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Research papers, University of Canterbury Library

In most design codes, infill walls are considered as non-structural elements and thus are typically neglected in the design process. The observations made after major earthquakes (Duzce 1999, L’Aquila 2009, Christchurch 2011) have shown that even though infill walls are considered to be non-structural elements, they interact with the structural system during seismic actions. In the case of heavy infill walls (i.e. clay brick infill walls), the whole behaviour of the structure may be affected by this interaction (i.e. local or global structural failures such as soft storey mechanism). In the case of light infill walls (i.e. non-structural drywalls), this may cause significant economical losses. To consider the interaction of the structural system with the ‘non-structural ’infill walls at design stage may not be a practical approach due to the complexity of the infill wall behaviour. Therefore, the purpose of the reported research is to develop innovative technological solutions and design recommendations for low damage non-structural wall systems for seismic actions by making use of alternative approaches. Light (steel/timber framed drywalls) and heavy (unreinforced clay brick) non-structural infill wall systems were studied by following an experimental/numerical research programme. Quasi-static reverse cyclic tests were carried out by utilizing a specially designed full scale reinforced concrete frame, which can be used as a re-usable bare frame. In this frame, two RC beams and two RC columns were connected by two un-bonded post tensioning bars, emulating a jointed ductile frame system (PRESSS technology). Due to the rocking behaviour at the beam-column joint interfaces, this frame was typically a low damage structural solution, with the post-tensioning guaranteeing a linear elastic behaviour. Therefore, this frame could be repeatedly used in all of the tests carried out by changing only the infill walls within this frame. Due to the linear elastic behaviour of this structural bare frame, it was possible to extract the exact behaviour of the infill walls from the global results. In other words, the only parameter that affected the global results was given by the infill walls. For the test specimens, the existing practice of construction (as built) for both light and heavy non-structural walls was implemented. In the light of the observations taken during these tests, modified low damage construction practices were proposed and tested. In total, seven tests were carried out: 1) Bare frame , in order to confirm its linear elastic behaviour. 2) As built steel framed drywall specimen FIF1-STFD (Light) 3) As built timber framed drywall specimen FIF2-TBFD (Light) 4) As built unreinforced clay brick infill wall specimen FIF3-UCBI (Heavy) 5) Low damage steel framed drywall specimen MIF1-STFD (Light) 6) Low damage timber framed drywall specimen MIF2-TBFD (Light) 7) Low damage unreinforced clay brick infill wall specimen MIF5-UCBI (Heavy) The tests of the as built practices showed that both drywalls and unreinforced clay brick infill walls have a low serviceability inter-storey drift limit (0.2-0.3%). Based on the observations, simple modifications and details were proposed for the low damage specimens. The details proved to be working effectively in lowering the damage and increasing the serviceability drift limits. For drywalls, the proposed low damage solutions do not introduce additional cost, material or labour and they are easily applicable in real buildings. For unreinforced clay brick infill walls, a light steel sub-frame system was suggested that divides the infill panel zone into smaller individual panels, which requires additional labour and some cost. However, both systems can be engineered for seismic actions and their behaviour can be controlled by implementing the proposed details. The performance of the developed details were also confirmed by the numerical case study analyses carried out using Ruaumoko 2D on a reinforced concrete building model designed according to the NZ codes/standards. The results have confirmed that the implementation of the proposed low damage solutions is expected to significantly reduce the non-structural infill wall damage throughout a building.

Images, UC QuakeStudies

A photograph captioned by BeckerFraserPhotos, "An old advertisments which was revealed on a building on Lichfield Street when its neighbour was demolished. The advertisement reads 'New Zealand Candle Co Ltd.' and then adds 'Five Medal, British Sperm', which are brands of candle".

Audio, Radio New Zealand

The Aromaunga Baxters Flowers nursery in Heathcote, Christchurch sits right above the point where the earthquake struck on 22 February 2011. The greenhouses on the steep slopes of the Port Hills, as well as a big old villa and other brick buildings were badly damaged. Ten years on co-owner John Baxter says the earthquake damage is still being repaired, but sales have been boosted by a lack of imported flowers due to Covid-19 restrictions.

Images, UC QuakeStudies

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".

Images, UC QuakeStudies

Defence Force personnel walking down Norwich Quay during an operational tour of Lyttelton taken by Commander Joint Forces New Zealand, Air Vice Marshal Peter Stockwell and Chief of Army Tim Keating to view the aftermath of the Christchurch Earthquake.

Images, UC QuakeStudies

A photograph taken near the intersection of Manchester Street, Lichfield Street and High Street. A mural has been painted on a brick wall. Behind this is the old Post Office building (now C1 Espresso). There is a sculpture by Ronnie Van Hout on the roof.

Images, UC QuakeStudies

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".

Images, eqnz.chch.2010

The base of the tower on the right of this picture has sunk about 25cm so that the lower course of bricks have disappeared below ground level. Meanwhile the other end of the building has sunk about 50cm splitting the building into thirds. The sand you can see is what came bubbling up out of the ground due to liquifaction. Unfortunately the build...

Images, UC QuakeStudies

A photograph of the Wellington Emergency Management Office Emergency Response Team posing for a photograph on Lichfield Street. In the background is the earthquake-damaged John Burns & Co. Ltd Building. The top storey of the side wall of the building has collapsed and the rubble has spilled into the car park below. Several cars which were crushed by the falling rubble have been stacked next to the building.

Images, UC QuakeStudies

The damaged Ozone Hotel on Marine Parade. Fallen bricks lie on the ground in front of the building, which is surrounded by security fencing. The photographer comments, "A bike ride to New Brighton and the beach 3 weeks after the Feb 22 quake. Roads were still very rough and under reconstruction. Some buildings are still standing. but don't look too healthy".

Images, UC QuakeStudies

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".

Images, UC QuakeStudies

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".

Images, UC QuakeStudies

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".

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