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Technicians APPLY, Technologists ADAPT, Engineers ORIGINATE Technicians APPLY, Technologists ADAPT, Engineers ORIGINATE

Vol: Vol:11 No: No: 11 ETAMORPHS JOURNAL ETAMORPHS JOURNAL http://users.senet.com.au/~metamorf http://users.senet.com.au/~metamorf mailto: [email protected]

mailto: [email protected] _Aug-2003_Aug-2003

A MEANDERING INTRODUCTION A MEANDERING INTRODUCTION

Steven CONRAD Harrison

Steven CONRAD Harrison, , B.Tech(Mfg & B.Tech(Mfg & Mech.), MIIE, graMech.), MIIE, gradTIEAustdTIEAust

Welcome! This is where I get to take a serious and not so

Welcome! This is where I get to take a serious and not so serious look at technology in all its forms, includingserious look at technology in all its forms, including that of society itself. Yes, from my viewpoint society is a

that of society itself. Yes, from my viewpoint society is a technologtechnology. Hence I will not be considering they. Hence I will not be considering the impact of technology on society, but whether the

impact of technology on society, but whether the technologtechnology that is y that is society, is appropriate for the needs of society, is appropriate for the needs of the people it is supposed to benefit.

the people it is supposed to benefit. Are the conditions of the “social-contract” acceptable and practical?Are the conditions of the “social-contract” acceptable and practical?

Technolog

Technology represents order, form and structure (morph) and for it to be of any y represents order, form and structure (morph) and for it to be of any value it has to be capable of value it has to be capable of adapting to a dynamic environment, to be able to evolve,

adapting to a dynamic environment, to be able to evolve, to transcend, transform and go beyond (meta) itsto transcend, transform and go beyond (meta) its origins.

origins.

Metamorphs is an

Metamorphs is an enterprise setup to pursue enterprise setup to pursue broad ranging interests concerning technology, encompbroad ranging interests concerning technology, encompassingassing the arts and sciences, the

the arts and sciences, the philosophphilosophy there-of, and the y there-of, and the application in the field of engineering to develop newapplication in the field of engineering to develop new technologie

technologies. Here s. Here engineeengineering is ring is broadly defined as:broadly defined as: the search for the means of the search for the means of obtaining theobtaining the maximum benefit from the

maximum benefit from the available but otherwise limited resources.available but otherwise limited resources.

The concept of what is engineering, who are engineers, and how should they be trained, how many do we

need, and what value are they

need, and what value are they, will , will be a common thread running throughout all future essays published inbe a common thread running throughout all future essays published in this journal.

this journal.

For those that are unaware, in

For those that are unaware, in Australia, we currently have four Australia, we currently have four grades of engineering practitiogrades of engineering practitioners:ners: technicians, enginee

technicians, engineering officers, engineering technologists and engineers. Only the latter ring officers, engineering technologists and engineers. Only the latter three grades arethree grades are given status by the institution of

given status by the institution of engineers Australia (IEAust). Technicianengineers Australia (IEAust). Technicians are the s are the closest to the traditionalclosest to the traditional engineers of old; they work with

engineers of old; they work with the real systems and are the real systems and are able to build what they design. All able to build what they design. All the other gradesthe other grades are concerned primarily with the design and management of technology, and they have to be exceptionally are concerned primarily with the design and management of technology, and they have to be exceptionally lucky to get

lucky to get out off the design office out off the design office and get anywhere near the real systems they and get anywhere near the real systems they design. These other design. These other grades are educated in the use of

grades are educated in the use of analytical tools, which allow them to evaluate increasingly complexanalytical tools, which allow them to evaluate increasingly complex systems: whether they actually apply these tools in

systems: whether they actually apply these tools in practice is another matter altogether.practice is another matter altogether.

From simple observation, it should be apparent that most things that we need have already been produced, From simple observation, it should be apparent that most things that we need have already been produced, there may be a shortage of supply, and the systems may not be as effective or efficient as we desire them to there may be a shortage of supply, and the systems may not be as effective or efficient as we desire them to be, but they do

be, but they do exist. So we exist. So we have houses, roads, trucks, railways, trains, pipelines, pumps and power have houses, roads, trucks, railways, trains, pipelines, pumps and power stations, just to name a few

stations, just to name a few..So the question is: where is the complexity that demands the need for So the question is: where is the complexity that demands the need for

engineers?

In the building and construction industry where I work,

In the building and construction industry where I work, engineerinengineering is mainly concerned with producing, whatg is mainly concerned with producing, what I shall call

I shall call ““proof-calculationsproof-calculations”, the purpose of which ”, the purpose of which is to demonstrate to the is to demonstrate to the satisfaction of regulatingsatisfaction of regulating authorities that a proposed structure is adequate for its

authorities that a proposed structure is adequate for its purpose, as defined by compliance with acceptedpurpose, as defined by compliance with accepted codes of practice.

codes of practice.With respect to the definition of engineerinWith respect to the definition of engineering that I g that I gave above, no engineering is carriedgave above, no engineering is carried out. Further more the entire exercise can

out. Further more the entire exercise can be viewed as a considerable waste of resources, both time be viewed as a considerable waste of resources, both time andand paper, and the cause of unnecessary delays.

paper, and the cause of unnecessary delays. It should be noted that

It should be noted that we have available a limited number of materials that are we have available a limited number of materials that are manufacturemanufactured into a d into a limitedlimited number of structural sections, that are

number of structural sections, that are otherwise fabricated and erected into a limited number of commonotherwise fabricated and erected into a limited number of common structural configuration

structural configurations. Hence with s. Hence with the exception of the most exotic the exception of the most exotic architectural offering, most of thearchitectural offering, most of the complex aspects of engineering design can be carried out once and published as design manuals. Most complex aspects of engineering design can be carried out once and published as design manuals. Most especially in this age of

especially in this age of computers; this presents an interesting irony.computers; this presents an interesting irony. Prior to the

Prior to the wide scale availability of computers, there were far wide scale availability of computers, there were far more engineering hanmore engineering handbooks with more pre-dbooks with more pre-calculations than there are today. In the age of manual calculation, it caused too much delay, to have every calculations than there are today. In the age of manual calculation, it caused too much delay, to have every individual designe

individual designer working out everything from first r working out everything from first principles, hence repetitive elemenprinciples, hence repetitive elements of design werets of design were worked out and published. So for instance manufacturers of structural sections worked out

worked out and published. So for instance manufacturers of structural sections worked out and published theand published the section properties, but not just the

