Information on damage caused by the Canterbury earthquakes of 2010 and 2011, for homeowners, tenants, insurers, lawyers, realtors, builders, developers, engineers and building consent authorities.
Seismic isolation is an effective technology for significantly reducing damage to buildings and building contents. However, its application to light-frame wood buildings has so far been unable to overcome cost and technical barriers such as susceptibility to movement during high-wind loading. The precursor to research in the field of isolation of residential buildings was the 1994 Northridge Earthquake (6.7 MW) in the United States and the 1995 Kobe Earthquake (6.9 MW) in Japan. While only a small number of lives were lost in residential buildings in these events, the economic impact was significant with over half of earthquake recovery costs given to repair and reconstruction of residential building damage. A value case has been explored to highlight the benefits of seismically isolated residential buildings compared to a standard fixed-base dwellings for the Wellington region. Loss data generated by insurance claim information from the 2011 Christchurch Earthquake has been used by researchers to determine vulnerability functions for the current light-frame wood building stock. By further considering the loss attributed to drift and acceleration sensitive components, and a simplified single degree of freedom (SDOF) building model, a method for determining vulnerability functions for seismic isolated buildings was developed. Vulnerability functions were then applied directly in a loss assessment using the GNS developed software, RiskScape. Vulnerability was shown to dramatically reduce for isolated buildings compared to an equivalent fixed-base building and as a result, the monetary savings in a given earthquake scenario were significant. This work is expected to drive further interest for development of solutions for the seismic isolation of residential dwellings, of which one option is further considered and presented herein.
A graph showing changes in residential building work.
Cracking in the brickwork of a residential building.
A video of an address by Mike Greer, Director of Mike Greer Homes Ltd, at the 2014 Seismics and the City forum. This talk was part of the Building Opportunities section, and focused on the housing needs and the residential building opportunities in the inner city, Greater Christchurch, and the Canterbury region.
Building wreckage behind a residential property on Peterborough Street.
The Canterbury Earthquake Sequence (CES), induced extensive damage in residential buildings and led to over NZ$40 billion in total economic losses. Due to the unique insurance setting in New Zealand, up to 80% of the financial losses were insured. Over the CES, the Earthquake Commission (EQC) received more than 412,000 insurance claims for residential buildings. The 4 September 2010 earthquake is the event for which most of the claims have been lodged with more than 138,000 residential claims for this event only. This research project uses EQC claim database to develop a seismic loss prediction model for residential buildings in Christchurch. It uses machine learning to create a procedure capable of highlighting critical features that affected the most buildings loss. A future study of those features enables the generation of insights that can be used by various stakeholders, for example, to better understand the influence of a structural system on the building loss or to select appropriate risk mitigation measures. Previous to the training of the machine learning model, the claim dataset was supplemented with additional data sourced from private and open access databases giving complementary information related to the building characteristics, seismic demand, liquefaction occurrence and soil conditions. This poster presents results of a machine learning model trained on a merged dataset using residential claims from the 4 September 2010.
A map showing the location of heritage buildings in the residential red zone.
A photograph of a dusty monitor in an earthquake-damaged building on Poplar Street taken during the Residential Access Project. The Residential Access Project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes after the 22 February 2011 earthquake. Dislodged bricks can also be seen around the monitor.
An entry from Deb Robertson's blog for 20 September 2012 entitled, "A few snapshots of the residential red-zone....".
View down the side of a damaged residential property, where parts of the wall and building rubble has fallen.
A significant portion of economic loss from the Canterbury Earthquake sequence in 2010-2011 was attributed to losses to residential buildings. These accounted for approximately $12B of a total $40B economic losses (Horspool, 2016). While a significant amount of research effort has since been aimed at research in the commercial sector, little has been done to reduce the vulnerability of the residential building stock.
A photograph of a room inside a flat on Poplar Street taken during the Residential Access Project. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes. The building's outer wall has crumbled leaving the room exposed.
A photograph of a room inside a flat on Poplar Street taken during the Residential Access Project. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes. The building's outer wall has crumbled leaving the room exposed.
A photograph of a room inside a flat on Poplar Street taken during the Residential Access Project. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes. The building's outer wall has crumbled leaving the room exposed.
A photograph of a room inside a flat on Poplar Street taken during the Residential Access Project. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes. The building's outer wall has crumbled leaving the room exposed.
A photograph of a room inside a flat on Poplar Street taken during the Residential Access Project. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes. The building's outer wall has crumbled leaving the room exposed.
