Vol. 26 – 30

President's Report

John Snook

Abstract

 

Note From the Editor

Stewart Hobbs

Abstract

 

Citation - John Hare



Abstract

 

Alert - Anomalous Documentation for Proprietary Products



Abstract

 

Letter to the Editor

Denis Morgan

Abstract

 

Observations from the 2010/2011 Canterbury Earthquakes and Subsequent Experimental Pull-Out Test Program of Wall-to-Diaphragm Adhesive Connections

Dmytro Dizhur, Josiah Campbell, Arturo Schultz, and Jason Ingham

Abstract
The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the initial reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof or floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e. anchorages having plates on the exterior façade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragms. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal mesh sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5o to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein.
 

Simplified Structural Analysis of Cellular Mat Foundations

Asif Iqbal PhD

Abstract
Analytical models for structural analysis of cellular mat foundations are presented here. Winkler springs are adopted to represent the soil and soil properties are assumed constant over the whole area under the foundation and yield-line theory is used to lump the Winkler springs under the slabs to corresponding locations under adjacent floor beams. Superstructure rigidity is not considered the in the analysis. A closed-form solution is discussed initially and then a simplified model is proposed for application in practical designs. The validity of the simplified model is demonstrated through comparison of results with finite-element analysis.
 

Building Seismic Performance - Submission to the Ministry of Business, Innovation and Employment



Abstract
The Structural Engineering Society of New Zealand (SESOC) is pleased to provide its response to the Ministry of Business, Innovation and Employment’s Building Seismic Performance Consultation Document.
 

Secondary Response Analysis of Equipment Floors - A Case Study: Wairau Road 220 kV GIS Building

Sheri Javadian

Abstract
AECOM New Zealand Ltd. was the designer of a new Gas Insulation Switchgear (GIS) building at the existing Wairau Road Substation. One of the main tasks was to generate the response spectrum curves for the main equipment fixing points on the floor slab. A 3D Finite Element model was developed and a series of linear and non-linear Time History Analyses were performed following two different approaches. This paper summarises the findings of this exercise. The results showed that the introduction of soil-structure interaction increased the response by a minimum of 50%. It was also concluded that the method proposed by NZS1170.5 results in conservative responses when the non-linear effects of soil structure interaction were taken into account. The study showed that the analysis based spectra were the governing design criteria, except for the horizontal response in the long direction of the building.
 

Standards NZ and MBIE Updates



Abstract

 

News from the Regional Structural Groups



Abstract

 

Financial and Treasurer's Report

John Snook

Abstract

 

ASEC 2014 Second Call for Papers



Abstract

 

President's Report

John Hare

Abstract

 

President's Report

John Hare

Abstract

 

President's Report

John Hare

Abstract

 

President's Report

John Hare

Abstract

 

President's Report

John Hare

Abstract

 

President's Report

John Hare

Abstract

 

Note From the Editor

Stewart Hobbs

Abstract

 

Letter to the Editor

Simon Dorries, Hugo Jackson, Cameron Smart

Abstract

 

New Zealand Legislation Building Act 2004 - Meaning of Building



Abstract

 

SESOC Higher Qualification and Improved Practice Discussion Paper

John Hare

Abstract

 

Introducing the Engineering Reference Group

John Hare

Abstract

 

100 Years of Stainless Steel

Nancy Baddoo

Abstract

 

'Toys that Save Millions'

Bill Addis

Abstract
Small-scale physical models have been used to determine the most efficient form of pure compression and tensile

structures since the 17th century, and to predict structural behaviour of some full-size structures since the mid-19th

century. This paper traces the development of model testing in the design of building structures from its origins in the

design of bridges and ship hulls in the 19th century, to the design of gravity and arch dams in the early 20th century,

through the early days of designing concrete shell roofs in the 1920s and 30s, to its most sophisticated use in the 1960s

and, in conjunction with computer modelling, in the 1970s. The great strength of model testing was, and is, to deal with

new types of structures without design codes and even without precedent.
 

True Pitch Helixes - Importance to integrity of Screw Pile and Anchor Design

Daniel Coats

Abstract
There are few if any good practice notes or design guides with a specific focus on the importance of quality of

helices employed in the manufacture of screw piles. In this paper we consider the significant effect the quality

of helix plate may have on manufacture, installation and ultimate design capacity and integrity of screw piles.

The objective of this paper is to give an understanding and guidance in specification of helices for screw

piling and anchoring.
 

Prequalification of Mechanical Splices for Reinforcing Bars in Seismic Conditions

Gary Connah

Abstract
This paper examines and compares current guidelines and requirements for the prequalification of mechanical

splices for reinforcing bars in Seismic Conditions as set out in the following major international standards:

” NZS 3101:2006 – Concrete Structures Standard – Part 1 The Design of Concrete Structures

” AC 133:2010  ICC Acceptance Criteria For Mechanical Connector Systems For Steel Reinforcing Bars

” ISO 15835:2009 – Steels for the reinforcement of concrete – Reinforcement couplers for mechanical splices

of bars

The comparison of these international documents demonstrates a significant amount of common understanding but also

highlights a clear opportunity to rationalise and harmonise current practice for product prequalification, amongst these

international design codes.

Like many other areas of building products, the coupler industry is largely self regulated with no industry body to promote

best practice. The need to develop a good set of prequalification requirements as well as a common understanding

assessment process is vital to the continued promotion of fit-for-purpose mechanical splices in the New Zealand market.

Keywords: Coupler, Mechanical Splice, prequalification
 

Design and Modelling of Post-Tensioned Timber Frames Without Supplementary Energy Dissipation

M.P. Newcombe

Abstract
New Zealand innovations in structural timber have led to post-tensioned (PT) timber buildings that are a viable structural

system for multi-storey commercial buildings. Extensive experimental testing and analysis has enabled the development

of analytical methods for modelling the lateral response of PT timber frame structures. Applying these analytical methods

allows the determination of the governing lateral load criteria for a given building.

This paper presents a sensitivity study that identifies the governing lateral loads for PT timber frames. It is examined if

supplementary energy dissipation (SED), that provides hysteretic damping, is effective at reducing the required strength

and stiffness of the frames for seismic design. Multiple performance levels, building heights, locations and building aspect

ratios are considered. For frames without SED, it was found that either serviceability limit state (SLS) or ultimate limit state

(ULS) earthquake loading governed the strength/stiffness of the frame for seismic design. This depended primarily on the

design drift limit for SLS design. For frames with SED, it was found that SLS earthquake will govern the seismic design

(unless SLS drift limits are very large). Hence SED will not reduce the required size of the structural elements and the

amount of post-tensioning in most situations.

Leading on from the conclusion, the consequence of excluding SED on the accuracy of time-history analysis (THA); is examined and modelling approaches are suggested. A key consideration is the elastic damping model. Based on

experimental shake-table test data, a user-specified damping model is suggested. However, if this option is not available,

a tangent stiffness Rayleigh damping model is generally conservative. Time-history results for a 6 storey frame are

presented using two THA packages and the effects of different elastic damping models are examined.
 

Footfall Induced Vibration in Longspan Composite Steel Beams - used in two projects at the University of Auckland

V.N. Patel and R.J. Built

Abstract
Floor vibration due to human activity has become increasingly recognised by structural engineers, architects, and building

owners as an inherent issue in long-span steel framed floor systems. In the past, attention was primarily focused on

strength and deflection serviceability limits. However, as designers seek to push the limits on structural spans, grid

spacings and adopt light-weight, low damping structural steelwork floor systems, more detailed consideration is required

of the design tools and processes available to analyse and predict the vibration performance of floor systems.

Selection from published criteria of an acceptable vibration limit is sometimes possible depending upon the intended

use of the space and the availability of manufacturers data for any vibration sensitive equipment. Building Owners and

User Groups often have little understanding or quantitative feel for what performance the proposed acceptable vibration

limit actually represents. The theoretical predication of vibration performance against actual measured performance can

sometimes vary significantly. This can lead to dispute post-construction as to whether the floor has an acceptable level

of vibration. Post construction remediation of a space that is deemed to be too lively is often difficult, therefore, it is

important that the vibration design criteria proposed are discussed and agreed and the limits of theoretical predications

of vibration performance are clearly understood by all parties at the outset.

