Discussion: View Thread

  • 1.  Two-Way Slab Design

    Posted 07-07-2020 05:45 PM
    Hi all,

    I find myself wrestling to wrap my head around the concept of designing two-way slabs with regards to applying the diaphragm design forces per ASCE 7-05 Sec. / lateral loads per ACI 318-05 Sec.

    I understand that in most cases the lateral load analysis is done by special purpose programs, accounting for the effect of modified stiffness properties, torsional members etc. However, I'm not exactly sure how to execute this.

    Do you know of any good resources (articles, technical papers, videos etc.) that discuss how to begin approaching this, in sufficient detail?

    Also, if one were to use the ACI Equivalent Frame Method (EFM), is it simply a case of modifying the stiffness properties of the sections and determining design moments by using the Moment Distribution Method considering Sidesway, for combining the effects of gravity and lateral loading (quite tedious but just curious)?


    Justin Redman Aff.M.ASCE
    Graduate Civil Engineer
    Port of Spain

  • 2.  RE: Two-Way Slab Design

    Posted 07-08-2020 08:49 AM

    The CRSI Design Guide for Reinforced Concrete Diaphragms is a great resource that provides explanatory materials, including stiffness modeling and analysis. Also included are worked out design examples to illustrate the proper application of the code requirements. It is based on ACI 318-14.

    Your question references the ACI318-05 edition. In the 2014 edition of ACI 318, a new chapter devoted to the design and detailing of reinforced concrete diaphragm was included for the first time. 

    Amy Trygestad P.E., M.ASCE
    New Prague MN