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built-Technicians APPLY, Technologists ADAPT, Engineers ORIGINATE Technicians APPLY, Technologists ADAPT, Engineers ORIGINATE

pre-enginee

pre-engineered solutions decreasing, especially in this red solutions decreasing, especially in this age of computers, when analytical software age of computers, when analytical software andand

electronic publications allow engineers and designers to be

electronic publications allow engineers and designers to be more pro-active?more pro-active? Why wait around to be givenWhy wait around to be given

the opportunity to design the world’s longest span bridge or the

the opportunity to design the world’s longest span bridge or the world’s tallest building?world’s tallest building?If you are reallyIf you are really creative and interested in engineering, instead of wasting time following the rules of dull

creative and interested in engineering, instead of wasting time following the rules of dull computer games,computer games, apply the physical laws of the universe and design and invent that which has not yet been imagined. Or on apply the physical laws of the universe and design and invent that which has not yet been imagined. Or on the less innovative side, if

the less innovative side, if you are a you are a qualified enginqualified engineer: design and publish the relatively routine, beforeeer: design and publish the relatively routine, before some one asks you to.

some one asks you to. Why design 12m span sheds on a daily Why design 12m span sheds on a daily basis, waiting to design a large 30m basis, waiting to design a large 30m spanspan shed, when it is

shed, when it is a trivial exercise to a trivial exercise to design the 30m span structure anyway. Reverse the process, design the 30m span structure anyway. Reverse the process, instead of instead of designing structures to suit an architects building envelope, design and publish the structures first and let designing structures to suit an architects building envelope, design and publish the structures first and let architects find a use

architects find a use for them. That is for them. That is structural engineers can stretch and extend the imaginations of structural engineers can stretch and extend the imaginations of architects, rather than the other way

architects, rather than the other way round. After all, many of round. After all, many of our most monumental structures have beenour most monumental structures have been designed by holding a competition, and then selecting one of many designs as a winner. To put it an other designed by holding a competition, and then selecting one of many designs as a winner. To put it an other way, structural engineers in conjunction with fabricators can design and develop exotic structural forms way, structural engineers in conjunction with fabricators can design and develop exotic structural forms which then extend what is considered routine to an

which then extend what is considered routine to an architect. Instead of architects keep hitting a architect. Instead of architects keep hitting a brick wall:brick wall: can’t do that! With

can’t do that! With the engineer that they need to employ, who can the engineer that they need to employ, who can achieve their aims, being located on theachieve their aims, being located on the other side of the

other side of the world and unknown, because it is the world and unknown, because it is the architects that get the fame.architects that get the fame. What a real design-engineer should want to do: is put

What a real design-engineer should want to do: is put all the knowledge from their formal all the knowledge from their formal studies to use. Thestudies to use. The structural design of a 21m portal

structural design of a 21m portal frame shed is no different frame shed is no different than designing a 12m shed. The exercise onlythan designing a 12m shed. The exercise only becomes interesting when other aspects are

becomes interesting when other aspects are taken into consideration:taken into consideration: at what span does a fixed-base portalat what span does a fixed-base portal

frame become impractical. If such a

frame become impractical. If such a span is beyond normal applications, then another aspect to consider isspan is beyond normal applications, then another aspect to consider is

how quickly can frames be fabricated and erected? What is

how quickly can frames be fabricated and erected? What is the minimum amount of material that can bethe minimum amount of material that can be

used in the structure? What type of

used in the structure? What type of materials can be used? Are materials more useful manufactured directlymaterials can be used? Are materials more useful manufactured directly

into sections or supplied as sheets?

Steel for example can be formed into

Steel for example can be formed into hot rolled structural sections, such as universal beams, which I hot rolled structural sections, such as universal beams, which I mightmight add have considerably less than universal application. Or steel can be formed into high

add have considerably less than universal application. Or steel can be formed into high strength coil strip,strength coil strip, which can then be manufactured into a whole variety

which can then be manufactured into a whole variety of structural sections to suit of structural sections to suit specific applicationspecific applications. Mores. More over a solid coil

over a solid coil of galvanised steel can be transported to a of galvanised steel can be transported to a construction site and roll-formed into an entireconstruction site and roll-formed into an entire building. Such method of construction reducing problems of

building. Such method of construction reducing problems of detailing joints for detailing joints for long members, insteadlong members, instead members can be rolled to the

members can be rolled to the required length on site. Transportation costs can be reduced. When fabricatedrequired length on site. Transportation costs can be reduced. When fabricated in a factory structural members are limited in size due to transportation restrictions. Further more it is the in a factory structural members are limited in size due to transportation restrictions. Further more it is the dimension and geome

dimension and geometry of the try of the members that determines the number of trucks and trips members that determines the number of trucks and trips required to deliver required to deliver all components to site, not the

all components to site, not the weight. With steel coil, weight. With steel coil, there is no fresh there is no fresh air between members stacked on aair between members stacked on a truck, just solid steel.

truck, just solid steel. Admittedly roll-forming on site requires roll-forming equipmeAdmittedly roll-forming on site requires roll-forming equipment for each building under nt for each building under construction at the same time. But

construction at the same time. But then the number of trucks rthen the number of trucks required by the construction industry will haveequired by the construction industry will have also been reduced, so it is

also been reduced, so it is in effect exchanging one set of in effect exchanging one set of machines for another. Then again, adversemachines for another. Then again, adverse weather conditions, predictab

weather conditions, predictable or not, le or not, make factory work more productive than on site make factory work more productive than on site construction.construction. So is sheet metal

So is sheet metal of any value for of any value for fabricating buildingfabricating buildings?s? Since an industry Since an industry already exists, manufacturing andalready exists, manufacturing and supplying fixed-base portal frame sheds fabricated from cold-formed c-section, the answer is clearly yes. So supplying fixed-base portal frame sheds fabricated from cold-formed c-section, the answer is clearly yes. So the real questions of concern are:

the real questions of concern are: 1.

1. What What are thare the lie limitations mitations of the of the available available c-sections?c-sections?

2.

2. What additioWhat additional sizes nal sizes are required are required to extend thto extend the range e range of sheds thof sheds that can be at can be built?built?