Beca Ltd (Beca) are currently in the process of designing two projects at the University of Auckland, utilising long-span

partial-composite cellular steel beams. Both buildings will utilise existing structural frame layouts and foundations. As

the new structure is to be built on the existing foundations, there is a necessity to keep it as lightweight as possible. The

question of vibration sensitivity has been raised as a potential issue as both buildings contain research laboratories. An

in-depth investigation has been conducted into the factors affecting vibration performance in order to give the Client and

User Groups confidence that footfall induced vibration will not be an issue with the proposed floor structure.
 

SESOC Management Committee President’s Report

John Hare

Abstract

 

Note From the Editor

Stewart Hobbs

Abstract

 

Building (Earthquake-Prone Buildings) Amendment Bill

Submission to The Local Government and Environment Select Committee

Abstract

 

Draft 2014 IPENZ Code Of Ethics

Submission to IPENZ Codes of Ethics Working Group

Abstract

 

Confidential Reporting on Structural Safety (Cross)



Abstract

 

Floor Diaphragms

J.M. Scarry

Abstract
Floor diaphragms form a critical component of seismic resistant buildings, but unfortunately, in the main their analysis

and design in New Zealand leaves much to be desired. No worse example exists than the CTV Building in Christchurch.

Despite the critical importance of diaphragms, there is a paucity of code provisions and design guidance relating to them.

Common diaphragm design deficiencies include diaphragms where valid load paths do not exist; diaphragms where the

floors are not properly connected to the lateral load resisting elements, diaphragms that lack adequate flexural capacity

and where re-entrant corners are not properly accounted for, and transfer diaphragms into which the reactions from the

walls above cannot be properly introduced or transmitted.

Three main types of diaphragm action are discussed – ‘inertial,’ ‘transfer’ and ‘compatibility.’ These are, respectively, the

direct inertial load on a floor that must be carried back to the lateral load resisting elements, the transfer forces that occur

when major changes in floor area and lateral load resisting structure occur between storeys, and the compatibility forces

that must exist to force compatible displacements between incompatible elements, such as shear walls or braced frames

and moment frames, or as a result of redistribution.

The author presents a simple Truss Method that allows complex diaphragms to be analysed for multiple load cases,

providing accurate force distributions without the multiple models that rigorous Strut and Tie methods would require.
 

Post-Earthquake Performance of Clarendon Tower Sub-Assemblies

N J Brooke and B J Davidson

Abstract
In the aftermath of the Canterbury earthquakes, the reparability of ductile reinforced concrete moment

resisting frames has been a topic of much discussion. This paper presents results from laboratory testing

of reinforced concrete beam-column sub-assemblies extracted from Clarendon Tower, a 19 storey building

that was damaged by the Canterbury earthquake sequence. Sub-assemblies were repaired and/or retrofitted

before being subjected to quasi-static cyclic loading. By comparison of the results with results from previous

laboratory testing of similar specimens it is shown that the performance of the repaired specimens equalled or

exceeded the performance that would have been expected from undamaged specimens. No effects related

to low cycle fatigue of reinforcement were observed during the testing.
 

High Capacity Connections Using Timber Rivets: From Theory to Practice

Pouyan Zarnani and Pierre Quenneville

Abstract
The development of a structural wood connection providing high load transfer, joint stiffness, and ease of

manufacturing led to the invention of the timber rivets. Timber rivets are hardened steel nails with a rectangular cross

section used in steel-timber-steel connections. Rivets are already part of the Canadian CSA-O86 and American NDS

wood standards. However, there is no closed-form solution for the strength prediction of this type of connection under

brittle failure mode as a result of wood rupture. Also, the standards restrict the use of rivets to specific configurations

and for glulam and sawn timber of some limited species. A design approach is presented which allows the practitioners

to predict the connection capacity associated with different brittle wood failure mechanisms under either longitudinal or

transverse loadings.

An extensive testing regime has been conducted at the University of Auckland and the results verified the proposal and

proved its reliability. A design guide was also developed for timber rivets in Australasian engineered timber products.

Timber rivets have since been used in different timber structures in New Zealand
 

MBIE Update from Standards New Zealand



Abstract

 

News from the Regional Structural Groups



Abstract

 

SESOC Treasurer’s Report and Financial Summary



Abstract

 

A7BS “Concrete Thin Plate” – Alternative shear wall and load transferring plate element in existing building structure retrofit and new structures

Edgar A Agda

Abstract
Innovative and Affordable Alternative Concrete Shear Wall Plate System for Existing Building Retrofit and New

Building Structures

Concrete shear wall structures that were developed since the 1930s are one of the building types that have low susceptibility

to damage that might be caused by earthquakes (SESOC Journal April 2013, p.44 fig 1.). As demonstrated in the areas

where there were incidents of disasters such as earthquakes, tornadoes, cyclones and tsunamis, buildings with shear

walls had high survival rates against structural damage.

Providing a high percentage of shear walls to a building system or even going to the extent of making all walls become part

of the building shear strength provides strength capacities against forces of nature. A concrete shear wall can comprise a

deep beam concrete plate to transfer load on well-planned structural retrofit, anchoring the existing wall to new diaphragm

concrete plate.

The hindrance to the system was the cost, flexibility, constructability and issues related to fire, insulation, noise control,

services, cladding finish and other Building Code requirements.

A well researched and tested innovative shear wall system, used in the last 20 years, has been applied to provide

engineering solutions to a problem faced by the owner of an existing building which is considered a heritage structure.

These successful applications of the system resulted in the development of a new building structure system which

sought to address all the problems in using the existing concrete shear wall system. This new system has been proven

economical, sustainable and workable. It is called the A7BS alternative building system with single or double permanent

cavity form panels. The system currently holds a local Australian patent and an international patent has been applied for.
 

SESOC Management Committee President’s Report

Paul Campbell

Abstract

 

Note From the Editor

Stewart Hobbs

Abstract

 

Letters to the Editor

Colin Gurley

Abstract

 

ASEC 2014 Post Conference Summary

Stewart Hobbs

Abstract

 

Steel Industry Quality Initiative Reduces Risk for Engineers

Alistair Fussell

Abstract

 

SCOSS Reports (IstructE)



Abstract

 

Timber Pole Retaining Walls in Cohesive Soils - Design Variables Investigation

Barry Brown

Abstract
The following is a DRAFT paper produced by Barry Brown FIPENZ CPEng IntPE(NZ) to investigate

the basis of “non-standard” design methods for timber pole retaining walls, why they have arisen,

and whether their use, in fact, can be justified in producing a B1 compliant design.

SESOC members’ comments are sort after in relation to the following draft paper.
 

Concrete Encased Steel Columns - Assessment and Acceptance Criteria for use in Non-Linear Analysis

Dion Marriott

Abstract
An assessment methodology for Concrete Encased Steel (CES) columns using a single (composite) flexural element is

proposed. Assessment is based on the adoption of a backbone curve and rotation limit states of an equivalently reinforced

concrete column, with modifications specific to a CES column. The proposed assessment is intended for use in non-linear

methods of analysis, including non-linear dynamic analysis. This paper provides some background into existing design

standards, analysis methods, and experimental testing of CES columns. Following this background, the proposed assessment

methodology is presented and the response compared to the four cyclic tests on scaled CES specimens. The assessment

methodology compares well, and provides a reasonable level of conservatism when compared to the testing reported herein,

and should prove to be a useful tool until such time as more comprehensive testing on CES columns is undertaken to better

establish flexural, shear, and axial limit states.
 

Soil-Structure Interaction Effects on Tall Buildings with Mat Foundation

A. Iqbal1 and T. M Al-Hussaini

Abstract
Finite element analysis is performed to study soil-structure interaction (SSI) effects on static and seismic response of tall

buildings on mat foundations. Simplified numerical models consisting of beam-column elements and lumped masses are

used to model building superstructure including mat. For the static analysis the soil is represented by equivalent springs

lumped at the foundation nodes. Results from the static analysis show that the mat can be modelled realistically with beamcolumn

elements to represent the thick slabs. It is also found that the superstructure rigidity has some effects on the overall

settlements and bending moments in the mat.

