We’ve delivered the first phase of the C5 evidence project to MBIE. This project has been set up by MBIE with two potential phases of assessments, which will take place over two years.

In the first phase, MBIE asked Engineering New Zealand to commission a sample of seismic assessments of varying building typologies to understand how the Yellow chapter affects findings when compared with the Red Book. 

These were some key findings:

  • Scores for individual elements within all buildings changed when comparing the Red Book and the Yellow Chapter.
  • Different weaknesses were highlighted by these different scores.
  • In three cases, the Yellow Chapter identified different governing susceptibilities from the Red Book. This means that the “weakest link” governing the overall %NBS result was different under the respective guidelines.
  • In three buildings, the governing element score did not change the %NBS result
  • In pre-1976 buildings, the individual score changes were more related to columns.
  • In post-1976 buildings, the individual score changes were more related to floors (such as diaphragm actions or precast unit issues).

MBIE has advised it requires more data to support conclusions, so a second phase will focus specifically on floor systems. Following this phase, we understand that MBIE will consider the policy implications of citing the Yellow Chapter within the EPB regime.

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