Table Of ContentFCR / MCR Toolkit ELEMENT 29
Swiss Centre for Development Cooperation
in Technology and Managemant
Roof Truss Guide
Design and Construction of Standard Timber
and Steel Trusses
FCR / MCR Toolkit ELEMENT 29
‘Swiss Centre for Development Cooperation
in Technotogy and Management
Roof Truss Guide
Design and Construction of Standard Timber
and Steel Trusses
FCR/MCR Toolkit Overview
Natia Kit
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Daniel Morales, ISP, Prprnes
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Table of Contents
INTRODUCTION
Objectives of this quide
Contents ofthis guide
Vallaty of dats
PRINCIPLES OF ROOF TRUSS DESIGN
What I 9 roof truse?
‘thon to une a roof truss
Roof shapes suitable for the truss
Loads on tusses
‘ead combinations
Truss spacing
Structural analysis
Roof russ selection step-by-step
Stability of the Truss.
OPTIONS FOR STATIC SYSTEMS
‘overview
‘Simple supported Truss
‘Threehinged Truss
Double-hinged Truss
TIMBER TRUSSES
Design Considerations.
‘Timber Quality
Fixings and Fastenings
‘System Optlons
Nai
Botts Pins
il Patas
Plywood gusset plates
Root Tse ude
Baa
642
Timber Sessoning and Prasorvative Treatment
Neil Truss
Gensel
Deslen
Detaiis
‘-aomng {Lateral restain.ag system
Manufacturing
Eectng
Nall Truss Samples
‘Assumpions and Lins af Applicaton
Flt eoot nail tis
roof nal uss, S m span
at roof nal ase, 101m sow
Sirgl plich eof nalltuss, Srm san
Sirgle pich oof, &m span
‘Single p toh roof nal wuss 16-m pan
Double pitch roof nll truss, 6 m span
Daoub'e pitch roof nell uss, 8m span
Doub ph reof nal wuss, 19m span
Bmsan
Noll Trusa Sample with Plywoad Guetet Plates
Assumptions nnd ints af applicator
DDouble Pich Roof Nall Truss with Phywoed Gusest Pato,
span
Bolted Timber Truss Sample
‘Aecumptions and Limis et App leaton
Double Plch Roo, Tight Fiting Bol T-ues, Span 8.9 m
WORKED EXAMPLE OF A TIMBER TRUSS
The task
How t9 proceed (refer to 28 Roof trusa selection step-by-step]
STEEL TRUSSES
Design Considerations.
System Options
Materials
Fixing and Jointing
Welding
Bolted wih gusset plates
oot Muse ude
Flotshoe
Angle Ber Truss
Gerorat
Dosign
Bets
aracng
‘Angle Bar Truss Somples
Assumptions and Limits ot Aplcation
fiers, 6m ena
Double Pitch Root Single Angle Bars, 8 m span
oube Pen Roof, Single Angle Bars, 19 m span
Doubs Pitch Root: Singla Angle Bas, 12 m span
Sincla Pitch Rect Single Angle Bars. 8m span
Single Pitch oot Single Angle Prem, aim span
Bingla Fitch Root, Single Angle Bars, 10m pa
Flat Roof; SIngle Angle Bers. 6 rm s25n
Flat Reof, Single Angle Bars, 8 m s3an
Flat Roof; Single Anne Bers, 10.m span
Single Fitch Root Single Angle Bars, 12 m sen
Double Pitch Roof, Daubla Angle Bas. 14 m span
‘Singlo Pin Roof; Double Angle Bars, Sper 12 m
Flat Roof; Doubles Angla Bare, 14 m span
‘Stoo! Tube Trust
General
Cesigr
eras
Bracing
‘Steel Tube Truse Samples
Assumptions and Lime of Applicator
Double koh Reo, Tube Truss, 6m epn
Doubla Pitts Rutt, Tube Truss, 8 m span
(Double Pitch Reof, Tube Truss, 10-m span
Double Fitch Roof, Tube uss, 12% span
Singla Pich Root, Tubo Truss, 6 m spar
Single Pitch Root, Tube Truss, 8 m epan
Singla Pic Fool, use Truss, 10m spar
Flat Roof, Tune Truss, 8m span
FlatReaf, Tuse Truss, 8 tn span
Flat Roof, Taha Truss, 10 m spar
Flat Rol, Tube Truss, 12 m eps
849 Reinforcing Bar Truse ar
5.101 General ut
5.102 Design war
6103 Dalal 148
BANA Brecing 48
6.11 Rebar Truss Samples us
841.4 Assumptions and Limits of Apalleaton 139
5411.2 Rebar Jost 200 B98 for 3 m span (¢ 0.5 m) 150
8.11.3 Rebar Jolt 300 B10 for 4 m-pan (0:5) 153
5-14 Rabar Jolt 300 412 for im span (2 DS m)
5.11.9 Jauale Pich Root it m spen} fo Rehar Joists 800 F.LDA
6.1.8 —Dauole Ptah Root (6 m spon} for Rebar Jalsts 300 Bd 08
5.11.7 Deuale Pach Roat[@ m spen} for Rebar Joists 300 B10 187
6.11.8 Feubla Pitch Roat (10 m scan) for Rebar Josts BCC BU 12 a
7 WORKED EXAMPLE STEEL TRUSS 175
71 Thotask 5
72 Howto proceed 18
a ALTERNATIVE ROOF TRUSSES: 7
84 Timber Pele Truss "7
52 Bamboo Truse a
a BIBLIOGRAPHY 417
‘Sample Structural Analysis
Dimensions and Design Information of Angle
Bara and Tubes Used In this Manual
4
44
12
18
Introduction
Objectives of this guide
“The roof russ guido intonced te
1 facta the design and carsiveian of root busses
+ improve the quality aFtressos
+ recuse desigr and Fabrication costs
+ achieve more cost ere melarie-afecive rect russes
The guide is primaly addressed to oontracters, hulls
prectinng angingera and architects consbuelng “oo? slfccutes
‘at pater omphasis on MCR covered built ngs.
