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Following the extensive damage to Christchurch’s infrastructure in the 2010 and 2011 Canterbury earthquakes, a complete rebuild of the city centre has been undertaken, with a particular focus on seismic-resilient buildings. This paper explores the application of different seismic-resilient technologies to buildings in Christchurch, by interviewing the structural engineers responsible for the design of six case study structures. Focus is given to the structural performance and benefits of each technology, and the key factors driving the clients’ and engineers’ decision to use the system. Comparisons are then made between resilient technologies, looking at the relative construction times and cost, areas of difficulty in design and construction, and the expected performance. Assessments are made of the knowledgeability of stakeholders, including clients and engineers, in resilient design, and the aspects that need to be addressed in the ongoing research and development of new and existing resilient technologies. Results show that the main factors identified driving clients’ and engineers’ decisions to use a seismic-resilient design were the structural performance, ease of construction and publicity. Key issues that need to be addressed during the development of new resilient systems are the durability, constructability and cost of a design, in addition to the production of design and construction aids, to both support engineers and contractors in the process, and encourage them to undertake a seismic-resilient design. Ideas are presented for increasing client and public awareness of different resilient systems available so that the demand and commission for seismic-resilient buildings in the city may increase.

The concept of post-tensioned rocking structures was successfully applied to timber in 2005, in prestressed laminated timber (Pres-Lam) technology. When applied to moment-resisting frames, the tech...

Computer-numerical-control (CNC) fabrication of interlocking-plate timber structures is a promising form of construction for housing with the potential to be socially, economically and environmentally sustainable. The primary mechanisms of load transfer in these structures rely on direct contact and friction between interlocking elements, without the nails and screws used in conventional timber structures. The development of these connections is relatively new, and therefore the application of interlocking plates structural systems in real projects is so far limited. In this study, the WikiHouse interlocking-plate timber structural system for digitally fabricated houses is presented from a design and fabrication point of view. The main structural elements of the system, the beams and columns, are hollow section members fabricated using computer-numerical-control (CNC) cut plywood panels. In the first part of the paper, the concept of Wikihouse and its fabrication process are presented. Then, the performance of the structural beams is investigated by means of experimental testing on full scale 5 m specimens. Finally, an analytical model to calculate the beam capacity and displacements is derived based on elastic beam bending and joint flexibility. Results show that the specimens failed in a ductile manner. Furthermore, it was found that the joints between the panels introduce extra flexibility to element, and that rigid-body rotations occurring in the joints within the span make a substantial contribution to the overall deflection.

The 2010 and 2011 Christchurch earthquakes proved that a shift is necessary in the current design practice of structures to achieve better seismic performance. Moreover, environmental concerns have...

This paper presents preliminary experimental investigations carried out to evaluate the feasibility of using gravel–rubber mixtures as low-cost geotechnical seismic-isolation foundation systems for low-rise buildings in New Zealand. One-dimensional compression and direct shear tests are performed to evaluate the compressibility and strength properties of three types of rigid-soft granular mixtures prepared using a combination of uniformly-graded rounded and angular gravels as well as large and small recycled rubber particles. The mixtures are prepared at volumetric rubber contents (VRC) of 10%, 25%, and 40%. The concept of skeleton material is adopted to establish whenever the gravel or rubber matrix would govern the overall mechanical behavior of the mixtures. It is shown that the compressibility of the mixtures highly depends of the skeleton material. Mixtures with VRC 35°) irrespective of the VRC and rubber particle size.

The extensive generation of end-of-life (ELT) tires worldwide has resulted in adverse environmental effects and threats to public health and safety including tire fires and leaching of contaminants into the soil environment, groundwater, and surface water. It is becoming imperative to investigate more sustainable and large-scale opportunities for the reuse of ELTs. One novel engineering solution is their reuse in structures with enhanced seismic resilience. This is particularly important in countries such as New Zealand and Japan where past earthquakes have caused widespread damage and socioeconomic loss. Research is being carried out to investigate a seismic-resilient engineered foundation-soil system for low-to-medium-density low-rise residential housing composed of a layer of granulated tire rubber (GTR) and gravel, and a flexible rubber–concrete raft foundation. It is essential to ensure that such innovations do not result in long-term negative impacts on the environment as tires contain hazardous compounds used in their manufacturing and the steel fiber within the tires can leach heavy metals (e.g., zinc, manganese, lead, cadmium). Preliminary batch leaching tests undertaken on (1) GTR and (2) GTR: gravel mixtures (20–40% rubber content by volume) indicated leaching of calcium (Ca), sodium (Na), magnesium (Mg), and potassium (K) which was contributed to the gravel and low levels of zinc (Zn), which were attributed to the tires.

