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The information given above is a bit dated with reference to both the ETABS version and the ACI code versions, as the above referred document pertains to ETABS version 7 and ACI 318-99. Whereas the ETABS 2015 & ACI 318-14 are the latest ETABS & ACI code versions in use today. (ETABS 2016 has been released a few days ago, however, AFAIK no changes have been made in it regarding present topic). As such, a little update correlating the previous & present situation, would be beneficial for all those interested. Here are my 2 cents: 1. According to ETABS Concrete Frame Design Manual, beam design in ETABS is done, a. As a Rectangular or T-beam, for the Maximum Positive Moment b. As a Rectangular beam always for the Maximum Negative Moment. 2. For ACI 318-99 and ETABS version 7, this is mentioned in 3rd paragraph under the heading 'Determine Factored Moments' on Page-37 of the reference provided by Ayesha earlier. 3. The same beam design principle has been followed in later ETABS versions (including ETABS 2015), for the later ACI code versions (including ACI318-14). 4. For ACI 318-02 and ACI318-05, this is indicated in Section 3.4.1.1 of the relevant ETABS Concrete Frame Design Manual, whereas for the newer ACI codes (2008, 2011 & 2014 versions), it is given in Sections 3.5.1.1 of the following ETABS 2015 Manuals for the mentioned ACI codes: a. ETABS Concrete Frame Design Manual (ACI 318-08) b. ETABS Concrete Frame Design Manual (ACI 318-11) c. ETABS Concrete Frame Design Manual (ACI 318-14) 5. Concrete Frame Design Manuals for the ACI 318-08 and earlier ACI codes, are generally installed along with ETABS 9 software, and are available in 'Manuals' sub-folder. Regards.

You have got it wrong. One needs to satisfy drift limits by considering the loss of stiffness due to cracking. The code has specifically directed us to do that. I will give you the reference of UBC 97. For the determination of design level displacement, the code says, "The mathematical model shall comply with Section 1630.1.2." The section says : Stiffness properties of reinforced concrete and masonry elements shall consider the effects of cracked sections". Can't comment anymore on that.