Newsletter | December 2019

Message from the Chair

Hi all

We have had a very exciting year. To have started at the beginning of the year recognising the need and taking action to set up the SIG to having it established and sponsoring events for our 100 plus members by the end of the year feels pretty good. The response has been overwhelming and I believe shows that we have hit on a nerve for many engineers.

I see the next twelve months as being a period of consolidation and an opportunity to continue to promote Engineering General Practice as an important part of the engineering landscape in New Zealand. To achieve this we must use our collective voice to continue advocating our cause with Engineering New Zealand, MBIE and the CPEng Assessment system. Creating professional development opportunities relevant to our practice and the means to have these delivered to our members is a vital part of establishing our credibility.

To achieve these goals it is important that we continue to reach out to engineers at a local level and help them establish networks in their local area. It is of enormous value in our everyday practice to have contact with other professionals who live and work ‘just down the road’ and are experiencing the same challenges. The collective mind that is created by such a network means that each of us does not feel so alone and can move on developing our businesses and improving our professional practice with confidence.

I look forward to the New Year – working with you all to strengthen our position and finding new and better ways of supporting all of us in our professional endeavours.

Finally – Merry Christmas and a Happy New Year. Enjoy the holiday and the chance it brings to spend time with those closest to you – it is my belief that our relationships with loved ones are the foundation of our wellbeing.

Pete van Grinsven
EGP Chair

Your Committee

The newly elected committee held its first official meeting in Silverdale, north of Auckland on 31 October 2019.  The Chair outlined the work done to date and positions were elected as follows:

Secretary                                           Bruce Tricker - Auckland

Treasurer                                           Jennifer Lo - Auckland

CPD Coordinator                               Julie Elliott - Auckland

CPEng Liaison                                   Don Thomson - Wellington

Councils / TLA's Liaison                    Aaron Holland - Auckland

Public Liaison                                    Gordon Hughes - Auckland

Jack of all trades                               Ian Watson (keeps us on our toes)

The EGP One Question Survey

In a time-poor world, what could be simpler than a one question survey?  Here is our first one – if you have ideas for future surveys email general.practitioners@engineeringnz.org 

What is your preferred method for doing general calculations in the office (1 highest, rate as many as you use regularly):
o   Good old pencil/pen and paper
o   Excel spreadsheets
o   Mathcad
o   Tekla Tedds
o   Other ___________________

Results in the next news and events email

Progress to date

We have already been ratified by the Engineering New Zealand board and you can now find us amongst the other technical groups on the Engineering New Zealand website. We have designed a logo, now accepted by Engineering New Zealand and started discussions on a number of initiatives – particularly around promotion of General Practice engineering,  professional development specific to our needs and how to upskill the assessment team to recognize ‘good general practice’

Continuing Professional Development

Your steering committee has been beavering away to begin to meet the objectives and recently held a meeting to progress things.

• Julie and Jennifer are working to reserve a domain name and establish a website. We hope to incorporate a forum where ideas can be exchanged and help can be asked for. It is also intended that a platform for remote attendance at meetings can be established in time for our first AGM (hopefully in mid October)
• Aaron has been writing a BOK for civil engineering and looking at the Geotechnical BOK to adapt them for our specific needs. He has also done considerable work in the area of gaining recognition with councils for the engineering general practitioner.
• Gordon has been looking at the structural BOK, devising a QA system that is suited to the general practice engineer and working on a set of guidelines to assist members in setting up a local support group.
• Pete has been communicating with branch chairs through Engineering New Zealand with the idea that visits to each of the regions by one of our committee members can be arranged over the next few months.
• Ian has been recording our meetings and keeps us all on track. He also brings the perspective of the sole practitioner to the group.

We are really excited going forward as we now have a larger pool of venues to air the webinar.  BECA, Calibre and WSP are on board to make this happen; special thanks goes to Daryn Glasgow, Carl Ashby (WSP) and Priyani de Silva-Currie for helping create this opportunity.  Martin Pratchett from Engineering New Zealand has been a great enabler of these webinars.  Please watch this space for the 2020 webinar series to kick off in February next year.  We are always open for suggestions of CPD webinars.  Please feel free to share a topic of interest and perhaps a suggested presenter to general.practitioners@engineeringnz.org.

