Vol. 36 – 40

SESOC President Report

Brooke, N
Abstract
 

Note from the Editor

Stewart Hobbs
Abstract
 

Letter to the Editor

John Scarry, Roger Shelton
Abstract
 

Fellows Awards Dinner 2023


Abstract
 

Professional Indemnity Insurance

Engineering New Zealand.
Abstract
Engineering New Zealand is frequently asked why we recommend retaining a statement of $200,000 Professional indemnity (PI) insurance minimum on our producer statements. This article explains why PI insurance is required, why we recommend not changing the standard amount on the producer statement, and possible alternatives to increasing the minimum. 

Specifying concrete with lower up-front carbon

Carman, N., Cook, D., Denmead, P., Gibbs, M., Keen, J., Moses, P., Riley-Smith, H., Toma, C.
Abstract
What can structural engineers do to lower the up-front carbon of buildings and infrastructure that we are designing?

Items that have a large influence on carbon (such as changing building form or changing material) are often perceived as difficult to implement on projects. However, there are other relatively simple steps that structural engineers can take to reduce the up-front carbon of projects. The maxims to build nothing, build less and build clever should always be the starting point as shown in Figure 1, but next in line is to specify low carbon.
One of the simplest and most impactful ways for a structural engineer to reduce the embodied carbon of a project is by changing how our materials are specified, noting that Building Code structural performance and durability requirements still need to be met. Steel and concrete make up the majority of the up-front carbon of structures and therefore should be the subject of the most scrutiny.

This article provides recommendations on how concrete with lower up-front carbon can be specified. 

NBS Rating Liability

Engineering New Zealand
Abstract
UPDATE
A New Building Standard (%NBS) rating is information derived from seismic assessments. Purchasers and lessees often rely on these assessments when entering property transactions. However, %NBS ratings are a common area for dispute.

This year in TADD Management Ltd v Weine, the High Court reviewed the liability of a vendor and their engineer regarding a 60%NBS (obtained through an Initial Seismic Assessment (ISA)) which was used in marketing material of the property but was substantially different to later %NBS ratings of 10% and 30% (in two Detailed Seismic Assessments) by other engineers.

The court held the vendor liable to the purchaser for $592,000 due to contractual misrepresentation and common mistake. Because it found the vendor liable, and because the vendor had joined the engineer to the proceedings, it was required to consider whether the
engineer was liable to the vendor in negligence, breach of contract or breach of the Fair Trading Act 1986. 

Warehouse review findings report

Engineering New Zealand
Abstract
EXECUTIVE SUMMARY
Following the Masterton buildings inquiry, Engineering New Zealand Te Ao Rangahau commissioned a review of 20 warehouses across New Zealand to understand if issues of poor design quality observed in the Masterton cases were seen elsewhere.

The results of the Warehouse Review suggest issues relating to poor design and internal quality control seen in the Masterton buildings are not isolated. Some design engineers are incorrectly designing or leaving out critical details in their design of warehouses; for example, the restraint of large concrete panels is a commonly-identified issue. Inadequate restraint of a panel may present a life safety risk if it were to collapse in an earthquake.

As a result of this review, Engineering New Zealand will partner with collaborating technical societies and other relevant organisations to provide guidance for better engineering practice as it relates to warehouse design. We will work with stakeholders to disseminate the guidance and educate engineers.

This report is intended for engineers and building consent authorities. If you own a warehouse and have questions about its design, please contact a Chartered Professional Engineer for review. 

Don't forget the `weld' in welded beams and columns

Scarry, J.
Abstract
The electric arc welding together of two flange plates and a web plate to form a doubly symmetric H section for buildings used to be reserved for large girders and very large columns that were deeper or heavier than the largest rolled sections available.

However, recent decades have seen doubly symmetric welded beam and column sections produced in New Zealand on a regular basis, or imported from steel mills in Australia and Asia. Improvements in fabrication equipment and fabricator productivity have improved the cost-competitiveness of welded sections. 

Unified approach for the seismic design of Moment Resisting Concrete-To-Concrete Connections

Borosnyoi-Crawley, D., Genesio, G
Abstract
Post-installed rebar systems provide a versatile way for concrete-to-concrete connections and are used extensively in the building of new concrete structures and also the seismic retrofitting of existing reinforced concrete structures. Post-installed rebars can provide significantly higher bond strength compared to cast-in straight rebars under confined conditions.

Until recently, international guidelines did not allow the utilization of this higher bond strength in design. The European Organization for Technical Assessment (EOTA) recently published Technical Report TR 069 for seismic design of post-installed rebar connections with improved bond-splitting behavior. This document represents the current state-of-the-art in the seismic design of concrete-to-concrete structural connections.

