roof design | truss design | different type truss design

Design of Roof Trusses

* Roof trusses are supported on walls or a series of columns

* Bracings In the end panel of roof level bracings are to be provided using ISA 9060, 8 mm.

Diagonal bracings are provided in the last but one panel at bottom chord level. For very long

buildings additional diagonal bracings are provided at every 4 to 5 days.

* Members of Trusses

1. Top chord members

2. Bottom chord members

3. Struts: Compression members not belonging to top or bottom chords

4. Slings: Tension members not belonging to top or bottom chord.

5. Sag tie: Member subjected to zero forces but provided to reduce sag of bottom chord member.

* Pitch of truss

1. Minimum pitch for GI sheeting = .

2. Minimum pitch for A.C. sheeting = .

3. Preferable pitches: , if snow load is expected , if snow is not expected

* Spacing

(a) 3 to 4.5 m upto 15 m span

(b) 4.5 to 6.0 m for 15 to 30 m span

(c) More than 40 m span, spacing of 12 to 15 m may be used with cross trusses replacing purlins.

* Purlins

1. As far as possible should be located on panel joints of top chord members.

2. Angle iron purlins if spacing is 3 to 4 m.

3. Channels if spacing is 4 to 5 m.

4. For still larger spans use I-sections

* If angles are used outstanding legs should be at top

* Sheetings 1 G.I. sheets

1. Common size

(i) 8 corrugation, 75 mm wide and 19 mm deep, overall width 660 mm

(ii) 10 corrugations, 75 mm wide and 19 mm deep, overall width 810 mm

2. Gauges 16, 18, 20, 22 and 25

3. Lengths 1.8 m, 2.2 m, 2.5 m, 2.8 m, and 3.0 m

4. Overlaps 1, 1 or 2 corrugations

5. End laps 100 mm, if slope is more and 150 mm, if slope is less than 20°.

6 Hooks 8 mm dia at a maximum pitch of 350 mm.

* A.C. sheets

Shapes Corrugated or trafford

Lengths 1.75 m, 2.0 m, 2.5 m and 30 m

Thickness 6 mm or 7 mm

Maximum permissible spacing 1.4 m for 6 mm sheets and 1.6 m for 7 mm sheets

Overlap Longitudinal 150 mm

Side One corrugation

End Bearings

1. One end fixed or hinged. This is achieved by anchor bolt holes of circular shape.

2. Sliding end bearing is achieved by providing oval shaped holes for anchor bolts.

3. Foundation bolts embedded in concrete are used for anchorin

roof design, truss design, different type design, छत डिजाइन, पुलिंदा डिजाइन |, Ghar kaise banaye, ghar kaise design kara, best home design, best house design, best design of house, balcony railing design, mera ghar key design, mere ghar ki design, simple house design, ghar ka naksha, house design, modern design, main gate design