Wind Load Design of Astoria

Post on 27-Aug-2014

30 views 1 download

Transcript of Wind Load Design of Astoria

STEP 1:DESIGN CRITERIA

1. Basic Wind Speed and Wind directionality Factor V=200 mph

2. Importance Factor

3. Exposure Category And Velocity Pressure Exposure Coefficient Exposure Category = C Building qualifies as Low-Rise Building h= 13.4 + 0.6/2 h= 13.7

4. Topographic Factor

where:

kd =0.85

Iw = 1.15

kh = 1.073

kz = 2.01(z/ zg ) 2/α

kz = 2.01(z / zg ) 2/α

kz = 2.01(9.5/ 275) 2/9.5

kz = 1.07

kzt = 1.0

5. Gust Effect Factor G or Gf

G = 0.925(1+1.7gQIzQ / 1+1.7gv Iz )

G = 0.925(1+1.7gQIzQ / 1+1.7gv Iz )

Iz =

Q=

6. Enclosure Classification Partially enclosed

7. Internal Pressure Coefficient

b. Wall pressure

Leeward Windward Side wall c. Roof pressure

windward leeward

9. Velocity Pressure

10. Design Wind Load 1. For Wall

a. windward (+) p = 1.98((0.80)-(+0.55)) (-) p= 1.98((0.8)-(-0.55))

b. Leeward (+) p=1.98*(-0.426)-(0.55) (-) p= 1.98*(-0.426)-(-0.55) c. Sidewall (+) p=1.98*(-0.7)-(0.55) (-) p= 1.98*(-0.7)-(-0.55)

2. For Roof

a. Windward

gv =

gQ =

Gcpi = ± 0.55

8. External Pressure Coefficient Cp or GCpf

a. assume roof angle of 20⁰

qh = 47.3 x 10-6 Kz K zt KdV2 Iw

qh = 47.3 x 10-6 *1.07*1.0*0.85*200*1.15

qh =

p= qh [(GCpf )][(Gcpi)]

(+) p = 1.98((-0.502)-(+0.55)) (+) p= 1.98((-0.0612)-(+0.55)) (-) p = 1.98((-0.502)-(-0.55)) (-) p= 1.98((-0.0612)-(-0.55))

b. Leeward (+) p = 1.98((-0.6)-(+0.55)) (-) p= 1.98((-0.6)-(-0.55))

(table 207-1 )

(table 207-2)

Occupancy Category III ( section 207.5.5)

3. Exposure Category And Velocity Pressure Exposure Coefficient(section 207.5.6.3)(section 207.5.6.4.2)

table 270-4 ( via interpolation)

table 207-5

α= 9.5

z= h

section 507.5.7

(assumed since near open fields)

section 207.5.8

section 207.5.8.1

0.21 equation ( 207- 5)

note no. 2 For 4.5m ≤ z ≤ zg

zg = 275

c( 10/ z )1/6

0.903 equation ( 207- 6)

3.4 section 207.5.8.1

3.4 section 207.5.8.1

section 207.5.9section 207.2

section 207.5.11.1

0.55 figure 207-5-0.55 figure 207-5

section 207.5.11.2

L/B 20.505/ 14.96 = 1.37

-0.426 (by interpolation)0.8-0.7

h/L = 13.7/ 50.505 = 0.67 -0.502, 0.0612 by interpolation

-0.6

section 207.5.10

1.98

section 207.5.12.2.2

0.4952.673

-1.9320.246

-2.475-0.297

√ 1 / 1+ 0.63( B+ h / Lz ) 0.63

Cp

normal to ridge θ ≥ 10⁰

-2.083-1.210.0950.968

2.277-0.099