Purlin splice, gable, eave and ridgespurlin to rafter connection

Standard purlin to rafter connection

Issue 08

Autumn edItIon mAy 2011

multinail welcomes comments, suggestions and feedback for future editions. Please contact us at africa@multinail.com

Contents

New EziTie Purlin Restraint . . . . . . 1

Engineering Corner . . . . . . . . . . . . 2

Wind Loads . . . . . . . . . . . . . . . . . . 3

What is the most economical Hip? 4

Hip Overlays? . . . . . . . . . . . . . . . . 5

Optimising your webbing . . . . . . . . 5

Making the pieces fit together . . . 6

Multinail signs preferred supplier agreement with Innosteel . . . . . . . 7

Have you reviewed you plant layout lately? . . . . . . . . . 8

Contact Details . . . . . . . . . . . . . . . 8

new ezitie Purlin RestraintMultinail South Africa is pleased to release an improved product for purlin restraints on top chords.

The EziTie is a direct replacement for the industry standard Hurricane Clip with a host of benefits;

For the installer - No nails required, easier to install •

For the designer - Same hold down capacity as the Hurricane Clip•

For the truss plant owner – same price as a hurricane clip with nails•

For the truss plant manager – no more nails to count•

For the inspector – easy to view correct installation•

For more information please visit our web site or call your local Multinail office.

2 multImAIl // Autumn edItIon // mAy 2011

Engineering CornerIn the past few weeks, a number of faxes/e-mails requiring your signature, have been sent to multinail Fabricators, keeping you up to date with multinail engineering products, code changes and teAC meeting decisions.

Please keep in mind, the CPA (Consumer Protection Act) is now up and running. More information on the Act to follow in later newsletters.

A quick synopsis of the letters sent out so far:

Public Buildings:• Designs to be sent to Engineering for checking

Torsional Restrain:• Strapping requirement changed from 6m to 5m

Beams and Rafters:• Actual/planed size to be used in the design, not the invoiced size

Technical Literature:• Documents required for an audit

Ring Shank EziNail:• New 38 x 3.15mm ring shank EziNails for all Multinail products

73mm Bottom Chords:• Rules and good design principles

It is important that we all keep abreast of changes taking place in the industry, technical updates and good fabrication practices, or things can go wrong!

www.mulitnail.co.za

Wind LoadsThis article has been written using SABS 0160 – 1989 (as amended 1993).

In South Africa we have three regional basic wind speeds: 40m/s, 45m/s and 50m/s, as shown in figure 3 below.

There are a number of “K” factors which are applied to the wind speed, e.g. “Kr”, “Kp” and “Kz”.

“Kr” is for mean return period; “Kp” is a constant for site altitude; and “Kz” wind speed multiplier.

Then we have the different terrain categories: Category 1, 2, 3, and 4, where a terrain category defines the characteristic of those surface irregularities.

Category 1: Exposed smooth terrain including open sea coasts, lake shores and treeless plains

Category 2: Open terrain with widely spaced obstructions such as open parklands, outskirts of suburbs, with few trees.

Category 3: Terrain having numerous closely spaced obstructions the size of domestic houses. This includes housing suburbs, industrial areas etc.

Category 4: Terrain with numerous large, tall, closely spaced obstructions.

Hence choosing the correct terrain category, altitude and mean return are all crucial to the correct wind loading. This code is based on terrain category 2 regional basic wind speed, isopleths of 3 second gust speed and at a height of 10m.

Why then does wind create so much damage? The reason is simple, the equation to convert wind speed to velocity pressure:-

Qz = kpVz2

Qz = Free stream velocity pressure measured in N/m2.

Kp = A constant dependent on site altitude.

But “Vz2” the characteristic wind speed at height “z” is

squared.

The wind speed goes from 40m/s (144km/hr) standard to say 50m/s (180km/hr). Cyclonic wind loading is in the region 58.8m/s (210km/hr). Due to the fact that the velocity is squared, the increase in force is 213% more, not just an increase of 45%!

Your standard gable to gable roof experiences both internal pressure and external suction. However, remember that the local pressure coefficient Cp more than doubles under your eaves. Hence, the need for double hurricane clips at all eaves, overhangs and ridges.

In conclusion, never under estimate the wind forces on a roof, it will be to your detriment.

4 multImAIl // Autumn edItIon // mAy 2011

What is the most economical Hip?This new section in MultiMail is to advise current Multinail fabricators on tricks and tips to produce the most economic truss design.

As we all know it can be difficult and time consuming to select the most economical hip style for a range of different spans and loads. To assist this process for Multinail Fabricators we have run a number of examples which we would like to share with you;

Tables2: Truncated Girder with set back at software default position.

