The decision on what to do with Christchurch's earthquake damaged redzone is one step closer, with the end of the public consultation period on the plan for the area. Over the past month Christchurch people have been asked to comment on a draft land use plan for the 602 hectares of land. Now those pitching ideas want the authorities to get on with the next step, so they can have some certainty about whether their projects can go ahead.
Red Cross aid worker Rosemarie North is in the Banten province of Java where authorities have lifted the alert level for the Anak Krakatau volcano to its second-highest level. She has worked on and off for the Red Cross since 2003 in all kinds of situations, including post-conflict in Sierra Leone, landslides in the Philippines and Papua New Guinea, refugee camps in Chad, earthquakes in Nepal and Christchurch, and tsunamis in Southeast Asia and Samoa. [image_crop:72149:full]
Over 900 buildings in the Christchurch central business district and 10,000 residential homes were demolished following the 22nd of February 2011 Canterbury earthquake, significantly disrupting the rebuild progress. This study looks to quantify the time required for demolitions during this event which will be useful for future earthquake recovery planning. This was done using the Canterbury Earthquake Recovery Authority (CERA) demolition database, which allowed an in-depth look into the duration of each phase of the demolition process. The effect of building location, building height, and the stakeholder which initiated the demolition process (i.e. building owner or CERA) was investigated. The demolition process comprises of five phases; (i) decision making, (ii) procurement and planning, (iii) demolition, (iv) site clean-up, and (v) completion certification. It was found that the time required to decide to demolish the building made up majority of the total demolition duration. Demolition projects initiated by CERA had longer procurement and planning durations, but was quicker in other phases. Demolished buildings in the suburbs had a longer decision making duration, but had little effect on other phases of the demolition process. The decision making and procurement and planning phases of the demolition process were shorter for taller buildings, though the other phases took longer. Fragility functions for the duration of each phase in the demolition process are provided for the various categories of buildings for use in future studies.
Hon PAULA BENNETT to the Prime Minister: Does she stand by all her statements?
Dr DEBORAH RUSSELL to the Minister of Finance: What does the Treasury’s 2018 Investment Statement show about the state of the Government’s balance sheet?
Hon AMY ADAMS to the Minister of Finance: How much capital expenditure is this Government forecast to spend in the period 2018-2022 compared to the previous Government over these same years, and how much of the difference is funded by an increase in debt?
Hon PAUL GOLDSMITH to the Minister for Economic Development: Does this Government have a broad economic development strategy; if so, what is it?
Dr DUNCAN WEBB to the Minister responsible for the Earthquake Commission: What announcements has the Government made about changes to how the Earthquake Commission operates?
Hon DAVID BENNETT to the Minister of Corrections: Does he stand by his statement on the Marae programme that “the problem right now is that corrections doesn’t have any flexibility…we’re in a real bind”?
Hon SCOTT SIMPSON to the Associate Minister for the Environment: Does she agree with the statements in the Annual Report of the Environmental Protection Authority, “we have our share of science deniers, who oppose fluoride, 1080, vaccinations, glyphosate, genetic modification, and much more” and “our Chief Scientist is prominent in emphasising the evidence, data, and science that underpins EPA decision making”; if so, why?
JENNY MARCROFT to the Minister for Regional Economic Development: What recent announcements has he made pertaining to the Provincial Growth Fund?
SIMEON BROWN to the Minister of Justice: Should maximum legislated sentences reflect the seriousness of the crime committed?
Hon NICKY WAGNER to the Minister for Greater Christchurch Regeneration: Does she stand by all her answers to written questions?
ANGIE WARREN-CLARK to the Minister for the Environment: What does he think New Zealanders have to celebrate on World Water Day?
MELISSA LEE to the Minister of Broadcasting, Communications and Digital Media: Does she stand by all her Government’s policies and actions in the Broadcasting, Communications and Digital Media portfolio?
One of the most controversial issues highlighted by the 2010-2011 Christchurch earthquake series and more recently the 2016 Kaikoura earthquake, has been the evident difficulty and lack of knowledge and guidelines for: a) evaluation of the residual capacity damaged buildings to sustain future aftershocks; b) selection and implementation of a series of reliable repairing techniques to bring back the structure to a condition substantially the same as prior to the earthquake; and c) predicting the cost (or cost-effectiveness) of such repair intervention, when compared to fully replacement costs while accounting for potential aftershocks in the near future. As a result of such complexity and uncertainty (i.e., risk), in combination with the possibility (unique in New Zealand when compared to most of the seismic-prone countries) to rely on financial support from the insurance companies, many modern buildings, in a number exceeding typical expectations from past experiences at an international level, have ended up being demolished. This has resulted in additional time and indirect losses prior to the full reconstruction, as well as in an increase in uncertainty on the actual relocation of the investment. This research project provides the main end-users and stakeholders (practitioner engineers, owners, local and government authorities, insurers, and regulatory agencies) with comprehensive evidence-based information to assess the residual capacity of damage reinforced concrete buildings, and to evaluate the feasibility of repairing techniques, in order to support their delicate decision-making process of repair vs. demolition or replacement. Literature review on effectiveness of epoxy injection repairs, as well as experimental tests on full-scale beam-column joints shows that repaired specimens have a reduced initial stiffness compared with the undamaged specimen, with no apparent strength reduction, sometimes exhibiting higher displacement ductility capacities. Although the bond between the steel and concrete is only partially restored, it still allows the repaired specimen to dissipate at least the same amount of hysteretic energy. Experimental tests on buildings subjected to earthquake loading demonstrate that even for severe damage levels, the ability of the epoxy injection to restore the initial stiffness of the structure is significant. Literature review on damage assessment and repair guidelines suggests that there is consensus within the international community that concrete elements with cracks less than 0.2 mm wide only require cosmetic repairs; epoxy injection repairs of cracks less and 2.0 mm wide and concrete patching of spalled cover concrete (i.e., minor to moderate damage) is an appropiate repair strategy; and for severe damaged components (e.g., cracks greater than 2.0 mm wide, crushing of the concrete core, buckling of the longitudinal reinforcement) local replacement of steel and/or concrete in addition to epoxy crack injection is more appropriate. In terms of expected cracking patterns, non-linear finite element investigations on well-designed reinforced concrete beam-to-column joints, have shown that lower number of cracks but with wider openings are expected to occur for larger compressive concrete strength, f’c, and lower reinforcement content, ρs. It was also observed that the tensile concrete strength, ft, strongly affects the expected cracking pattern in the beam-column joints, the latter being more uniformly distributed for lower ft values. Strain rate effects do not seem to play an important role on the cracking pattern. However, small variations in the cracking pattern were observed for low reinforcement content as it approaches to the minimum required as per NZS 3101:2006. Simple equations are proposed in this research project to relate the maximum and residual crack widths with the steel strain at peak displacement, with or without axial load. A literature review on fracture of reinforcing steel due to low-cycle fatigue, including recent research using steel manufactured per New Zealand standards is also presented. Experimental results describing the influence of the cyclic effect on the ultimate strain capacity of the steel are also discussed, and preliminary equations to account for that effect are proposed. A literature review on the current practice to assess the seismic residual capacity of structures is also presented. The various factors affecting the residual fatigue life at a component level (i.e., plastic hinge) of well-designed reinforced concrete frames are discussed, and equations to quantify each of them are proposed, as well as a methodology to incorporate them into a full displacement-based procedure for pre-earthquake and post-earthquake seismic assessment.