For seismic analysis, the soil is modelled by frequency independent springs with viscous damping. Two and three-dimensional

models for different building layouts are used. Building height is varied from six to ten stories. The influence of soil flexibility on

the response of the mat and the superstructure is studied. Parametric studies are performed to evaluate the effects of different

parameters on the behaviour of the building. It is observed that soil-structure interaction, in general, results in reduced base

shear under seismic loading. SSI effects not only depend on building configuration, but also are very much influenced by

ground motion characteristics. SSI effects are also found to be beneficial for building with mass eccentricity where torsional

response is important.
 

Cost Effective Base Isolation for Houses, Light Commercial Buildings & Schools

Colin Ashby

Abstract
Base isolation can be cost effective, not only for multi-storey buildings but for houses, light commercial buildings and schools.

Allowing the building to simply slide using friction as damping avoids harmonics and keeps things simple and cheap.

The author has tried out some simple experiments to determine the co-efficient of friction of various common materials and

has come up with some interesting results.

The second challenge is to keep the building on the building platform, and a discreet no maintenance used tyre buffer system

is described and has been patented.

The third challenge at least on liquefiable materials is to keep the building level after a seismic event as base isolation does

not work too well on a slope. The author has considered different relevelling methods but has reached the conclusion that

prevention is better than cure. This is perhaps best achieved by constructing a broad short pile/soil raft and taking into

consideration the centre of buoyancy and mass.

A very cost effective base isolation for houses, light commercial buildings and schools is possible even on liquefiable ground

utilising the methods outlined in this paper. Generally the cost is a little more time and effort, half a metre of concrete, a few

old tyres, an extra sheet of DPC and a tub of car polishing wax.
 

Guidelines for Building Failure Investigations

Mike Stannard and Richard Sharpea

Abstract
The New Zealand Government has undertaken a number of investigations into building failures in the last few years –

notably those into the failures of some buildings in the February 2011 Christchurch earthquake. The need to have both more

comprehensive guidelines for undertaking these and the legal powers to enable them has been recognised. The Ministry

of Business Innovation and Employment contracted the development of the guidelines in 2013. This paper describes the

essence of the guidelines, and how it is intended that they will be implemented. Drawing on the wealth of international

knowledge on forensic engineering practice and the recent experiences in New Zealand, a standard operating procedure

has been developed which addresses the competing needs of the emergency responders, coronial imperatives and material

testing. The minimum qualifications of the investigator(s) and the systematic recording of all evidence are covered, as is the

form of the report expected.
 

Design Wind Speeds for Really Temporary Structures

Russell Keays

Abstract
The design wind speeds for temporary structures included in AS/NZS1170 cover the general situation where a structure is

expected to sustain whatever wind might happen over the next 6 months. It does not provide guidance on wind actions that

might occur in the next few hours or days. This paper suggests a method for establishing design wind speeds from forecasts.

It draws on the writer’s experience to show a number of applications in construction, and makes suggestions where existing

guidelines might be reviewed.
 

MBIE News & Update



Abstract

 

News from the Regional Structural Groups



Abstract

 

SESOC Treasurer’s Report



Abstract

 

SESOC Management Committee President’s Report

Paul Campbell

Abstract

 

Note from the Editor

Stewart Hobbs

Abstract

 

Bridge Analysis - Are we Data Managers or Engineers?

Dr Peter Shaw, Dr Ross Pritchard, Dr Rob Heywood

Abstract
The Queensland Department of Transport and Main Roads (TMR) commenced a programme to theoretically assess

the capacities of existing bridges on the freight network in order to develop a family of assessment ratios to facilitate

rapid bridge assessments for permit vehicle applications.

Assessors from consultancies undertaking the capacity checks were required to model a bridge to carry a variety

of reference vehicles and check the structural capacities of bridge components to determine those which were

critical. There was pressure to keep the cost of the assessments down and hence young, inexperienced engineers

undertook the majority of the work.

The results were inconsistent across assessors and some were unexpected considering the design classes of the

bridges. The assessment work was reviewed and some serious issues were uncovered.

Errors were found in modelling and analysis, capacity calculations and application of third party software. The usage

of 3D modelling and moving load generators was problematic.

Many assessors used spreadsheets to automate member structural capacity calculations and process the large

amount of data generated and these were a major source of errors. Quality checking was not effective and showed

a lack of understanding of fundamental engineering principles.

This paper outlines some of the issues uncovered by the TMR reviews, some of the approaches taken to minimise

errors in future assessments and examines the implications of technology and training of engineers, for bridge

analysis, assessment and design.
 

Seismic Assessment and Retrofit of Heritage Steel Buildings in New Zealand

Dr Majid Naderi

Abstract
In the early 20th century, steel frame buildings were built to different standards from those used in modern

construction. Riveted, built-up members and connections were often used, with joints and members encased in

concrete for fire protection. These early steel buildings were designed based upon observations of past building

performance rather than through detailed calculations and predictions of structural behaviour.

The walls were infill masonry or concrete, either unreinforced or very lightly reinforced and floors were typically

cast in place reinforced concrete. The strength and stiffness of the semi-rigid connections and masonry infill as

well as the effect of floor slabs integral with their supporting beams were not well documented and probably not

well understood. Examples of these structures can be found throughout the cities and towns of New Zealand and

many are quite prestigious, in full service and often enjoying heritage status. Developing methods of assessing their

seismic strength and serviceability is a major objective of the paper described herein. Assuming that their seismic

strength is inadequate leads to the further objective of devising a retrofitting technique that will raise their strength to

acceptable levels (without violating the heritage constraints). Seismic strength results from the resistance of the infill

walls and steel frames, coupled together by the floor diaphragms.

A search for candidate buildings due for demolition was undertaken in the hope of obtaining full scale, as-built

beam, column and joint assemblies that could be removed and tested. When this was unsuccessful it was decided

to adopt the archetypal, 1928, 9 storey Hope Gibbons building in downtown Wellington as a case study. It offered

typical construction details, a near complete set of drawings and limited access to sample material properties.

The experimental tests were conducted on half scale replicas of typical internal and external beam-column joints

(including secondary beam stubs, integral composite floor slab and concrete encasing) to determine momentrotation

characteristics, failure mode, and effect of concrete slab, crack development and opportunities for retrofit

methods to enhance seismic performance. This will be explained in the second part of the paper.

The accuracy and validity of current NZSEE recommendations for seismic assessment of steel riveted joints was

discussed and a new function is suggested to replace the current recommendations (Third part of the paper).

The retrofit technique to enhance connection strength, using CFRP will be explained in the fourth part of the paper.

As part of the strengthening plan, time-history and push-over analyses were completed to assess the as-built and

retrofitted strength and stiffness of a typical building.
 

Compatibility Forces in Floor Diaphragms of High Rise Buildings

J.M Scarry

Abstract
Seismically loaded floor diaphragms in multi-storey

buildings incorporating lateral load resisting elements with

different deflection characteristics, for example, a shear wall

core and a perimeter moment frame, are subject not only

to direct inertial forces, but also significant internal forces

that are required to enforce compatibility of deflections

between the various lateral load resisting elements.

Using the Truss Method developed by the author, these

compatibility forces were studied by way of example, using

a 30 storey base building model incorporating a shear wall

core and a perimeter moment frame. Each floor diaphragm

in the base model was modelled as a truss incorporating

compression only diagonal elements. The results of this

study show that these compatibility forces are significant

and must not be ignored in design. However, determining

them requires a significant increase in the modelling and

analytical work over that normally undertaken. The study

identifies several factors that affect the magnitude of these

compatibility forces.
 

The Connection Response of Rocking Timber Walls

M.P. Newcombe

Abstract
Structural systems that incorporate rocking timber walls are becoming more prevalent in New Zealand. Primarily

this is due to the application of new post-tensioned timber systems in several buildings and the increased use

of solid timber construction in the form of Cross-Laminated Timber (CLT), Laminated Veneer Lumber, Gluelaminated

timber (Glulam) and round wood throughout New Zealand.

