Metamorphs: Technical Praxis: 2015

Monday, 14 September 2015

C-Sections Available in Australia

Depth/Thickness	10	12	15	19	24	30
50
75
100	X	X	X	X
150		X	X	X	X
200			X	X	X
250				X	X
300					X	X
350						X

Table 1: Section Sizes Available

C-Sections around Australia are typically designated by a two part code. The first part giving the depth of the section in millimetres and the second part giving the thickness of the material mulltiplied by 10. These two parts are then combined in different ways and have other characters added to distinguish one manufacture from another. For example Lysaght is would be C10010, whilst Stramit would be C100-10, for a c-section, whilst a z-section would be Z10010 and Z100-10. Where in each case the depth of section is 100mm and the base metal thickness (BMT) is 1mm.

Depth/Thickness	10	12	15	19	24	30
50
75
100	1.74	2.07	2.58	3.25
150		2.84	3.54	4.46	5.62
200			4.44	5.68	7.15
250				6.43	8.10
300					10.01	12.60
350						X

Table 2: Mass/Unit Length [kg/m]

Revisions:
[14/09/2015] : Original

Technical Praxis: The Art of getting things done.

Technical Praxis: The Art of getting things done, was the last name I adopted for a group I created on LinkedIn, and have since shut down. It having a membership of 1 person. Future discussion will be in my group Pre-Engineered Manufactured Building Systems Group.

The following is a lists of post titles I was able to manually retrieve:

#TechnicalPraxis #Adelaide South Australia, a linkedIN group to discuss local #technical and #engineering practice.
#StructuralDesign #TechnicalPraxis #Adelaide South Australia, quality of services, availability, specialities not covered, any comments?
#Agricultural #Engineering #TechnicalPraxis : Anyone know anything about practice in South #Australia, opportunities deficiencies?
#TechnicalPraxis Manufactured #Structural Products And Simplified Wind Classification
#TechnicalPraxis South #Australia Local government authorities.

#TechnicalPraxis South #Australia City of Salisbury Development Approval
#TechnicalPraxis South #Australia City of Tea Tree Gully Development Approval
#TechnicalPraxis South #Australia City of Port Adelaide Enfield Development Approval
#TechnicalPraxis South #Australia Adelaide City Council Development Approval
#TechnicalPraxis South #Australia Lower Eyre Peninsula Development Approval
#TechnicalPraxis South #Australia Yorke Peninsula Development Approval

#TechnicalPraxis South #Australia : SA Atlas: wind load classification, zoning and more
#TechnicalPraxis South #Australia Water sensitive urban design #wsud
#TechnicalPraxis South #Australia #mining #engineering Olympic Dam
#TechnicalPraxis South #Australia #environmental protection authority #epa
#TechnicalPraxis South #Australia Department of #environment and natural resources
#TechnicalPraxis South #Australia #TransportSA
#TechnicalPraxis South #Australia steel design #StructuralDesign #engineering
#TechnicalPraxis South #Australia
#TechnicalPraxis South Australia Steel Shed Group #StructuralDesign #quality #engineering
#TechnicalPraxis Drafting, Printing and Copying

The following is a list of posts I was going to write:

#TechnicalPraxis Photcopiers
#TechnicalPraxis Time management Software
#TechnicalPraxis Software
#TechnicalPraxis File and Folder Management

Pre-Engineered Manufactured Structural Products

List of posts I have moved from the Pre-Engineered Manufactured Structural Products group I had on Linkedin.

Most of this can now be discussed on: Pre-Engineered Manufactured Building Systems Group

Tracebility in the #building industry, and #retail hardware

{Previously posted in LinkedIn group I created: Pre-Engineered manufactured structural Building products, and have since shut down. It having a membership of 30 people. Most of these people also in my group Pre-Engineered Manufactured Building Systems Group which has over 2000 members.}

In recent years in Australia, there have been problems in quality of materials supplied to industry as there as been increase in supply of imported materials: quality of steel sections and bolts among the major issues.

Part of the problem is poor specifications by engineers and other designers, assuming only one source of material (eg. BHP). Another is lack of actual control on provision of certificates. However that is the high end of the industry.

At the small builder end DIY end of the industry, it is always a problem. One is the amount of construction carried out without approval and assessed afterwards to avoid demolition. The other is that engineering just supplying evidence-of-suitability for the proposal to gain development approval. There after no engineering supervision or input of any kind to the project. So reliant on developers, owners, builders and more specifically suppliers to provide the correct material.

Purchase orders, invoices, cart-notes and receipts are typically no real evidence that materials supplied meet the engineering specifications. Or if building constructed in first place, evidence of of the critical quality characteristics of the materials which have gone into the building works.

I suggest that there is need for some universal coding system to common specification requirements that can simplify and allow cross-referencing between purchase orders, cart-notes and invoices. So that can trace accountability for defective materials entering into a construction project. In particular holding the retailers accountable, for not understanding anything about the materials they supply.

