10 Plenary Session
Damage, Death and Downtime Risk Attenuation in the 2011 Christchurch Earthquake
J.B. Mander & Y. Huang
Following a catastrophic earthquake, 3d (damage, death and downtime) rapid estimates of the extent and severity of losses are desperately needed in order to better aid in post-event response and recovery. A quantitative risk analysis approach is advanced to investigate the 3d loss types for typical New Zealand construction as exemplified by the Redbook building for the 2011 Christchurch earthquake. The results are presented in terms of attenuation curves which show that within the central business district: the expected loss ratio (related to insurance claims) is about 50% of the asset value; the expected chance that someone is killed is 5%; and the expected downtime is 1-year. However, considerable uncertainties also exist, thus one can only be 90% confident that these results will not be higher than: 100% damage, implying collapse is a distinct possibility; 10% chance of fatalities, implying there may also be some deaths and possibly significant injuries; and 2-year downtime due to reconstruction demand surge. These salutary results demonstrate that in spite of structures being well-engineered, downtime in particular is unacceptably large. Two methods can be used to solve this problem: to make the structure slightly stronger and more robust through damage avoidance design.
Costs of Base-isolation and Earthquake Insurance in New Zealand
A.W. Charleson & N.J. Allaf
The first phase of the study addresses the costs and savings associated with base-isolating a building, compared to those of a fixed-base building. Four relatively new base-isolated public hospital buildings were chosen as case studies. Each building was visited, and as many of the design and construction team members as possible, including client, structural engineer, quantity surveyor, architect and contractor were interviewed. In addition, several manufacturers of base-isolation bearings provided information. From this phase, not only are some actual costs determined but the key factors affecting the construction cost of base-isolation are identified.
The study then focuses upon earthquake insurance. This phase consisted of interviewing several experienced earthquake insurance industry personnel. Based upon their knowledge, approximate insurance premium rates for fixed-base buildings are provided and future trends in earthquake insurance and implications for base-isolated buildings are discussed. Some of these issues should be considered by building owners and their design teams.
Using Seismic Isolation and Energy Dissipation to Create Earthquake-Resilient Buildings
R.L. Mayes, A.G. Brown & Dario Pietra
Seismic isolation with energy dissipation is a technology that has been used in New Zealand since 1978 for bridges and buildings. During this period it has seen limited use, tending to be applied mainly to historically significant buildings, or buildings that have special functional requirements.
Seismic isolation has the ability to significantly improve the seismic performance of existing buildings through a seismic retrofit, or to create new earthquake-resilient buildings. Both of these applications are of greater relevance throughout New Zealand following the Canterbury earthquakes. Consequently, the consideration of seismic isolation is no longer limited to those buildings at the top end of the Importance Level spectrum.
This paper examines the broad technical issues associated with isolation and energy dissipation. It discusses the benefits and costs of seismic isolation, and present guidelines for cost estimation at the feasibility stage of projects. We will explore the cost-benefits for building owners, and discuss whether base isolation can replace earthquake insurance for the building and its contents, and business interruption insurance.
The Flawless Reinsurance Loss Model for the Perfect(New Zealand) Earthquake
Michael Barkhausen, Russell Blong, Peter Cheesman, Ben Miliauskas & Michael Spranger
The Christchurch earthquakes have taught us a number of reinsurance lessons and a lot about aspects of less than perfect insurance loss models for New Zealand. At least some loss models will be improved but it will take a few years. This paper summarises: (i) some of the reinsurance lessons learnt; (ii) the reasons insurance loss models are constructed and the ways in which they can be used and abused; (iii) elaborates some of the difficulties in building an earthquake loss model for New Zealand; (iv) considers the problems involved in damage data analysis; and (v) identifies some of the issues that will remain unresolved even when the next generation of loss models is completed.