In the past, simplistic design approaches have been applied to determine the lateral strength of rocking timber

walls, which do not assess the compression stresses in the timber. However, new rocking wall systems can

introduce high axial loads (due to the application of post-tensioning or multi-storey gravity loads) that result in

high compression stresses within rocking connections. Furthermore, for post-tensioned timber walls the forces

in tendons (and hence the lateral strength of the wall) depend on the rotation and the length of the compression

region within the connection. Therefore, more advanced analysis methods are required to evaluate strength and

material strains for these systems.

This paper introduces a new approach for assessing the connection response of rocking timber walls. Using

this approach, the depth of the compression region, the compression stresses in the timber and the moment

capacity of a rocking wall connection can be more accurately determined. The design approach is calibrated

using a Finite Element sensitivity study and is validated using experimental data.
 

Historical Development and Observed Earthquake Performance of Unreinforced Clay Brick Masonry Cavity Walls

Dmytro Dizhur, Xi Jiang, Chengliang Qian, Nasser Almesfer, Jason Ingham

Abstract
An informative background to unreinforced masonry (URM) cavity walls is presented in sequence of historical

development, typical construction details, and observed damage in major past earthquakes. From URM building

surveys it was found that URM cavity walls make up approximately 40% of URM construction in New Zealand,

with the remainder having solid interconnected multi-leaf walls. Based on a detailed review of 125 URM cavity wall

buildings that were damaged during the 2010/2011 Canterbury earthquakes, it was concluded that unretrofitted

URM cavity walls generally suffered irreparable damage due to the lack of effective wall restraint and weak mortar

strength. The majority (approximately ¾) of the observed damage to URM cavity wall construction was a result of

out-of-plane type wall failures. Three types of out-of-plane wall failures that were commonly observed in cavity walls

were: (1) Cantilever type failure with the entire top section of a wall or building façade collapsing (36%); (2) Oneway

bending type failure, which tended to occur in long spanning walls and/or walls without side support (7%); (3); Two-way bending type failure, which tended to occur in walls restrained at all boundaries (57%). In-plane damage

of URM cavity walls was less widely observed (approximately ¼) compared to out-of-plane damage, and commonly

included diagonal shear cracking in piers, spandrels and walls as well as to a lesser extent shear sliding on mortar

bed joints or between building storeys.

It was found that the original cavity wall ties were typically corroded due to moisture ingress. These badly corroded

wall ties further diminished the lateral loadbearing capacity of cavity walls and their resistance to shear and flexural

actions. It was identified that the most commonly encountered ties were horse-toe steel wire ties, having a crosssection

that was typically found to be significantly deteriorated due to corrosion at the mortar bed joints. Pull-out of

wall ties from mortar joints was observed.
 

The 2014 South Napa Earthquake and its Relevance for New Zealand

Bruce Galloway and Jason Ingham

Abstract
The South Napa earthquake occurred on Sunday, 24 August 2014 at 3.20 am local time at a depth of 10.7 km,

having MW 6.0 and causing significant damage to unreinforced masonry (URM) buildings in the City of Napa

and generating strong ground shaking in a region well known for its wine production. Parallels exist between the

damage in past New Zealand earthquakes, particularly to unreinforced masonry buildings, and the disruption in

the Marlborough region following the recent 2013 MW 6.5 Seddon earthquake. Furthermore, the event was the

largest to have occurred in Northern California since the 1989 Loma Prieta earthquake 25 years earlier, and hence

was an important event for the local community of earthquake researchers and professionals regarding the use of a

physical and virtual clearinghouse for data archiving of damage observations. Because numerous URM buildings in

the City of Napa had been retrofitted, there was significant interest regarding the observed performance of different

retrofitting methods.

Following a brief overview of the earthquake affected area and previous earthquakes to have caused damage in

the Napa Valley region, details are provided regarding the characteristics of the 2014 South Napa earthquake, the

response to the earthquake including placarding procedures and barricading, and more specific details of observed

building and non-structural damage. Aspects of business continuity following the South Napa earthquake are also

considered. One conclusion is that in general the seismic retrofitting of URM buildings in the Napa region proved

to be very successful, and provides an important benchmark as New Zealand begins to more actively undertake

seismic assessment and retrofitting of its earthquake prone building stock. It is also concluded that there are sufficient

similarities between New Zealand and California, and a rich network of contacts that has developed following the

hosting of many US visitors to New Zealand in conjunction with the 2010/2011 Canterbury earthquakes, that it is

sensible for the New Zealand earthquake engineering community to maintain a close focus on ongoing earthquake

preparedness and mitigation methods used and being developed in USA, and particularly in California.
 

News from the Regional Structural Groups & SESOC Treasurer’s Report



Abstract

 

SESOC President's Report

Paul Campbell

Abstract

 

Note from the Editor

Stewart Hobbs

Abstract

 

Letter to the Editor

John Scarry

Abstract

 

Cross Report



Abstract

 

Building Act Emergency Management Proposals



Abstract

 

Building (Earthquake-Prone Buildings) Amendment Bill



Abstract
INTRODUCTION

SESOC has a membership of approximately 1600,

most of whom are practising structural engineers. We

are a collaborating technical society of the Institute of

Professional Engineers NZ (IPENZ). Many of our members

are actively involved with providing earthquake prone

building assessments on behalf of building owners.

Additionally, many of our members have participated in

the review of buildings after the Christchurch earthquakes,

some as volunteers in the immediate safety evaluation

phase, many more since in the detailed evaluations as the

recovery begins.

SESOC is non-political and its aim is to contribute to

society and the economy by fostering good engineering

practice in our built environment.
 

TIMBER DESIGN AWARDS 2015



Abstract

 

SEISMIC ASSESSMENT AND RETROFIT OF HERITAGE STEEL BUILDINGS IN NEW ZEALAND

Dr Majid Naderi

Abstract
In the early 20th century, steel frame buildings were built to different standards from those used in modern

construction. Riveted, built-up members and connections were often used, with joints and members encased in

concrete for fire protection. These early steel buildings were designed based upon observations of past building

performance rather than through detailed calculations and predictions of structural behaviour.

The walls were infill masonry or concrete, either unreinforced or very lightly reinforced and floors were typically

cast in place reinforced concrete. The strength and stiffness of the semi-rigid connections and masonry infill as

well as the effect of floor slabs integral with their supporting beams were not well documented and probably not

well understood. Examples of these structures can be found throughout the cities and towns of New Zealand

and many are quite prestigious, in full service and often enjoying heritage status. Developing methods of

assessing their seismic strength and serviceability is a major objective of the paper described herein. Assuming

that their seismic strength is inadequate leads to the further objective of devising a retrofitting technique that will

raise their strength to acceptable levels (without violating the heritage constraints). Seismic strength results from

the resistance of the infill walls and steel frames, coupled together by the floor diaphragms.

A search for candidate buildings due for demolition was undertaken in the hope of obtaining full scale, as-built

beam, column and joint assemblies that could be removed and tested. When this was unsuccessful it was

decided to adopt the archetypal, 1928, 9 storey Hope Gibbons building in downtown Wellington as a case

study. It offered typical construction details, a near complete set of drawings and limited access to sample

material properties.

The experimental tests were conducted on half scale replicas of typical internal and external beam-column joints

(including secondary beam stubs, integral composite floor slab and concrete encasing) to determine moment-

rotation characteristics, failure mode, and effect of concrete slab, crack development and opportunities for

retrofit methods to enhance seismic performance. This will be explained in the second part of the paper.

The accuracy and validity of current NZSEE recommendations, June 2006, for seismic assessment of steel

riveted joints was discussed and a new function is suggested to replace the current recommendations (Third

part of the paper).

The retrofit technique to enhance connection strength, using CFRP will be explained in the fourth part of the

paper. As part of the strengthening plan, time-history and push-over analyses were completed to assess the as-

built and retrofitted strength and stiffness of a typical building.
 

CONCRETE – CURE IT OR KILL IT

Des Bull and John Hare

Abstract
This paper is intended to be a discussion paper, investigating current issues with the curing of concrete,

and proposing a path forward that could work for all of the industry.
 