Post-tensioned timber (Pres-Lam) buildings have been constructed throughout the world, beginning in 2010. The technology, which originated from low-damage concrete building applications, re...

This design concept was originated in response to a government-sponsored design contest for the North Frame Pedestrian Bridge (NFPB). The bridge, located on the Ōtākaro/Avon River in Christchurch, ...

The health monitoring of civil infrastructure is becoming more common for investigating actual structural behaviour, allowing early damage detection and helping to protect critical structures. In the New Zealand infrastructural context in particular, the introduction of high-productivity motor vehicles (HPMVs) along with the damage caused by recent earthquakes has resulted in a growing need for verification that bridges are performing as expected. The application of “classical” instruments such as accelerometers and linear variable differential transformers (LVDTs) are very expensive due to high installation costs and the need for a continuous power supply. However, radar interferometry is a promising alternative which can detect structural displacements without directly accessing the bridge, offering not only time and cost savings but also the capability to investigate structures where access is difficult or hazardous. This paper presents a health assessment of a bridge crossing the Rangitata Riv...

Since 2010, twelve post-tensioned timber (Pres-Lam) buildings have been constructed throughout the world. In high seismic areas, Pres-Lam technology typically combines unbonded post-tensioning tendons and supplemental damping devices to provide moment capacity to beam-column, wall-foundation or column-foundation connections. Over time creep within the timber elements leads to losses in post-tensioning forces reducing the connection moment capacity. This paper analyses how different post-tensioning loss scenarios, depending on the beam-column joint detailing, impact the building’s seismic response. Two case study buildings were designed and investigated using the Acceleration Displacement Response Spectrum (ADRS) method and Non-Linear Time History Analysis (NLTHA) to predict seismic performance. These buildings were considered to be located in areas of high and low seismic risk, leading to designs with and without the use of damping devices, respectively. The results show that the building with additional damping responded with similar peak displacements, even under extreme loss scenarios. In comparison, when supplemental damping was not used, peak displacements increased significantly with post tensioning losses.

Since 2010, the construction of post-tensioned wooden buildings (Pres-Lam) has been growing rapidly worldwide. Pres-Lam technology combines unbonded post-tensioning tendons and supplemental damping devices to provide moment capacity to beam–column, wall–foundation, or column–foundation connections. In low seismic areas, designers may choose not to provide additional damping, relying only on the post-tensioning contribution. However, post-tensioning decreases over time due to creep phenomena arising in compressed timber members. As a consequence, there is a reduction of the clamping forces between the elements. This reduction affects the seismic response of Pres-Lam buildings in the case of low- and high-intensity earthquakes. Therefore, understanding and accounting for the post-tensioning losses and their uncertainty are paramount for a robust assessment of the safety of Pres-Lam constructions. So far, however, there have been no comprehensive studies which tackle the overall seismic performance of such systems in the presence of time-varying post-tension losses and the associated uncertainty. This study tackles this research gap by introducing a comprehensive seismic evaluation of Pres-Lam systems based on time-dependent fragility curves. The proposed fragility analysis is specifically designed to account systematically for time-varying post-tension losses and the related uncertainty. The method is applied to two case studies, designed, respectively, with and without supplemental damping devices. In terms of structural performance, results show that the use of additional dissipaters mitigates the effect of post-tensioning loss for earthquakes of high intensity. Conversely, performance under low-intensity earthquakes is strongly dependent on the post-tensioning value, as the reduction of stiffness due to the anticipated rocking motion activation would lead to damage to non-structural elements.

Pres-Lam technology relies on unbonded post-tensioning tendons to provide moment capacity to timber beam-column, wall-foundation, or column-foundation connections. When designing buildings ...