For less common materials where coding not suitable, then some standards in place and code of practice for presentation of purchase orders, cart-notes, invoices bet set in in place so that is some documentary evidence, at least of what was intended and contended to have been supplied to the building works.

For example specify requirements for a verandah post saying using Duragal SHS at fy=450MPa, but builders and DIY's find ready fabricated posts at local hardware store for which there are no technical specifications. So have to drop down to using the lowest strength tubes available: say fy=250 or fy=350MPa . If allow for maybe imported then say around 180, or 200 MPa to allow for greater uncertainty.

A certain amount of control needs to be in place regarding what the hardware retailers supply.

-o0o-

Australian Certification Authority for Reinforcing Steel (ACRS)
Then One Steels Build with Standards Site:
There is also the Australian Building Codes Board Product Certification CodeMark Scheme:

All very nice but would be a lot better if had more wide spread usage.

Then what about Australian Standards, where is the equivalent of the British standards kitemark. Why haven't suppliers been getting their products independently certified as compliant with Australian Standards in the first place?

Australian standards seems to have focused on the QA standards and 5 ticks for quality assured businesses. Seems easier to be QA accredited than actually supply product to the standards. Though I believe the accreditation was modified a few years back, and dependent on proving compliance with national product standards where they exist. But QA accredited is not proof of the product. The products require the product compliance standards, not the 5 ticks for QA.

The systems appear to be there, but not being used. So what is the obstacle?

In South Australia there are a multitude of builders who supply a variety of products based on standard calculations

In South Australia there are a multitude of builders who use standard calculations to gain development approval for application of a variety of products: pergolas, verandahs, retaining walls, balustrades, sail-shades, sheds.

What the customer wants however doesn't always match the available calculations held by the supplier. The suppliers rely on the local councils identifying problem areas and requesting further information. The customer, then experiences a delay as the supplier attempts to find a consulting engineer to produce calcs-for-council. The design having already been determined: worst already constructed and inline for demolition if not proven adequate.

The point of the customer going to the supplier in the first place is to avoid wasting time with architects and engineers designing the structure they want. They want the structure delivered and installed in a short time frame.

It is therefore important that such suppliers employ technical people on staff and not rely on consulting engineers. Consultants design buildings one at a time, and are reactive. A manufacturer needs to be proactive, and identified the potential needs of the market and pre-engineered potential solutions. So that when the customer comes along a design-solution to meet their needs is readily available, proven, and easy to implement.

This group is set up to discuss the difference approaches required to design of a end-product that could be made and installed a 1000 times or more per year, based on a single design. It is thus important that such design be correct.

For those interested in the specifics of sheds and steel buildings, refer to the SA Shed Group. For structural products other than sheds, this is the group to discuss the issues.

Aluminium balustrades: HAZ

{Previously posted in LinkedIn group I created: Pre-Engineered manufactured structural Building products, and have since shut down. It having a membership of 30 people. Most of these people also in my group Pre-Engineered Manufactured Building Systems Group which has over 2000 members.}

Manufacturers of Aluminium balustrades use standard calculations for the balustrades they supply. Typically those balustrades are designed to be cast into the concrete floor slab. Occasionally however, it is not viable to cast-in the posts, and welded end plates and anchors are specified. This flows into council and requests for further information result for the base connection. Aluminium is not a commonly used structural material, and therefore the code not always held by consultants. With the pressures of time, it appears that little attention is given to the properties of aluminium, and the calcs-for-council requested simply size up some mechanical anchors such as Ramset Dynabolts. In some Australian states, it appears that such things are permitted to be self-certified. Thus posing an hazard.

For the welding of the post to an end-plate to produces a heat affected zone (HAZ) in the post in the vicinity of the maximum post moment. In the HAZ the strength of the aluminium is approximately half that of the parent material. Thus the post is potentially no longer adequate for purpose. The other issue is that not all grades of aluminium are suitable for welding, and the given balustrade design may not be made from suitable material for welding. So a quick fix end plate design is not appropriate.

Such product should be fully designed, giving consideration to its potential applications, and the designer should have experience in aluminium design, or at least willing to get up to speed on aluminium design.

Builders turning up once in a millennium to fix their problems doesn't produce much motivation for a consultant to specialise in a given product design and material: not the least of which is they have to go out buy all the new codes and get familiar with them for a single job: that causes delays. It is therefore preferable that the designers be employed on staff by the builder/manufacturer, or otherwise put a lot more work through the consultants they wish to use.

Design the product not the project. Then assess suitability of product for the project. Further more calc's-for-council constitutes neither design nor engineering, and produces low quality products.

-o0o-

Looking at a system which avoids the problem of welding aluminium, by making use of a steel bar insert.