CROSS LAMINATED TIMBER IN NEW ZEALAND: RESEARCH AND APPLICATION PERSPECTIVE

Asif Iqbal

Abstract
Cross Laminated Timber (CLT) has been one of the latest and most significant types of engineered wood products

developed for structural applications. In the last two decades there has been some remarkable progress in the

technology to use CLT in building structures. Although it arrived in the region later than in Europe and North

America, CLT has quickly gained popularity within the engineering community in New Zealand. There are significant

challenges in applications such as seismic demands. Some research has already been done locally to provide

guidelines for applications. A number of projects involving CLT applications have been completed. There is also

potential that the applications will extend into emerging markets in Asia. Recent research initiatives have been taken

to facilitate further applications are elaborated here.
 

STRUCTURAL FIRE DESIGN FOR STEEL FRAMED CARPARKS

Linus Lim and Martin Feeney

Abstract
This paper presents a guide on a proposed performance based method for the structural fire design of steel framed

carpark buildings. The current NZBC C/AS7 has stringent fire resistance rating requirements for structural elements

of carparking buildings which would require the elements to be protected with passive fire protection. Using this

proposed analytical method, it is possible to quantitatively demonstrate that the beams within a typical multi-bay

steel framed carpark can be unprotected. The methodology involves the analysis of the capacities of composite

steel beams under exposure to realistic vehicle fires. This approach removes the assumption of full compartment

involvement that is assumed by other simpler methods. The localised thermal loading on parts of the structural

beams, localised loss of strength of the beam and redistribution of actions to other beams are also included

in the analysis. The method can also accommodate spread of fire from multiple cars and is flexible enough to

accommodate different thermal loadings due to different types of vehicle fires.
 

STEEL MOMENT FRAME WITH SUPPLEMENTAL FLUID VISCOUS DAMPERS – 12 MOORHOUSE AVENUE A CASE STUDY

Andrew Brown, Masako Uno, Joel Stratford and Josiah Thompson

Abstract
Increasing building damping is an effective method of reducing seismic forces and improving building performance

during earthquake events. The use of supplemental fluid viscous dampers in combination with a conventional

moment frame structure is one application which provides a significant increase in structural damping, as well as

providing low damage design.

This paper provides a case study of a five storey commercial building currently under construction in Christchurch

where supplemental fluid viscous dampers are combined with a steel moment frame structure to provide a dual

seismic resisting system. The paper outlines the analysis and design procedure, from preliminary through to

detailed design, including incorporation of overseas literature and design codes for development of a suitable

New Zealand based design procedure for buildings of this form. We will compare the performance of the structure

designed using DDBD methods with the response of structure predicted by non-linear time history analysis.
 

FATAL ACCIDENT IN DUTCH SWIMMING POOL CAUSED BY ENVIRONMENTALLY CRACKED BOLTS

Jan Heselmans and Peter Vermeij

Abstract
In November 2011 a 5 month old baby sadly got killed in a Dutch indoor swimming pool because 2 speakers and

a speaker frame landed on her head. The speakers fell from a height of 5 meters after a stainless steel bolt was

broken due to environmental cracking. Worldwide there have been many incidents, and several accidents, with

cracking stainless steels in the swimming pool atmosphere. In 1985 in Switzerland 12 people were killed by a

cracked stainless steel element that caused the collapse of a swimming pool roof.

This paper will describe how this accident could happen and what has been done in the Netherlands since 2001,

when the entire ceiling and air channels came down in another swimming pool (luckily this occurred during closing

time). Further a new document MIS1203-2012 will be discussed: “Materials Selection and Inspection of Fasteners

and other Loaded Elements in the Indoor Swimming Pool Atmosphere”.
 

DRILLING, CUTTING OR FORMING HOLES IN CONCRETE SUSPENDED FLOOR SLABS



Abstract

 

NEWS FROM THE REGIONAL STRUCTURAL GROUPS



Abstract

 

SESOC President's Report

Paul Campbell

Abstract

 

Note from the Editor

Stewart Hobbs

Abstract

 

SESOC Joint Presentation Series: Structures and Fire – Briding the Gap



Abstract

 

SCOSS Report



Abstract

 

Development of Guidelines for Engineers Designing and Specifying Buckling Restrained Braced Frames

Kevin Cowie, Greg MacRae and Charles Clifton

Abstract

 

Structural Steel and Composite Items of Interest From Sabbatical Visit

G.C. Clifton

Abstract
From July 2015 to January 2016, Charles Clifton was on sabbatical leave at institutions in the UK, USA and

Canada. This brief, first person report covers items of interest to the New Zealand structural engineering

profession gained from that leave. It covers aspects of fire engineering and earthquake engineering.
 

Impact of the New Codes for Design of Cement Silos

Khaled Eid

Abstract
The new Euro code BS EN 1991-4 actions on silos has significant impact when compared to other commonly

used codes such as the Din 1055 part 6 or ACI313-18 when considering the eccentric discharge , previous

codes state only there will be significant wall moment without stating how to calculate it.

This paper will highlight the impact of the asymmetric loading in designing silos with eccentric discharge by

presenting a practical case study comparison for a 14000 m3 raw meal homo inverted cone silo 52 metre height

and 23 metre diameter designed by ACI and the new Euro code, keeping the same wall thickness to identify the

effect on pre stressing, conventional steel reinforcement, cost and design time.
 

Sequentially Coupled Thermal-Stress Analysis of a New Steel Concrete Composite Slab Under Fire

Nandor Mago, Stephen Hicks and W. Ian Simms

Abstract
The paper describes the numerical simulations required to estimate the performance of a composite slab using

a re-entrant profiled steel sheet, prior to conducting a loaded fire test to verify the performance predicted by

the simulations and obtain a fire rating according to accepted international standards. The purpose of the

simulations was to optimise the design of the composite slab, by eliminating unnecessary reinforcement bars.

Heat transfer analysis involving convection, conduction and boundary radiation was undertaken on a detailed

solid modelled slab as part of a new steel-concrete slab product development. The simulation accounted for the

thermal contact resistance at the cold-formed steel-concrete interface. The novelties of the model to incorporate

the temperature dependent formulation of the interface thermal conductance provided a realistic prediction of

the cross-sectional temperature field, which matched the fire test measurements.

The slab top surface temperatures were assessed according to EN 1363-1:2012 to enable comparisons to be

made with the insulation performance criteria. Following the uncoupled heat transfer analysis, the temperatures

calculated through the thickness were used as an input into a sequentially coupled thermal-stress analysis of an

equivalent shell modelled slab. This was necessary due to the excessive computing time required for the detailed

solid modelled concrete slab that was used for the heat transfer analysis. Nevertheless, the calibrated shell

that represented the composite slab model accounted for the dissimilar temperature-time (T-t) curves through

the slab depth, since the bottom surface, close to the fire source, heats up at a much higher rate than the top

surface. From the explicit-quasi static simulation, the load bearing capacity was calculated, which is expressed

by the limiting largest deflection and deflection rate for flexural loaded structural members as given in EN

1363-1:2012. From these analyses, it was found that the overall fire resistance was limited by the load bearing

capacity criteria.

The predicted insulation and load bearing capacity compared very favourably with the fire test measurements,

which are also presented in this paper, and provides confidence in the methodology used in this study.

Keywords: Coupled, Thermal-Stress, Steel, Explicit, Concrete, Heat Transfer.
 

Structures Testing Laboratory at the University of Auckland Newmarket Campus

R.S. Henry, H.W, Morris, G.C. Clifton, K.J. Elwood and Q.T. Ma

Abstract
A new Structures Testing Laboratory complex with a 14.5 m high test space was constructed at the Newmarket

campus of the University of Auckland and opened in 2015. This world class facility has a 9 m high reaction wall

in two directions, a 20 x 10 m strong floor with basement access, a 3.6 m square 15T capacity earthquake

shake table, an extensive set of test equipment and integrated ancillary laboratories and workshops. The

layout of the lab, the extent and capacity of the more significant pieces of equipment, the overall capability and

management of the facility are described. This facility has been provided to support the high quality research

being undertaken by the structures group in the internationally ranked department of Civil and Environmental

Engineering. There are a number of significant research activities that are initiated in the department, and those

from national collaborations such as QuakeCoRE and international collaborations. In addition, the new facilities

offer increased opportunities for commercial testing projects.
 