EOTA TR 069 allows the design of moment resisting connections with post-installed rebars under static, quasi-static, and seismic loading conditions without the need for an overlap splice configuration. The injection mortar systems are required to be assessed by European Assessment Document EAD 332402, and as such, their real bond performance is utilized for design, not limiting it to the performance of cast-in rebars.

This paper provides an overview of TR 069 together with a literature review of its development and recommends future actions for its adoption in New Zealand. 

Structural options for a 12-storied timber hybrid building

Iqbal, A
Abstract
Design options for a conceptual building with a concrete podium, timber or concrete core, and timber structural systems for the balance of the building are explored. The building is designed to be used for commercial occupancy. The assumed location is in Vancouver, Canada, which is a region with high seismic risk and considerable wind load. Timber is intended to be the primary material for the structure, although limited use of other materials is considered for the design.

The structural systems include concrete and concrete-timber hybrid cores in combination with frames, shear walls, and braced frames. The design concepts and various structural system combinations found suitable are compared for their relative merits. This design exercise confirms the feasibility of structural systems as well as provides insights into practical design aspects. 

CROSS Report


Abstract
 

Building code system & standards activity update


Abstract
 

ENZ Technical groups Feb report


Abstract
 

MBIE Updates


Abstract
 

News from the Regional Structural Groups


Abstract
 

SESOC Emerging Structural Engineers Report


Abstract
 

SESOC Membership Report


Abstract
 

SESOC Treasurer's Report


Abstract
 

SESOC President Report

Brooke, N
Abstract
 

Notes from the Editor

Stewart Hobbs
Abstract
 

Letter to the Editor

Brooke, N, Donnell, B. , Aliloom, A.
Abstract
 

SESOC Engineering Excellence Awards


Abstract
 

Sustainable design at SESOC Conference 2023


Abstract
 

SESOC Conference June 2023


Abstract
 

NBS Rating Liability

Engineering New Zealand.
Abstract
UPDATE
A New Building Standard (%NBS) rating is information derived from seismic assessments. Purchasers and lessees often rely on these assessments when entering property transactions. However, %NBS ratings are a common area for dispute.

This year in TADD Management Ltd v Weine, the High Court reviewed the liability of a vendor and their engineer regarding a 60%NBS (obtained through an Initial Seismic Assessment (ISA)) which was used in marketing material of the property but was substantially different to later %NBS ratings of 10% and 30% (in two Detailed Seismic Assessments) by other engineers.

The court held the vendor liable to the purchaser for $592,000 due to contractual misrepresentation and common mistake. Because it found the vendor liable, and because the vendor had joined the engineer to the proceedings, it was required to consider whether the
engineer was liable to the vendor in negligence, breach of contract or breach of the Fair Trading Act 1986. 

Design advice for FRP ties on diaphragms

de/ Rey Castillo, E., Kanitkar, R., Borwankar, A., Niroomandi, A., Rogers, R
Abstract
Concrete floor diaphragms of existing buildings are often inadequate to resist tension forces developed as the diaphragm spans between the lateral load resisting elements. A common
strengthening method to provide additional tension capacity is through fibre reinforced polymer (FRP) ties. However existing research is not applicable because it was conducted on thin and short
FRP ties which are dissimilar to those typically required for diaphragm strengthening applications. This paper summarises the progress to date on an extensive research programme, including
experimental testing on thick and long FRP ties, and a summary of the upcoming work. More importantly, specific FRP detailing advice is provided which is intended to prevent inadequate designs that may result in undesirable
premature failure modes occurring during an earthquake. This advice is to: a) use an FRP design strain significantly lower than the fracture strain of the FRP and compatible with the deformation tolerance of the
floor system, b) provide robustness and redundancy in the FRP detailing to protect the building against unpredictable performance through FRP anchor detailing, and c) consider the expected global
ductility and deformation of the structure, specifically any damage that may be induced in the slab due to deformation incompatibilities and the corresponding impact on any FRP ties.
This project is still underway, so this paper is not to be taken as specific design guideline. More content will be published in the coming months. 