The answer to the first question is provided by the free draft copy of:

The answer to the first question is provided by the free draft copy of: MEMBER SELECTION CHARTS FORMEMBER SELECTION CHARTS FOR PORTAL FRAMED SHEDS (Volume 1.1)

PORTAL FRAMED SHEDS (Volume 1.1), that accompanies this essay. It is a draft issue, and as , that accompanies this essay. It is a draft issue, and as not yetnot yet been fully checked. However, its use to

been fully checked. However, its use to identify what isidentify what is not possiblenot possible, is far better , is far better than the guesstimating thathan the guesstimating thatt currently occurs in the industry.

currently occurs in the industry. Thus we have a high Thus we have a high level of confidence of what is level of confidence of what is outside the capabilities of outside the capabilities of the available c-sections, however, that which is within

the available c-sections, however, that which is within the range of the c-sections rthe range of the c-sections requires further equires further demonstration of structural

demonstration of structural adequacyadequacy. {Persons intending to make use of the attached design charts should . {Persons intending to make use of the attached design charts should seek the services of a qualifie

seek the services of a qualified structural engined structural engineer (eg. Either MIStructE er (eg. Either MIStructE or NPER(structural)), to provideor NPER(structural)), to provide guidance on the suitability of the charts

guidance on the suitability of the charts for their particular purposes.}for their particular purposes.} The answer to the second question; what additional sizes of

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a rectangle in the ratio

a rectangle in the ratio of 3:1 being acceptable, if process doesn’t determine otherwise. The most commonof 3:1 being acceptable, if process doesn’t determine otherwise. The most common spans of shed offered by

spans of shed offered by the shed industry are 7.6m, 9m and the shed industry are 7.6m, 9m and 12m. Further more the sheds being bought are12m. Further more the sheds being bought are not the pre-engineered solution

not the pre-engineered solutions being offered, customers want to s being offered, customers want to vary both the heights and spans of vary both the heights and spans of thethe available sheds. This results in the shed industry supplying a

available sheds. This results in the shed industry supplying a lower quality product than is expected by lower quality product than is expected by thethe customers. Goods and Service together make up the overall definition of the

customers. Goods and Service together make up the overall definition of the product supplied.product supplied. The more traditional way of obtaining a building was to

The more traditional way of obtaining a building was to employ a builder (architect) who both designed andemploy a builder (architect) who both designed and constructed the building. Today the more formal way, is

constructed the building. Today the more formal way, is to employ an architect, who to employ an architect, who designs the buildingdesigns the building space and envelope and then employs enginee

space and envelope and then employs engineers as sub-consultants for all rs as sub-consultants for all the specialised aspects of thethe specialised aspects of the building design. The resulting design docum

building design. The resulting design documents are then put out ents are then put out to tender, various parties submit estimatedto tender, various parties submit estimated costs of supplying. Then some criteria are

costs of supplying. Then some criteria are used to select the most used to select the most appropriate tendeappropriate tenderer to contract rer to contract for thefor the supply. Unfortunately, more often than not the lowest bidder wins the

supply. Unfortunately, more often than not the lowest bidder wins the contract. Once the contract as beencontract. Once the contract as been awarded, an expensive game of variations starts. This is

awarded, an expensive game of variations starts. This is where the contractor declares that certain aspectswhere the contractor declares that certain aspects of supply are outside the scope of

of supply are outside the scope of the contract, and where the client’s rthe contract, and where the client’s r epresentativeepresentatives contend that it s contend that it waswas inside the scope of the

inside the scope of the contract. The problem is thatcontract. The problem is that general consultantsgeneral consultants do not specify everything that isdo not specify everything that is required, and

required, and general contractorsgeneral contractors do not know everything that is do not know everything that is required. Plus there is an aspect of required. Plus there is an aspect of greedgreed by all parties, the

by all parties, the buyer doesn’t want to pay the buyer doesn’t want to pay the full cost of full cost of supply, whilst the supplier having already loadedsupply, whilst the supplier having already loaded their price to account for items missing from the specification, attempts to get paid twice for it.

their price to account for items missing from the specification, attempts to get paid twice for it.

As a consequence alternatives have been sought to this expensive and stressful adversarial game. One As a consequence alternatives have been sought to this expensive and stressful adversarial game. One solution as been “design and construct” contracts. Unfortunately these contracts tend to be

solution as been “design and construct” contracts. Unfortunately these contracts tend to be structured thestructured the opposite way round to the normal contract: that

opposite way round to the normal contract: that is the builders now employ the is the builders now employ the designers, and indesigners, and in consequen

consequence the designers have less authority to ce the designers have less authority to act in the best act in the best interests of the building owner. However,interests of the building owner. However, whilst independen

whilst independent designers may have the authority to t designers may have the authority to ensure construction complies with their designs, theensure construction complies with their designs, the design itself is not

design itself is not necessarily fit for the necessarily fit for the purpose required by the owner. Building regulations do not help inpurpose required by the owner. Building regulations do not help in this respect either, for

this respect either, for they have little to they have little to do with owners needs and are more concerned with public safety.do with owners needs and are more concerned with public safety. {I will discuss the concept of risk and safety more fully in

{I will discuss the concept of risk and safety more fully in future issues.}future issues.} The main lack of quality

The main lack of quality in the tendering/contractinin the tendering/contracting process is g process is that of design, or more that of design, or more specifically thespecifically the documenting and specifying of the design, followed by comprehending and complying with the design documenting and specifying of the design, followed by comprehending and complying with the design documents. For example many consultants in order to keep costs down,

documents. For example many consultants in order to keep costs down, cram as much data as cram as much data as possible ontopossible onto a single drawing sheet. They then argue that the

a single drawing sheet. They then argue that the information was there all the time, information was there all the time, and therefore theand therefore the contractor should have been aware of it, and

contractor should have been aware of it, and hence taken it into consideration. Using computer sciencehence taken it into consideration. Using computer science terminology, the data may well have been there, but t

terminology, the data may well have been there, but t here was definitely no information. Specificationshere was definitely no information. Specifications should not be produced in a manner that presents a game of search and seek, and if you don’t know to look, should not be produced in a manner that presents a game of search and seek, and if you don’t know to look, then you won’t find.

then you won’t find. This lack of quality is

This lack of quality is therefore largely due to a lack therefore largely due to a lack of specialisation, a lack of of specialisation, a lack of adaptation and evoluadaptation and evolution, ation, a failure to build on past

failure to build on past experience. Continuexperience. Continuously re-inventing the wheel, and each time, leaving a differentously re-inventing the wheel, and each time, leaving a different chunk out. Re-invention needs to be displaced by continuous improvement and original invention.

chunk out. Re-invention needs to be displaced by continuous improvement and original invention. This returns us to

This returns us to the shed industry. The existence of an the shed industry. The existence of an industry that supposedly supplies pre-engineindustry that supposedly supplies pre-engineered,ered, ready to fabricate buildings, is attracting more potential building owners away from the

ready to fabricate buildings, is attracting more potential building owners away from the traditional design andtraditional design and tender pathway, and more towards the direct buy

tender pathway, and more towards the direct buy path. Unfortunately this is placing all parties at path. Unfortunately this is placing all parties at aa disadvantag

disadvantage, for there is e, for there is more to a building project than the more to a building project than the supply of a simple envelope and its supportsupply of a simple envelope and its support structure. For the most

structure. For the most part the shed industry does not employ engineers or architects part the shed industry does not employ engineers or architects on staff any whereon staff any where within its field of activity. It

within its field of activity. It only contracts structural engineonly contracts structural engineers as a last resort ers as a last resort when the client wants a customwhen the client wants a custom structure, and building regulators have r

structure, and building regulators have r ejected the shed suppliers guess.ejected the shed suppliers guess. But as I