Ensuring Compliance of Structural Steelwork - Regardless of Origin

Alistair Fussell, Kevin Cowie, Dr Stephen Hicks and Dr Michall Karpenko

Abstract

 

Effects of Curing on the Performance of New Zealand Precast Concrete

Allan Scott, Brody Halliday, James McLean, Des Bull, Dene Cook and Paul Cane

Abstract
The beneficial effects of water curing on conventionally produced concrete are generally well understood and

supported by the guidance on curing provided in NZS 3101:2006 and NZS 3109:1997. The possible benefits

of additional water curing following the production of precast concrete elements, using elevated temperatures

however, has been the subject of considerable debate in New Zealand and overseas. Heat curing of concrete

provides enhanced strength and durability properties at an early age but is typically viewed as having lower longterm

strength and durability. The results of an investigation on the effects of additional water curing following

accelerated heat treatment of a representative precast concrete mix are presented in this paper and compared

to a conventionally cured general purpose cement concrete mix. The benefits of additional water curing after

heat treatment were marginal compared to the significant impact curing has on the properties of conventionally

cured concrete.
 

Displacement-Based RC Column Assessment for a Case Study Interwar Building

Kevin Q. Walsh, Dmytro Y. Dizhur, Peter Liu, Mostafa Masoudi and Jason M. Ingham.

Abstract
Following the devastating 1931 Hawke’s Bay earthquake, commercial buildings in the Hawke’s Bay, New

Zealand region were rebuilt in mostly homogenous structural and architectural styles. Most were constructed

of reinforced concrete (RC) two-way space frames in the Art Deco aesthetic popularised during the interwar

time period. Although most Art Deco RC columns in Hawke’s Bay have generally ductile detailing for their time

period of construction, they are nonetheless often expected to be brittle, earthquake-prone components based

on strength-based seismic assessments. The reported case study was intended to provide a displacementbased

example for undertaking a seismic assessment of Art Deco RC columns while appropriately accounting

for regional seismicity, material properties, building component interaction, column geometry, and reinforcement

detailing, as a resource for professional structural engineers tasked with seismic assessments and retrofit

designs for similar buildings.
 

Selection of Gap Infill Material for Structural Seismic Applications

Tushar Chaudhari and Gregory MacRae

Abstract
In common construction practice, placing gaps between structural or non-structural elements may allow better,

or more controlled, response than if stiff elements are permitted to contact each other. This paper considers two

situations where gaps in construction may limit damage during earthquake shaking. These are (i) concrete slab

isolation from a steel column, and (ii) non-structural element separation from a seismic frame. The development

of performance criteria for the gapping material is firstly described. Then different materials are tested to evaluate

their ability to match the performance criteria. The evaluation of appropriate material for a given situation is

performed using the Subjective Quantitative Assessment (SQA) considering the following characteristics related

to the material: (a) Compressibility under seismic deformation, (b) Construction compressibility, (c) Fire rating, (d); Water resistance, (e) Elasticity, (f) Cost/Ease of application, and (g) Sound resistance.
 

Delay of Onset of Charring to CLT Using Different Encapsulation Board Materials

T.R. Moser and M.J. Spearpoin

Abstract
The exposed surface of cross-laminated timber (CLT) panels subject to a fully developed fire will undergo

charring which could lead to the loss of structural capacity and/or compromise compartmentation integrity. By

encapsulating the CLT in one or more layers of non-combustible board the effects of the fire can be reduced.

This research evaluated the ability of a single layer of four types of non-combustible board to delay the onset of

charring and affect the initial rate of charring of a CLT substrate at 50 kW/m2 and 65 kW/m2 heat flux exposures

in a modified ISO 5657 ignition apparatus. The research used 13 mm thick standard gypsum, fire-rated gypsum,

12.5 mm thick fibrous board along with 12 mm and 15 mm thick magnesium oxide (MgO) board.

Results from 20 experiments showed the onset of char could be delayed by up to around 26 min for fire-rated

gypsum board at 50 kW/m2 but this reduced to around 15 min for the 12 mm thick MgO board at 65 kW/m2.

Once charring of the CLT substrate began the initial rate is found to be 0.51 ± 0.07 mm/min. When assessed

by their durability, standard gypsum performed the worst showing large cracks such that pieces could easily fall

away, the fire-rated gypsum boards only exhibited some surface cracking whereas the MgO and fibrous boards

did not show any damage. Given that the findings from this research are as a result of a series of bench-scale

experiments care should be exercised in applying the results to real-scale fires.

Keywords: Cross-laminated timber, char, magnesium oxide board, gypsum board
 

News from the Regional Structural Groups



Abstract

 

SESOC President's Report

Paul Campbell

Abstract

 

Note from the Editor

Stewart Hobbs

Abstract

 

Letters to Editor 1 -

Roger Shelton

Abstract

 

Letters to Editor 2 -

Raed El Sarraf

Abstract

 

Questions Raised on Structural Bolts

S. Hicks

Abstract

 

Conformity of Structural Steel Products and Structures

S Hicks

Abstract

 

SCOSS Report



Abstract

 

Some Aspects of the Design of Face Loaded Slender Precast Concrete Wall Panels (SPCWPs)

Gordon Hughes

Abstract
BUILDING REVIEWS, SEISMIC

ASSESSMENTS & CPENG

COMPETENCE
 

Aspects of Design for the Base Isolated Christchurch Justice and Emergency Services Precinct

D. Pettinga & S. Oliver

Abstract
The Christchurch Justice and Emergency Services Precinct is the first of the central government Anchor Projects

to be base-isolated as part of the Christchurch central city re-build. This city-block development houses both

the Ministry of Justice law courts and an amalgamated Importance Level 4 command centre facility for key

emergency services.

The project is unique in New Zealand in that four seismically separated two-way steel moment-frame buildings

benefit from the isolation effects, where the isolation plane is provided at the underside of a common first floor

podium level. The base-isolation system design had performance targets at both the 2500 year ultimate limit

state (ULS) and 7500 year collapse limit state (CLS) return periods, with the final scheme comprising of 50 large

diameter lead-rubber bearings and 82 flat-plate pot-bearings.

The isolation system was designed to the NZS 1170.5 ULS spectrum, however a site specific study also

provided uniform hazard spectra for a range of return periods. This paper summarises the design approach that

met relevant local standards, incorporated the benefits of non-linear time history verification, and provides an

outline to how similar complex isolation projects in New Zealand can be addressed in the future.
 

Structural Risk Assessment of Corroding Infrastructure

B Dockrill, R Melchers, B Eliasson, S Linton and C Herron

Abstract
Structural risk is not the same as corrosion risk. Therefore once assessment of infrastructure confirms corrosion

is active and the mechanism(s) of corrosion are understood this does not necessarily indicate an unacceptable

structural risk. Asset managers, infrastructure owners and stakeholders normally indicate a required service life

requirement. An implicit requirement is meeting structural and other safety requirements as defined by Australian

or other Standards. Maintenance and/or remedial work activities are only supported for the asset to achieve

desired functionality, serviceability, safety, operational and commercial outcomes for its required service life. The

paper explores the differences between structural and corrosion risk and how each of these risk types should

be considered in the assessment, management and maintenance of infrastructure to meet required service life,

structural safety and risk requirements. Some examples are used to illustrate this theme.

Keywords: Corrosion risk, structural risk, infrastructure assessment, service life.
 

Guidance for Authors of Producer Statements



Abstract

 

Sensitivity analysis of the vertical modulus of subgrade reaction, as estimated from CPT for the design of foundations and for comparison with values from SPT for a site in Christchurch

N. Barounis , P. Armaos

Abstract
The recently proposed methodology (Barounis et al., 2013) for estimating the subgrade modulus from CPT as

opposed to the conventional SPT correlation is a simpler, less expensive and quick procedure. CPT derived

values of the modulus for a predominantly sandy site in Christchurch are compared with the conventional

values at the same site correlated from SPT. A number of footings were analysed using common engineering

software. Comments are made on the results that could be the basis of future research with the ultimate target

of presenting a simple, reliable and less expensive tool for geotechnical engineers to estimate the modulus of

subgrade reaction for various soil types.
 