Case study: CRL Te Waihorotiu Station - Sustainability in design and construction

Page, E.
Abstract
The City Rail Link (CRL) engaged Link Alliance to design and build all station structures on Auckland’s $5.5 Billion underground railway project. The structures include two new underground
rail stations – Te Waihorotiu located beneath Albert Street, extending between Wellesley and Victoria Streets, and Karanga-a-Hape, between Beresford Square and Mercury Lane. The existing
Maungawhau surface station is to be redeveloped, and twin bored tunnels will connect the stations extending from Albert Street to Maungawhau where they bifurcate through a grade-separated
interchange. The CRL is the largest transport infrastructure project ever to be undertaken in New Zealand. It is estimated that it will allow the current rail network to at least double in capacity to cope with 54,000 passengers an hour at peak travel times, and is the catalyst for reshaping a vibrant and sustainable city for people to live in. This paper focuses on the sustainability objectives of the CRL project and aligning these with cultural, industry, and global initiatives to positively contribute to the environment and society. The paper will discuss the initiatives adopted during the design and construction of the Te Waihorotiu Station to achieve the sustainability targets; how efforts toward these targets were measured during the station’s progression; and a review of the lessons learnt and the future/legacy of sustainable design in major projects. 

Capacity design of nominally ductile shear wall systems in New Zealand

Blackbourn,T.
Abstract
The current provisions of NZS 3101:2006 (and its interaction with NZS 1170.5:2004) provide ambiguous instruction on the requirements for the capacity design of nominally ductile shear wall systems. The recent release of the National Seismic Hazard Model update, along with Earthquake Design for Uncertainty document, has been a timely reminder of the criticality of capacity design, even for nominally ductile structures. This paper highlights the perceived confusing aspects of the current requirements of NZS 3101:2006 and proposes a design pathway for a variety of wall-based structural systems that addresses compliance and best-practice requirements. 

Design and construction of the Christ Church Cathedral foundation retrofit

Schwass, L.K.
Abstract
The Christ Church Cathedral is a major landmark at the heart of Christchurch and has long been considered an iconic symbol of the city. In the 2010/2011 Canterbury earthquake sequence the
Cathedral sustained severe damage, leading to the building’s closure. In 2017 the Synod endorsed a solution to retain and reinstate as much of the Cathedral’s historic and cultural significance as possible. The primary feature of the reinstatement and strengthening of the Cathedral is introducing seismic isolation at the base. This paper focuses on design of the raft foundation below the isolation system, which was a complex and staged design requiring an innovative and collaborative design response. The two key evolving drivers as the design progressed were geotechnical considerations and construction sequencing. As understanding of the site and liquefaction design developed, and construction sequences evolved with the contractor, the number of load cases required to be analysed increased significantly. Dynamic tools such as grasshopper provided an effective way to respond to increasing complexity in foundation analysis and process the large quantity of data to provide an efficient and robust design. The complexity of design cases considered in the Cathedral foundation also highlighted a number of gaps in industry guidance and understanding. Ultimately more development is required at an industry level around liquefaction design, soft spot analysis, and combining static and dynamic soil conditions, to determine appropriate approaches to the increasing complexity of foundation design. This will be critical in providing a consistent benchmark for foundation design in the future. 

New horizons in the fire resistance of post-installed rebar connections

Borosnyoi-Crawley, D., Roessle, M., Kundu, K
Abstract
Post-installed rebars (PIR) provide versatile solutions for the rehabilitation and strengthening of existing concrete structures or for new concrete construction by offering a feasible and economical method for adding concrete sections to existing members. This paper provides a summary of the fire design of post-installed rebar connections according to Eurocode 2, where the system holds an ETA (give long-form of ETA at first instance) assessed as per European Assessment Document (EAD) 330087 and provides recommendations for the fire design of stress development and splicing of post-installed rebar connections in New Zealand, using the logic of Clause 4.10 of NZS 3101 that delegates the fire design to Eurocode 2 or other recognised method of calculation. It is demonstrated that a straightforward and transparent approach can be recommended for the adoption of EAD 330087 for the fire design of stress development and splicing of post-installed rebar connections based on NZS 3101 for scenarios of uniform temperature distribution along the development length or the splice length during a fire event. 

Recent New Zealand PhD thesis abstracts from University of Auckland and University of Canterbury

CROSS Report


Abstract
 

Building code system & standards activity update


Abstract
 

MBIE updates


Abstract
 

SESOC Emerging Structural Engineers Report


Abstract
 

SESOC Bridge Reports


Abstract
 

IStructE & Bridge Report


Abstract
 

News from the Regional Structural Groups


Abstract
 

SESOC Membership Report


Abstract
 

SESOC Treasurer's Report


Abstract
 

SESOC President’s Report

Brooke, N.J.

Abstract

 

Note from the Editor

Hobbs, S.

Abstract

 

Letter to the Editor

Stuart, T., Brooke, N.J.

