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Research papers, The University of Auckland Library

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 façade 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 diaphragms. 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 sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5o 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 snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein.

Research papers, The University of Auckland Library

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 façade 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 sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5o 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 snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein. http://www.confer.co.nz/nzsee/ VoR - Version of Record

Images, UC QuakeStudies

A photograph of the Cranmer Courts on the corner of Kilmore and Montreal Streets. The gable to the left has crumbled, and there is damage to the tip of the gable in the foreground. Wooden bracing has been placed on both walls to limit further damage from aftershocks.

Research papers, The University of Auckland Library

The 2010 Darfield earthquake is the largest earthquake on record to have occurred within 40 km of a major city and not cause any fatalities. In this paper the authors have reflected on their experiences in Christchurch following the earthquake with a view to what worked, what didn’t, and what lessons can be learned from this for the benefit of Australian earthquake preparedness. Owing to the fact that most of the observed building damage occurred in Unreinforced Masonry (URM) construction, this paper focuses in particular on the authors’ experience conducting rapid building damage assessment during the first 72 hours following the earthquake and more detailed examination of the performance of unreinforced masonry buildings with and without seismic retrofit interventions.

Images, UC QuakeStudies

Damage to the church hall of St John the Baptist Church in Latimer Square. The roof has been weather proofed with plywood and there are cracks in the buildings masonry. The remains of fallen bricks can be seen on the footpath. A safety fence has been erected around the building.

Images, UC QuakeStudies

Damage to the church hall of St John the Baptist Church in Latimer Square. The roof has been weather proofed with plywood and there are cracks in the buildings masonry. The remains of fallen bricks can be seen on the footpath. A safety fence has been erected around the building.

Images, UC QuakeStudies

An excavator bunching up scrap metal as part of efforts to clear the site of the demolished Hillary and Marshall Limited building on Manchester Street. A pile of scrapped wooden components can be seen at the back of the site, and a pile of masonry is visible in the foreground.

Images, UC QuakeStudies

A view looking west down Tuam Street across the High Street intersection. Road cones line the street. The photographer comments, "This was taken shortly after the 4th September earthquake. Police allowed us free access past the cordon and simply advised us to watch out for falling masonry. The access situation was much different after the February aftershock".

Images, UC QuakeStudies

A house on Avonside Drive showing damage from the 4 September 2010 earthquake. Numerous cracks in the masonry can be seen, and several sections of brick have fallen off the walls. The building's porch has also collapsed. A pile of dried liquefaction is visible in the driveway.

Images, UC QuakeStudies

The southern side of the Christ Church Cathedral with boarded up windows and damage to the roof above both of the transepts. Damaged masonry has been piled on the ground in front and one of the spires has been removed and braced with steel in the foreground.

Research papers, The University of Auckland Library

Following the 2010/2011 Canterbury, New Zealand earthquakes, a detailed door-to-door survey was conducted in the Christchurch region to establish the earthquake performance of lightweight timber-framed residential dwellings with a masonry veneer external cladding system. The post-earthquake survey involved documenting the condition of dwellings in areas that had experienced different levels of earthquake shaking, allowing comparison between the performance of different veneer systems and different shaking intensities. In total, just fewer than 1,100 residential dwellings were inspected throughout the wider Christchurch area. The survey included parameters such as level of veneer damage, type of veneer damage, observed crack widths, and level of repair required. It is concluded that based on observed earthquake performance at the shaking intensities matching or exceeding ultimate limit state loading, the post-1996 veneer fixing details performed satisfactorily and continued use of the detail is recommended without further modification. AM - Accepted Manuscript

Images, UC QuakeStudies

A view across London Street in Lyttelton showing damage to the Four Square supermarket and Lyttelton Coffee Company buildings. The Four Square's windows have been boarded up with plywood. and cracks are visible in the masonry of the Lyttelton Coffee Company building. Steel rods have been installed to support its sagging awning.

Images, UC QuakeStudies

A view across Battersea Street in Sydenham to Churchill's Tavern, which has been badly damaged in the 22 February 2011 earthquake. Masonry from the building's top storey has collapsed onto the footpath and several of its windows have fallen out. A member of the New Zealand Police Force is walking across Colombo Street in the background.

Images, UC QuakeStudies

A view across Worcester Street in Linwood to a block of shops, including Easy Traders Whiteware and Furniture. Masonry, structural components and the Easy Traders building's veranda have collapsed onto the road. The whole back section of the shops has also collapsed. The site is enclosed by a safety fence.

Images, UC QuakeStudies

Damage to the front gable of the Durham Street Methodist Church. Masonry has fallen from the top of the gable, and the resulting gap has been weather proofed with plywood, tarpaulins and metal tiles. The steel bracing propping the whole front wall can be seen at the bottom of the photograph.

Images, UC QuakeStudies

Damaged buildings on Manchester Street, seen from the Tuam Street intersection. Police emergency tape cordons off the street. The photographer comments, "This was taken shortly after the 4th September earthquake. Police allowed us free access past the cordon and simply advised us to watch out for falling masonry. The access situation was much different after the February aftershock".

