SESOC

Journals Abstracts

These are short abstracts of the material printed in our journal which is published twice annually. The Journal covers items of interest to structural engineers, including but not limited to: technical papers, project reports, materials information, code reviews.

Journal: Vol 16 No. 1 2003

 

Title
Guest Editorial_A Path towards Performance Based Seismic Design Vol 16 No 1 2003
Author/s

Arthur King
Abstract

Last month I was invited to attend a workshop as part of the Applied Technology Council project 58 team who are working towards preparing Performance Based Seismic Design guidelines for the USA. The concept of multiple performance levels with regards to earthquake design and retrofit (i.e. Operational Continuity, Immediate Occupancy, Damage Control, Life Safety, Structural Stability) has been working in California since the late 1990s through the National Earthquake Risk Reduction Program (NEHRP) recommendations. Although these provisions are non-mandatory they have established the working framework which can be used to assess the performance of existing buildings.
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Title
Letter to Editor_ Draft Loadings Standard Pt4 Earthquake Loading
Author/s

Richard Fenwick
Abstract

Recently I read the first two thirds of draft 8 of this standard. It was released as a "calibration test version", so that a number of structural designers could assess the proposed code requirements against those in the existing code by considering recent structures that they had designed. This draft standard is intended to be close to the final version. On the basis of this reading I sent in a number of comments to Standards. Some of these were minor but a few were of major importance. Similar comments on several of the previous drafts have also been sent. Firstly I note that my comments, along with all the other individuals who have submitted comments, have not once been acknowledged. Secondly I note that many of the points that I have raised have been ignored, even when pointing out basic errors in equations. The process of producing a standard lacks transparency, and I believe it needs to be revised.
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Title
Letter To D Gaunt Fri Re Timber Treatment Research and use of Untreated Radiata Pine in NZ Construction Vol 16 No 1 2003
Author/s

Esli Forrest (Editor)
Abstract

Because of concern about how untreated timber has come to be used in domestic construction in New Zealand with the resultant rotting timber framing, we sent the following letter asking these questions of the Forestry Research Institute. We received back an email from Mr. M. Hedley which gave the replies to the questions inserted in italics below. It serves to highlight the fact that industry funded standards are not working. The previous Minister of Internal Affairs was well warned by SESOC of the effects of removing government funding from Standards New Zealand, but chose to ignore what we predicted. Whoever funds a standard will get the standard that they want regardless of whether it is the public interest. Commercial control of standards is now all too apparent, as is the result.
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Title
Design Of Cold-Formed Stainless Steel Structures Vol 16 No 1 2003
Author/s

G Charles Clifton
Abstract

New Zealand is one of the largest users of stainless steel in the world (in terms of tonnage used for the size of the economy). With the introduction in 2001 of the Cold-Formed Stainless Steel Structures standard, AS/NZS 4673:2001, we now have a state of the art standard for design of cold-formed stainless steel structures. The standard was introduced to New Zealand users in early 2002 through a HERA seminar series. The notes from that series, HERA Report R4-111, provide a useful companion to the standard. This paper provides a brief summary and overview of the key factors involved in the design of cold formed stainless steel structures. This coverage includes addressing important practical aspects such as the material properties of stainless steels, the differences between stainless steel and carbon steel and important considerations in the design of thin-walled sections and connections. It also briefly covers considerations in the design for earthquake and fire. The paper provides an overview of these aspects only and references readers onto the relevant pans of the standard and the seminar notes for more information. It ends with coverage of some of the typical applications for stainless steel as taken from the seminar notes.
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Title
Recent Structural Research In New Zealand Vol 16 No 1 2003
Author/s

Bruce Deam, Richard Fenwick, John Butterworth
Abstract

Recently, a brief research report on structural research at Auckland and Canterbury Universities was published in the "Structural Engineer". An updated version of this is given below. Most of the structural research at Auckland and Canterbury Universities is related to the seismic behaviour of structures. Currently there are research projects looking at the seismic behaviour of reinforced and pre-stressed masonry, structural steel, reinforced concrete and timber structures, together with a number of analytical topics that are material independent. In this report three projects, which are expected to have a major influence on the way in which structures are designed and detailed for seismic resistance, are briefly reviewed. In all cases the first phase of the research projects is nearing completion, though additional work is planned in all cases.
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Title
Quality Control Of Structural Timber In New Zealand Vol 16 No 1 2003
Author/s

G B Walford, D Gaunt
Abstract

The change in New Zealand's pine forest management towards faster growth has caused an increase in the proportion of juvenile wood with its problems of low stiffness and distortion. While juvenile wood has always been present, the increased likelihood of its occurrence means that it is now more important for producers to verify that structural timber has the properties expected of it. While machine grading is more efficient at sorting sawn timber for stiffness than is visual grading, both methods need to be backed up with a third party-audited quality control system. Without such a back-up an amendment to NZS 3603 was proposed whereby a capacity reduction factor would be applied to Modulus of Elasticity, as well as to strength design values. This issue is still under debate.
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Title
Design Of Opening Corners Between Reinforced Concrete Walls and Slabs Vol 16 No 1 2003
Author/s

