Technical Activities :

The Performance of Precast Floor Systems in Major Earthquakes

Significant research recently undertaken at Canterbury and Auckland Universities has involved the testing of sections of modern precast concrete seismic frame construction featuring different floor systems. This work has highlighted the complexities of the interaction between precast floor systems and seismic frames in major earthquakes.

The tests have again shown that very good performance can be expected from the primary beam and column frame elements. However the recently completed University of Canterbury test to destruction of a hollowcore floor system, conducted by Jeff Matthews, has revealed the failure of the floor units at a lower level of seismic loading than implied by current design standards and raised concerns regarding past and present detailing practices.

A Technical Advisory Group (TAG) has subsequently been formed to disseminate the results of the research to industry and provide input into the direction of future testing.

An initial paper prepared by the TAG in September 2002 to assist in interpreting the results of the University of Canterbury research and recommending future research is available from Dene Cook, Chairman of the Technical Advisory Group on Flooring Systems at dene@cca.org.nz.

The TAG has subsequently met on 10 July of this year to discuss the results of four PCNZ funded tests conducted on hollowcore flooring at Canterbury University. The tests focused on floor performance when subjected to rotations relative to the supporting beams. The seating details tested are those recommended in the TAG’s paper of September 2002. The tests demonstrated that the details recommended performed significantly better than the control unit, which has similar seating details to those used in the Jeff Matthews test. The Group is now preparing a paper which interprets these results.

Past Events

Industry Workshop on Seismic Testing of Pre-cast Flooring at University of Canterbury

A workshop to discuss the issues arising from this major test was organised by the New Zealand Society for Earthquake Engineering in conjunction with the New Zealand Concrete Society and SESOC. Held on 12 April 2002 at the University of Canterbury, this workshop attracted 22 participants representing design, research and pre-cast concrete sectors, along with EQC as funding agency.

Summary of Key Observations and Outcomes

The seismic load testing of a typical modern pre-cast floor and primary seismic frame assemblage is in its latter stages at the University of Canterbury. This PhD project by Jeff Matthews, supervised by Des Bull and John Mander, is of particular significance due to its size and configuration - it features two single-bay ductile frames supporting 300 series hollowcore flooring, spanning 11.8 m, with a two-bay ductile frame in the longitudinal direction (refer PDF summary document 24K).

This full-scale specimen of a 1990's building designed for Wellington forms part of a research programme undertaken in conjunction with the University of Auckland, and funded by EQC, concrete industry organisations and FRST programmes.

For further information read the 2 page summary outcome document (24K PDF) or view the annotated presentation slides (948K PDF).