Damage to concrete buildings with precast floors during the 2016 Kaikoura earthquake

  • Richard S. Henry University of Auckland, Auckland, New Zealand
  • Dmytro Dizhur University of Auckland, Auckland, New Zealand
  • Kenneth J. Elwood University of Auckland, Auckland, New Zealand
  • John Hare Holmes Group Ltd, Christchurch, New Zealand
  • Dave Brunsdon Kestrel Group Ltd, Wellington, New Zealand

Abstract

The 2016 Kaikoura earthquake resulted in shaking in excess of design level demands for buildings with periods of 1-2s at some locations in Wellington. This period range correlated to concrete moment frame buildings of 5-15 storeys, many of which had been built in Wellington since the early 1980s, and often with precast concrete floor units. The critical damage states used to assess buildings during the Wellington City Council Targeted Assessment Programme are described and examples of observed damage correlating to these damage states are presented. Varying degrees of beam hinging were observed, most of which are not expected to reduce the frame capacity significantly. Buildings exhibiting varying degrees of residual beam elongation were observed. Cases of significant beam elongation and associated support beam rotation resulted in damage to precast floor unit supports; in one case leading to loss of support for double-tee units. The deformation demands also resulted in damage to floor diaphragms, especially those with hollowcore floor units. Cracking in floor diaphragms was commonly concentrated in the corners of the building, but hollowcore damage was observed both at the corners and in other locations throughout several buildings. Transverse cracking of hollowcore floor units was identified as a particular concern. In some cases, transverse cracks occurred close to the support, as is consistent with previous research on hollowcore floor unit failure modes. However, transverse cracks were also observed further away from the support, which is more difficult to assess in terms of severity and residual capacity. Following the identification of typical damage, attention has shifted to assessment, repair, and retrofit strategies. Additional research may be required to determine the reduced capacity of cracked hollowcore floor units and verify commonly adopted repair and retrofit strategies.

References

Bradley B, Wotherspoon L and Kaiser A (2017). “Ground motion and site effect observations in the Wellington region from the 2016 Mw7.8 Kaikoura, New Zealand earthquake”. Bulletin of the New Zealand Society for Earthquake Engineering, 50(2): 94-105.

Brunsdon D, Hare J and Elwood K (2017). “Engineering assessment processes for Wellington buildings following the November 2016 Kaikoura earthquakes”. Bulletin of the New Zealand Society for Earthquake Engineering, 50(2): 338-342.

PCFOG Committee (2009). "Seismic Performance of Hollow-Core Floor Systems". Preliminary Draft, Department of Building and Housing, Wellington, NZ. http://www.nzsee.org.nz/db/PUBS/HollowCoreFloorSystems.pdf.

NZSEE, SESOC (2016). “Wellington City Council Targeted Building Assessment Programme: Engineering Guidelines for Targeted Damage Evaluation following the November 2016 Kaikoura Earthquakes”. New Zealand Society for Earthquake Engineering (NZSEE), and Structural Engineering Society (SESOC), Wellington, NZ. http://www.sesoc.org.nz/public_resources/Wellington-Targeted-Damage-Evaluation-Guidelines.pdf?285

Kestrel Group (2017). “Wellington City Council Targeted Assessment Programme Following the Kaikoura Earthquake of 14 November 2016”. Technical Report, Kestrel Group, Wellington, New Zealand, 58 pp.

Marder KJ, Elwood KJ and Clifton GC (2017). “Post-earthquake residual capacity of damaged reinforced concrete buildings”. 16th World Conference on Earthquake Engineering, Santiago, Chile.

Fenwick R, Bull D and Gardiner D (2010). "Assessment of Hollow-core Floors for Seismic Performance". Report 2010-02, Department of Civil and Natural Resources Engineering, University of Canterbury, Christchurch, NZ. http://www.ir.canterbury.ac.nz/bitstream/handle/10092/4211/12626196_CNRE%20Assessment%20of%20Hollow-core%20Floors%20for%20Seismic%20Performance.pdf?sequence=1

Matthews J (2004). "Hollow-core Floor Slab Performance following a Severe Earthquake". PhD thesis, Department of Civil and Natural Resources Engineering, University of Canterbury, Christchurch, NZ.

Corney SR, Henry RS and Ingham JM (2014). “Performance of precast concrete floor systems during the 2010/2011 Canterbury earthquake series”. Magazine of Concrete Research, 66(11): 563-575.

MBIE (2017). “Investigation into the Performance of Statistics House in the 14 November 2016 Kaikōura Earthquake”. Report prepared by the Ministry of Business, Innovation and Employment (MBIE), Wellington, NZ.

Hare J, Fenwick R, Bull D and Built R (2009). “Precast double tee support systems”. SESOC Journal, 22(1): 10-44.

SNZ (2006). "NZS3101: Concrete Structures Standard". Standards New Zealand, Wellington, NZ.

SNZ (1995). "NZS3101: Concrete Structures Standard (Amendment No. 3)", Standards New Zealand, Wellington, NZ.

Jensen J (2006). “Experimental Investigation of Existing Hollow-core Seating Connections Pre and Post Retrofit”. ME Thesis, Department of Civil and Natural Resource Engineering, University of Canterbury, Christchurch, NZ.

Woods L (2008). “Significance of Negative Bending Moments in the Seismic Performance of Hollow-core Flooring”. ME Thesis, Department of Civil and Natural Resources Engineering, University of Canterbury, Christchurch, NZ.

Published
2017-06-30
How to Cite
Henry, R. S., Dizhur, D., Elwood, K. J., Hare, J., & Brunsdon, D. (2017). Damage to concrete buildings with precast floors during the 2016 Kaikoura earthquake. Bulletin of the New Zealand Society for Earthquake Engineering, 50(2), 174-186. https://doi.org/10.5459/bnzsee.50.2.174-186
Section
Articles

Most read articles by the same author(s)

1 2 3 > >>