Unreinforced masonry (URM) cavity-wall construction is a form of masonry where two leaves of clay brick masonry are separated by a continuous air cavity and are interconnected using some form of tie system. A brief historical introduction is followed by details of a survey undertaken to determine the prevalence of URM cavity-wall buildings in New Zealand. Following the 2010/2011 Canterbury earthquakes it was observed that URM cavity-walls generally suffered irreparable damage due to a lack of effective wall restraint and deficient cavity-tie connections, combined with weak mortar strength. It was found that the original cavity-ties were typically corroded due to moisture ingress, resulting in decreased lateral loadbearing capacity of the cavity-walls. Using photographic data pertaining to Christchurch URM buildings that were obtained during post-earthquake reconnaissance, 252 cavity-walls were identified and utilised to study typical construction details and seismic performance. The majority (72%, 182) of the observed damage to URM cavity-wall construction was a result of out-of-plane type wall failures. Three types of out-of-plane wall failure were recognised: (1) overturning response, (2) one-way bending, and (3) two-way bending. In-plane damage was less widely observed (28%) and commonly included diagonal shear cracking through mortar bed joints or bricks. The collected data was used to develop an overview of the most commonly-encountered construction details and to identify typical deficiencies in earthquake response that can be addressed via the selection and implementation of appropriate mitigation interventions. http://www.journals.elsevier.com/structures
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September earthquake, but the Cotterill family are picking up the pieces and rebuilding. Master bedroom where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
A black and white photograph of a pile of rubble in front of a window. In the background behind the window a gap in the building can be seen. The photographer comments, "The result of the Christchurch earthquakes".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cotterill family are picking up the pieces and rebuilding. Builders repair the master bedroom where a large brick chimney came through the room narrowly missing the Cotterills and totally obliterating their bed".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cottrell family are picking up the pieces and rebuilding. Master bedroom where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cotterill family are picking up the pieces and rebuilding. Builders repair the master bedroom where a large brick chimney came through the room narrowly missing the Cotterills and totally obliterating their bed".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cottrell family are picking up the pieces and rebuilding. Master bedroom where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cottrell family are picking up the pieces and rebuilding. Master bedroom where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cottrell family are picking up the pieces and rebuilding. Master bedroom where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cottrell family are picking up the pieces and rebuilding. Master bedroom where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cottrell family are picking up the pieces and rebuilding. Master bedroom where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
St Marys Church
St Marys Church
Damage to TJ's Kazbah in New Brighton. The tower and east end of the building have collapsed onto two parked cars. The photographer comments, "The occupants of the business and rooms all managed to escape alive. A digger was used to make the building safe and then used to sift through the rubble for any surviving belongings. It was a very emotional time for the ex-occupants. The damaged cars were removed before the digger demolished the building".
Damage to TJ's Kazbah in New Brighton. The east and north walls and part of the upper floor have collapsed, tipping rubble and the contents of the rooms out onto the street. The photographer comments, "The occupants of the business and rooms all managed to escape alive. A digger was used to make the building safe and then used to sift through the rubble for any surviving belongings. It was a very emotional time for the ex-occupants".
Photograph captioned by Fairfax, "Gunyah homestead was badly damaged during the September 4th 2010 earthquake, but the Cottrell family are picking up the pieces and rebuilding. What remains of the master bedroom bed where a large brick chimney fell through the roof crushing the bed where William and Simonetta Cottrell had been sleeping moments before".
one of Christchurch's abandoned suburbs. The land moved - bricks and block walls everywhere collapsed - two multi story buildings folded - 184 people died. Wooden framed houses largely stayed up, many concrete slabs cracked, power poles leaned in liquid ground, surface bubbled, services ruptured .... damage to the cbd still gets the most cover...
Photograph captioned by Fairfax, "Christchurch Earthquake. A massive 7.4 magnitude earthquake has hit Christchurch and the wider South Island, causing widespread damage, two serious injuries and power cuts to most of the city. Marsha Witehira had the bricks from the wall of her house fall onto her bed where she was sleeping. Both sides of her house have collapsed".
Photograph captioned by Fairfax, "Christchurch Earthquake. A massive 7.4 magnitude earthquake has hit Christchurch and the wider South Island, causing widespread damage, two serious injuries and power cuts to most of the city. Marsha Witehira had the bricks from the wall of her house fall onto her bed where she was sleeping. Both sides of her house have collapsed".
Photograph captioned by Fairfax, "Christchurch Earthquake. A massive 7.4 magnitude earthquake has hit Christchurch and the wider South Island, causing widespread damage, two serious injuries and power cuts to most of the city. Marsha Witehira had the bricks from the wall of her house fall onto her bed where she was sleeping. Both sides of her house have collapsed. Witehira (L) is comforted by a friend".
A photograph of TJ's Kasbah in North New Brighton, taken before the February 2011 earthquake. The photographer comments, "Here is what 1 Bowhill Road looked like before the Christchurch earthquake. It was called the Ozone store, which originally was incorporated in the blue Ozone building on the other side of the road".
Photograph captioned by Fairfax, "Christchurch Earthquake. A massive 7.4 magnitude earthquake has hit Christchurch and the wider South Island, causing widespread damage, two serious injuries and power cuts to most of the city. Marsha Witehira had the bricks from the wall of her house fall onto her bed where she was sleeping. Both sides of her house have collapsed. Witehira (R) is comforted by a friend".
A digitally manipulated photograph of the Ozone Hotel's sign, leaning against a cordon fence. The photographer comments, "This sign was all that remained after the demolition of the historical Ozone Hotel, which was damaged in the Christchurch earthquakes. The sign disappeared so hopefully it will reappear at a later date in a museum. The bits of blue were the painted bricks of the hotel, which made it really stand out".