A normal steel bar (Grade 300 plus), has lower strength than the aluminium tube, whilst a BisPlate insert has higher strength. At first it appeared that the flat bar insert was just being used as a means of connecting to the slab, but on further inspection the BisPlate insert is being used to increase the capabilities of the post. (the tube is filled with grout)

Pushed to the extremes the aluminium post could just be considered decoration slipped over a structural section.

Seems like there is scope for some more efficient design of aluminium balustrades and guard railing. Starting by designing the extruded components for strength, and connectivity first and incorporating aesthetics second.

Should sail-shades, be treated as cable-nets and tension membranes?

Mobile Scaffolding Units

SIP: Structural Insulated Panels

{Previously posted in LinkedIn group I created: Pre-Engineered manufactured structural Building products, and have since shut down. It having a membership of 30 people. Most of these people also in my group Pre-Engineered Manufactured Building Systems Group which has over 2000 members.}

In recent years partly involved with testing SIP's at UniSA, here in South Australia. Whilst there are benefits with SIP's there are problems breaking into a market where brick veneer houses dominate.

There is a lot more to product design than getting some structural testing done. One noticeable point is that the quality characteristics of bricks are not explicitly specified, and yet perceived as the material to use.

People with European heritage tend to want double brick, but when discover the cost opt, for brick veneer. We have highly reactive clay soils, and footings to support such decorative veneer use a lot of concrete, and tend to be expensive. There is no real design goes into such slabs and footings, more of an automatic choice, that's the way its done, with no real thought: even though insistence that engineer be involved for site specific conditions. I don't believe that people really understand that the brick is largely just a decoration, and that they are spending a lot of money on footings simply the minimise cracking of that decoration.

So I think one of the first things that anyone needs to do before introducing a new structural product for wall construction, is identify the quality characteristics of brick, and carry out value analysis on the brick veneer construction. Then provide a comparison between the brick veneer construction and the alternative being promoted.

Simply saying faster to construct doesn't really sell it. Also new technologies also require an appropriately trained workforce and a suitable set of tools. Also need to understand that small building contractors have a certain friendship with their subbies: which goes to concrete slab, timber framing and brick veneer. To introduce new materials, need to find a reliable supplier of the materials, and reliable subcontractor to install. Along with other trades that want to work with the materials, such as electricians and plumbers.

So whilst SIP's are a product with benefits, cannot expect to get anywhere by simply selling the materials. Do basically need some stock plans of buildings for comparison: that is buildings in brick veneer compared against same building constructed with SIP's.

Plaster Wall Panels (load bearing)

Problems of Evidence-of-Suitability, and Structural Failures: the philosophy of science

University of South Australia, always on look out for student projects

Balustrade and Barrier Heights the reasoning?

{Previously posted in LinkedIn group I created: Pre-Engineered manufactured structural Building products, and have since shut down. It having a membership of 30 people. Most of these people also in my group Pre-Engineered Manufactured Building Systems Group which has over 2000 members.}

The industrial platforms code (1992) differentiates between guardrails (900<h<1100) and handrails (800<h<1000), whilst the Building code of Australia (BCA) is not so clear. If a guardrail is too low then people can topple over, if it is too high then people can fold and fall under it. So a single rail has to be just right height to function, but population heights are distributed: and consequently it is not entirely feasible to have a single rail that will function for all people. Similarly if a handrail is too low it is uncomfortable to use, if it is too high it cannot be reached. The BCA does not limit the height of a handrail it only sets a minimum.

It is therefore preferable that a more complete barrier is formed with infill below the guardrail. In industrial applications that is typically just a kneerail. In other applications additional horizontal rails are considered a climbing hazard, so infill is typically vertical rails. Vertical rails also provide some function as grabrails/handrails for children who cannot otherwise reach a handrail. However infill below the guardrail only prevents shorter people from folding and falling under the guardrail, it won't stop taller people toppling over.

The height set for the barrier has to be greater than the centre of gravity of the human body, not equal to, but that varies from person to person. At the end of the day a code compliant guardrail cannot stop someone falling over. A barrier really needs to be infilled between floor and top edge, and the top edge needs to be up around the 95th percentile shoulder height of the population: so that not relying on a fine balance in the range of centre of gravity.

AS1657:2013 seems to have become as confused as the BCA, with respect to differentiating between guardrails and handrails. The typical industrial gurardrail was set 1000mm height because handrail and guardrail were one and the same component: and 1000mm met both the guardrail and handrail height requirements. In terms of AS1428 however such guardrail may be considered too high to be a handrail.

The height set is a matter of economy and works most of the time for normal circumstances. Glass panel and other solid panel infills, lack the additional rails for grip in a fall that vertical infill rails provide. From metric data handbook 95th percentile shoulder height is 1528mm, so top edge around 1550mm is likely a better barrier to falling. Architects are increasingly opting for 1200mm to 1800mm barrier heights. The latter seems like the better option, full height walls seem even better.

The point is that the function of the guardrail is not to prevent falls but to minimise falls, if wish to prevent falls then a more appropriate barrier is required.

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Monday, 14 September 2015