Designers of modern low-rise and mid-rise multi-family buildings often face challenges due to fewer opportunities for shear walls at exterior wall lines (e.g., more glass and larger openings), increased building heights, and multi-story shear wall effects. While corridor-only shear walls are becoming more popular to address the lack of adequate exterior shear walls, methods of analysis for open-front structures are also evolving to reflect more complex building geometries. The goal of this presentation is to provide guidance on how to analyze an open-front or corridor-only shear wall diaphragm, and help engineers better understand flexibility issues associated with these types of structures. Although it will focus on seismic design of these conditions, comparison of wind and seismic design methods will also be covered.
The techniques and examples covered in this presentation are intended to demonstrate one method of analysis. It is anticipated that this information will serve as guidance for designers to consider and refine their own methods and techniques.
Key questions to be answered in this presentation include:
- When does a loss in stiffness in the exterior walls cause an open-front diaphragm condition?
- What is the deflection equation for open-front/cantilever diaphragms?
- How is diaphragm flexibility defined for open-front/cantilever diaphragms vs. ASCE 7-16, Figure 12.3-1?
- What are the available methods of distributing torsional forces into the diaphragm?
- Do shear walls located along diaphragm chord lines affect the diaphragm chord forces?
- How are torsional irregularities determined and addressed for open-front/cantilever diaphragms?
Terry Malone, PE, SE, WoodWorks
Terry is a licensed structural engineer in Washington, Oregon and Arizona. Prior to joining WoodWorks, he was a principal in consulting structural engineering firms in Washington and Oregon, conducted third-party structural plan reviews and has served as a faculty member at St. Martin’s College in Lacey, Washington. Terry has over 35 years of wood design experience and has taken an active role as a presenter providing seminars at state and local ICC chapters and professional engineering organizations. Terry is author of The Analysis of Irregular Shaped Structures: Diaphragms and Shear Walls, published by McGraw-Hill and ICC. He is a member of the Structural Engineers’ Association of Arizona and the International Code Council.