1. THANG NGUYEN DAO – JOHN W. VAN DE LINDT
THE UNIVERSITY OF ALABAMA
JUNE 20, 2011

2. PBWE Expectations:
Occupant Comfort
• Little or no reduction in living/occupant comfort.
• Almost a durability issue; no damage or water entry
limited to moisture, i.e. no pooling.
Continued Occupancy
• Up to moderate reduction in comfort but no threat to
safety or injury. Electrical, plumbing, and egress still
present.
• Loss of first gable or roof sheathing panel.

3. PBWE Expectations:
Life Safety
• Safety normally provided is not presented
• Roof truss-to-wall connection failure; supporting
column/post failure
Structural Integrity
• Visible signs of structural distress, i.e. permanent
deformation, structure not safe
• Collapse of roof; loss of lateral capacity

4. PBWE Expectations (Continued):
Manageable Loss
• Cost to repair structure is below a selected percentage
of reconstruction/replacement value. This is dependent
on numerous factors, and is often the result of
rainwater intrusion and structural failure.
• Loss distribution based on the assembly of damageable
components.

5. Example of various levels of building performance as a
function of Hazard Level.

6. Fragility definition:
Fr = P[G(X)<0|D = y]

7. Finite element method
Wind-Driven Rain.
Debris trajectory.
Numerical hurricane model.
Loss modeling

8. Finite element method
Beam element
Shell element
New non-linear nail model

9. Rain-water intrusion
evaluation:

11. Construction of fragilities for windborne debris
impact to window: Panel initial position
Roof-sheathing trajectories
during a hurricane hour
Target
window
Roof-sheathing trajectories that hit the
windows during a hurricane hour

12. Structural loss:
Structural components or assemblies are defined as
parts of building that resist wind load, or carry dead
load and live load during a hurricane.
Non-structural loss:
The non-structural or content loss is often due to rain
water intrusion.

13. STRUCTURAL PROPERTIES HURRICANE PROPERTIES
Non-linear Wind load
structural analysis statistics
Statistics of Wind driven
structural capacity rain
Windborne debris
Structural impact risk analysis (not Rainwater
included for single
component fragility intrusion
house)
Structural damage Non-structural component
states damage states
COST DISTRIBUTIONS
GIVEN DAMAGE STATES
Structural loss Non-structural
loss
TOTAL LOSS

14. Structural loss
Wall
Missile structure
Damage Damage Roof sheathing Roof truss
impacts on (Max
state description panels members
C
windows drift/height
1
Damage State D1
P(C|D1)
in walls)
1,
No damage or very All rooms in 1|
1 No No Negligible
minor damage damage level 1
At least one room One One truss
C
2
> 0.1 % and
2 Minor damage reach damage window member 2| Damage State D2
P(C|D2)
0.5 %
2,
level 2 failure failure
> one and Hurricane
At least one room > one and properties
the > 0.5 % and
3 Moderate damage reach damage the larger of
larger of 1% …
level 3 5% and 3
20% and 3
> the
larger of
At least one room > the larger |
C
20% and 3 > 1 % and
4 Severe damage reach damage of 5% and 3 Damage State Dn
P(C|Dn)
and the 3%
,
level 4 and 20%
larger of
50% and 6
At least one room > the
5 Destruction reach damage larger of > 20% >3%
level 5 50% and 6
Structural damage state for Residential Construction Classes (revised from Vickery et al., 2006)
| | . |

15. Non-structural loss (continued):
Total loss:

16. Example on PBWE with different expectations
Load Coefficient Distribution
Mean Source
Type of variation Type
Lee &
Dead 3.5 psf
0.10 Normal Rosowsky
load (168N/m2)
(2004)
Wind Ellingwood
0.8Wn1 0.35 Normal
load (1999)
Structure Distribution
Mean COV Source
40ftx60ftx12ft Resistance Type
Finite Element
69 psf
Panel Model, Dao and
(3.17 0.24 Log Normal
capacity van de Lindt
kN/m2)
(2008)
1,312 lbs Ellingwood et al
H2.5 clip 0.10 Normal
(5.84 kN) (2004)

17. Continued Occupancy: Life Safety:

18. Illustrative example of loss estimation:

19. Structural Non-Structural loss Total loss

20. Method can be used for PBWE of wood-frame
structure
The framework is felt to be a viable design alternative,
provided details are worked out, i.e. calibration.
During this research many assumptions was made, but
the result still presents a good level of accuracy when
qualitative comparison to hurricane Katrina is made.