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Showing content with the highest reputation on 06/01/17 in Posts

  1. Dear Saiful Islam, Immediate deflection vs long-term deflection is one issue. Linear analysis vs non-linear analysis is another. In ETABS, generally we are almost always performing linear analysis. That means deflection is directly related to the load applied without long-term non-linear effects. So let's ignore non-linear analysis for a moment. In linear analysis, now the question is how do we get immediate and long-term deflection. Immediate deflection could be non-cracked deflection or cracked deflection. Practically speaking, long-term deflection will always be on cracked sections. Although anything "cracked" is essential a non-linear problem, but here let's stick to out point of doing linear analysis only. Now, generally we are not interested in immediate non-cracked deflection. This leaves us with cracked - short-term & long-term deflections in LINEAR analysis. As you are doing LINEAR analysis in ETABS, you cannot get cracked deflections directly. For this, you may apply stiffness reduction modifier option available in ETABS. As you are not applying any stiffness reduction modifier, that means, its NON-CRACKED. This is the answer to your question. However, exploring further, if you want to obtain long-term deflection, you can multiply the immediate deflection by a long-term factor given in ACI chapter 9. ----------------------------- Now comes the non-linear analysis: You can use SAFE for non-linear analysis and get long-term cracked deflections (non-linear) without using modifiers. The cracked non-linear analysis in SAFE will give you long-term cracked deflection which will depend on the extent of cracking which will depend on the reinforcement which will depend on the moment applied. This moment again will depend on the stiffness of cracked section including the reinforcement. So you see, its a non-linear iteration problem. To read further about, linear vs non-linear and elastic vs inelastic analysis, please refer to the book 'Modelling for structural analysis' by Powell.
    2 points
  2. Dear All, I have just finished modifying a bunch of stuff related to member roles and I am very excited to announce it. There are some new member roles that have been created: 1) SEFP Associate As you know that I have been requesting help with a number of stuff on SEFP and there are very generous people who have volunteered. To recognize their effort, I have created this role. An example is @Saad Pervez, who is doing an excellent job running our Social Media pages. From now onwards, you will find him assigned to SEFP Associates. Thanks Saad for your help. 2) SEFP Contributor There are a few members who have been with us through thick and thin. Because, they have regularly answered questions and contributed to forum by not only providing information but their engineering judgement, this role has been created in recognition of their efforts. @Ayesha has been assigned to this and we look forward to add more members to their club. 3) SEFP VIP @EngrUzair deserves this without any question. He is the most senior member of the forum providing invaluable support. Not only this but he has also been a teacher at our beloved Alma Mater. I have created this category in recognition to his efforts. We "might" be adding very few people to this role in upcoming years. 4) Moderators and Super Moderators Our current staff consists of @waqar saleem, @Rana and @BAZ. @Rana and @BAZ have global moderation over the forum and @waqar saleem is currently moderating all the technical sections. They all are doing a great job and I am very thankful them. Because of overall moderation assignment, I have split moderators in Super Moderator and Moderators. Supermods might also get portion of Admin rights over coming years. I have a plan for that but nothing set in stone. Like always, please provide your feedback and let me know what else should be done/ undone. Thanks.
    1 point
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