But as I said the disadvantages of the design/tender process are attracting more people to thesaid the disadvantages of the design/tender process are attracting more people to the design/con

design/construct process, but that struct process, but that also is loosing out to also is loosing out to the direct buy option. Hence there is the direct buy option. Hence there is plenty of futureplenty of future potential, if the

potential, if the scope for improvement is scope for improvement is recognised, exploited and improvemerecognised, exploited and improvement achieved.nt achieved. However, the starting point is

However, the starting point is product design and that requires structural engineering input. For example theproduct design and that requires structural engineering input. For example the attached design charts can be used by informed suppliers to

attached design charts can be used by informed suppliers to identify whether or not there is identify whether or not there is justification for justification for variation in section size. Perhaps it

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If you think you are just a

If you think you are just a supplier of sheds to your local market, think again. General steel fabricatosupplier of sheds to your local market, think again. General steel fabricators havers have already started loosing contracts to

already started loosing contracts to international players. Advanced design and detailing software operatedinternational players. Advanced design and detailing software operated by international fabricators with automated beam-lines have allowed them

by international fabricators with automated beam-lines have allowed them to produce custom designs, withto produce custom designs, with little error, and this

little error, and this has been in record making supply times. It has been in record making supply times. It is fabricators and their workshop detailers thatis fabricators and their workshop detailers that are doing this, not consultants. So clearly

are doing this, not consultants. So clearly once a fabricator has computer based instructions for a once a fabricator has computer based instructions for a commoncommon everyday structure, then that structure can become a st

everyday structure, then that structure can become a st andard product offering, which can be produced andandard product offering, which can be produced and supplied even faster than it was

supplied even faster than it was first supplied, simply because the design and engineering have alreadyfirst supplied, simply because the design and engineering have already been done. The only delay concerning design that remains, is that of

been done. The only delay concerning design that remains, is that of regulation and building controlregulation and building control. The. The Building approval process is an activity of

Building approval process is an activity of quality assurance and is more concerned with documents thanquality assurance and is more concerned with documents than reality. The focus is

reality. The focus is on the specifications complying with codes of practice rather than on the specifications complying with codes of practice rather than the constructionthe construction complying with the specifications. If the specifications are compliant, then approval for building is granted. If complying with the specifications. If the specifications are compliant, then approval for building is granted. If the specifications are compliant, then there is the

the specifications are compliant, then there is the assumption that a decent set of documents exist againstassumption that a decent set of documents exist against which the actual

which the actual construction can eventually be checked for construction can eventually be checked for compliancecompliance.. {I will discuss {I will discuss quality assurancequality assurance (QA) in future issues,

(QA) in future issues, and how an objective of compliance with ISO and how an objective of compliance with ISO 9000, is contradictory to QA principles.}9000, is contradictory to QA principles.} So if you

So if you want the building approval process to execute more rapidly then improve both the want the building approval process to execute more rapidly then improve both the documentadocumentationtion and information that is available about the product being supplied, educate the public about the product. If and information that is available about the product being supplied, educate the public about the product. If everyone knows what is required, then it

everyone knows what is required, then it ceases to be necessary to ceases to be necessary to produce multi-page engiproduce multi-page engineering reportsneering reports every time some one wants to

every time some one wants to construct a common structural form. As construct a common structural form. As for owner/builders if they have accessfor owner/builders if they have access to published pre-engineered solutions, then they won’t have to endure the expense of paying to have their to published pre-engineered solutions, then they won’t have to endure the expense of paying to have their own inadequate designs/co

own inadequate designs/constructions rejected, along with paying tnstructions rejected, along with paying t o strengthen what they o strengthen what they have already built.have already built. Well that’s today’s thoughts. If you think I wander all over the place with my ideas, then you are right. It Well that’s today’s thoughts. If you think I wander all over the place with my ideas, then you are right. It is notis not my intention to be clear and precise. I am taking a journey along winding roads, and pointing out what I can my intention to be clear and precise. I am taking a journey along winding roads, and pointing out what I can see on the way. I do not know what will

see on the way. I do not know what will lie around the next bend, but when we turn into it, I will lie around the next bend, but when we turn into it, I will describe whatdescribe what I see there. If you’re willing to endure another bumpy ride then tune in for the next issue. That’s

I see there. If you’re willing to endure another bumpy ride then tune in for the next issue. That’s unpredictabl

unpredictable too, it e too, it could be tomorrow, or it could be tomorrow, or it could be next month.could be next month.

PS: PS:

Persons requiring more information on the attached design charts can contact the author: Persons requiring more information on the attached design charts can contact the author: Conrad Harrison

Conrad Harrison

mailto:[email protected] mailto:[email protected]

So that there is

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MEMBER SELECTION CHARTS

FOR PORTAL FRAME SHEDS

10°

10° Doubly

Doubly Pitched

Pitched Frames

Frames

FOR

WIND

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MEMBER

MEMBER SELECTION CHASELECTION CHARTSRTS

FOR PORTAL FRAMED SHEDS FOR PORTAL FRAMED SHEDS

(Volume 1: DRAFT ISSUE) (Volume 1: DRAFT ISSUE)

Steven CONRAD Harrison Steven CONRAD Harrison

2003 2003

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All rights reserved. No part of this report may be of this report may be reproduced, stored in a retrieval system,reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, or otherwise,

or transmitted, in any form or by any means, electronic, mechanical, or otherwise, withoutwithout

the prior written permission of the copyright owner. the prior written permission of the copyright owner. CAUTION:

CAUTION:

The author, by making the information in thi

The author, by making the information in this document publicly available cannot bes document publicly available cannot be

considered as rendering professional service. Users of this document are therefore considered as rendering professional service. Users of this document are therefore advised to seek the services of a qualified practitioner of structural engineering, to advised to seek the services of a qualified practitioner of structural engineering, to thoroughly review the proposed project and the suitability of applying the i

thoroughly review the proposed project and the suitability of applying the information in thisnformation in this

document for such purpose. This advice shall be obtained, prior to applicati

document for such purpose. This advice shall be obtained, prior to application for buildingon for building

approval. The person or party r

approval. The person or party rendering such advice shalendering such advice shall accept full l accept full responsibility forresponsibility for such ap

such applications of said inforplications of said information.mation. DISCLAIMER:

DISCLAIMER: There is n

There is no warranty for o warranty for this document and the information contained herein, this document and the information contained herein, to the to the extentextent permitted by applicable law. Except when otherwise stated in writing the author

permitted by applicable law. Except when otherwise stated in writing the author andand

copyrig

copyright holders provide the document "as is" without ht holders provide the document "as is" without warranty of any kind, eitherwarranty of any kind, either expre

expressed ssed oo r implied, including, but not limited to, the implied warranties of merchantabilityr implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose.

and fitness for a particular purpose.

