A red-stickered house with cracks running down the brick wall. The house has also separated slightly from the foundations and is now on a lean. The brick wall on the house next door has partially crumbled.
Spray painted markings on a brick wall.
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.
The ground of The Pump House in Linwood. A pile of brick sits next to the damage brick wall.
A photograph of the earthquake damaged M J Knowles Building on Tuam Street. The wall has either collapsed or been removed leaving the inside of the building exposed. Loose bricks from the wall cover the footpath.
A photograph of the earthquake damaged M J Knowles Building on Tuam Street. The wall has either collapsed or been removed leaving the inside of the building exposed. Loose bricks from the wall cover the footpath.
A photograph of the earthquake damaged M J Knowles Building on Tuam Street. The wall has either collapsed or been removed leaving the inside of the building exposed. Loose bricks from the wall cover the footpath.
A photograph of a damaged house has been reflected in the lower part of the image and digitally manipulated.
A photograph of the earthquake damaged M J Knowles Building on Tuam Street. The wall has either collapsed or been removed leaving the inside of the building exposed. Loose bricks from the wall cover the footpath.
A damaged church hall. The brick walls have partially collapsed.
A photograph of a brick wall of 7 Hutcheson Street.
Damaged building with sections of its brick wall boarded up.
A photograph of a brick wall of the Cranmer Centre.
Large cracks run through the brick cladding of this house in Wainoni. The photographer comments, "During the numerous earthquakes in Christchurch the land which ran alongside the Avon river on Avonside Drive slumped towards the waterway. Houses which were wooden framed and had an external brick veneer started to sink into the liquefied soil. This caused the brick walls to crack, but the houses' occupants though shook up were saved by the wooden framework from the houses collapsing on them".
A damaged brick building, the side wall of which has collapsed.
A damaged brick building, the side wall of which has collapsed.
Damage to a house. Sections of the brick exterior walls have crumbled.
A trailer of bricks in front of a house with damaged walls.
A brick wall with flaked paint. The adjourning building has been demolished.
Scaffolding around Satchmo Hairdressing, where sections of the brick wall have crumbled.
Detail of damage to the former Princess Cinema in New Brighton. Bricks have fallen from the wall, exposing the interior. The photographer comments, "This is the side view of the back of the old Princess Cinema in New Brighton after the earthquake in Christchurch, New Zealand on 22 February. The bricks seem to be just about to fall, but stayed in place after several big aftershocks. This building has now been knocked down as it was so dangerous".
A damaged brick building on Tuam Street. Bricks have fallen from the wall exposing the interior, where a wooden structure can be seen to have collapsed. The photographer comments, "This is the damage caused by the numerous earthquakes in Christchurch, New Zealand. It closely resembles a face and the round blob in the square hole at the top of the nose is a pigeon".
A damaged house, the outer brick wall of which has completely fallen away.
A photograph of the house at 410 Oxford Terrace. Sections of the brick fence at the front have been removed. Some of the bricks are stacked on the remaining wall, or have fallen on the footpath in front.
Graffiti on a brick wall reads "Pray hope and don't worry". The photographer comments, "Seen on a wall on Moorhouse Avenue, Christchurch".
Digitally manipulated image of graffiti on a brick building on St Asaph Street. The graffiti depicts a sticking plaster over a broken section of the wall, with the words "I'll kiss it better". The photographer comments, "After the 22 February 2011 earthquake in Christchurch band aid plasters starting to appear in different parts of the city on damaged buildings. A year later most can still be seen. This one was once a whole plaster, but it has slowly broken up where it crossed the gap. The red bricks seen to symbolise the terrible wounds caused to the City and it's people".
Detail of a building where the brick walls have crumbled, exposing the internal fixtures.
Bricks fallen from the wall and chimney of the Caxton Press building. Some windows have been boarded up, and in front is a pile of bricks that has been cordoned off with tape and road cones.
A photograph of Knox Church on Bealey Avenue. Much of the brick wall is missing, exposing the wooden framing of the gables and the inside of the church.
A close up of the entrance to the cathedral. Bricks have fallen from the wall causing damage to the balustrade. Bracing has been placed against the front wall to limit further damage.