Abstract

 

Upfront & whole-of-life embodied carbon: what structural engineers need to know

Symons, K., Moses, P., SESOC Sustainability Task Force

Abstract
The term ‘embodied carbon’ is now commonplace in structural engineering. Working knowledge or at least familiarity with the concept of the emissions associated with building structures is fast becoming something expected from the engineers who design and specify them. Reducing the embodied carbon of their designs has been shown to be an extremely effective action structural engineers can take to address the climate emergency1.

You can’t manage what you don’t measure, so calculation or assessment of embodied carbon is the first step to reducing these emissions.

The idea of assessing ‘whole-of-life’ embodied carbon of a building, which requires estimating emissions associated with processes and activities that will occur many years in the future, can be both daunting and confusing. In line with SESOC’s Position Statement on Sustainable Design2, this paper is intended to support structural engineers to understand the difference between upfront and whole-of-life emissions, and the relative impact of actions to reduce these emissions.
 

Understanding carbon emissions of structural timber products: the full story

Moses, P., Oliver, L., Symons, K.

Abstract
Structural engineers are increasingly being expected to engage with and talk about the relative benefits of different structural solutions and materials with respect to their embodied carbon outcomes. Engineering New Zealand has just released Draft Practice Note 32: Climate Action – the role of the engineer1. SESOC also has a position statement on Sustainable Design2. In this context, it becomes increasingly important that structural engineers understand the carbon profile of different structural materials.

The carbon profile of structural timber products is complex. Before talking about the sources of carbon emissions and removals over the lifetime of a timber product, it is helpful to understand the underlying concepts. Therefore the first part of the article discusses the carbon cycle as it relates to trees, and explains sequestration and biogenic carbon. The second section discusses carbon emissions in the timber industry, and what to consider when designing and specifying timber on a project for lower-carbon outcomes.
 

Building a hybrid future together - Seminar

Hybrid Buildings Seminar

Abstract
On 2 November 2023, Timber Unlimited hosted a Hybrid Buildings Seminar in Auckland in collaboration with the Timber Design Society (TDS), aimed at discussing current practice in the industry especially as it relates to engineered timber.

Timber Unlimited is a collaboration between the New Zealand Timber Design Society, Wood Processors and Manufacturers Association, BRANZ and SCION. Timber Unlimited is hosted at SCION Research and is financially supported for establishment through the Ministry for Primary Industries.
 

Updating New Zealand’s guidance for seismic assessment of existing concrete buildings

Brooke, N.J.

Abstract
It is five years since the technical guide used as the basis for seismic assessments of existing concrete buildings in New Zealand was last updated. Since that update, use of the guide and ongoing research has led to identification of aspects of the guidance document that warrant further improvement. To address this need, Compusoft Engineering were commissioned to produce change proposals for Section C5 and other related parts of the guidance.
Key change proposals include:
• Better defining the intent of assessments in Section C1,
• Changes to Section C5 to improve assessment of splices and mechanical connections, to include guidance for corroding structures, to resolve contradictions related to stiffness modifiers, and improving the clarity of provisions aimed at preventing loss of gravity load carrying capacity,
• Improvements to diaphragm assessment provisions in Sections C2 and C5, particularly as they relate to collector elements and the impact of wide cracks on diaphragm load paths, and
• Adjusting procedures for assessment of precast concrete floors so that the outcomes align better with experimental results.
While not yet evaluated quantitatively, it is expected that the proposed changes would generally improve
assessment outcomes and lead to higher earthquake ratings for buildings.
 

Paradigm change in the seismic design of post-installed fasteners in New Zealand

Borosnyoi-Crawley, D.

Abstract
The current requirements for post-installed mechanical anchors and post-installed adhesive anchors in New Zealand is given in Section 17.5.5 of NZS 3101:2006 that compare the topic to European documents both for fastener assessment and design. NZS 3101 is largely based on ACI 318 in the majority of its content. In 2023, the ACI 355 Committee updated the old simulated seismic testing protocols of fasteners in both ACI CODE-355.2 and ACI CODE-355.4 which is expected to be acknowledged in the next edition of ACI CODE-318 in 2025. This paper gives an overview of the current challenges in the seismic assessment and design of fasteners in New Zealand, supplemented with a detailed introduction and critical analysis of the current international state-of-the-art, and provides recommendations for immediate, short-term and long-term actions in these topics in New Zealand.
 

CROSS Report



Abstract

 

Building code system & standards activity update



Abstract

 

MBIE Updates



Abstract

 

SESOC Emerging Structural Engineers Report



Abstract

 

SESOC Bridge Reports



Abstract

 

News from the Regional Structural Groups



Abstract

 

IStructE update



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SESOC Membership Report



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SESOC Treasurer’s Report



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