News from the Regional Structural Groups



Abstract

 

SESOC President's Report

Paul Campbell

Abstract

 

Note from the Editor

Stewart Hobbs

Abstract

 

Letters to Editor -

Raed El Sarraf, Tony Stuart

Abstract

 

Structural Engineering CPENG Level Draft Body of Knowledge and Skills



Abstract
STRUCTURAL STANDARDS: HAVE YOUR SAY

The Structural Engineering Society is seeking feedback

on its draft Body of Knowledge and Skills for structural

Chartered Professional Engineers.

The document on the following pages are intended to

define the minimum technical capabilities that a structural

Chartered Professional Engineer (CPEng) is expected

to have in order to competently investigate, design and

supervise the construction of structural works in New

Zealand. This Body of Knowledge and Skills (BOKS); is intended to complement and inform the CPEng

assessment process. The BOKS has been developed to

address concerns about the consistency and quality of

structural engineering.

BOKS are being developed also for geotechnical

engineering and engineering geology.

The document has been developed in response

to concerns raised by industry including SESOC,

Building Consent Authorities, MBIE and the Canterbury

Earthquakes Royal Commission.
 

Submissions to the MBIE - Building Performance Standards Long-term funding projection and Standards



Abstract
This submission has been prepared by members of the SESOC Management Committee. It is intended to reflect the

views of the wider membership of the Society, although only limited feedback has been received.

SESOC is a collaborating technical society of IPENZ, with a membership of approximately 1700, most of whom are

practising structural engineers. Our members are users of New Zealand Standards and use them on a daily basis as

part of the regulatory process in the building industry. The majority of our members will be interested in the structure

area, however we also collaboratively work with other disciplines in associated areas such as geotechnical and fire.
 

Submissions to the MBIE - Proposals for Regulations under the Building (Earthquake-Prone Buildings) Amendment Act 2016



Abstract
This submission has been prepared by members of

the SESOC Management Committee. It is intended to

reflect the views of the wider membership of the Society,

although only limited feedback has been received.

SESOC is a collaborating technical society of IPENZ,

with a membership of approximately 1700, most of

whom are practising structural engineers. Many of our

members undertake building assessment reviews and

will be responsible for carrying out reviews under these

proposed regulations.
 

Submissions to the MBIE - Proposals for a methodology to identify earthquake-prone buildings



Abstract
This submission has been prepared by members of the SESOC Management Committee. It is intended to reflect the

views of the wider membership of the Society, although only limited feedback has been received.

SESOC is a collaborating technical society of IPENZ, with a membership of approximately 1700, most of whom are

practising structural engineers. Many of our members undertake building assessment reviews and will be responsible

for carrying out reviews under this proposed methodology.
 

SCOSS Report



Abstract

 

Basis for and Implications of Key Changes to 2016 Structural Steel Product Standards

Alistair Fussell, Kevin Cowie, Stephen Hicks, Michail Karpenko

Abstract
In April 2016, the suite of AS/NZS structural steel

product standards were republished (AS/NZS 1163,

3678, 3679.1-2) (SA/NZS, 2016). This paper provides a

summary of the key changes, the basis for these changes

and interim recommendations until full supply of steel

products to the latest standard is available.
 

Air New Zealand Hangar Extension 1976

A reflection by David C Hopkins

Abstract
This major structural modification enabled Air New Zealand to service two DC10 aircraft under cover adjacent to their existing workshops. It was the second alteration to the original hangar which was built to take three DC8 aircraft.
 

Effect of Boundary Conditions and Other Factors on URM Wall Out-of-Plane Behaviour: Design Demands, Predicted Capacity, and In Situ Proof Test Results

Kevin Q.Walsh, Dmytro Y. Dizhur, Ivan Giongo, Hossein Derakhshan and Jason M. Ingham

Abstract
Unreinforced masonry (URM) building construction is prominent in the form of loadbearing, partition, and infill

walls. Significant out-of-plane (OOP) failures of URM walls often occur during moderate and severe earthquake

shaking and such walls are often identified in structural engineering assessments as being amongst the most

vulnerable elements to OOP demands, especially earthquakes. For undamaged, in situ wall conditions where

material properties are known and boundary conditions reflect idealised conditions assumed in analytical predictive

models, these predictive models are easily applied, although the accuracy of the model outputs may still not be

well understood. Furthermore, when in situ conditions do not reflect idealised conditions assumed in analytical

predictive models, engineers are often uncertain as to which analytical models and inputs are most appropriately

applied. Hence, experimental and analytical campaigns were undertaken to provide specific examples for structural

engineering practitioners assessing the OOP seismic behaviour of URM walls. A total of nineteen experimental

proof tests were performed in situ in six different buildings. The considered wall configurations represented a variety

of geometries, boundary conditions, pre-test damage states, and material properties. It was observed that twoway

OOP flexure as compared to one-way vertical OOP flexure, can substantially improve the OOP load-carrying

capacity of tested infill walls, and that the boundary restraints and presumed “arching’ action in walls bounded by

the building frame can greatly increase the OOP capacity of URM walls. The effects of simulated in-plane damage

on the OOP capacity of a URM infill wall was also investigated, and the damage was found to reduce out-ofplane

strength by up to 40%. The experimental results were compared to predictive results for eighteen of the

tests. The average ratio and associated coefficient of variation (CV) of predicted strengths to measured strengths

were determined to be 0.84 (CV 0.56) and 0.93 (CV 0.25) for the “unbounded” and “bounded” wall conditions,

respectively.
 

A Direct Displacement-Based Seismic Design Procedure for Moment Frames with Non-Linear Viscous Dampers - Part 1: Development of the Design Procedure

Dion Marriott

Abstract
This paper presents a Direct Displacement-Based Design procedure for ductile moment frames equipped with

non-linear viscous dampers (NLVD) or linear viscous dampers (LVD). The design procedure is termed Direct DBDViscous,

and was developed for use within a new design or retrofit design environment. The proposed design

procedure differs from existing procedures in that equivalent viscous damping (EVD) relationships have been

developed and calibrated to non-linear response history analyses, employing both far-field and near-fault ground

motions. The procedure focuses on relating the local damper properties of the braces at each level to an equivalent

global damping coefficient of the SDOF substitute structure for use within an existing Direct-DBD framework. The

design procedure is first presented for an elastic SDOF viscous-only system, and is then extended to MDOF ductile

moment frame systems. In a companion paper, the design procedure is verified through an analytical study of three

prototype frame buildings using non-linear time history analysis.
 

News from the Regional Structural Groups



Abstract

 

SESOC President's Report

Jason Ingham

Abstract

 

Note from the Editor and Obituary

Stewart Hobbs

Abstract

 

SESOC Committee



Abstract

 

Letters to Editor -

John Scarry

Abstract

 

Seismic tests on moment resisting stainless steel connections

HERA

Abstract

 

The Seismic Restraint of Building Services or the Lack Thereof

John Scarry

Abstract
On 26 July 2017 I had the pleasure to attend a very

interesting all day seminar in Wellington on what the face

of it would be a less than riveting subject – the seismic

restraint of building services. ‘Our Workplace – Open for

Business’ was organised by John Lucas of the Insurance

Council of New Zealand, and attended by contractors

who install building services, materials manufacturers

and suppliers, architects, structural and building services

engineers, academics involved in relevant research, central

and local government representatives, insurers and re-

insurers. The speakers were similarly diverse. There was

plenty of time for questions, and there was significant

audience participation.

For many, the most interesting, and alarming, presentation

was from Terry Johnson of Reveal Seismics Ltd. Terry has

been involved in the installation of building services since

the early 1980’s, and for many years now has campaigned

for the consistent and proper seismic restraint of building

services. Terry said that it has been 34 years since a

NZ standard for the seismic restraint of building services

was introduced, NZS 4219:1983, yet despite his vast

personal experience and network of contacts, he said he

is not aware of 34 commercial or institutional buildings

that actually have comprehensive let alone fully compliant

seismic restraint of building services – less than one

building a year since the standard was introduced.

This is simply not good enough. Leaving aside the legal

requirements that building services must be seismically

restrained, according to Terry a recent study by MBIE

concluded that given the current widespread lack of

seismic restraint in buildings in the Wellington CBD, an

ultimate limit state seismic event from the Wellington Fault

would cause economic devastation through the failure

of building services alone, even if no building suffered

structural collapse.

