Predicting building collapse due to seismic motion is critical in design and more so after a major event. Damaged structures can appear sound, but collapse under following major events. There can thus be significant risk in decision making after a major seismic event concerning the safe occupation of a building or surrounding areas, versus the unknown impact of unknown major aftershocks. Model-based pushover analyses are effective if the structural properties are well understood, which is not valid post-event when this risk information is most useful. This research combines Hysteresis Loop Analysis (HLA) structural health monitoring (SHM) and Incremental Dynamic Analysis (IDA) methods to determine collapse capacity and probability of collapse for a specific structure, at any time, a range of earthquake excitations to ensure robustness. The nonlinear dynamic analysis method presented enables constant updating of building performance predictions using post-event SHM results. The resulting combined methods provide near real-time updating of collapse fragility curves as events progress, quantifying the change of collapse probability or seismic induced losses for decision-making - a novel, higher resolution risk analysis than previously available. The methods are not computationally expensive and there is no requirement for a validated numerical model. Results show significant potential benefits and a clear evolution of risk. They also show clear need for extending SHM toward creating improved predictive models for analysis of subsequent events, where the Christchurch series of 2010-2011 had significant post-event aftershocks after each main event. Finally, the overall method is generalisable to any typical engineering demand parameter.
The performance of buildings in recent New Zealand earthquakes (Canterbury, Seddon and Kaikōura), delivered stark lessons on seismic resilience. Most of our buildings, with a few notable exceptions, performed as our Codes intended them to, that is, to safeguard people from injury. Many buildings only suffered minor structural damage but were unable to be reused and occupied for significant periods of time due to the damage and failure of non-structural elements. This resulted in substantial economic losses and major disruptions to our businesses and communities. Research has attributed the damage to poor overall design coordination, inadequate or lack of seismic restraints for non structural elements and insufficient clearances between building components to cater for the interaction of non structural elements under seismic actions. Investigations have found a clear connection between the poor performance of non-structural elements and the issues causing pain in the industry (procurement methods, risk aversion, the lack of clear understanding of design and inspection responsibility and the need for better alignment of the design codes to enable a consistent integrated design approach). The challenge to improve the seismic performance of non structural elements in New Zealand is a complex one that cuts across a diverse construction industry. Adopting the key steps as recommended in this paper is expected to have significant co-benefits to the New Zealand construction industry, with improvements in productivity alongside reductions in costs and waste, as the rework which plagues the industry decreases.
Ground motion observations from the most significant 10 events in the 2010-2011 Canterbury earthquake sequence at near-source sites are utilized to scrutinize New Zealand (NZ)-specific pseudo-spectral acceleration (SA) empirical ground motion prediction equations (GMPE) (Bradley 2010, Bradley 2013, McVerry et al. 2006). Region-specific modification factors based on relaxing the conventional ergodic assumption in GMPE development were developed for the Bradley (2010) model. Because of the observed biases with magnitude and source-to-site distance for the McVerry et al. (2006) model it is not possible to develop region-specific modification factors in a reliable manner. The theory of non-ergodic empirical ground motion prediction is then outlined, and applied to this 10 event dataset to determine systematic effects in the between- and within-event residuals which lead to modifications in the predicted median and standard deviation of the GMPE. By examining these systematic effects over sub-regions containing a total of 20 strong motion stations within the Canterbury area, modification factors for use in region-specific ground motion prediction are proposed. These modification factors, in particular, are suggested for use with the Bradley et al. (2010) model in Canterbury-specific probabilistic seismic hazard analysis (PSHA) to develop revised design response, particularly for long vibration periods.
Photo taken Jan 2011 - the cracks in the front of the building get a little bigger with each aftershock.
former site of sweet shop, Christchurch City Mission charity shop and Soul Food Cafe
Still standing in Jan 2011 - but the buildings future is unknown - It is probably destined to be demolished.
Revealed after the SoulFood Cafe building was demolished - Haircutting for 6d and a shave for thruppence? how old is this?
The Greek Souvlaki place was closed for several months while the building next door got demolished.
Same view as a previous shot - taken in January 2011 after the block of buildings was demolished.
The window that was hanging precariously finally fell when the Boxing Day 4.9 shock hit at 10.30am
Another hole has appeared in the street where a building has been demolished. Selwyn Dealers next door sensibly moved all their stock away from the adjoining wall just in case.
Christchurch woman Pam Sharpe has endured earthquakes, fires and dealing with insurance companies, but then she received a parking ticket. She tells Checkpoint what happened next.
A memorial for the 185 people who died in the 2011 Christchurch earthquake will be blessed tonight, ahead of the unveiling tomorrow, on the sixth anniversary.
More information on the earthquake zones in Canterbury has been revealed, and some people will soon be told they won't have to abandon their properties.
A layout for the "Press Box" feature, featuring an item on the cancellation of Rugby World Cup games in Christchurch following the 22 February 2011 earthquake.
A page banner promoting articles about the Transitional Cathedral and about a review of the New Zealand Fire Service's response to the 22 February 2011 earthquake.
A photograph of an earthquake-damaged building, previously the site of Portobello Antiques on Tuam Street. The second storey wall has collapsed leaving the inside exposed.
Photograph captioned by Fairfax, "Christchurch Earthquake 22 February 2011. People flocking to Liquor King on Stanmore Road where they were selling beer for $1 per bottle."
Photograph captioned by Fairfax, "Band Together concert in Hagley Park for earthquake relief. Jordan Luck (left) and Ray Colombus (middle) lead the artists at the finale".
Christchurch artist Phillip Trusttum and gallery owner Jonathan Smart on how visual artists are accepting what's been lost and looking to the future, post the earthquake.
More now on the the Government's move to sure-up the country's transport, water, sewerage, energy and communication networks in the wake of the Canterbury earthquakes.
The Education Minister is waiting for the Canterbury Earthquake Royal Commission to report back before considering a national survey of all school buildings in the country.
Photograph captioned by Fairfax, "Give Enterprise a Life Line business meeting in the Christchurch Town Hall re: the aftermath of the 4 September earthquake. Mathew Carpenter".
Photograph captioned by Fairfax, "Checkout manager Nicola Murdock from Pak'nSave with trolleys full of food being donated for the victims of the Christchurch Earthquake".
Photograph captioned by Fairfax, "Checkout manager Nicola Murdock from Pak'nSave with trolleys full of food being donated for the victims of the Christchurch Earthquake".
Photograph captioned by Fairfax, "Samson, a cat belonging to Helen Milner and Barry Hayton, who went missing after the Canterbury earthquake and returned five weeks later".
Photograph captioned by Fairfax, "Samson, a cat belonging to Helen Milner and Barry Hayton, who went missing after the Canterbury earthquake and returned five weeks later".
Photograph captioned by Fairfax, "Samson, a cat belonging to Helen Milner and Barry Hayton, who went missing after the Canterbury earthquake and returned five weeks later".
Photograph captioned by Fairfax, "Australian heritage architects Edward Clode and Barney Collis survey the earthquake damage to the Cranmer Courts, which have been converted into apartments".
Photograph captioned by Fairfax, "Checkout manager Nicola Murdock from Pak'nSave with trolleys full of food being donated for the victims of the Christchurch Earthquake".