Contents of this guide
Validity of data
‘Fre rol buss gulae provides:
1+ nands-on eduiee on design and constuction of rof russes
1+ eyou! etewinga and constuction fetes for he most common
[ber and stool busses
+ dosigy elas Inthe for of standard detatng shies
4 teforences on more elaborate: roof wuss cesigns ond
‘onetuction expects
“The manuat iso:
4+ tart book forthe structural analysis of roof russes
4+ a auide ine for tha production of roof fies and assoc ated
issues {producion management, qualty cori) and lst,
rmar<aingh
For ifnematon om these subjects, pease consul the respoctiva
‘Toot Elements (se8 overview Insite fon cove.
ate
The Roof Tniss Gulde should be ysed in consultation with
tha FER IMCR Toolkit No. 24: Roof Slructure Guide,
The manual does at:
+ folo a porous slendaed of 8 country or regin
1+ gle information 07 pertouler problems af spastic oauntiss
{highztiade snow or ayclone Sooding}
+ ncluda desiga aids and semple russes for orye hanga’s and
hala with epanain excess of 15 to 29 m.
‘The materia prasenied in his guido is hasod on gonzral
engineering practice Is UF to the reases te exam ne tha valet
Df tha propesed design forthe application. ‘The authors of this
guide eo ret bear eny responsibil for damage or Fare af roct
frusees constructed in consullation oF thie mama.
7 ool tase ule
2 Principles of roof truss design
24 What is # roof truss?
A tress is @ strutura wit sralght pieces forming trian
support a load, The members of the rianglos ara pi
tensien and somprassion but do nat berd
under
2 agers or sts 2) Te Garin Upporsto!
coat /
9 Pea Zor 2) bean toed
Sear pat ‘reer
22 When touse 2 roof truss
Foot tusses are cliaaclersed by an economic use of
constuction matorials (Cirber, steel Cempcead cf individual
lightweight places, a Muss can cls provide considerable
advantage in eneport ard ascambly as comparcd (0
onvontonal roo stuctres, On the other Nend, tusses ste mere
lataurintensive and raquize econrectlon devices. Howaver, if @
(greater number of enteot russes can be manufactured then
Sonsidarable ezchomies of scale c2n ba achiaved
the str.cural naight of @ russ is uualy lager than the height of
Similar sirsclures using cold beams. For roots, however, this
UsuBly no disadvantage as reste rust often - dspnding on “vot
‘covet materiat used - be higher at the ridge and lover atthe eaves
fo faciitats roof z-ainage and ensue water ghiness,
Comspatars 9° the Truss While the use of ste! “or roof structure almost invaretly salls for
a criss, tie with timber arrJeluves wharo the truss has Stor
‘orrpettors, These are the purin and the rater rect
‘Tre putin oot
Tre raher root
rr cane
ater
‘The purin roof consists of hota raters and purins, Tha lage
put Is supported by posts. The rafters act as simple suppcvted
beams betveen the puns, ether wi or witout cantilever
pana ‘Static system of puri a0
‘The rata cor ocglrates ftom tert consist. R-carsls of te
afters and ati beam, which form a tlangle, Tha simplest form of
te rater ref Is thus (denteal wit the basic element of He ts.
‘Slifnoee 2° the raters can ba incraased with ccllar beam ne
the ridge, A bevel shoulder tradfionalyy made ire conection
between the raters and tha fe bam. This had tye disadvantage
thatthe slope ofthe root was not uniform but became Nate atthe
rater foot to accommadata the bevel shoulder Today, stael
Connectors ate offen Used and root slopes vera urifarm, he
‘tere can also rest on 2 conera:e slab, which then replaces the
Je hea.
cater State system “afer toot
¥
‘The folowing table presents the mein features, and che sree and
sons of the three besiz design options fof root sinzcutes. lean
assist designers In selecting the most appropriate root structure
far a spacite apploation
Note. large hangers and halls are ret considered
