Wind loading calculations, worked example, Portal Frame

Описание: This video shows you step by step all the formulas, tables and figures considered when designing for Wind Loading of a Mono-Pitched Portal Frame.

British Standard used: BS 6399-2.

Portal Frame Dimension
Length: 73m
Width: 36m
Height: 7.35m

Site Altitude : 88.8m
Closest distance to sea: 10.7 km
Roof pitch angle: 5 degrees

Formula's used in steps.
Step 1 - Dynamic Pressure, qs
qs= 0.613 Ve^2
Ve = Effective wind speed m/s

Step 2 - Effective Wind Speed, Ve
Ve = Vs x Vb
Vs = site wind speed
Vb = basic wind speed

Step 3 - Site Wind Speed, Vs
Vs = Vb x Sa x Sd x Ss x Sp
Sd = direction factor = 1.00
Ss = seasonal factor = 1.00
Sp = probability factor = 1.00
Vb = 24.5 m/s
Sa = Altitude factor = 1 + 0.001 x Delta S

Step 4 - Effective Wind Speed, Ve was worked out

Step 5 - External Surface Pressure, Pe
Pe = qs x Cpe x Ca
qs = dynamic pressure
Cpe = external pressure co-efficient
Ca = size effect factor

Step 6 - External Pressure Co-efficient worked out, Cpe

Step 7 - Internal Surface Pressure, Pi
Pi = qs x Cpi x Ca
qs = dynamic pressure
Cpi = internal pressure co-efficient
Ca = size effect factor

Step 8 - Net Surface Pressure, P
P = Pe - Pi
Pe = external pressure
Pi = internal surface pressure

Tables used in BS 6399-2:
Table 4 - Factor Sb for standard method
Table 9 - External pressure co-efficients Cpe for monopitch roofs of buildings

Figures used in BS 6399-2:
Figure 4 - Size effect factor Ca of standard method
Figure 6 - Basic wind speed Vb (in m/s)
Figure 19 - Key for monopitch roofs

Thank you for watching this video. I hope it was helpful.