Since the information contained in this document may be applied under conditions beyond Since the information contained in this document may be applied under conditions beyond the author’s control, users are further advised that they have been cautioned and that t

the author’s control, users are further advised that they have been cautioned and that t hehe

entire risk as to the

entire risk as to the suitability of the document for suitability of the document for a particular purpose is a particular purpose is with the user. Nowith the user. No responsibility can be accepted by the author or copyright holders for any l

responsibility can be accepted by the author or copyright holders for any loss or damageoss or damage

caused by any person acting or refraining from action as a result of this information. caused by any person acting or refraining from action as a result of this information. Furthermore the author and copyright holders make no representation or warranty Furthermore the author and copyright holders make no representation or warranty regarding accuracy of any information contained in thi

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required by applicable law or agreed to

required by applicable law or agreed to in writing, in writing, will the author or copyright holders bewill the author or copyright holders be

liable t

liable to the o the user or affected third parties for damages, including any general, special,user or affected third parties for damages, including any general, special, incidental or consequen

incidental or consequential damages arising directly, indirectly, or remotely tial damages arising directly, indirectly, or remotely from the use orfrom the use or omission of any information contained in this

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PREFACE

For the building and construction industry, design and engineering are largely viewed as a For the building and construction industry, design and engineering are largely viewed as a regulatory hindrance and delay. Not even manufacturers and suppliers of so called regulatory hindrance and delay. Not even manufacturers and suppliers of so called “pre-enginee

engineered” produred” productcts employ engineers to design and develop such prs employ engineers to design and develop such products. They onlyoducts. They only employ engineers to produce calculations to demonstrate structural adequacy to gain employ engineers to produce calculations to demonstrate structural adequacy to gain building approval.

building approval. Man

Many ony onee -off construction projects consist of common structural elements that have been-off construction projects consist of common structural elements that have been designed a multitude of times before. Yet engineers sit down and start

designed a multitude of times before. Yet engineers sit down and start from scratch,from scratch,

writing out and conducting calculations they have

writing out and conducting calculations they have completed a hundred times before.completed a hundred times before.

Mean while fabricators and construction

Mean while fabricators and construction contractors are wondering what all contractors are wondering what all the delay the delay is,is,

for they believe they already know what size

for they believe they already know what size beams and connections to use, for likewisebeams and connections to use, for likewise

they have constructed such items a hundred times before. The only way our building they have constructed such items a hundred times before. The only way our building approval process works is on the basis of experience, such that t

approval process works is on the basis of experience, such that the approvinhe approving authg authorityority

knows that the proposed structure is adequate because it has been approved a hundred knows that the proposed structure is adequate because it has been approved a hundred times befo

times before. re. Such experience also allows the identificatiSuch experience also allows the identification of unique structures thaton of unique structures that require more engineering attention and detail, than is given to the more com

require more engineering attention and detail, than is given to the more com monmon

structures. structures.

Not only is the entire process wasteful of time, it also wastes other resources, such as the Not only is the entire process wasteful of time, it also wastes other resources, such as the paper used in the documentation and

paper used in the documentation and the space required to file such documentthe space required to file such documents, and thes, and the

energy required to produc

energy required to produce and manage. Structural materials e and manage. Structural materials are also wasted, due to are also wasted, due to widewide ranging competency in the skills of the engineering practitioners involved. Such variation in ranging competency in the skills of the engineering practitioners involved. Such variation in competency also results in high variation in the risk of failure of such structures, to the competency also results in high variation in the risk of failure of such structures, to the extent that some neighbou

extent that some neighbourhoods have the potential trhoods have the potential to be highly dangerous environments.o be highly dangerous environments.

A dangerous environment because both the design engineers and the approving A dangerous environment because both the design engineers and the approving authorities can be equally incompetent, resulting in poor designs being granted buil

authorities can be equally incompetent, resulting in poor designs being granted buildingding

approval. approval.

It does not have to stay this wa

It does not have to stay this wa y. Computers, electronic multimedia and the internet openy. Computers, electronic multimedia and the internet open

up an entirely new market place for

up an entirely new market place for engineering practitioners. That is the publication andengineering practitioners. That is the publication and

distribution of pre-enginee

distribution of pre-engineered solutions to a red solutions to a world market place.world market place.

Engineering practitioners should end

Engineering practitioners should end up up competing on the basis of competing on the basis of competency, not justcompetency, not just

availability and price. For exa

availability and price. For example, omple, o ne engineer produces a set of tables for floor beamsne engineer produces a set of tables for floor beams using simplistic calculations. Another engineer produces a similar set of

using simplistic calculations. Another engineer produces a similar set of tables but usingtables but using

more detailed design, such as allowing for vibration, thus implicitly

more detailed design, such as allowing for vibration, thus implicitly demonstrating thatdemonstrating that

many of the solutions in the first set of tables are inadequate. If the building approval many of the solutions in the first set of tables are inadequate. If the building approval process is working properly then designs based on the first

process is working properly then designs based on the first set of tables should start beingset of tables should start being

rejected

rejected, with the second set of , with the second set of tables becoming the de ftables becoming the de facto standard.acto standard.

It is this potential to improve an industry that this first guidebook in a series aimed at It is this potential to improve an industry that this first guidebook in a series aimed at providi

providing “pre-engineng “pre-engineered” solutionered” solutionss , is published. The first edit, is published. The first editions are thereforeions are therefore published to

published to identify current practidentify current practice and the state ice and the state of an industry. of an industry. It is consequentlyIt is consequently expected that future editions will present significantly diff

expected that future editions will present significantly different solutions.erent solutions.

Steven CONRAD Harrison

Steven CONRAD Harrison,,B.Tech(Mfg & B.Tech(Mfg & Mech.)Mech.), MIIE, , MIIE, gradTIEAustgradTIEAust

Adelaide Adelaide January 2003 January 2003

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THE GUIDEBOOKS

Each guidebook covers

Each guidebook covers an elementary structural form, an elementary structural form, providing member selection tables.providing member selection tables. Each guidebook will be supported by several supplementary guides presenting the

Each guidebook will be supported by several supplementary guides presenting the structural calculations that are the foundations of the t

structural calculations that are the foundations of the tables. Where calculations areables. Where calculations are

presen

presented in a tabular fted in a tabular format, additional supplements wilormat, additional supplements will present design theory and al present design theory and a detailed worked example.

detailed worked example. By publishing

By publishing in in this manner several guidebooks can be assembled to form this manner several guidebooks can be assembled to form more completemore complete coverage of a building assembly. For example whilst

coverage of a building assembly. For example whilst the rafters and cthe rafters and columns in a fullyolumns in a fully

fixed portal frame are dependent one upon t

fixed portal frame are dependent one upon the other, once the frame analysis is he other, once the frame analysis is completecomplete

and the members are selected, a whole

and the members are selected, a whole variety of moment resisting connections can bevariety of moment resisting connections can be

used to assemble the frames. It therefore does not make sense,

used to assemble the frames. It therefore does not make sense, to produce a guidebookto produce a guidebook

that limits the frame design to one type of connection, and requires other authors to that limits the frame design to one type of connection, and requires other authors to duplicate the work of producing frame selection tables, when what i

duplicate the work of producing frame selection tables, when what interesnterests them its them iss

publishing a connection design. publishing a connection design.