Richard Fenwick, Bruce Deam
Abstract

Some commonly used detailing for opening comers between walls or walls and slabs results in strengths which are less than the theoretical strengths of the members meeting at the comer. This paper shows how these comers can be designed and detailed, using diagonal bars, to achieve satisfactory performance. Some details, which do not perform satisfactorily, are described and a method of assessing the ultimate strength of comers reinforced with U bars that overlap in the comer is given. The paper may also be of interest to designers who use the strut and tie method as it outlines actions that should be considered in such an analysis.
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Title
Holistic Behaviour Of Concrete Buildings In Fire Vol 16 No 1 2003
Author/s

Professor Colin Bailey
Abstract

(Originally Published in The Proceedings of The Institution Of Civil Engineers, Structures and Buildings 152, August 2002. It is republished here with kind permission of Thomas Telford Limited). This paper discusses various modes of structural behaviour of a concrete building when subjected to a fire, based on observations from a full-scale test. Although some data were lost during the test, the available results and observations presented provide a valuable insight into the holistic behaviour of concrete buildings, when subjected to fire. The tested building was constructed using elements formed from normal and high-strength concrete and was designed for 60 minutes fire resistance, using the UK design Code. High-strength concrete was used for the columns within the fire compartment and since it has previously been shown that this type of concrete is susceptible to spalling, polypropylene fibres were added to the concrete mix during construction to alleviate the problem. Both the UK and European codified design methods suggest that concrete spalling within the fire compartment should have been nominal and could effectively be ignored during the design. However the test showed that spalling of the floor slab was extensive and exposed the bottom steel reinforcement. Although concrete spalling considerably reduced the flexural strength of the slab, collapse did not occur. This could be attributed to the slab behaving in compressive membrane action, which is currently not considered in codified design methods. The test also showed significant lateral displacement of external columns due to thermal expansion of the heated slab. The main observations from the test show that designers will need to understand the behaviour of entire structures in fire, to ensure that premature collapse will not occur.
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Title
Overstrength Factor For Pacific Steel Micro-Alloy Grade 500 Reinforcement_April 2002 Vol 16 No 1 2003
Author/s

Des Bull, Chris Allington
Abstract

With Grade 500 reinforcement in to the market place in New Zealand, designers need to be aware that the overstrength factor of 1.25 for members constructed with Grade 430 steel cannot be applied to those members constructed with Grade 500 steel. The overstrength factor is defined as the ratio of the maximum strength of a concrete member, M, to the nominal strength of the concrete member, Mn. The nominal capacity is usually calculated using the lower 5" percentile yield strength of the reinforcement [I, 21. The ability to accurately determine the maximum overstrength capacity of an inelastic member is the fundamental principal in "capacity design". This paper presents the summary of results from a study aimed at determining the overstrength factor for plastic hinge zones of reinforced concrete beam and column members constructed using Pacific Steel Micro-Alloy Grade 500 longitudinal reinforcement, with the chemistry of current production.
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Title
Issues of Non-Compliance with the Steel Reinforcing Materials Standard Vol 16 No 1 2003
Author/s

Des Bull
Abstract

For a number of years, alternative sources of supply of steel reinforcement have been available in New Zealand, other than those provided by Pacific Steel, Otahuhu. Supplies have been obtained from a number of countries including South Africa, Korea, Singapore and India. Some of the issues with this imported reinforcement are: Is the range of reinforcing steel appearing on sites "fit for purpose"? Does the reinforcement comply with the minimum requirements of the Standard AS/NZS 4671:2001: "Steel Reinforcing Materials"? Are design engineers applying due diligence in ensuring that this reinforcement meets the requirements of AS/NZS 4671? Can "elastic design" be considered as an excuse to not seek compliance with ASNZS 4671?
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Title
Articles For Discussion Some Site Observations and our Non-Existent Building Control System Vol 16 No 1 2003
Author/s

E. J. Forrest, Ernie Lapish
Abstract

In the light of recent concerns about domestic construction standards I have done some observations to see what happens during site inspections. A particular site was chosen because there were known problems with the founding material.
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Title
Project Corner Britomart Underground Railway Station Vol 16 No 1 2003
Author/s

Melvyn Maylin, Sulo Shanmuganathan
Abstract

This paper describes the design and construction of the Britomart underground railway station in Auckland, New Zealand. This is the first underground station built in New Zealand. The station was constructed by cut and cover techniques using both top-down and bottom-up methods to suit the site geology. The station is approximately 300 m long, 45 m wide, and 12 m deep from the ground level. It connects to an existing tunnel at Britomart Place. The site is on a reclaimed land and the sea is within 100 metres. Close proximity to the sea and ground movement restrictions due to adjacent heritage buildings posed considerable challenges to the design team. This paper focuses on solutions adopted to overcome the site and design constraints.
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Title
The Feasibility of Round Pole Timber and Lime Concrete Composite Flooring Vol 16 No 1 2003
Author/s

Tobias Hodsdon
Abstract

An Undergraduate At Bath University, writes about his Young Researcher Grant-Funded Project (Reproduced from the Structural Engineer) Examples of timber and concrete composite structures can be found across Europe, commonly used to construct floors and walls. The technique has also been used for bridge decks in America and France. Such systems are comprised of a layer of timber either sawn or in the round, working as the tension element, with a layer of concrete on the top forming the compression element. Mechanical fasteners provide the shear connection between the two layers and allow composite structural action.
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