Journals >> Abstract VOLUME 20 No. 1 (April 2007)
SESOC MANAGEMENT COMMITTEE
President's Report (Mr. Ashley Smith)
Note from the Editory (Mr. Tyson Giles)
TECHNICAL PAPERS
Material Strains and Relevance to Seismic Design (Richard Fenwick and Rajesh Dhakal)
With the seismic provisions in the Loadings Standard, NZS 4203:1992 being replaced by NZS 1170.5:2004 (Structural Design Actions – Earthquake Actions), a number of changes have been made to seismic design in New Zealand. The most significant of these is that the level of detailing used in potential plastic regions (nominally ductile, limited ductile or ductile) be determined on the basis of the predicted magnitudes of deformation they are required to sustain in the ultimate limit state. Previously the level of detailing was determined principally on the basis of the structural ductility factor. However, it is shown that the structural ductility factor does not give a reliable guide to the deformation sustained in the individual plastic region. The paper outlines the background to the change in the way that the level of detailing is determined and it discusses how the predicted inelastic deformation demands can be found in the design of concrete structures.
Material Strain Limits for Seismic Design of Concrete Structures (Richard Fenwick and Rajesh P Dhakal)
The design of structures to resist seismic actions to New Zealand Standards requires the level of detailing used in potential plastic regions to be based on the predicted material strain levels that they sustain in the ultimate state. For potential plastic hinges in reinforced concrete sections, curvatures are used rather than strains in reinforcement or concrete. This substitution is made as it is difficult to calculate realistic reinforcement and concrete strains in plastic hinges subjected to cyclic loading. Test results from 37 beams, 25 columns and 36 walls were examined. From each of these the maximum nominal curvature sustained when the lateral force reduced to 80 percent of the theoretical strength was found. From the results of the tests, design curvature limits for plastic hinges have been developed. These limits will be submitted to Standards with the proposal that they are incorporated in an amendment to the Structural Concrete Standard NZS 3101:2006. They have a more rational basis than the existing curvature limits in the Standard and they are easier to use in design.
Using Disasters as a Learning Tool in Higher Education (Alan Jennings and Pauline Mackinnon) (Reprinted from IStructE’s – “The Structural Engineer” Volume 84 No.15)
Since the first 'Learning from Disasters' exercises were conducted at Queen’s University Belfast in 1994 and also at the University of Glasgow in 1997, much has been learnt not only by the students but also by the organizers about disasters and how to maximize the learning experience. The report discusses how the exercises have progressed and also how the awareness of disasters could improve the preparation for study topics and, at a later date, a life in industry.
Comment: The References and the Disasters Checklist are most valuable, and sobering.
A Concrete Beam Design Program to be Available to Members on the SESOC Website (Esli J. Forrest)
BeamDes will be a program available on terms similar to the well-received Soils Program. BeamDes will be based on NZS3101:2006 for the design of concrete beams. It will encompass four difference member shapes, and cover the cases External Span, Internal Span, Cantilever and Bridge Member. Although the appropriate Moment Envelope needs to be calculated separately, the program will calculate reinforcement at three locations on both the top and the bottom of a beam, and two at a cantilever.
The program will do the complete beam design including serviceability, durability and fire, torsion and shear design. It will have everything detailed in the Help file, which has both a table of Contents and an Index. Also it has a detailed description of the Capacity design process, and a full step-by-step guide through the design process.
The program will be available for download and installation on the user’s computer, and then be registered to that user in the same way as the Soils program.
Articles for Discussion
IPENZ STRUCTURAL TASK FORCE - SESOC Committee Update.
Comment: While it will be realized that this paper is on a work in progress, it covers matters of fundamental importance to the profession, and the paper should be read in full.
The John Scarry open letter to IPENZ in 2002 raised concerns about the standard of structural engineering in New Zealand.
Since then, an IPENZ Structural Engineering Taskforce has recommended several changes for the industry, and Parliament has passed the Building Act 2004 which has set up of the Department of Building and Housing (DBH).For each of the seven major Taskforce recommendations, the SESOC Management Committee has identified the key issues, outlining what has already been done, and what further work SESOC has planned.
The IPENZ Structural Taskforce Recommendations are as follows:
1: Development of Standards and Codes of Practice.
2: Identification of Competent Structural Engineers.
3: Professional Involvement Through all Stages of Project Delivery.
4: Expanded Technical Leadership Role for the DBH to Provide a Code of Practice for TLA’s to follow.
5: Improved Consent and Audit Processes.
6: Responsibilities of Building Owners.
7: Evaluation of New Materials.
For each of these recommendations, the following aspects are discussed:
Key Issues
Progress to Date
Outstanding Issues and SESOC Proposals
SESOC Priorities
PROJECT CORNER
Reinforcement Corrosion and Its Remediation with a Case Study of Cathodic Protection of Prestressed Beams. Reprinted from IStructE’s – “The Structural Engineer” Volume 84 No.23 (Dr. Mohammad Ali and Peter Wiles).
The paper presents a discussion on reinforcement corrosion in concrete, prevention/control methodologies and a case study of corrosion control to a jetty at Devonport, Auckland. The reinforcement in this paper refers to both ordinary reinforcement and prestressing steel.
Learning Experiences (Contributions from Members)
The article details six situations where trouble has occurred, outlining what the trouble was, what caused it, and the lessons learned. They are submitted by members without any company or project identification, for the warning / education / help of the wider engineering profession.
Further anonymous experiences by members would be appreciated.
Update from Standards New Zealand (Stuart Ng, Standards New Zealand)
The situations regarding NZS 4219, NZS 4223, NZS 4230, NZS 3404:1997
Test Your Skill – A Structural Checking Test (Richard Fenwick)
NEWS FROM THE REGIONAL STRUCTURAL GROUPS
Auckland Structural Group – Paul Campbell
Canterbury Structural Group – Dene Cook
Waikato Structural Group – John Dale
Wellington Structural Group – Graeme Beattie
These consist of reports of past meetings, and planned future meetings.