Referencing

At this stage the proposed referencing of the guidebooks is to refer to each product At this stage the proposed referencing of the guidebooks is to refer to each product assembly as a volume. For example:

assembly as a volume. For example: Volumes

Volumes 1)

1) Fully Fixed Fully Fixed Doubly Pitched Doubly Pitched Portal Frames: Portal Frames: ShedsSheds 2)

2) Fully Fixed Fully Fixed Doubly Pitched Doubly Pitched Portal Frames: Portal Frames: CanopiesCanopies

Thus each volume will consist of several guidebooks, which will form the sections of each Thus each volume will consist of several guidebooks, which will form the sections of each volume.

volume. Sections Sections

1)

1) Portal Portal Frame Frame Member Member SelectionSelection 2)

2) Portal Portal Frame Frame Connection Connection SelectionSelection 3)

3) Portal Portal Frame Frame Pier Pier SelectionSelection 4)

4) End Wall ColumnEnd Wall Column/Mull/Mullion ion Member and Member and Pier SelectionPier Selection 5)

5) Longitudinal Longitudinal Bracing Bracing SelectionSelection 6)

6) Purlin Purlin SelectionSelection 7)

7) Girt Girt SelectionSelection

In some circumstances, due to the reusability

In some circumstances, due to the reusability of information, volumes and/or sections willof information, volumes and/or sections will

also be divided up int

also be divided up into parts. For examplo parts. For example: e: (1) (1) Region Region A1: A1: TC3 (2) Region A1: TC2.TC3 (2) Region A1: TC2. Each guidebook will also be supported by one or more supplements that

Each guidebook will also be supported by one or more supplements that present detailedpresent detailed

design data that will allow each guidebook to be checked. design data that will allow each guidebook to be checked. Supplements

Supplements 1)

1) Design Design ActionsActions 2)

2) Design Design Action Action EffectsEffects 3)

3) Member Member DesignDesign

4)

4) Design Design TheoryTheory 5)

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INTRODUCTION...1 INTRODUCTION...1 IND

INDEPENEPENDENT DENT CERTCERTIFIIFICATICATIONON ...2...2 DESIG

DESIGN N BACKGBACKGROUNDROUND ...2...2 Introduction...2 Introduction...2 Gene

Generatration ion of of CharChartsts ...3...3 Buil

Building Loadsding Loads ...3...3 Build

Building ing DimenDimensionssions ...4...4 Memb

Member Desiger Designn ...4...4 The Futur

The Future and e and KnowKnown Concernn Concernss ...5...5 INST

INSTRUCTIRUCTIONS FOR ONS FOR USINUSING G THE CHARTSTHE CHARTS ...7...7 USE

USE OF OF CHARTS CHARTS FOR FOR ALTERNATIALTERNATIVE VE DESIGNSDESIGNS ...8....8 Simp

Simpliflified ied DesiDesign gn RuleRuless ...9...9 Allo

Allowing For Shieldwing For Shielding from ing from WindWind ...9...9 All

Allowiowing ng For For TopTopogrographyaphy ...9...9 Allowing For Different Terrain Category...10 Allowing For Different Terrain Category...10 Allo

Allowing For wing For DifDifferferent Bay ent Bay SpaciSpacingng ...10...10 Alter

Alternatinative ve MaterMaterialsials ...11...11 Moment

Moment Capacity Capacity Required Required for for Actual Actual DimensionsDimensions ...12....12 Opt

Optimiimisinsing g ProProducductiotionn ...12...12 Desi

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INTRODUCTION

This first guidebook is produced for the benefit of

This first guidebook is produced for the benefit of that portion of the shed industry thatthat portion of the shed industry that

supplie

supplies gabs gablele -end sheds, with a 10 degree r-end sheds, with a 10 degree roof pitch, and fabricated from cold-oof pitch, and fabricated from cold-formeformed C-d C-sections.

sections.

The frames for these sheds are: The frames for these sheds are:

Fully Fixed Doubly Pitched Portal Frames with Constant Frame Size. Fully Fixed Doubly Pitched Portal Frames with Constant Frame Size.

As such they require moment resisting connections and footings. Since there are a variety As such they require moment resisting connections and footings. Since there are a variety of ways of providing such connections and footings, such details

of ways of providing such connections and footings, such details have been left to otherhave been left to other

guidebooks, with this guidebook concentrating on the design of the main portal frames. guidebooks, with this guidebook concentrating on the design of the main portal frames. It is presented as a series of height/Span charts produced for various bay spacings, for It is presented as a series of height/Span charts produced for various bay spacings, for AS1170 loadin

AS1170 loading requirements for building importance level 2. This g requirements for building importance level 2. This roughly equates to theroughly equates to the building having a 10% probab

building having a 10% probability of experiencing a load grility of experiencing a load greater than its eater than its critical design critical design loadload due to wind, in any 50 year period, and failing. Other wind loading parameters are: Region due to wind, in any 50 year period, and failing. Other wind loading parameters are: Region A1, terrain cate

A1, terrain category 3, topography flat, and no shieldinggory 3, topography flat, and no shielding ..

From these charts it is possible to identify what size of c-section is required for a given From these charts it is possible to identify what size of c-section is required for a given eaves height and buildin

eaves height and building width. See the instructions g width. See the instructions section for details on section for details on how to use.how to use. Whilst this is the age of computers, and the charts themselves were generated by Whilst this is the age of computers, and the charts themselves were generated by

computer, it is not currently considered to be of benefit to develop software for the shed computer, it is not currently considered to be of benefit to develop software for the shed industry. Software would require providing all sales people with a computer, and would industry. Software would require providing all sales people with a computer, and would require training to a level whereby the user

require training to a level whereby the user knows that the answer given by the software isknows that the answer given by the software is

garbage or not. garbage or not.

