On-Demand Webinar

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This webinar was co-sponsored by ASCE's Structural Engineering Institute (SEI) and ASCE Continuing Education

Instructor:  T. Eric Stafford, P.E.

Course Length: 90 minutes

Purpose and Background

The envelope procedure in ASCE 7 is one of the least understood procedures for calculating wind loads in ASCE 7. The envelope procedure is an alternative method for determining main wind force resisting system loads on low-rise buildings. It differs from the directional procedure in that fust and pressure coefficients are combined (GCp) and wind pressures are applied to various zones that have to be rotated around the building. Additionally, the envelope procedure will give different wind pressures from the directional procedure. While the envelope procedure is the most confusing and least understood method, it forms the basis of all the prescriptive methods referenced in building codes including many of the simplified tables. This course will provide a detailed description of how to calculate wind loads using the envelope procedure including the appropriate method for applying the loads on the building.

Primary Discussion Topics

• Detailed description of the envelope procedure with its uses and limitations
• Step by step procedure for calculating design wind pressures using all applicable variables for the envelope procedure
• Discussion of applicable building types and how to apply the loads on the building
• Example calculations and applications
• Comparisons to the directional procedure

Learning Outcomes

Upon completion of this course, you will be able to:

• Comprehend the basis of the envelope procedure and how it differs from the directional procedure
• Obtain an in-depth understanding of all the variables applicable to the envelope procedure
• Know the applicable building types appropriate for the envelope procedure
• Examine the appropriate application of the loads on the building and learn new recommended solutions for uniquely shaped buildings
• Review wind load calculations on example buildings
• Compare results from the envelope procedure with those determined from the directional procedure

Webinar Benefits

• Understand the unique limitations of the envelope procedure
• Avoid costly errors by getting a comprehensive review of all applicable variables for determining wind pressures using the envelope procedure
• Get a better understanding of the basis of the envelope procedure and how it is an appropriate alternative to the directional procedure
• Become more comfortable with using the envelope procedure for certain buildings

Assessment of Learning Outcomes

Students' achievement of the learning outcomes will be assessed via a short post-assessment (true-false, multiple choice and fill in the blank questions).

Intended Audience

• Structural Engineers
• Architects
• Code Officials
• Code Consultants

Webinar Outline

• Overview
• Basis of the envelope procedure
• Unique difference between the envelope procedure and the directional procedure
• Calculating design wind loads using envelope procedure
• Users and limitations
• Discussion of all applicable variables (wind speed, velocity pressure, exposures, GCp, etc.)
• Calculation of velocity pressure and design wind pressure
• Discussion of applicable building types
• Application of end zones to rectangular and non-rectangular buildings
• Calculating design wind loads using simplified method for low-rise buildings (simplified envelope procedure
• Users and limitations
• Discussion of all applicable variables (wind speed, velocity pressure, exposures, GCp, etc.)
• Calculation of velocity pressure and design wind pressure
• Example calculations and application of loads (45 minutes)
• Calculation and application of loads on example buildings
• Comparisons of loads from the directional procedureescription to come