Lessons from recent earthquakes have provided a tough reality check of the current seismic design approach, highlighting a critical mismatch between societal expectations over the reality of seismic performance of modern buildings. The performance-based design criteria and objectives need a paradigm shift towards low-damage design philosophy and technologies that should The project provided the opportunity to coordinate a unique research effort for the development and possible future implementation in the European Environment of an integrated low-damage building systems, including structural skeleton and non-structural components for the next generation of buildings.embrace the entire building system. The final goal is the development of a cost-affordable high-performance building system, including structural skeleton, non-structural elements, services and soil foundation systems, capable of sustaining a design level earthquake with limited damage, controllable socio-economic losses and minimum disruption of business. The modern society is waiting for an “earthquake proof” and eco-friendly building at affordable costs. This paper provides an overview and the preliminary results of the EU-funded SERA project titled “(Towards the) Ultimate Earthquake proof Building System: development and testing of integrated low-damage technologies for structural and non-structural elements”. A damage-control building system based on post-tensioned rocking and dissipative mechanisms that combines self-centering and dissipating capabilities was “dressed” with traditional or lowdamage enclosures and fit-outs. A two-storey 1:2 scaled fully prefabricated and dry-assembled building with two bays timber-concrete low-damage seismic frames in one direction and post-tensioned rocking dissipative timber low-damage seismic walls in the other direction was designed and pre-assembled in Italy, then transported and tested on the 3D shaking table of the National Laboratory of Civil Engineering (LNEC) in Lisbon. The building also comprised two different flooring systems, namely a timber-concrete composite floor (TCC) at the first level and a prestressed timberconcrete floor (3PT) at the second level. Three test stages were performed: 1) the bare structural skeleton solution; 2) the structural skeleton including internal gypsum partitions and 3) the integrated skeleton + envelope system. Exterior GFRC panels in the frame direction and spider glazing systems in the wall direction with an internal low-damage clay brick infill wall were investigated during the last stage. Preliminary test results will be herein discussed After many cycles of input motions at different seismic intensities, the integrated low-damage system proved a very high seismic performance, confirming the unique potential of low-damage building system and the opportunity for their widespread implementation in the design and construction practice.

The concept of post-tensioned timber structures has been developed and implemented since 2005. The technology relies on unbonded post-tensioned timber elements to create a moment-resisting ...

Since 2010, twelve post-tensioned timber (Pres-Lam) buildings have been constructed throughout the world. The technology relies on unbonded post-tensioning tendons to provide moment capacit...

This design concept originated in response to a government-sponsored design contest for a ‘North Frame Pedestrian Bridge'. The bridge, located along the Ōtākaro / Avon River in Christchurch, New Zealand, is one of a series of projects contributing to post-earthquake recovery for a rebuilding city that seeks to attract people to visit and live, while retaining its unique identity. The contest stipulated that engineers and artists must collaborate to produce the design. In response, the University of Canterbury established a design team of senior Engineering and Fine Arts students, supervised by three professors. The brief required the team to combine a strong design aesthetic with a tightly constrained and functional built object. This resulted in a unique design, fitting for inclusion in the public art collection, whilst also being capable of moving pedestrians and cyclists safely and effectively over the river. The design speaks to Christchurch's post-earthquake rebuild on many levels. For example, referencing the pre-colonial river by embodying the Māori eel trap form (the hīnaki), yet, composed of post-colonial modern materials. With its implications of constraint and sustenance, it conceptually encourages the viewer to pause and consider the relationship between the natural, spiritual and human worlds. The structural system, based on a weathering steel tridimensional “Vierendeel” girder/truss, also responds to the artistic form of a traditional Māori fishing net. Both truss and trap are made of repeated rings, of variable size, and connected by an organic net. As the design is currently under tender, further details of the design concept will be revealed after the bid disclosure.

Many seismic events, heavy damage and failures of Unreinforced Masonry (URM) walls proved to be both a considerable economical loss and a serious hazard for human safety. URM infill walls affect both the strength and the stiffness of Reinforced Concrete (RC) frame structures undergoing lateral loads. A few macro-models that include out-of-plane actions were proposed, but limited studies have shown their application to realistic RC frame structures. The calibrated M&G model has been applied to the infill walls in RC planar frames representative of low-rise buildings. Nonlinear static pushover analyses are performed on the frames with the simultaneous application of static forces on the walls elements in the out-of-plane direction. The panel is modelled by using two elastic beams with an out-of-plane plastic hinge in the contact point. When the central node excesses the pre-defined in-plane/out-of-plane displacement domain, the panel is removed without interrupting the analysis.