Research papers, The University of Auckland Library

In the early morning of 4th September 2010 the region of Canterbury, New Zealand, was subjected to a magnitude 7.1 earthquake. The epicentre was located near the town of Darfield, 40 km west of the city of Christchurch. This was the country’s most damaging earthquake since the 1931 Hawke’s Bay earthquake (GeoNet, 2010). Since 4th September 2010 the region has been subjected to thousands of aftershocks, including several more damaging events such as a magnitude 6.3 aftershock on 22nd February 2011. Although of a smaller magnitude, the earthquake on 22nd February produced peak ground accelerations in the Christchurch region three times greater than the 4th September earthquake and in some cases shaking intensities greater than twice the design level (GeoNet, 2011; IPENZ, 2011). While in September 2010 most earthquake shaking damage was limited to unreinforced masonry (URM) buildings, in February all types of buildings sustained damage. Temporary shoring and strengthening techniques applied to buildings following the Darfield earthquake were tested in February 2011. In addition, two large aftershocks occurred on 13th June 2011 (magnitudes 5.7 and 6.2), further damaging many already weakened structures. The damage to unreinforced and retrofitted clay brick masonry buildings in the 4th September 2010 Darfield earthquake has already been reported by Ingham and Griffith (2011) and Dizhur et al. (2010b). A brief review of damage from the 22nd February 2011 earthquake is presented here

Images, eqnz.chch.2010

The September Canterbury earthquake. These pictures were taken of The New Zealand Army, along with Police, minding the cordons. This was beside The Press building, and behind the Christchurch Cathedral. Note: these photos were taken on a cellphone; mind the quality.

Images, UC QuakeStudies

A view across London Street in Lyttelton to The Volcano Cafe, The Lava Bar, and Coastal Living Design Store. Masonry from the buildings has collapsed onto the footpath, and the site has been cordoned off with wire fencing. The buildings' yellow recycling bins are still waiting on the curb for collection.

Images, UC QuakeStudies

Scaffolding that has been constructed on the Manchester Street face of the Octagon Live Restaurant (formerly Trinity Church), which is being repaired. Masonry has fallen from one of the building's gables, and the resultant gap has been weather proofed with plywood and a tarpaulin. The site has been enclosed in a safety fence that cuts off one lane of the road.

Images, UC QuakeStudies

A police officer talks to the driver of a NZ Post truck at a cordon across Tuam Street. Military personnel stand nearby. The photographer comments, "this was taken shortly after the 4th September earthquake. Police allowed us free access past the cordon and simply advised us to watch out for falling masonry. The access situation was much different after the February aftershock".

Research papers, The University of Auckland Library

During the Christchurch earthquake of February 2011, several midrise reinforced concrete masonry (RCM) buildings showed performance levels that fall in the range of life safety to near collapse. A case study of one of these buildings, a six-story RCM building deemed to have reached the near collapse performance level, is presented in this paper. The RCM walls on the second floor failed due to toe crushing, reducing the building's lateral resistance in the east–west direction. A three-dimensional (3-D) nonlinear dynamic analysis was conducted to simulate the development of the governing failure mechanism. Analysis results showed that the walls that were damaged were subjected to large compression loads during the earthquake, which caused an increase in their in-plane lateral strength but reduced their ductility capacity. After toe crushing failure, axial instability of the model was prevented by a redistribution of gravity loads. VoR - Version of Record

Research papers, The University of Auckland Library

The Manchester Courts building was a heritage building located in central Christchurch (New Zealand) that was damaged in the Mw 7.1 Darfield earthquake on 4 September 2010 and subsequently demolished as a risk reduction exercise. Because the building was heritage listed, the decision to demolish the building resulted in strong objections from heritage supporters who were of the opinion that the building had sufficient residual strength to survive possible aftershock earthquakes. On 22 February 2011 Christchurch was struck by a severe aftershock, leading to the question of whether building demolition had proven to be the correct risk reduction strategy. Finite element analysis was used to undertake a performance-based assessment, validating the accuracy of the model using the damage observed in the building before its collapse. In addition, soil-structure interaction was introduced into the research due to the comparatively low shear wave velocity of the soil. The demolition of a landmark heritage building was a tragedy that Christchurch will never recover from, but the decision was made considering safety, societal, economic and psychological aspects in order to protect the city and its citizens. The analytical results suggest that the Manchester Courts building would have collapsed during the 2011 Christchurch earthquake, and that the collapse of the building would have resulted in significant fatalities.

Images, UC QuakeStudies

Scaffolding that has been constructed on the Manchester Street face of the Octagon Live Restaurant (formerly Trinity Church), which is being repaired. Masonry has fallen from one of the building's gables, and the resultant gap has been weather proofed with plywood and a tarpaulin. The site has been enclosed in a safety fence that cuts off one lane of the road.

Images, UC QuakeStudies

The A and T Burt building on Ferry Road in Woolston. Bricks from the top section of the building have fallen away. Signs advertising two businesses housed in the building, Superheat and Junk and Disorderly, can be seen sitting in front of it. The footpath is covered with brick dust and small pieces of masonry from when the larger pieces were cleared away.

Images, UC QuakeStudies

A view across Worcester Street in Linwood to a block of shops showing severe damage after the 22 February 2011 earthquake. The businesses include Talon Arms and Wick's Fish. Masonry and structural components from the buildings has collapsed onto the footpath and road. A sign in front of Talon Arms has been spray painted with the words, "Guns gone".

Images, UC QuakeStudies

St John's Presbyterian Church on Winchester Street in Lyttelton. The ground around the church has been strewn with masonry from the church's walls and collapsed tower. The building's front door has been red-stickered and a sign that reads "No entry" is stuck to it. The spire of the collapsed tower has fallen in front of the church, which has been enclosed by a safety fence.

Images, UC QuakeStudies

People walk along Tuam Street carrying bags and boxes. Brick dust covers the street where fallen bricks have been cleared, and on the left emergency tapes cordons off Manchester Street. The photographer comments, "This was taken shortly after the 4th September earthquake. Police allowed us free access past the cordon and simply advised us to watch out for falling masonry. The access situation was much different after the February aftershock".