Photograph captioned by BeckerFraserPhotos, "Inside the Sumner electrical sub-station which was severely damaged by rock fall from the cliffs above during the 22 February 2011 earthquake.
Photograph captioned by BeckerFraserPhotos, "Inside the Sumner electrical sub-station which was severely damaged by rock fall from the cliffs above during the 22 February 2011 earthquake.
Photograph captioned by Fairfax, "Christchurch Earthquake aftermath. Day after the earthquake that rocked in Christchurch, Mana Tamaiparea filling water bottles at a Civil Defence centre in Kaiapoi North School".
Several concrete cladding panels were damaged during the 2011 Christchurch Earthquakes in New Zealand. Damage included partial collapse of panels, rupture of joint sealants, cracking and corner crushing. Installation errors, faulty connections and inadequate detailing were also contributing factors to the damage. In New Zealand, two main issues are considered in order to accommodate story drifts in the design of precast cladding panels: 1) drift compatibility of tieback or push-pull connections and 2) drift compatibility of corner joints. Tieback connections restrain the panels in the out-of-plane direction while allowing in-plane translation with respect to the building frame. Tieback connections are either in the form of slots or oversized holes or ductile rods usually located at the top of the panels. Bearing connections are also provided at the bottom of panels to transfer gravity loads. At the corners of a building, a vertical joint gap, usually filled with sealants, is provided between the two panels on the two orthogonal sides to accommodate the relative movement. In cases where the joint gap is not sufficient to accommodate the relative movements, panels can collide, generating large forces and the likely failure of the connections. On the other hand, large gaps are aesthetically unpleasing. The current design standards appear to recognize these issues but then leave most of the design and detailing to the discretion of the designers. In the installation phase, the alignment of panels is one of the main challenges faced by installers (and/or contractors). Many prefer temporary props to guide, adjust and hold the panels in place whilst the bearing connections are welded. Moreover, heat generated from extensive welding can twist the steel components inducing undesirable local stresses in the panels. Therefore, the installation phase itself is time-consuming, costly and prone to errors. This paper investigates the performance of a novel panel system that is designed to accommodate lateral inter-story drift through a ‘rocking’ motion. In order to gauge the feasibility of the system, six 2m high precast concrete panels within a single-story steel frame structure have been tested under increasing levels of lateral cyclic drift at the University of Canterbury, New Zealand. Three different panel configurations are tested: 1) a panel with return cover and a flat panel at a corner under unidirectional loading, 2) Two adjacent flat panels under unidirectional loading, and 3) Two flat panels at another oblique corner under bidirectional loading. A vertical seismic joint of 25 mm, filled with one-stage joint sealant, is provided between two of the panels. The test results show the ability of the panels with ‘rocking’ connection details to accommodate larger lateral drifts whilst allowing for smaller vertical joints between panels at corners, quick alignment and easy placement of panels without involving extensive welding on site.
A rubbish truck collects rubbish from the red bins along Rocking Horse Road in Southshore. The uneven surface of the road can be seen, with water pooling in the foreground.
Photograph captioned by Fairfax, "Christchurch was rocked by a large aftershock shortly after 8am this morning. The city was filled with the sounds of sirens after the large aftershock".
A line of shipping containers along the base of the cliffs in Sumner protects the road from rockfalls. In the foreground on the right is what remains of Shag Rock.
An aerial photograph captioned by BeckerFraserPhotos, "The RSA (red roof and three skylights) and electrical substation (red front with the door open) very badly damaged by the rock falls".
A digitally manipulated image of the head of a digger resting on a pile of soil. The photographer comments, "You can go anywhere you like when you are a rock star".
What more can one say except that Shag Rock is now about one third it's original height. Whitewash Head in the background with the road that now drops over a cliff.
After being rocked awake by the massive 7.8 earthquake that hit North Canterbury last November, RNZ reporter Phil Pennington was among the first reporters to be sent to Kaikoura to assess the damage.
Highlights from Radio New Zealand National's programmes for the week ending Friday 10 September. This week........we have a review of our coverage of the earthquake that rocked Christchurch on Saturday morning.
Photograph captioned by Fairfax, "Christchurch Earthquake. Christchurch was rocked by a large aftershock shortly after 8am this morning. The city was filled with the sounds of sirens after the large aftershock".
During the past two decades, the focus has been on the need to provide communities with structures that undergo minimal damage after an earthquake event while still being cost competitive. This has led to the development of high performance seismic resisting systems, and advances in design methodologies, in order respect this demand efficiently. This paper presents the experimental response of four pre-cast, post-tensioned rocking wall systems tested on the shake-table at the University of Canterbury. The wall systems were designed as a retrofit solution for an existing frame building, but are equally applicable for use in new design. Design of the wall followed a performance-based retrofit strategy in which structural limit states appropriate to both the post-tensioned wall and the existing building were considered. Dissipation for each of the four post-tensioned walls was provided via externally mounted devices, located in parallel to post-tensioned tendons for re-centring. This allowed the dissipation devices to be easily replaced or inspected following a major earthquake. Each wall was installed with viscous fluid dampers, tension-compression yielding steel dampers, a combination of both or no devices at all – thus relying on contact damping alone. The effectiveness of both velocity and displacement dependant dissipation are investigated for protection against far-field and velocity-pulse ground motion characteristics. The experimental results validate the behaviour of ‘Advanced Flag-Shape’ rocking, dissipating solutions which have been recently proposed and numerically tested. Maximum displacements and material strains were well controlled and within acceptable bounds, and residual deformations were minimal due to the re-centring contribution from the post-tensioned tendons. Damage was confined to inelastic yielding (or fluid damping) of the external dampers.