The problem with a co

The problem with a computer program tmputer program to design sheds for a specific projecto design sheds for a specific project, is that it does, is that it does not give insight into the capabilities of the available materials, and allow product design not give insight into the capabilities of the available materials, and allow product design decisions to be made that optimise production. For example design softwar

decisions to be made that optimise production. For example design software may advisee may advise

that a C20015 is adequate for a given structure, but it won’t advise that a C15024 is that a C20015 is adequate for a given structure, but it won’t advise that a C15024 is stronger, and that adopting that wil

stronger, and that adopting that will allow end plates to be standardised for the rl allow end plates to be standardised for the range ofange of

sheds sold. sheds sold.

Hence the design charts that make the design task visual and graphical. The simplest

Hence the design charts that make the design task visual and graphical. The simplest useuse

is to draw the rectangular elevati

is to draw the rectangular elevation of the shed on the chart, find the desion of the shed on the chart, find the design curve thatgn curve that envelo

envelopes it, and read pes it, and read off the size of off the size of c-section required.c-section required.

Another reason for producing such guidebooks is an attempt to encourage shed Another reason for producing such guidebooks is an attempt to encourage shed fabricators and su

fabricators and suppliers to increase the engineering content of ppliers to increase the engineering content of their products. Thus fartheir products. Thus far suppliers have employed consulting civil engineers to provide structural engineering suppliers have employed consulting civil engineers to provide structural engineering services. Such consultan

services. Such consultants are typically involved with one-off ts are typically involved with one-off designs producidesigns producingng calcu

calculationlations for bs for b uilding approval. Such projects generally involve simplified design, with auilding approval. Such projects generally involve simplified design, with a lack of detail compensated by conservatism. Such conservatism is beneficial for one

lack of detail compensated by conservatism. Such conservatism is beneficial for one -off-off

projects, where mistakes during fabrication and construction,

projects, where mistakes during fabrication and construction, and last minute changes canand last minute changes can

be catered for

be catered for without the need to without the need to scrap work done. scrap work done. Such an approach to design howeverSuch an approach to design however is inappropriate for standard products. Removing the conservatism, whilst ignoring the is inappropriate for standard products. Removing the conservatism, whilst ignoring the detail as the potential to result

detail as the potential to result in dangerous designs. Unfortunately this is how the cold-in dangerous designs. Unfortunately this is how the cold-formed shed industry has evolved.

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In consequenc

In consequence future editions of e future editions of this guidebook are likely to suggest reduced heights andthis guidebook are likely to suggest reduced heights and spans for each of the c-sections considered. This does not however have

spans for each of the c-sections considered. This does not however have to be the case to be the case ifif

more effort is placed into engineering, beyond structural analysis and member selection. more effort is placed into engineering, beyond structural analysis and member selection. For example quality engineering, value analysis and risk analysis could more clearly For example quality engineering, value analysis and risk analysis could more clearly identify the limitations of such structures, and the most appropriate application.

identify the limitations of such structures, and the most appropriate application. ForFor

example do such structures really need to be classified with importance level 2. example do such structures really need to be classified with importance level 2. For more guidance refer to the guide book to be ti

For more guidance refer to the guide book to be titled “Pre-Engineered Buildingtled “Pre-Engineered Building

Structures”, and those guide books to be written on specific structural assemblies, such as Structures”, and those guide books to be written on specific structural assemblies, such as gable sheds.

gable sheds.

INDEPENDENT

INDEPENDENT CERTI

CERTIFICATION

FICATION

For those that have read the caution and the disclaimer at

For those that have read the caution and the disclaimer at the beginning of this guidebook,the beginning of this guidebook,

it should be clear that certification of this guide book by an independent engineer, is a it should be clear that certification of this guide book by an independent engineer, is a pointless exercise. Engineers

pointless exercise. Engineers considering doing so should considering doing so should think vthink very carefully ery carefully beforebefore taking such

taking such action. action. What exactly would What exactly would such certification imply? such certification imply? Would such cWould such certificationertification remove the need for a qualified engineering practitioner to review the suitability of these remove the need for a qualified engineering practitioner to review the suitability of these design charts on a project by project basis?

design charts on a project by project basis?

Building authorities and regulators considering demanding such independent certification Building authorities and regulators considering demanding such independent certification should also very carefully consider the

should also very carefully consider the impact of such demands on the over allimpact of such demands on the over all

effectiveness and quality of the building approval process. If

effectiveness and quality of the building approval process. If no engineering pracno engineering practitionertitioner

has

has been appointed as designer responsible for determining the suitabilbeen appointed as designer responsible for determining the suitability of thisity of this guidebook for a particular project, then that person involved in the project and most guidebook for a particular project, then that person involved in the project and most suitably qualified to make such judgement, is most likely to be

suitably qualified to make such judgement, is most likely to be held responsible. In otherheld responsible. In other

words the building controller, ceases to be

words the building controller, ceases to be the independent approving authority, andthe independent approving authority, and

becomes the designer responsible instead. Hence no i

becomes the designer responsible instead. Hence no independent check and a buildingndependent check and a building

control system with limited effectiveness. control system with limited effectiveness.

It should be noted that this guidebook is produced for

It should be noted that this guidebook is produced for use as an estimation tool by use as an estimation tool by non-

non-engineers and as a final design reference by qualified engineering pr

engineers and as a final design reference by qualified engineering practitioners. Qualifiedactitioners. Qualified

is meant to imply that the engineering practitioner

is meant to imply that the engineering practitioner hhas the capability as the capability and competency toand competency to

either reproduce

either reproduce, if they had the , if they had the time, or refute the contents of this guidebook. It alsotime, or refute the contents of this guidebook. It also means that no such qualified person would merely accept the contents of this document, means that no such qualified person would merely accept the contents of this document, and would therefore conduct their own checks to verify the suitability of using it as a design and would therefore conduct their own checks to verify the suitability of using it as a design reference. At a minimum such checks would consist of verifying at least three design

reference. At a minimum such checks would consist of verifying at least three design points along the steep descending segment of each design curve that is going to

points along the steep descending segment of each design curve that is going to be used.be used.

For consultants with plenty of historical

For consultants with plenty of historical designs this should be a relatively trivial designs this should be a relatively trivial task.task. On

Once again all users are advised to ce again all users are advised to read the caution and disclaimer at read the caution and disclaimer at the beginning ofthe beginning of this document. this document.

DESIGN BACKGROUND

Introduction

The frames presented in these charts are: The frames presented in these charts are:

Fully Fixed Doubly Pitched Portal Frames with Constant Fram

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As such

As such connections at base, knee and ridge joints connections at base, knee and ridge joints all need to be moment resisting.all need to be moment resisting. Further more, not only does the

Further more, not only does the connection of the column to the footing system need tconnection of the column to the footing system need to beo be

moment resisting, but the footing system

moment resisting, but the footing system itself also needs to resist itself also needs to resist moments.moments.

