Compound sink[10-15m]

Howe Truss[10-30m]

Pratt Truss[10-30m]

Spacing Of Truss- IT should be in a range 1/5 to 1/3 of the span for minimizing the cost of roofing

Types of load;- Dead Load[DL]

Live Load[LL]

Wind Load{WL]

1) Dead Load DL-

W=$[\frac{Span \ in \ 'w'}{3} +5]\times 10 Pa$

=$[\frac{L}{3} +5]\times $ 10 . Pa

20 Line load on Purline=750-[$\theta-10^{\circ}]\times$20---Pa

$\lt$ 400Pa

Live load on Truss=$\frac{2}{3}\times $ Line load intensity

3) Wind load

WL=[Cpe-Cpi]$\times$Pd ....Kpa

Also Pd=0.6$\times Vz^{2}$

Also Vz=Vd$\times k_{1}\times k_{2}\times k_{3}$... from table

wher Cps=external process coefficient as per table

Cpi= internal process coefficient as pet table

Pd=Design wind process

Vz=Design wind speed in m/sec

Vb=Basic wind speed from map of India [IS 875 PArt IV]

K$_{1}$=Risk coefficient as per table

k$_{2}$= Terrain Height and structure size factor as per table

k$_{3}$= Topography factored as per table

Table For Internal Pressure Coefficient[Cpi]

Note:- Internal pressure may be +ve or -ve depending upon directions of flow of wind

Take +ve when internal pressure is action from inside to outside and vice versa

W.L(8 worst combinations)

1) External WL

a) Wind ward

b) Lee ward

2) Internal WL

perpendicular to ridge

parallel to ridge

Types of Numerical:

1) panel load calculation for roof truss [Dl, LL, WL]

2) Design of purline or procedure

3) Design of Roof Truss member as per the forces given