Bulletin of the New Zealand Society for Earthquake Engineering

Installation methods for ground motion sensors in community-engaged earthquake early warning system

Chanthujan Chandrakumar — 2025-09-02

This research investigates installation methods for ground motion accelerometers within a community-engaged Earthquake Early Warning (EEW) network, where untrained volunteers install sensors in their homes. Four installation methods were evaluated on plush wool-type carpets using a two-dimensional horizontal axis shake table with sinusoidal waveforms within the expected frequency range of earthquake ground motions and real-world earthquake acceleration data from historical events. The performance of these methods in accurately capturing key characteristics of ground motions was assessed through statistical and frequency analysis relative to a reference accelerometer fixed to the shake table. The initial findings with two-dimensional horizontal shake table testing indicate that both the loosely placed sensor and the anti-slip sticker method provide effective solutions, with the loosely placed sensor offering optimal accuracy and ease of installation and the anti-slip sticker method providing greater stability. The study highlights the need for future research to explore additional installation methods and floor types using three-dimensional shake tables to enhance broader applicability.

Seismic performance and loss assessment of light timber frame residential houses in New Zealand: State of the art

Kexin Wang — 2025-09-02

Past earthquake experiences in New Zealand indicate that light timber-frame (LTF) residential housing stock in New Zealand could suffer significant damage in major earthquakes, leading to significant downtime and economic losses for the community. It is necessary to develop a rigorous approach to predict seismic damage on LTF residential houses and estimate the subsequent economic losses. This paper provides an overview of recent research advances in the fields of seismic performance assessment and seismic loss models for LTF residential houses in New Zealand. It systematically reviews the evolution of residential houses in New Zealand, experimental and simulation studies of plasterboard bracing walls and LTF buildings, numerical modelling methods currently used for wood shear walls, and prevailing building seismic loss estimation models. In addition, recent technological advancements and current design recommendations relevant to such LTF houses and bracing walls are highlighted. Possible future research directions are recommended to better understand the seismic performance and develop a loss estimation framework for LTF residential houses in New Zealand.

Investigating the impacts of design ductility values and importance levels on the performance of base-isolated buildings in New Zealand

Claire Dong — 2025-09-02

This study investigates the performance of base-isolated buildings designed according to the recommendations provided in the NZSEE/MBIE base isolation design guidelines. In total 16 case study buildings were designed for a site in Wellington, New Zealand, including four fixed-base buildings (for comparison) and 12 isolated buildings with various inelastic-spectrum-scaling factors, k_μ (equivalent to force-reduction factors) and importance levels. The performance of each building design was subsequently assessed using the FEMA P-58 framework. Three-dimensional numerical models were developed in OpenSees to perform the non-linear time history analysis with 180 pairs of ground motions across nine intensity levels. Results suggest that the average annual rate of collapse and the expected annual loss of the isolated buildings are both around four times lower than fixed-base buildings. This study also investigated the impacts of superstructure design ductility (controlled via the inelastic-spectrum-scaling factor, k_μ) and the design importance level. Results showed that a high k_μ is likely to worsen the performance of the base-isolated building. For a k_μ = 2, the peak storey drift demands were increased by 50% ~ 100%, whereas the peak floor acceleration demands were only slightly reduced. As a result, the expected annual loss increased. Observations showed an increase in k_μ reduced the median value of the superstructure collapse fragility and could change the failure mechanism from isolator failure to superstructure failure. To improve performance, one could allow for more isolator displacement capacity at k_μ = 1 or impose suitable superstructure deformation limits if a higher k_μ is permitted. Lastly, the results showed that designing a base-isolated building with a higher importance level increased the peak floor acceleration demands by 50% to 60% and had a mixed impact on the peak storey drift demands. However, it did reduce the annual rate of collapse rate by around a factor of two.

The applicability of 3D effects to pseudo-static design acceptance criteria: The recovery design for Wall 375

Elena Zabolotnii — 2025-09-02

The legislated use of pseudo-static analysis in many jurisdictions mandates its continued application by practitioners. This paper offers guidance to slope stability practitioners on the use the method’s three-dimensional formulation to meet Design Acceptance Criteria. The paper demonstrates that three-dimensional seismic k-coefficients cannot be used as 1:1 substitutes to meet historically established DAC and presents a case for developing the correct equivalencies. The case study of the recovery design along Wall 375 along New Zealand’s State Highway No. 1 in the aftermath of the Kaikoura earthquake is used for illustrative purposes.

Communicating seismic building risk with commercial building tenants

Catalina Miranda — 2025-09-02

In Aotearoa New Zealand, the interpretation of seismic risk information and the subsequent demands put on building owners and developers to address seismic risk are shaping the performance of our building stock. Commercial building tenants in particular can significantly influence property developers and landlords, who respond to tenant preferences to ensure they can lease and make a return on their property investment(s). However, there are many cases that indicate commercial building tenants do not fully understand the seismic risk information they receive nor how to incorporate the information into their decision-making regarding leasing or vacating a building.

This research identified key challenges with current approaches for communicating seismic building risk with commercial building tenants through a series of interviews with commercial building tenants, property managers and structural engineers.