Pitches overhangsspans

5m 5.5m 6m

17.5150 TRUSSED HIP TRUSSED HIP HT+Y

600 HT+Y TRUSSED HIP HT+Y

20150 TRUSSED HIP TRUSSED HIP HT+Y

600 HT+Y TRUSSED HIP HT+Y

22.5150 TRUSSED HIP HT+Y HT+Y

600 TRUSSED HIP HT+Y HT+Y

26150 TRUSSED HIP TRUSSED HIP HT+Y

600 TRUSSED HIP HT+Y HT+Y

30150 TRUSSED HIP TRUSSED HIP HT+Y

600 TRUSSED HIP TRUSSED HIP HT+Y

PItCHes oVeRHAnGsPAns

6.5m 7m 7.5m 8m 8.5m

17.5150 HT+Y HT+Y HT+Y HT+Y FULL Y

600 HT+Y HT+Y HT+Y HT+Y HT+Y

20150

TRUSSED HIP

TRUSSED HIP

HT+YTRUSSED

HIPFULL Y

600 HT+Y HT+Y FULL Y HT+Y FULL Y

22.5150 HT+Y HT+Y HT+Y HT+Y FULL Y

600TRUSSED

HIPHT+Y FULL Y HT+Y FULL Y

26150

TRUSSED HIP

TRUSSED HIP

HT+YTRUSSED

HIPFULL Y

600TRUSSED

HIPTRUSSED

HIPFULL Y HT+Y FULL Y

30150

TRUSSED HIP

HT+Y HT+YTRUSSED

HIPFULL Y

600TRUSSED

HIPTRUSSED

HIPFULL Y HT+Y FULL Y

Designer News #1

Variables

36mm timber widths1. 73, 111, 149 and 225mm timber depths2. SABS Grades 5 and 7 only. 3. 111 TC’s standard4. Tiled Roof Load 57 kg/m5. 2 including battensCeiling 14 kg/m6. 2 including battens760mm truss spacing7. Wind loading of 40 m/s8.

Table 1. Dutch hips (girder at the apex) for spans up to 6m

www.mulitnail.co.za

Hip Overlays?

Optimising your webbing

How often have you been required to quote or detail a roof with an Overlay Hip/Valley and the Girder Truncated Girder is too ‘Shallow for Effective Webbing’?

An important detailing/designing aspect to remember about trusses, especially Girders, and the Girder Truncated Girder in this case is, the more depth there is to a truss the easier it will design and web.

Designer News #2

Designer News #3

\;A

\ /;NN

B;W

\|/;N

How well do you know your webbing codes? do you understand these?

How well do you understand the Standard Webbing Codes (A-J;N;W), and the Special Webbing input using the Back Slash, Vertical and the Forward Slash (\ | /)?

You can often quickly save costs and be more competitive by changing the direction of a web or set of webs, or change the Standard Web Pattern, that may eliminate Web Ties/Braces.

For a refresher course on optimizing your webbing, call your nearest Multinail office.

Don’t forget to read the warnings, it could save you time.

Changing the detailing input format as below improves the height of the girder trusses and in turn dramatically improves the design.

6 multImAIl // Autumn edItIon // mAy 2011

Making the pieces fit togetherThe manufacturing process of trusses is made up of 4 key functions being;

Materials Handling1.

Cutting2.

Jigging3.

Pressing4.

In order of importance Materials Handling is by far the most easily achieved method to reduce costs and increase efficiency. But more on this item in the next MultiMail.

The second most important manufacturing process is cutting. When looked at objectively, a roof truss in nothing more than a jigsaw puzzle with multiple pieces.

If individual timber truss components are the correct size and marked clearly then everything goes together well. But failure to cut and / or mark the members correctly can create a host of problems – all of which affect your bottom line.

Multinail offers 2 solutions to these problems;

Vector saw Semi-automated truss component cutter•

Angle and length set automatically•

Accurate to 0.5mm in length and 0.5 degrees on angle•

Easy to learn – no truss cutting experience required•

Highly robust•

Manufactured, installed, guaranteed, serviced and •supported by Multinail

turbosaw Cuts a 5 segment “round” end onto truss webs•

Cutting Heads are set in place, never need to be moved•

Operator adjusts length only•

Webs can be cut to stock lengths for later use•

Can cut up to 20 pieces at a time•

www.mulitnail.co.za

Multinail signs preferred supplier agreement with Innosteel

This month Multinail has signed a preferred supplier agreement with Gauteng based Innosteel, allowing Multinail Licensed Fabricators to distribute their competitive range of steel roof structures.

Under the terms of the agreement any licensed Multinail fabricator may send building plans to Innosteel who will provide a free design and quotation. Pending acceptance by the customer, the Multinail fabricator may choose to have the steel components supplied by Innosteel directly to their yard for assembly and / or distribution, or, have the components sent directly to the building site.

This agreement allows the Multinail fabricator network to quote for and supply markets that either specify steel only, or that are remote. Innosteel will provide all necessary documentation and engineering for all materials provided.

Innosteel Contact detailsUnit 17 & 18 Fivestar Business ParkCorner of Beyers Naude and Juice RoadHoneydew 2040 Roodepoort Gauteng e-mail: info@innosteel.co.zaTel: 011 794 5436Fax: 011 794 2775

Africa 1

Have you reviewed you plant layout lately?At Multinail we pride ourselves on being more than experts in software, metal connectors and timber engineering. Machinery selection and Truss Plant layouts are a key service offered by Multinail to assist fabricator consolidation, growth, relocation and management.

To learn more about Multinail’s range of services please call your local office.

Layout #1

Cape Town Head Office · Unit 9A, Cabernet Street · Saxenburg Park · Blackheath · Cape Town 7580 T: +27 (0)21 905 2556 · F: +27 (0)21 905 2667 · W: www.multinail.co.za · africa@multinail.com

Contact DetailsMultinail has been on the move in the last 12 months, relocating to new premises in both Cape Town and Johannesburg. See below the current office addresses and contact details.

Johannesburg support office 33 Brunton Circle Foundersview South Foundershill ModderfonteinT: +27 (0)11 452 6004 F: +27 (0)11 452 4571W: www.multinail.co.za

Cape town Head office Unit 9A, Cabernet Street Saxenburg Park Blackheath Cape Town 7580T: +27 (0)21 905 2556 F: +27 (0)21 905 2667 W: www.multinail.co.za