’s scientific contributions

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.

The improved M02A version of the M0 (mechanical and optical) type of accelerograph, currently in use in the N.Z. strong-motion recorder network is described. The improvements relate mainly to the mechanical drive, including the film rewind, and to the electronics for the timing features. In particular the elapsed time from a previous visit to the instrument is obtained by interrogating a clock during the running of the film. Production of the M02 instrument has been suspended in favour of the M02A and all the instruments in the N.Z. network will be converted to M02As.

The development of hysteretic dampers for the protection of structures against earthquake attack, carried out at the Physics and Engineering Laboratory over the past six years, is described. Details of both steel and lead devices and their application to bridges and base isolated buildings are given. Steel devices are designed to absorb energy by plastic deformation in torsion or bending, while lead devices rely on plastic extrusion or shear. The characteristics of PTFE sliding bearings are also described and the possibility of using this type of bearing to permit sliding on base isolated systems, and to allow dissipation of energy in joints in conventional structures, referred to. The most promising development is in the lead rubber bearing in which the properties of load-bearing and damping are combined in one unit.