The Evaluating Maternity Units (EMU) study is a mixed method project involving a prospective cohort study, surveys (two postnatal questionnaires) and focus groups. It is an Australasian project funded by the Australian Health and Medical Research Council. Its primary aim was to compare the birth outcomes of two groups of well women – one group who planned to give birth at a primary maternity unit, and a second group who planned to give birth at a tertiary hospital. The secondary aim was to learn about women’s views and experiences regarding their birthplace decision-making, transfer, maternity care and experiences, and any other issues they raised. The New Zealand arm of the study was carried out in Christchurch, and was seriously affected by the earthquakes, halting recruitment at 702 participants. Comprehensive details were collected from both midwives and women regarding antenatal and early labour changes of birthplace plans and perinatal transfers from the primary units to the tertiary hospital. Women were asked about how they felt about plan changes and transfers in the first survey, and they were discussed in some focus groups. The transfer findings are still being analysed and will be presented. This study is set within the local maternity context, is recent, relevant and robust. It provides midwives with contemporary information about transfers from New Zealand primary maternity units and women’s views and experiences. It may help inform the conversations midwives have with each other, and with women and their families/whānau, regarding the choices of birthplace for well childbearing women.
The Christchurch earthquakes have highlighted the importance of low-damage structural systems for minimising the economic impacts caused by destructive earthquakes. Post-tensioned precast concrete walls have been shown to provide superior seismic resistance to conventional concrete construction by minimising structural damage and residual drifts through the use of a controlled rocking mechanism. The structural response of unbonded post-tensioned precast concrete wall systems, with and without additional energy dissipating elements, were investigated by means of pseudo-static cyclic, snap back and forced vibration testing with shake table testing to be completed. Two types of post-tensioned rocking wall system were investigated; a single unbonded post-tensioned precast concrete wall or Single Rocking Wall (SRW) and a system consisting of a Precast Wall with End Columns (PreWEC). The equivalent viscous damping (EVD) was evaluated using both the pseudo-static cyclic and snap back test data for all wall configurations. The PreWEC configurations showed an increase in EVD during the snap back tests in comparison to the cyclic test response. In contrast the SRW showed lower EVD during the snap back tests in comparison to the SRW cyclic test response. Despite residual drifts measured during the pseudo-static cyclic tests, negligible residual drift was measured following the snap back tests, highlighting the dynamic shake-down that occurs during the free vibration decay. Overall, the experimental tests provided definitive examples of the behaviour of posttensioned wall systems and validated their superior performance compared to reinforced concrete construction when subjected to large lateral drifts.
The full scale, in-situ investigations of instrumented buildings present an excellent opportunity to observe their dynamic response in as-built environment, which includes all the real physical properties of a structure under study and its surroundings. The recorded responses can be used for better understanding of behavior of structures by extracting their dynamic characteristics. It is significantly valuable to examine the behavior of buildings under different excitation scenarios. The trends in dynamic characteristics, such as modal frequencies and damping ratios, thus developed can provide quantitative data for the variations in the behavior of buildings. Moreover, such studies provide invaluable information for the development and calibration of realistic models for the prediction of seismic response of structures in model updating and structural health monitoring studies. This thesis comprises two parts. The first part presents an evaluation of seismic responses of two instrumented three storey RC buildings under a selection of 50 earthquakes and behavioral changes after Ms=7.1 Darfield (2010) and Ms=6.3 Christchurch (2011) earthquakes for an instrumented eight story RC building. The dynamic characteristics of the instrumented buildings were identified using state-of-the-art N4SID system identification technique. Seismic response trends were developed for the three storey instrumented buildings in light of the identified frequencies and the peak response accelerations (PRA). Frequencies were observed to decrease with excitation level while no trends are discernible for the damping ratios. Soil-structure interaction (SSI) effects were also determined to ascertain their contribution in the seismic response. For the eight storey building, it was found through system identification that strong nonlinearities in the structural response occurred and manifested themselves in all identified natural frequencies of the building that exhibited a marked decrease during the strong motion duration compared to the pre-Darfield earthquakes. Evidence of foundation rocking was also found that led to a slight decrease in the identified modal frequencies. Permanent stiffness loss was also observed after the strong motion events. The second part constitutes developing and calibrating finite element model (FEM) of the instrumented three storey RC building with a shear core. A three dimensional FEM of the building is developed in stages to analyze the effect of structural, non-structural components (NSCs) and SSI on the building dynamics. Further to accurately replicate the response of the building following the response trends developed in the first part of the thesis, sensitivity based model updating technique was applied. The FEMs were calibrated by tuning the updating parameters which are stiffnesses of concrete, NSCs and soil. The updating parameters were found to generally follow decreasing trends with the excitation level. Finally, the updated FEM was used in time history analyses to assess the building seismic performance at the serviceability limit state shaking. Overall, this research will contribute towards better understanding and prediction of the behavior of structures subjected to ground motion.