This article is based on material from Terry Johnson’s

presentation to the seminar. This article does not

constitute any form of guidance on the actual analysis,

design and installation of seismic restraints for building

services. It is merely an informative ‘wakeup call’ for

structural engineers to take serious note of this aspect of

aseismic performance, and to promote best practice on all

projects, even if not directly responsible for this aspect of

the design.
 

PARTS DESIGN TO 1170.5 2004 SECTION 8: Face Loaded Precast Panels in Industrial Buildings

David Southwick

Abstract
Industrial buildings often consist of steel portal frames with precast concrete wall panels providing both a bracing and

cladding function. Within industrial areas, these buildings are numerous. Therefore, their structural design should be

routine.

Given the generic nature of these buildings, there should be widespread understanding of their design requirements.

However, while undertaking peer reviews, assessments of existing buildings and CPEng assessments, it has become

apparent that many designers are not designing the reinforcing and associated wall panels fixings to Section 8

Requirements for Parts and Components of NZS 1170.5.

In some cases, designers are advising that the design of the panels is an Alternative Solution, and that lower

earthquake actions are justified. This situation would then require careful consideration by a peer reviewer and building

consent authority, adding an unnecessary compliance burden to an otherwise routine project.

Publications are available that clarify the matter. In particular, the BRANZ publication Slender Precast Concrete Panels

with Low Axial Load which includes, Appendix C: Determination of Forces on Building Parts (NZS 1170.5 Section 8)

and Section 12: Example Design Calculations, both clearly outline that panels and eave connections are assessed as

parts. Determination 2013/057 also provides a clear ruling on the matter.
 

NZS 1170.5 P-DELTA EXAMPLE

Stuart Oliver

Abstract
One of the recommendations from the MBIE Investigation into the performance of Statistics House during the 14th

of November 2016 Kaikoura Earthquake (MBIE, 2017) was “that the provisions of the NZS 1170.5 (SNZ, 2016) for

P-delta effects in the design of new buildings needed clarification.” The Standar d provides references (e.g. Fenwick)

describing the “P delta” effects of the seismic performance of ductile structures, but little information to assist the

designer to implement the mandatory clauses.

This paper attempts to address this shortcoming by providing a step-by-step design example demonstrating how to

determine if an analysis for P-delta actions is required. The example will also demonstrate how to determine P-delta

actions, and the overall base shear and horizontal deflections for the building including P-delta effects.

It is important to note that the P-delta analysis options included in common linear elastic structural analysis programs

do not implement the provisions of NZS 1170.5. This is described in Clause C6.5.1 which notes that elastic analyses

do not allow for the incremental increase in displacements associated with yielding of ductile structures.
 

SEISMIC RETROFIT OF MASONRY WALLS USING TIMBER STRONG-BACKS

Dmytro Y. Dizhur, Marta Giaretton, Ivan Giongo, Jason M. Ingham

Abstract
A high proportion of New Zealand’s clay brick unreinforced masonry (URM) structures have not been retrofitted to

resist earthquake forces, and in particular to prevent out-of-plane failures which are the most critical deficiencies

of URM buildings. Despite a number of seismic improvement techniques having been applied previously there is a

significant lack of experimentally validated simple and cost-effective solutions that also consider the impact on the

building tenants, aesthetics and heritage building fabric. The main objectives of the research presented herein were to

develop and validate seismic securing techniques for URM solid- and cavity-walls that satisfied the above conditions.

Full-scale shake-table testing of two cavity and three double-leaf solid clay brick URM walls was undertaken. The

vertical timber framing that is typically considered to be a non-structural support for the inner wall lining was used

as part of the retrofit solution and was fixed to the wall using mechanical screw-ties in order to form a strong-back.

The intended outcomes of the research reported herein included (i) measuring via laboratory testing the improvement

of seismic capacity in terms of peak ground acceleration (PGA) achieved and maximum out-of-plane displacement

experienced by the URM solid- or cavity-walls due to strong-back retrofit installation; (ii) comparing the performance

of different strong-back configurations; (iii) providing construction details, and providing analytical formulations for

response prediction.

Keywords: unreinforced masonry, seismic retrofit, seismic rehabilitation, strong backs, masonry anchors, cavity

walls, brick walls, out-of-plane, earthquake resistance
 

A DIRECT DISPLACEMENT-BASED SEISMIC DESIGN PROCEDURE FOR MOMENT FRAMES WITH NON-LINEAR VISCOUS DAMPERS – PART 2: VALIDATION OF THE DESIGN PROCEDURE

Dion Marriott

Abstract
This paper presents the validation of a Direct Displacement-Based Design procedure for ductile moment frames

equipped with non-linear viscous dampers (NLVD) or linear viscous dampers (LVD). The design procedure is

outlined in detail within a companion paper, Marriott (2017), and termed Direct-DBD-Viscous, and developed for

use within a new design or retrofit design environment. The design procedure is validated through an analytical

study of three prototype frame buildings subjected to 20 far-field ground motions evaluated via non-linear dynamic

analysis. Through these studies it is shown that the design procedure is able to reliably predict peak story drift and

displacements. The procedure is also capable of quantifying the required viscous damping properties and damper

distribution up the height of the structure in order to achieve the design performance objectives. It is shown that a

design procedure that considers only the fundamental mode, or an inelastic mode shape, such as the procedure

proposed herein, is unable to predict peak damper forces associated with higher mode amplification. However, a

simple velocity multiplier is suggested to account for the predicted damper spikes.
 

ESTIMATION OF THE STATIC VERTICAL SUBGRADE REACTION MODULUS K S FROM CPT FOR SHALLOW FOUNDATIONS ON COHESIONLESS SOILS

Nick Barounis, Johnny Philpot

Abstract
In this paper, an integrated methodology is introduced for estimating the static vertical subgrade reaction modulus

from CPT for shallow foundations on cohesionless soils. The proposed methodology relies on fundamental

concepts of soil mechanics and foundation engineering. The methodology returns similar equivalent values to the

SPT correlation proposed by Scott (1981). As a result, it produces values that are in alignment with the traditional

SPT approach. The proposed methodology can be used in conjunction with other methods for low risk projects.
 

SOIL CLASSIFICATION IN THE PALMERSTON NORTH AREA USING STRONG GROUND MOTION RECORDS

Jonathan Dymoch

Abstract
The site soil classification of the Palmerston North area is investigated by applying the Nakamura method to strong

ground motion records of the PNRS, PNBS and PNMS sites. A comparison of the method is made with the TEPS

site in Wellington for which soil has previously been classified. The calculations showed that Palmerston North may

be classified as soil class C however, further calculations should be undertaken to verify the method.
 

IMPROVEMENTS IN FINITE ELEMENT ANALYSIS FOR COMPLEX STRUCTURAL DESIGN

Ben Horsfall, Max Waters, Matt Bishop

Abstract
This article highlights the step change that has occurred in advanced computational methods to solve highly

nonlinear structural systems. There has been considerable improvements in computational power and finite

element analysis (FEA) softwares in recent years.

Four years ago high level computational analysis was considered research. It is now practical to analyse these

types of systems at a commercial level. To investigate this premise, BVT re-analysed an existing HERA study [1]

from 2013 using the latest techniques and hardware, obtaining a 42x reduction in solve time with a more

complex model.
 

USING INTUMESCENT COATINGS TO ACHIEVE BUILDING CODE COMPLIANCE ON STEEL STRUCTURES

Allan Jowsey, AkzoNobel

Abstract
Intumescent Coatings are the first and natural choice for structural steel fire protection on commercial projects

in Europe due to them being a cost effective and set & forget solution when the correct system is selected.

Their use in the Australasian region is dramatically increasing as alternative building code compliance, fire

engineering and structural steel solutions are proposed for projects.

However Intumescent coatings are often incorrectly understood and specified, leading to the project not

knowing exactly what is required and less than optimum costing of projects.

Keywords: Steel, Fire, Cellulosic, Intumescent, Specification.
 

SCOSS report



Abstract
Adapted from IStructE SCOSS and CROSS reports
 

MBIE and Standards New Zealand Update



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News from the Regional Structural Groups



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The Institute of Structural Engineers Report



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