CADDtools ASCE 7-16 Wind Load Program by Howard Goding

A Wind load Pic

Here is a web enabled Asce7-16 wind load program. The program displays the Wall Components and Cladding design pressures for the selected conditions. I use these programs to verify the design pressures provided by the architects or to create them for estimating or engineering purposes. It is highly recommended you review the building code to understand where the information comes from. Refer to the bottom of this page for various building code web site links.

The Asce 7-16 Building Code has four parts for determining the components and cladding. This program utilizes Part 1: Low-Rise Buildings h<= 60 and Part 3: Buildings with h>60 ft to calculate the design pressures. The program will automatically determine Part 1 or Part 3. I added a check box to force the program to utilize part 1 when using the exception rule in part 3 which allows the use of part 1 for heights greater then 60ft and less than 90 feet. See the calculator below to verify the exception can be used. The Wind speed maps are separated into risk category 1 through 4. Refer to your local jurisdictions to determine which map and wind speed to use. The program calculates the LRFD (Load Resistance Factor Design) and ASD (Allowable Stress Design) design pressures. In these calculations the ASD velocity pressure is reduced by 60%.

Some of the changes are a new variable Ke was added to the velocity pressure formula. Ke represents a Ground elevation factor and the value is determined from a calculation above sea level. See the interactive map showing your elevation above sea level and the calculated Ke variable. The Kz value on exposure B was revised on heights under 30 feet. You will notice smaller design pressures under those conditions. Finally, I added programing to accommodate the use of feet and inches to be converted to decimal feet as the program requires. This will cover the mean roof height and least building width. The program will let you know when the conversion has happened after the design pressures are calculated.

CADDtools video of the day.

To get started select and enter your project information below.

Be sure to enter all required fields. If you enter your email address, you can be rest assured it is safe and will not be sold. You may get an email about updates to the wind load program or changes to this website. Thank you in advance.


Design Load Method: ASCE7-16 Strength Design Load & Allowable Stress Design

Wind speed = mph (required)
From Wind Speed Maps Figure 26.5

Building Exposure =
Defined from 26.7.3, page 266 & Figures C26.7-5 through C26.7-7, pages 745-747

Internal Pressure Coefficient =
From Table 26.13-1, page 271

Roof Angle =
From Figure 30.3-1, page 335

Kzt =
Kzt default = 1.00
Refer to section 26.8 and figure 26.8-1 to determine the wind speed-up effect. See below for additional information about Kzt.

Kd =
Kd default = 0.85
Refer to Table 26.6-1, page 266. See below for additional information about the Kd factor.

Ke = (New) (Use the calculator below)
Ke default = 1.00, value should be between 1.00 and 0.35
Ground Elevation Factor refer to Table 26.9-1 , page 268

Mean Roof Height = ft (required)
Example 30'-6" is written as 30.5

Least Building width = ft
For determining Zone 5 dimension "a". Example 55'-8" is written as 55.67

Custom Tributary Area = sq feet
Enter an optional Tributary area between 10 and 500 square feet at (MRH <= 60 ft) or between 20 and 500 square feet at (MRH > 60 ft).

The following fields are optional and will show up on you printed page.

Project Name = optional

Company Name = optional

User Name = optional

E-mail = optional

Exception from part 3 page 363 (Use the calculator below)
If the mean roof height is greater then 60 and less then 90 - Part 1 can be used if the height-to-width ratio is 1 or less.
By checking the Exception box (Part 1) will be used to perform the calculations.


CADDtools Calculators

Check if Exception in Part 3 is applicable
(Enter decimal feet only. Example 62'-6" is written as 62.5 )
Enter Mean Roof Height: ft
Enter largest Building Width: ft



Ground Elevation factor (Ke) Calculator
(Enter decimal feet only. Example 97'-6" is written as 97.5 )
Enter elevation above sea level : ft


Find the elevation above sea level and Ke value with Google maps.
Latitude: Longitude:

A note about the Kzt factor:

  • Kzt is a topographic effect factor to account for speed up over hills. Since I reside in Florida I use Kzt equals one and established that as the default value. Refer to your states Kzt values and adjust the value as required. I found a paper from the Florida International University stating "few places in the state of Florida would warrant an escarpment factor greater than 1.0, therefore Kzt is unnecessary in the current endeavor". I found a great site showing the Kzt factors for Seattle, Washington from the Department of Planning and Development, their values range from 1.12 to 2. Follow the link to the Seattle Washington website for information.

    • A note about the Kd factor:

  • Kd is a directionality factor. Over the years the Kd factor value has stirred up some controversy as to whether the value is 0.85 or should be one. I have set the default value to 0.85; if you are uncertain what value to use change the value to one for a worst case scenario.

    • A note about the Design Load Method:

  • The ASCE7-16 code utilizes the Strength Design Load also called (LRFD Load Resistance Design Load) method and the Allowable Stress Design Load (ASD) method. The Florida Building Code 2020 (FBC2020) utilizes an Ultimate Design Wind Speed Vult and Normal Design Wind Speed Vasd in lieu of LRFD and ASD. The FBC2020 uses a wind speed conversion where the Vasd is reduced by 60 percent; this happens by multiplying the Vult by (0.775 which is the square root of 0.6). Since the velocity pressure is reduced by 0.6 in the formula for ASCE7-16 and is reduced by 0.775 in the wind speed which is used in the velocity pressure formula for FBC2020 this makes the design pressures for both methods the same.

    • ASCE7-05 Design Load calculator

    Archived

    This is a link to an archived ASCE7-05 design pressure calculator. Follow the link to CADDtools ASCE7-05

    Links you may need

    This website funded by the sale of MetalOpt go to MetalOpt.com to purchase.

    American Society of Civil Engineers web site. Follow the link to ASCE.org

    This is the Florida Department of Community Affairs Building Code Information Systems web site. Here you can view the current Florida Building code. Follow the link to floridabuilding.org