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 18 No. 1 2005

 

Title
Letter to Editor Vol 18 No 1 2005
Author/s

John Scarry
Abstract

Re: The Introduction Of Grade 500qt Reinforcing By Pacific Steel
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Title
Theoretical Analysis And Realworld Design Vol 18 No 1 2005
Author/s

Jacques Heyman
Abstract

(reprinted from The Structural Engineer Volume 83 No. 8) Jacques Heyman shows that stresses in a real structure can never be calculated uniquely – structural response to loading is governed by small unknown movements imposed by the environment
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Title
Factors To Consider In The Use Of Grade 500e Longitudinal Reinforcement In The Beams Of Ductile Moment Resisting Frames Vol 18 No 1 2005
Author/s

Nicholas Brooke, Les Megget, Jason Ingham
Abstract

This paper examines a number of issues surrounding the use of Grade 500 reinforcement in moment resisting frames. These issues include the use of this reinforcement in plastic hinges and its increased bond strength demands and higher overstrength factors relative to previously Grade 430 reinforcement. In particular the effect of the recent amendment to NZS 3101:1995 on the design of interior beam-column joints is assessed. It was found that for more than 60% of joints the number of Grade 500 reinforcing bars required to resist a given force was at least twice the number of Grade 300 bars. It is also shown that it is often more expensive to use Grade 500 longitudinal reinforcement than Grade 300. It is concluded that in many cases the use of Grade 500 longitudinal reinforcement in the beams of ductile moment resisting frames is not a practical design solution, but that Grade 500 reinforcement is ideal for limited ductile columns, as transverse reinforcement or in hybrid ductile jointed structures. It is important to note that all steel in this study referred to as Grade 500 is Grade 500E-MA not QT.
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Title
Reinforcing Steel In New Zealand - Pacific Steel Future Product Range and Other Design Issues Vol 18 No 1 2005
Author/s

Keith Towl, Graham Burrell
Abstract

Pacific Steel are extending their product range to include Quench and Tempered (QT) product. This paper forewarns of the coming changes, as well as taking the opportunity to review and discuss various issues pertinent to structural design engineers. The new reinforcing steel standard, AS/NZS 4671, and grade 500, are now 4 years old. However, there is still significant misunderstanding regarding the product in terms of specification and application. Some site practices which have been anecdotally reported are causing concern in the industry. Pacific Steel are extending their product range in late 2005 to provide both a Micro-alloyed (MA) and a Quench and Tempered (QT) Grade 500E product. This paper attempts to address the above overlapping and converging issues thereby providing the engineer with the knowledge necessary to design, specify and inspect safely and efficiently.
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Title
Quenched And Tempered Reinforcing Steel Vol 18 No 1 2005
Author/s

John Hare
Abstract

Pacific Steel’s decision to begin the manufacture of Quenched and Tempered (QT) Grade 500E reinforcing steel brings to the fore some issues that have been with us since before the introduction of Grade 500 steel and the joint standard, AS/NZS 4671. The following article, endorsed by the SESOC Management Committee, reviews some of the facts and opinions surrounding the use of QT steel and also other grades of reinforcing. Interim recommendations are given for structural engineers to complement those in the Department of Building & Housing Practice Advisory No. 7.
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Title
Use Of Weathering Steel In New Zealand Bridges Vol 18 No 1 2005
Author/s

Raed Zaki, Dr. Charles Clifton
Abstract

HERA has published a guideline for the use of weathering steel in New Zealand bridges. This is HERA Report R4-97, and it covers aspects for designing, construction, inspection, maintenance and even rehabilitation of weathering steel bridges. Weathering steel is a product with a limited and chequered history of use in New Zealand principally in building cladding applications. This has made engineers wary of its use in bridges, even though, in North America and Europe, there are examples of weathering steel bridges over 30 years old exhibiting excellent performance, in line with expectations. These examples clearly show that a well designed and detailed weathering steel bridge, in an appropriate environment, can provide an attractive, very low maintenance, economic solution and therefore extend the scope of cost-effective steel use in bridges. This paper offers a summary of the important issues relating to the use of weathering steel in New Zealand bridges, starting with a brief introduction to the material and what makes it different to conventional constructional steel.
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Title
Reinforced Concrete Seating Details Of Hollowcore Floor Systems Vol 18 No 1 2005
Author/s

