National Institute of Building Sciences

Diaphragm Seismic Design Part 1
2022-03-03 13:00 - 14:30 (America/New_York) | Virtual Event
The 2020 NEHRP Provisions and ASCE/SEI 7-22 incorporate several notable changes to seismic design of diaphragms. This includes expanded applicability of the ASCE 7-16 Section 12.10.3 alternative design provisions for diaphragms, originally developed in the 2015 NEHRP Provisions. This also includes new Section 12.10.4, codifying the rigid wall-flexible diaphragm (RWFD) methodology published in FEMA P-1026, Seismic Design of Rigid Wall-Flexible Diaphragm Buildings: An Alternative Method. These diaphragm design provisions have been largely driven by new research, including testing and numerical studies. They have been developed to better reflect diaphragm dynamic response and deformation capacity, and to provide improved performance, in some cases with reduced construction cost.
This material will be presented in two webinars. The first webinar will provide a general introduction to seismic design of diaphragms and then focus on design examples implementing Section 12.10.3 provisions. The second webinar will repeat the general introduction and then focus on design examples implementing new Section 12.10.4 alternative RWFD provisions.
Learning Objectives – Part 1

Become familiar with new diaphragm design provisions in 2020 NEHRP Provisions and ASCE/SEI 7-22
Understand available diaphragm design methods and when each can be used
Follow detailed implementation of the Section 12.10.3 Alternative Design Method
Understand how designs using the Section 12.10.3 provisions compare to the traditional design method

Diaphragm Seismic Design Part 2
2022-03-10 13:00 - 14:30
The 2020 NEHRP Provisions and ASCE/SEI 7-22 incorporate several notable changes to seismic design of diaphragms. This includes expanded applicability of the ASCE 7-16 Section 12.10.3 alternative design provisions for diaphragms, originally developed in the 2015 NEHRP Provisions. This also includes new Section 12.10.4, codifying the rigid wall-flexible diaphragm (RWFD) methodology published in FEMA P-1026, Seismic Design of Rigid Wall-Flexible Diaphragm Buildings: An Alternative Method. These diaphragm design provisions have been largely driven by new research, including testing and numerical studies. They have been developed to better reflect diaphragm dynamic response and deformation capacity, and to provide improved performance, in some cases with reduced construction cost.
This material will be presented in two webinars. The first webinar will provide a general introduction to seismic design of diaphragms and then focus on design examples implementing Section 12.10.3 provisions. The second webinar will repeat the general introduction and then focus on design examples implementing new Section 12.10.4 alternative RWFD provisions.
Learning Objectives – Part 2

Become familiar with new diaphragm design provisions in 2020 NEHRP Provisions and ASCE/SEI 7-22
Understand available diaphragm design methods and when each can be used
Follow detailed implementation of the Section 12.10.4 Alternative RWFD Provisions
Understand how designs using the Section 12.10.4 provisions compare to the traditional design method

Reinforced Concrete Ductile Coupled Shear Walls
2022-03-31 13:00 - 14:30
Coupled shear wall systems are recognized as distinct from isolated shear wall systems in Canadian and New Zealand codes; they are also accorded higher response modification factors in view of their superior seismic performance. ASCE 7 has so far made no such distinction.
A ductile coupled wall system of reinforced concrete has now been defined in ACI 318-19. Issue Team (IT) 4 of the Provisions Update Committee (PUC) of the Building Seismic Safety Council (BSSC) developed a successful proposal to add four line items to ASCE Table 12.2-1, Design Coefficients and Factors for Seismic Force-Resisting Systems, featuring the ductile coupled wall system of reinforced concrete. The line items are under: A. Bearing Wall Systems, B. Building Frame Systems, and D. Dual Systems with Special Moment Frames. Based on a FEMA P-695 study, R = 8, Cd = 8, and Ωo = 2.5 have been proposed in all the line items. The height limits are the same as for corresponding uncoupled isolated wall systems. Seven different changes made in ACI 318-19 for the design and detailing of special structural walls were implemented in the design of prototypes for the FEMA P-695 study.
The above changes appear in the 2020 Edition of NEHRP Recommended Seismic Provisions for Buildings and Other Structures. The changes have now also been approved for inclusion in the upcoming 2022 edition of ASCE 7, which will be adopted by the 2024 International Building Code.
The proposed presentation will outline the above development, will include relevant details of the specific changes to ASCE 7, and importantly, will feature a design example.
Learning Objectives:

Understand the basics of ductile coupled wall systems of concrete
Be familiar with the ACI 318 definition of this system and understand its nuances
Understand the ASCE 7-22 provisions concerning this system
Learn how to apply this system through a design example
