Search

found 76 results

Images for plastic; more images...

Images, UC QuakeStudies

A photograph of the back of two earthquake-damaged houses on Gloucester Street. The side wall of the house to the right has partially collapsed and the bricks have spilled onto the property to the left. Plastic sheeting has been placed over the roof and the top of the wall to protect against the weather.

Research papers, The University of Auckland Library

Reinforced concrete buildings that satisfied modern seismic design criteria generally behaved as expected during the recent Canterbury and Kaikoura earthquakes in New Zealand, forming plastic hinges in intended locations. While this meant that life-safety performance objectives were met, widespread demolition and heavy economic losses took place in the aftermath of the earthquakes.The Christchurch central business district was particularly hard hit, with over 60% of the multistorey reinforced concrete buildings being demolished. A lack of knowledge on the post-earthquake residual capacity of reinforced concrete buildings was a contributing factor to the mass demolition.Many aspects related to the assessment of earthquake-damaged reinforced concrete buildings require further research. This thesis focusses on improving the state of knowledge on the post earthquakeresidual capacity and reparability of moderately damaged plastic hinges, with an emphasis on plastic hinges typical of modern moment frame structures. The repair method focussed on is epoxy injection of cracks and patching of spalled concrete. A targeted test program on seventeen nominally identical large-scale ductile reinforced concrete beams, three of which were repaired by epoxy injection following initial damaging loadings, was conducted to support these objectives. Test variables included the loading protocol, the loading rate, and the level of restraint to axial elongation.The information that can be gleaned from post-earthquake damage surveys is investigated. It is shown that residual crack widths are dependent on residual deformations, and are not necessarily indicative of the maximum rotation demands or the plastic hinge residual capacity. The implications of various other types of damage typical of beam and column plastic hinges are also discussed.Experimental data are used to demonstrate that the strength and deformation capacity of plastic hinges with modern seismic detailing are often unreduced as a result of moderate earthquake induced damage, albeit with certain exceptions. Special attention is given to the effects of prior yielding of the longitudinal reinforcement, accounting for the low-cycle fatigue and strain ageing phenomena. A material-level testing program on the low-cycle fatigue behaviour of grade 300E reinforcing steel was conducted to supplement the data available in the literature.A reduction in stiffness, relative to the initial secant stiffness to yield, occurs due to moderate plastic hinging damage. This reduction in stiffness is shown to be correlated with the ductility demand,and a proposed model gives a conservative lower-bound estimate of the residual stiffness following an arbitrary earthquake-type loading. Repair by epoxy injection is shown to be effective in restoring the majority of stiffness to plastic hinges in beams. Epoxy injection is also shown to have implications for the residual strength and elongation characteristics of repaired plastic hinges.

Images, UC QuakeStudies

A photograph of a block of earthquake damaged shops on Manchester Street. The front brick wall of the closest shop has crumbled and the bricks have fallen onto the pavement below, taking the awning with them. Plastic fencing has been placed along the street as a cordon.

Images, UC QuakeStudies

A photograph of Wharetiki on Colombo Street. A temporary fence made out of wooden slats, plastic netting, and safety tape has been constructed in front of the property. USAR codes have been spray-painted on one of the front windows and a red sticker has been placed on the front door. The red sticker indicates that the building is unsafe to enter.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team inside an earthquake-damaged house. The wall to the left has collapsed and has been covered with plastic sheeting. Bricks and other rubble cover the floor of the room. A chest of drawers with clothing still inside has toppled to the left and is resting on the rubble.