Two images of a house, taken before and after the earthquakes. In the after photograph the chimneys are gone, a column supporting the car port has partly collapsed, windows are broken, and the previously neat lawn and driveway are overgrown. The photographer comments, "This was a house that I was selling up to the September 2010 earthquake in Christchurch. It was on Avonside Drive, which was an area that has been badly hit in every earthquake that has hit the area. In the September quake parts of the house moved in different directions and one of the upstairs doors had to be smashed open to release one of the sons from his bedroom. This occurred in the dark with numerous aftershocks shaking the house. Liquefaction poured up through the floor and flowed down the drive. Everyone got out OK, but soon after the house was red stickered meaning it was dangerous to enter. The house was looted many times even though there was constant police patrols. When the most violent earthquake occurred on 22 February 2012 both the tall heavy chimneys came crashing through into the living areas. Subsequent earthquakes and aftershocks have caused one of the brick fence pillars to fall and the front garage pillar to break up and twist. The family's troubles did not end there. They moved into the home of one of their parents and this mansion of a home was so badly affected by the February earthquake that no one could enter to collect any of their or their parents' belongings. They now own a new home, which they are fond of except when the ground shakes yet again. There has been to date 10,712 earthquakes and aftershocks since 4 September 2010".
A badly damaged house in Burwood. Parts of the house have moved in different directions, leaving walls and doors misaligned. The photographer comments, "Although this looks like an extreme wide angle shot it is actually a house tilted in every direction at the same time. The earthquake caused the ground to vibrate and compress so much that the sandy soil liquefied and caused the ground to collapse under this modern home".
The clock tower of the former Railway Station, encased in plywood to prevent further damage. A banner sponsored by The Press hangs below the clock, covered with words which symbolise the September earthquake. The photographer comments, "After the September earthquake the clocked stopped at 04:35 and everyone campaigned to have this clock left as it was. At that time the building was believed to be OK. Two more earthquakes later and the possible memorial will probably end up like a lot of Christchurch's heritage buildings on a huge pile of stone and bricks in Bottle Lake Forest".
The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the initial reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand, earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof or floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e., anchorages having plates on the exterior facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragm. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation, and the use of metal mesh sleeves. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5° to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a summary of the performed experimental program and test results, and a proposed pull-out capacity relationship for adhesive anchors installed into multi-leaf clay brick masonry are presented herein. AM - Accepted Manuscript
Following the 2010/2011 Canterbury earthquakes a detailed campaign of door to door assessments was conducted in a variety of areas of Christchurch to establish the earthquake performance of residential dwellings having masonry veneer as an external cladding attached to a lightweight timber framing system. Specifically, care was taken to include regions of Christchurch which experienced different levels of earthquake shaking in order to allow comparison between the performance of different systems and different shaking intensities. At the time of the inspections the buildings in the Christchurch region had been repeatedly subjected to large earthquakes, presenting an opportunity for insight into the seismic performance of masonry veneer cladding. In total just under 1100 residential dwellings were inspected throughout the wider Christchurch area, of which 24% were constructed using the older nail-on veneer tie system (prior to 1996) and 76% were constructed using screw fixed ties to comply with the new 1996 standards revision (post-1996), with 30% of all inspected houses being of two storey construction. Of the inspected dwellings 27% had some evidence of liquefaction, ground settlement or lateral spreading. Data such as damage level, damage type, crack widths, level of repair required and other parameters were collected during the survey. A description of the data collection processes and a snapshot of the analysis results are presented within. http://15ibmac.com/home/
Churches are an important part of New Zealand's historical and architectural heritage. Various earthquakes around the world have highlighted the significant seismic vulnerability of religious buildings, with the extensive damage that occurred to stone and clay-brick unreinforced masonry churches after the 2010-2011 Canterbury earthquakes emphasising the necessity to better understand this structural type. Consequently, a country-wide inventory of unreinforced masonry churches is here identified. After a bibliographic and archival investigation, and a 10 000 km field trip, it is estimated that currently 297 unreinforced masonry churches are present throughout New Zealand, excluding 12 churches demolished in Christchurch because of heavy damage sustained during the Canterbury earthquake sequence. The compiled database includes general information about the buildings, their architectural features and structural characteristics, and any architectural and structural transformations that have occurred in the past. Statistics about the occurrence of each feature are provided and preliminary interpretations of their role on seismic vulnerability are discussed. The list of identified churches is reported in annexes, supporting their identification and providing their address.
As part of the 'Project Masonry' Recovery Project funded by the New Zealand Natural Hazards Research Platform, commencing in March 2011, an international team of researchers was deployed to document and interpret the observed earthquake damage to masonry buildings and to churches as a result of the 22nd February 2011 Christchurch earthquake. The study focused on investigating commonly encountered failure patterns and collapse mechanisms. A brief summary of activities undertaken is presented, detailing the observations that were made on the performance of and the deficiencies that contributed to the damage to approximately 650 inspected unreinforced clay brick masonry (URM) buildings, to 90 unreinforced stone masonry buildings, to 342 reinforced concrete masonry (RCM) buildings, to 112 churches in the Canterbury region, and to just under 1100 residential dwellings having external masonry veneer cladding. In addition, details are provided of retrofit techniques that were implemented within relevant Christchurch URM buildings prior to the 22nd February earthquake and brief suggestions are provided regarding appropriate seismic retrofit and remediation techniques for stone masonry buildings. http://www.nzsee.org.nz/publications/nzsee-quarterly-bulletin/