This thesis presents the application of data science techniques, especially machine learning, for the development of seismic damage and loss prediction models for residential buildings. Current post-earthquake building damage evaluation forms are developed for a particular country in mind. The lack of consistency hinders the comparison of building damage between different regions. A new paper form has been developed to address the need for a global universal methodology for post-earthquake building damage assessment. The form was successfully trialled in the street ‘La Morena’ in Mexico City following the 2017 Puebla earthquake. Aside from developing a framework for better input data for performance based earthquake engineering, this project also extended current techniques to derive insights from post-earthquake observations. Machine learning (ML) was applied to seismic damage data of residential buildings in Mexico City following the 2017 Puebla earthquake and in Christchurch following the 2010-2011 Canterbury earthquake sequence (CES). The experience showcased that it is readily possible to develop empirical data only driven models that can successfully identify key damage drivers and hidden underlying correlations without prior engineering knowledge. With adequate maintenance, such models have the potential to be rapidly and easily updated to allow improved damage and loss prediction accuracy and greater ability for models to be generalised. For ML models developed for the key events of the CES, the model trained using data from the 22 February 2011 event generalised the best for loss prediction. This is thought to be because of the large number of instances available for this event and the relatively limited class imbalance between the categories of the target attribute. For the CES, ML highlighted the importance of peak ground acceleration (PGA), building age, building size, liquefaction occurrence, and soil conditions as main factors which affected the losses in residential buildings in Christchurch. ML also highlighted the influence of liquefaction on the buildings losses related to the 22 February 2011 event. Further to the ML model development, the application of post-hoc methodologies was shown to be an effective way to derive insights for ML algorithms that are not intrinsically interpretable. Overall, these provide a basis for the development of ‘greybox’ ML models.
A photograph of workers from the Residential Access Project sitting outside the Alice in Videoland Building on the corner of Tuam and High Streets. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes.
A photograph of Brandon, Elizabeth Ackerman and Danica Nel on the site of a demolished building on Tuam Street. The trio can be seen wearing hard hats and florescent vests. The photograph was taken during the Residential Access Project which gave residents temporary access within the red-zone cordon in order to retrieve items from their homes after the 22 February 2011 earthquake.
A photograph of an Urban Search and Rescue team member examining the contents of a flat on Poplar Street during the Residential Access Project. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes. The buildings wall has crumbled leaving the room exposed.
This study analyses the Earthquake Commission’s (EQC) insurance claims database to investigate the influence of seismic intensity and property damage resulting from the Canterbury Earthquake Sequence (CES) on the repair costs and claim settlement duration for residential buildings. Firstly, the ratio of building repair cost to its replacement cost was expressed as a Building Loss Ratio (BLR), which was further extended to Regional Loss Ratio (RLR) for greater Christchurch by multiplying the average of all building loss ratios with the proportion of building stock that lodged an insurance claim. Secondly, the total time required to settle the claim and the time taken to complete each phase of the claim settlement process were obtained. Based on the database, the regional loss ratio for greater Christchurch for three events producing shakings of intensities 6, 7, and 8 on the modified Mercalli intensity scale were 0.013, 0.066, and 0.171, respectively. Furthermore, small (less than NZD15,000), medium (between NZD15,000 and NZD100,000), and large (more than NZD100,000) claims took 0.35-0.55, 1.95-2.45, and 3.35-3.85 years to settle regardless of the building’s construction period and earthquake intensities. The number of claims was also disaggregated by various building characteristics to evaluate their relative contribution to the damage and repair costs.
A residential property that has been damaged by the earthquakes. Next to it is pile of building rubble and bits of furniture.
A residential property that has been damaged by the earthquakes. Next to it is pile of building rubble and bits of furniture.
The ultimate goal of this study is to develop a model representing the in-plane behaviour of plasterboard ceiling diaphragms, as part of the efforts towards performance-based seismic engineering of low-rise light timber-framed (LTF) residential buildings in New Zealand (NZ). LTF residential buildings in NZ are constructed according to a prescriptive standard – NZS 3604 Timberframed buildings [1]. With regards to seismic resisting systems, LTF buildings constructed to NZS3604 often have irregular bracing arrangements within a floor plane. A damage survey of LTF buildings after the Canterbury earthquake revealed that structural irregularity (irregular bracing arrangement within a plane) significantly exacerbated the earthquake damage to LTF buildings. When a building has irregular bracing arrangements, the building will have not only translational deflections but also a torsional response in earthquakes. How effectively the induced torsion can be resolved depends on the stiffness of the floors/roof diaphragms. Ceiling and floor diaphragms in LTF buildings in NZ have different construction details from the rest of the world and there appears to be no information available on timber diaphragms typical of NZ practice. This paper presents experimental studies undertaken on plasterboard ceiling diaphragms as typical of NZ residential practice. Based on the test results, a mathematical model simulating the in-plane stiffness of plasterboard ceiling diaphragms was developed, and the developed model has a similar format to that of plasterboard bracing wall elements presented in an accompany paper by Liu [2]. With these two models, three-dimensional non-linear push-over studies of LTF buildings can be undertaken to calculate seismic performance of irregular LTF buildings.
A photograph of the site of a demolished building on Tuam Street which is being used as a car park. The photograph was taken during the Residential Access Project which gave residents temporary access within the red-zone cordon in order to retrieve items from their homes after the 22 February 2011 earthquake.
West Auckland residents begin the cleanup after yesterday's tornado. The Canterbury Earthquakes Royal Commission calls for the seismic grading of all non-residential buildings.
A photograph of workers in fluorescent vests standing in front of the earthquake damaged McKenzie and Willis Building. The photograph was taken on 29 April 2011 during the Residential Access Project which gave residents temporary access within the red-zone cordon in order to retrieve items from their homes after the 22 February 2011 earthquake.
A photograph of two workers standing in the site of a demolished building on Tuam Street which is being used as a car park. The photograph was taken during the Residential Access Project which gave residents temporary access within the red-zone cordon in order to retrieve items from their homes after the 22 February 2011 earthquake.
A fence around a residential property where the side wall has collasped, exposing the interior structures and fixtures. Piles of building rubble are contained in the fencing.