To calculate wind load on shelters, Pipe racks, open structures, cable trays and pipes as per ASCE 7-16, use the following approach, accounting for the cylindrical shape and exposure to wind. ASCE 7-16 (“Minimum Design Loads and Associated Criteria for Buildings and Other Structures”) provides a systematic approach to determining wind loads on buildings and structures. The calculation involves determining wind speed, exposure categories, wind pressure, and applying appropriate load factors.

Step 1: Determine Basic Wind Speed (V)

• The Basic Wind Speed (V) is obtained from ASCE 7-16, Figure 26.5-1 based on geographic location.
• Expressed in miles per hour (mph) or meters per second (m/s).
• Example: Assume V = 130 mph (Risk Category II, Exposure C).

Step 2: Identify the Risk Category

ASCE 7-16 classifies buildings into four Risk Categories:

• Risk Category I – Low-risk structures (e.g., barns, storage).
• Risk Category II – Standard buildings (e.g., residential, offices, retail).
• Risk Category III – Public buildings (e.g., schools, jails, assembly halls).
• Risk Category IV – Essential facilities (e.g., hospitals, emergency services).

The wind importance factor (I_W​) is considered based on this category.

Step 3: Determine the Exposure Category

Exposure categories define the surrounding terrain’s effect on wind:

• Exposure B – Urban/suburban areas with closely spaced buildings.
• Exposure C – Open terrain with scattered obstructions (e.g., airports).
• Exposure D – Flat, unobstructed areas near large bodies of water.

For our example, we assume Exposure C.

Step 4: Compute Wind Pressure

Main Wind Force Resisting System (MWFRS) Pressure Calculation

Qz = 0.00256 . K_{z .} K_{d .} K_e . V²

Where:

• qz​ = Wind pressure (psf or N/m²)
• Kz​ = Velocity pressure exposure coefficient (Table 26.10-1 ASCE 7-16)
• Kd​ = Directionality factor (typically 0.85)
• Ke​ = Ground elevation factor (typically 1.0 at sea level)
• V = Basic Wind Speed (mph)

Design of wind load calculation as per ASCE 7-16.xls – download as Excel Spreadsheet (.xls), PDF File (.pdf), Text File (.txt) or read online for free on our blog spot.