Practical Strategies for the Modeling and Analysis of Diaphragms

May 13, 2020 @ 12:30 pm – 2:00 pm

Speaker: Allen Adams, P.E., S.E.
Bentley Systems, Inc. / RAM

Session Description:

The behavior of a building structure in response to an earthquake or wind, including the distribution of the lateral forces to the lateral force resisting elements such as moment frames, braced frames or shear walls, is heavily dependent upon the nature, extent and stiffness of the floor and roof diaphragms. It is important that the building model used in the analysis and design of a building accurately – or adequately – captures the effects of these diaphragms.

ASCE 7 has fairly extensive requirements related to diaphragms, but confidently determining the proper way of performing the necessary analyses that satisfy those requirements can be challenging. With an emphasis on semi-rigid diaphragms, this presentation will discuss the types of diaphragms identified by the Building Codes and commonly considered by engineers, review Building Code requirements pertaining to those diaphragms, and provide practical recommendations on the appropriate modeling of those diaphragms in analysis software.


Learning Objectives:

  • Understand the differences between rigid, semi-rigid, and flexible diaphragms and their impacts on analytical results
  • Review in-depth the 2018 IBC and ASCE 7-16 building code requirements pertaining to diaphragms
  • Learn about the sensitivity of analytical results to the various components of semi-rigid diaphragm model, including mesh size, material stiffness, and frame stiffness
  • Make appropriate decisions on diaphragm and load modeling, balancing the needed level of accuracy with the business demands of speed and simplicity


Handout and registration emails for this session will be sent to SE University companies on Friday, May 8th.