Wind Hazard Risk Assessment and Management for Structures

Chapter 2. Structural Components and Wind Directionality 24
University of Florida, 2009). The values of the parameters are listed in the caption of Figure
2.3, which shows the simulated wind records. For comparison, the historical wind records
(see Figure 2.4) are converted from 15-minute average to 3-second gust. The general trends
of the simulated wind speed and wind angle time series match the historical record quite
well. The magnitude of the wind velocity is also close to the historical data. Note that the
absolute accuracy of this model is not the major focus in this study. Since the objective is
to look at the effect of changing wind directionality in individual wind events, it is more
important for the wind time series model to be capable to generate wind time series that
have trends similar to those of the historical wind records, in terms of both wind speed and
wind angle.
2.3 Alternative Approaches to Wind-Load and Reliability
Assessment
Given the simulated tropical cyclone wind velocity time series described in the previous
section, wind loads may be computed and structural reliability analysis may be carried out,
for the two afore-mentioned approaches, in the way explained below.
2.3.1 Wind Load and Reliability Calculation
Damage of envelope components, which is the major factor in insurance claims (Sparks
et al., 1994), is mainly caused by wind loads during tropical cyclones (National Institute of
Standards and Technology, 2006b). Given a wind velocity time series over the time domain
[0, tL] (with wind speed V (t) and θ(t)), from bluff-body aerodynamics, the wind pressure
acting on a building envelope component at time t ∈ [0, tL] is given by (Holmes, 2007):
S(t) = 1
2 ρV (t)2 Cp(θ(t) − γ), (2.12)