Though generally considered “natural” disasters, cyclones and earthquakes are increasingly being associated with human activities, incubated through urban settlement patterns and the long-term redistribution of natural resources. As society is becoming more urbanized, the risk of human exposure to disasters is also rising. Architecture often reflects the state of society’s health: architectural damage is the first visible sign of emergency, and reconstruction is the final response in the process of recovery. An empirical assessment of architectural projects in post-disaster situations can lead to a deeper understanding of urban societies as they try to rebuild. This thesis offers an alternative perspective on urban disasters by looking at the actions and attitudes of disaster professionals through the lens of architecture, situated in recent events: the 2010 Christchurch earthquake, the 2010 Haiti earthquake, and the 2005 Hurricane Katrina. An empirical, multi-hazard, cross-sectional case study methodology was used, employing grounded theory method to build theory, and a critical constructivist strategy to inform the analysis. By taking an interdisciplinary approach to understanding disasters, this thesis positions architecture as a conduit between two divergent approaches to disaster research: the hazards approach, which studies the disaster cycles from a scientific perspective; and the sociological approach, which studies the socially constructed vulnerabilities that result from disasters, and the elements of social change that accompany such events. Few studies to date have attempted to integrate the multi-disciplinary perspectives that can advance our understanding of societal problems in urban disasters. To bridge this gap, this thesis develops what will be referred to as the “Rittelian framework”—based on the work of UC Berkeley’s architecture professor Horst Rittel (1930-1990). The Rittelian framework uses the language of design to transcend the multiple fields of human endeavor to address the “design problems” in disaster research. The processes by which societal problems are addressed following an urban disaster involve input by professionals from multiple fields—including economics, sociology, medicine, and engineering—but the contribution from architecture has been minimal to date. The main impetus for my doctoral thesis has been the assertion that most of the decisions related to reconstruction are made in the early emergency recovery stages where architects are not involved, but architects’ early contribution is vital to the long-term reconstruction of cities. This precipitated in the critical question: “How does the Rittelian framework contribute to the critical design decisions in modern urban disasters?” Comparative research was undertaken in three case studies of recent disasters in New Orleans (2005), Haiti (2010) and Christchurch (2010), by interviewing 51 individuals who were selected on the basis of employing the Rittelian framework in their humanitarian practice. Contextualizing natural disaster research within the robust methodological framework of architecture and the analytical processes of sociology is the basis for evaluating the research proposition that architectural problem solving is of value in addressing the ‘Wicked Problems’ of disasters. This thesis has found that (1) the nuances of the way disaster agents interpret the notion of “building back better” can influence the extent to which architectural professionals contribute in urban disaster recovery, (2) architectural design can be used to facilitate but also impede critical design decisions, and (3) framing disaster research in terms of design decisions can lead to innovation where least expected. This empirical research demonstrates how the Rittelian framework can inform a wider discussion about post-disaster human settlements, and improve our resilience through disaster research.