C J Macpherson, J B Mander And D K Bull
Abstract

(reprinted by kind permission of the New Zealand Earthquake Engineering Society) Recent earthquake engineering research has raised concerns of the seismic performance of precast prestressed concrete hollowcore floor systems. Experimental research showed that with simple detailing enhancements, significant improvement in the seismic performance of hollowcore floor systems can be expected. The present experimental research aims at validating several new detailing enhancements. Based on previous research findings, the present super-assemblage experiment included the following details: (i) a reinforced connection that rigidly ties the floor into the supporting beam, (ii) an articulated topping slab portion cast onto a timber infill solution that runs parallel to the hollowcore units and edge beams; (iii) specially detailed supporting beam plastic hinge zones reducing potential damage to the hollowcore units; (iv) Grade 500E reinforcing steel used in the main frame elements; and (v) mild steel deformed bars in the concrete topping in lieu of the customary welded wire mesh. The full-scale structure was cyclically tested in both the longitudinal and transverse directions to inter-storey drifts of ±5%. Observations show extremely positive results with minor damage incurred by the hollowcore flooring and the overall performance dictated by the performance of the moment resisting frame. Recommendations for the forthcoming revision of the New Zealand Concrete Standard, NZS 3101, are also made.
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Title
Structural Steel For Seismic Performance Vol 18 No 1 2005
Author/s

Clark Hyland, W. George Ferguson, John Butterworth
Abstract

Structural design engineers require steels forming the primary structural lateral load resisting system of a building to be able to sustain high levels of plastic strain without suffering brittle fracture. The ability to focus plastic deformation into designated hinge zones of the structure allows kinetic energy developed, by the structure, during an earthquake to be dissipated in a way that minimises the likelihood of sudden collapse. This reliance on the plastic deformation characteristics of steel indicates the need for suitable material performance criteria that can be clearly understood and communicated between the structural design engineer and the steel producer. Most structures fabricated from structural steel do not need to sustain the potentially large cyclic plastic strain levels imposed on earthquake resisting structures. Consequently materials research and development tends to focus on the properties of steels operating well within the elastic stress range of the material. This paper presents some interim results of research being undertaken on the effect of plastic strain and aging on the characteristics of structural steel used in New Zealand seismic resisting structures. Of particular interest is the effect of plastic strain and aging on the ability of the steel to develop ductile fracture in the presence of sharp notches and cracks, as often occur in fabricated steelwork. To investigate this characteristic, Charpy V-Notch (CVN) and Crack Tip Opening Displacement (CTOD) tests, were undertaken at the University of Auckland on steel taken from the flange of a 310UC158 Grade 300Plus section produced in Australia. The tests were made on the steel after it had been subjected to a range of plastic pre-strain levels and aging.
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Title
Fire Safety And Steel Construction Issues and Future Developments Vol 18 No 1 2005
Author/s

Dr Ian Bennetts
Abstract

The direct and indirect costs associated with the fire protection of structural steelwork has often been seen as an impediment to the construction of structural steel buildings, As a result the steel industry worldwide has undertaken research into aspects of fire safety in an attempt to develop more cost-effective solutions for fire safety and reduce the cost of fire protection. The development of fire-safety engineering as a discipline has assisted this process and there are now many examples of fire-engineered steel-framed buildings with reduced levels of fire protection applied to structural steelwork. This paper describes some of these examples and discusses some of the approaches that have been adopted in justifying these designs. Important issues, particularly in relation to high-rise buildings, are noted. These issues are the subject - or need to be the subject of further research and investigation. In particular, a better way of quantifying fire severity on large area floors, and the development of appropriate details and measures to avoid catastrophic building failure. There is an ongoing need for the cost-effective fire protection measures for structural steelwork to enable solutions that combine protected and unprotected steelwork.
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Title
Project Corner: Christchurch Women’s Hospital Vol 18 No 1 2005
Author/s

Gary Haverland
Abstract

The new $80m Christchurch Women’s Hospital has been in the planning for some time and was opened on the 30 March 2005. This article provides the background to this project and describes aspects of the design and construction of this 9 storey base isolated hospital building.
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