It is the moment resisting connections that minimise the size of sections required for

It is the moment resisting connections that minimise the size of sections required for bothboth

columns and rafters, and it is

columns and rafters, and it is therefore important that connections and footitherefore important that connections and footing systems beng systems be compatible with this design philosophy.

compatible with this design philosophy. Loads for the frames are

Loads for the frames are calculated using Australian/New Zealancalculated using Australian/New Zealand Standards:d Standards:

AS1170 Loading Codes AS1170 Loading Codes

Whilst member capacities are calculated using Australian/New

Whilst member capacities are calculated using Australian/New Zealand standard:Zealand standard:

AS4600 Cold Formed Structures Code AS4600 Cold Formed Structures Code

Generation of Charts

A computer program was written using Microsoft Excel and Visual

A computer program was written using Microsoft Excel and Visual Basic for Applications.Basic for Applications.

The program steps in 600mm increments through various building widths, increasing The program steps in 600mm increments through various building widths, increasing building eaves height in 100mm steps until the maximum moment in the

building eaves height in 100mm steps until the maximum moment in the frame exceedsframe exceeds

the section capacity of t

the section capacity of the c-section under consideration.he c-section under consideration.

The fram

The frame analysis is carried out using Kleinlogel e analysis is carried out using Kleinlogel formulae, and only member endformulae, and only member end moments are calculated and searched for the maximum f

moments are calculated and searched for the maximum frame moment.rame moment.

Each time the height is incremented, new centre-l

Each time the height is incremented, new centre-line dimensions are calculated and alline dimensions are calculated and all

frame loads are

frame loads are recalculated. Thus wind loading parameters such as terrain categoryrecalculated. Thus wind loading parameters such as terrain category multipliers and pressure coefficients that are dependent upon frame heights or height to multipliers and pressure coefficients that are dependent upon frame heights or height to width or length ratios, are updated to match the current frame being analysed.

width or length ratios, are updated to match the current frame being analysed. A minimum of four bay

A minimum of four bays has been assumed in the design, where the length of the buis has been assumed in the design, where the length of the buildinglding has an effect.

has an effect.

Building Loads

Wind loads have been calculated considering directions

Wind loads have been calculated considering directions of:of:

•

• theta = 0 degreestheta = 0 degrees •

• theta = 90 degreestheta = 90 degrees

Only one negative external pressure coefficient has been considered for each surface

Only one negative external pressure coefficient has been considered for each surface andand

direction. Whilst both a positive and negative internal pressure coefficient has

direction. Whilst both a positive and negative internal pressure coefficient has beenbeen

considered, these are: considered, these are:

•

• Positive: Positive: Cpi1 Cpi1 = +0= +0.4.4 •

• Negative: Cpi2 = - 0.3Negative: Cpi2 = - 0.3

These pressure coefficients were used to calculate both external and internal

These pressure coefficients were used to calculate both external and internal unifuniformlyormly

distributed loads for each of the frame surfaces. The effects of these individual loads were distributed loads for each of the frame surfaces. The effects of these individual loads were then calculated as the following primary load cases:

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DL: dead loads DL: dead loads LL: live loads LL: live loads

PL: occasional point loads PL: occasional point loads

WLi0\1 (theta=0): wind load due to internal pressure coefficient (

WLi0\1 (theta=0): wind load due to internal pressure coefficient (-ve)-ve)

WLi0\2 (theta=0): wind load due to internal pressure coefficient (+ve) WLi0\2 (theta=0): wind load due to internal pressure coefficient (+ve) WLe0 (theta=0): wind load due to external pressure coefficients

WLe0 (theta=0): wind load due to external pressure coefficients WLi90\1 (theta=90): wind load due to internal pressure coefficient

(-WLi90\1 (theta=90): wind load due to internal pressure coefficient (-ve)ve)

WLi90\2 (theta=90): wind load due to internal pressure coeffici

WLi90\2 (theta=90): wind load due to internal pressure coefficient (+ve)ent (+ve)

WLe90 (theta=90): wind load due to external pressure coefficients WLe90 (theta=90): wind load due to external pressure coefficients The effects of these primary load

The effects of these primary load cases were then combined in the following design loadcases were then combined in the following design load

cases. cases. 1.2 DL + 1.5 LL 1.2 DL + 1.5 LL 1.2 DL + 1.5 PL 1.2 DL + 1.5 PL 0.9 DL + WLi0\1 + WLe0 0.9 DL + WLi0\1 + WLe0 0.9 DL + WLi0\2 + WLe0 0.9 DL + WLi0\2 + WLe0 0.9 DL + WLi90\1 + WLe90 0.9 DL + WLi90\1 + WLe90 0.9 DL + WLi90\2 + WLe90 0.9 DL + WLi90\2 + WLe90

Building Dimensions

The eaves height and over all building width

The eaves height and over all building width are dimensions taken of the enclosingare dimensions taken of the enclosing

envelope located at the outer most surface of the girts and purl

envelope located at the outer most surface of the girts and purlins. In other ins. In other words thewords the

thickness and profile depth of both wall and r

thickness and profile depth of both wall and roof claddings are ignored.oof claddings are ignored.

These dimensions are conve

These dimensions are converted to centre-line dimensirted to centre-line dimensions of the frame always assuming:ons of the frame always assuming:

•

• 75mm deep girts and purlins75mm deep girts and purlins •

• 100mm deep columns and rafters.100mm deep columns and rafters.

Girts

Girts and purlins are also assumed to and purlins are also assumed to be flush with the surface of be flush with the surface of the columns and rafters.the columns and rafters.

Member Design

Because of the manner in which the charts are derived, the only consideration for member Because of the manner in which the charts are derived, the only consideration for member design has been maximum frame bending moment. Both axial and shear effects eit

design has been maximum frame bending moment. Both axial and shear effects either inher in

isolation or combination with bending have been ignored. isolation or combination with bending have been ignored.

In general for the loading conditions of the environmental region considered, the critical In general for the loading conditions of the environmental region considered, the critical load case that determines the section size is one of the wind loading conditions.

load case that determines the section size is one of the wind loading conditions. MemberMember

size is thus controlled mainly by bending in combination with axial tension and shear. size is thus controlled mainly by bending in combination with axial tension and shear. Gravitational loading producing column buckling seldom if ever control

Gravitational loading producing column buckling seldom if ever controls selection ofs selection of

member size. member size.

Furthermore, column buckling along with both flexural lateral and flexural t

Furthermore, column buckling along with both flexural lateral and flexural torsionalorsional

member instabilities can be controlled by the installation of an appropriate number of member instabilities can be controlled by the installation of an appropriate number of lateral and torsional restraints. Hence the member section capacity can be made to lateral and torsional restraints. Hence the member section capacity can be made to approach the effective section capacity of the

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