An improved seismic hazard model for use in performance-based earthquake engineering is presented. The model is an improved approximation from the so-called 'power law' model, which is linear in log-log space. The mathematics of the model and uncertainty incorporation is briefly discussed. Various means of fitting the approximation to hazard data derived from probabilistic seismic hazard analysis (PSHA) are discussed, including the limitations of the model. Based on these 'exact' hazard data for major centers in New Zealand, the parameters for the proposed model are calibrated. To illustrate the significance of the proposed model, a performance-based assessment is conducted on a typical bridge, via probabilistic seismic demand analysis (PSDA). The new hazard model is compared to the current power law relationship to illustrate its effects on the risk assessment. The propagation of epistemic uncertainty in the seismic hazard is also considered. To allow further use of the model in conceptual calculations, a semi-analytical method is proposed to calculate the demand hazard in closed-form. For the case study shown, the resulting semi-analytical closed-form solution is shown to be significantly more accurate than the analytical closedform solution using the power law hazard model, capturing the 'exact' numerical integration solution to within 7% accuracy over the entire range of exceedance rate. KEYWORDSperformance based earthquake engineering (PBEE); probabilistic seismic demand 2 analysis (PSDA); seismic hazard model; demand hazard.

This paper presents preliminary field observations on the performance of selected steel structures in Christchurch during the earthquake series of 2010 to 2011. This comprises 6 damaging earthquakes, on 4 September and 26 December 2010, February 22, June 6 and two on June 13, 2011. Most notable of these was the 4 September event, at Ms7.1 and MM7 (MM as observed in the Christchurch CBD) and most intense was the 22 February event at Ms6.3 and MM9-10 within the CBD. Focus is on performance of concentrically braced frames, eccentrically braced frames, moment resisting frames and industrial storage racks. With a few notable exceptions, steel structures performed well during this earthquake series, to the extent that inelastic deformations were less than what would have been expected given the severity of the recorded strong motions. Some hypotheses are formulated to explain this satisfactory performance.

This paper describes the performance of (or damage to) ceilings in buildings during the 22nd February 2011 Christchurch earthquake and the subsequent aftershocks. In buildings that suffered severe structural damage, ceilings and other non-structural components (rather expectedly) failed, but even in buildings with little damage to their structural systems, ceilings were found to be severely damaged. The extent of ceiling damage, where the ceilings were subject to severe shaking, depended on the type of the ceiling system, the size and weight of the ceilings and the interaction of ceilings with other elements. The varieties and extent of observed ceiling damage are discussed in this paper with the help of photographs taken after the earthquake.

This paper presents the probabilistic seismic performance and loss assessment of an actual bridge-foundation-soil system, the Fitzgerald Avenue twin bridges in Christchurch, New Zealand. A two-dimensional finite element model of the longitudinal direction of the system is modelled using advanced soil and structural constitutive models. Ground motions at multiple levels of intensity are selected based on the seismic hazard deaggregation at the site.Based on rigorous examination of several deterministic analyses, engineering demand parameters (EDP's) which capture the global and local demand and consequent damage to the bridge and foundation are determined. A probabilistic seismic loss assessment of the structure considering both direct repair and loss of functionality consequences was performed to holistically assess the seismic risk of the system. It was found that the non-horizontal stratification of the soils, liquefaction, and soilstructure interaction had pronounced effects on the seismic demand distribution of the bridge components, of which the north abutment piles and central pier were critical in the systems seismic performance. The consequences due to loss of functionality of the bridge during repair were significantly larger than the direct repair costs, with over a 2% in 50 year probability of the total loss exceeding twice the book-value of the structure. 2 KEYWORDSPerformance-based earthquake engineering (PBEE); soil-structure interaction (SSI); seismic loss estimation; downtime.

In many countries around the world, building and bridge structures with close proximity to known earthquake faults have been constructed with little consideration to the effects of strong ground shaking. This paper discusses some of the infrastructure and systems required in a country to prevent structural collapse, and hence major loss, in a major earthquake. The modus operandi of one group which seeks to reduce earthquake loss in these countries, the World Seismic Safety Initiative, is described. Finally, a case study is carried out on Myanmar where extraordinary strides that have been made toward earthquake risk reduction in a relatively short period of time.