We have also been enjoying the reach that the Engineering New Zealand Branch network provides and have been making our way around the country to hold drop-in sessions with members. This will continue in the New Year so please join us in your area soon.

CPEng assessment and Council recognition of Engineering General Practitioners

Work is underway to define an Engineering General Practitioner and what constitutes 'complex' engineering work, particularly with regard to members seeking re-assessment or registration on Council producer statement lists etc.

Aaron Holland from the EGP committee is collecting data currently and we will be reporting back on progress towards getting engineering 'general practice' better recognised, as it has been in the medical profession for many years.

Practice Thoughts for December

The Pitfalls of Using ‘Standard’ NZS 3604 Weights in Structural Design
By Bruce Tricker
 

Have you ever had a builder complain that the deflection in a beam or floor is much greater than what was expected?  For a moment, let's put aside the often-misguided belief by some in the building industry that “If it’s been engineered it shouldn’t have any sag”.

Firstly, the dead loads used to compile the various tables in NZS 3604 vary depending on the various sections but here are some examples taken from the BRANZ Engineering Basis of NZS 3604 (2013 version).

Floor                          0.35 or 0.40 kPa
Decks                        0.40 kPa
Balustrades               0.25 kPa
Light roof & ceiling    0.3 kPa or 0.35 kPa or 0.4 kPa or 0.45 kPa or 0.2 kPa with wind load
Heavy roof & ceiling  0.7 kPa or 0.75 kPa or 0.85 kPa or 0.4 kPa with wind load
Light Walls                 0.4 kPa or 0.2 kPa with wind uplift
Medium Walls            0.8 kPa or 0.2 kPa with wind uplift

As can be seen, there is some variation in the dead loads assumed in the tables, which is not completely explained in the BRANZ guide. These loads have however been a reasonable assumption for timber framed buildings in the past. A number of factors have influenced construction weights in the recent couple of decades though. Some examples:

• There has been a general move from 10mm plasterboard ceilings to 13mm.
• In multi-unit developments or minor dwelling conversions, fire rated walls and ceilings can often consist of multiple layers of 13mm, 16mm or 19mm fire resistant plasterboard.  Gib Fyreline for example is also a heavier product than the equivalent standard plasterboard.
• Upmarket dwellings can often have services in the ceiling or finishes which are more like a commercial building – ducted air conditioning, soundproofing layers, heavy tiles etc.
• Houses often have ‘wet room’ bathrooms with heavy tiles on membranes on compressed sheet flooring on timber firring etc.
• With trussed roof houses, there can be numerous non load-bearing partitions sitting on the floor.  These previously tended to line up with walls or beams below.

Let’s look at a practical scenario – upstairs bathrooms over a large living area:

8mm tiles, membrane, adhesive – say maximum 20kg/m2                            0.20
18mm compressed sheet                                                                                0.32
Timber firring, say average 20mm thick at 400c/c                                           0.01
290x45 joists at 400c/c                                                                                    0.16
70x35 timber battens at 450c/c                                                                        0.03
13mm standard plasterboard ceiling                                                                0.09
Nogs, fixings, services etc – say 20kg/m2                                                       0.20
TOTAL                                                                                                              1.01 kPa

This doesn’t allow for any partitions and is based on typical 8mm tiles – 12mm porcelain tiles can weigh over 30kg/m2 and natural stone is even heavier.  Despite this the actual weight of the floor is over two and a half times the allowance in the NZS 3604 joist tables.  In most cases, the deflection criteria will govern the design so you may be getting less than half the performance you expected.  At most, there is a 35% overload provision for dead loads at the ultimate limit state (1.35G).

The opposite can also apply.  Assuming a ‘standard’ light roof weight of say 0.45 kPa when designing a lintel can dramatically under-estimate the wind uplift.  Even with a plasterboard ceiling, a light roof can weigh less than 0.2kPa, and in an uplift situation, the compression face of a lintel is generally unrestrained, which is often overlooked in simple member design.

So, unless you are working well within conservative limits, it pays to calculate the actual dead loads for the particular building you are working on, rather than ‘standard’ weights used in NZS 3604.

Comments on your experiences are welcome, or if you have a topic on another issue facing engineering general practitioners let us know.  Email general.practitioners@engineeringnz.org.

Thank you again for joining our Special Interest Group for Engineering General Practitioners. 

Kind regards, 

Pete van Grinsven
Interim Chair 
SIG EGP

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