A damaged house teetering on the edge of the cliff in Sumner. The photographer comments, "About four meters of the rock face collapsed on June 13 undermining several houses along the cliff top".
Boarded-up broken windows on the old Christchurch City Council building in Tuam Street. The photographer comments, "What can happen to a building when the land is no longer solid as a rock".
Rolleston is a town in the Selwyn District of Canterbury, just outside the Christchurch City boundary. It was close to the epicenter of the September earthquake last year, but suffered little damage because it sits on very stable rock.
Having moved to Joshua Tree after the 2011 Christchurch earthquake, husband-and-wife duo Maryrose and Brian Crook are back on home soil for a string of shows with their swirling psychedelic-rock act The Renderers.
Despite their good performance in terms of their design objectives, many modern code-prescriptive buildings built in Christchurch, New Zealand had to be razed after the 2010-2011 Canterbury earthquakes because repairs were deemed too costly due to widespread sacrificial damage. Clearly a more effective design paradigm is needed to create more resilient structures. Rocking, post-tensioned connections with supplemental energy dissipation can contribute to a damage avoidance designs (DAD). However, few have achieved all three key design objectives of damage-resistant rocking, inherent recentering ability, and repeatable, damage-free energy dissipation for all cycles, which together offer a response which is independent of loading history. Results of experimental tests are presented for a near full-scale rocking beam-column sub-assemblage. A matrix of test results is presented for the system under varying levels of posttensioning, with and without supplemental dampers. Importantly, this parametric study delineates each contribution to response. Practical limitations on posttensioning are identified: a minimum to ensure static structural re-centering, and a maximum to ensure deformability without threadbar yielding. Good agreement between a mechanistic model and experimental results over all parameters and inputs indicates the model is robust and accurate for design. The overall results indicate that it is possible to create a DAD connection where the non-linear force-deformation response is loading history independent and repeatable over numerous loading cycles, without damage, creating the opportunity for the design and implementation of highly resilient structures.
Some Christchurch residents say the Christchurch City Council has been too slow to resolve the threat of rock fall to their homes, and they now hope the Canterbury Earthquake Recovery Authority will take over the job.
A photograph of section of an artwork on the wall of a building between New Brighton mall and Beresford Street. The section depicts a native bird standing on a rock in front of a kowhai tree.
Among the deformation features produced in Christchurch by the September 4th Darfield Earthquake were numerous and widespread “sand volcanoes”. Most of these structures occurred in urban settings and “erupted” through a hardened surface of concrete or tarseal, or soil. Sand volcanoes were also widespread in the Avon‐ Heathcote Estuary and offered an excellent opportunity to readily examine shallow subsurface profiles and as such the potential appearance of such structures in the rock record.
Recent major earthquakes such as Northridge 1994 and Izmit Kocaeli 1999 highlighted the poor performance of existing buildings constructed prior to the early 1970’s. Low lateral seismic design coefficients and the adopted “working stress design” methodology (essentially an elastic design) lacked any inelastic design considerations, thus leading to inadequate detailing. Insufficient development lengths, lapping within potential plastic hinge regions, lack, or total absence of joint transverse reinforcement, and the use of plain round reinforcement and hooked end anchorages were common throughout the structure. The behaviour is generally dominated by brittle local failure mechanisms (e.g. joint or element shear failures) as well as possible soft-storey mechanisms at a global level. Amongst several possible retrofit interventions, a typical solution is to provide the structure with additional structural walls i.e. external buttressing or column in-fills. Extensive developments on precast, post-tensioned, dissipative systems have shown promise for the use of rocking wall systems to retrofit existing poorly detailed frame structures. In this contribution, the feasibility of such a retrofit intervention is investigated. A displacement-based retrofit procedure is developed and proposed, based on targeting pre-defined performance criteria, such as joint shear and/or column curvature deformation limits. A design example, using the proposed retrofit strategy on a prototype frame is presented. A brief overview on experimental work ongoing at the University of Canterbury investigating the dynamic response of advanced rocking walls for retrofit purposes will be provided.
The Octagon Live Restaurant (formerly Trinity Church) on Worcester Street. Steel bracing has been placed on the tower to limit further damage from aftershocks. Sculptures of a cyclist, bungee jumper, rock climber and kayaker can be seen on the bracing posts.
Photograph captioned by Fairfax, "From left: Paul Ellis, Jason Gunn and Simon Barnett seemingly doing rock star impersonations to Jason Kerrison at Hagley Park while doing a site recce for the Band Together concert at Labour weekend".
Photograph captioned by Fairfax, "Christchurch Earthquake. Christchurch was rocked by a large aftershock shortly after 8am this morning. Construction workers on Gloucester Street stopped work after the aftershock which measured 5.1 on the Richter scale".
A video of an interview with Terry Huggins about a boulder crashing into the side of his neighbour's house in Sumner. The boulder came lose from the cliffs above and smashed through the deck of the house into one of the supporting poles. It is the third large boulder to hit the house, with one also lodged in a bedroom.
Structural damage to St Elmo Courts with diagonal cracks between the windows of the building. These cracks show that there has been rocking of the masonry piers which means there is no vertical reinforcement provided in the walls.
A photograph captioned by BeckerFraserPhotos, "The Cave House, well known for its bright colour, on Main Road in Redcliffs. The house was further demolished by the most recent rock fall in the 23 December 2011 earthquake".
20160703_144759_GT-S7275T-04 New sea wall at Redcliffs (185/366) I went for a drive in my second car mainly to charge the battery up and forgot to take my camera gear so only had my phone. This is the new rock wall to replace the severely damaged previous one (in the February 2011 earthquake). Work is still underway on the car parking and p...