The calcs shown below go through this process step-by-step for an HSS8x8x3/16 for the corrected version, as well as show the steps required to replicate the incorrect printed values.The flexural strength of concrete is indirectly the tensile strength of the concrete. I also feel it is helpful to see the exact process used in the calculation of the table. Note that I generated this table and that it did not come from AISC, therefore it is subject to any errors I might have made, however I went to all reasonable lengths to ensure its accuracy. The table below lists the affected sections and the corrected values. #Calculating flexture modulus manual#This error will be corrected whenever the next errata for the Manual is released. In the creation of the table the nominal wall thickness (tnom) was inadvertantly used instead of the design wall thickness (0.93tnom). This does not affect any of the other tables (rectangular HSS etc) nor does it affect the compact or non-compact shapes in the table. Resolution: There was a minor error made in the calculation of flexural capacities for SLENDER HSS sections in Table 3-13 (square HSS sections). RE: HSS Beam Section Modulus 2005 dik (Structural) 14 Dec 06 10:23 The tabulated values are based on a LRFD design strength of 0.9Mn and an ASD allowable strength of Mn/1.67. The smallest Mn value from these three is the Mn that will be used for the design and allowable strength determination. There are three Mn expressions for each limit state (namely, yielding, flange local buckling and web local buckling). The Section F7 limit states contain a Mn expression for slender flanges and a Mn expression for non-compact webs, hence I am confused why you asked this question. There you will find three limit state expressions. Be sure you are using 0.93 times the nominal thickness for all section properties, such as area, section modulus, moment of inertia, etc.īe sure to use the Section F7 expressions found in the 2005 AISC Specification. The tables in the Manual are not meant to be reversed engineered, as that defeats the entire purpose of using such tables. I guess the best you can hope for in rectifying the equations to the table is to get close. I wish there was a way of verifying the table numbers. RE: HSS Beam Section Modulus 2005 dik (Structural) 12 Dec 06 11:41 Would it have killed them to tack on the extra decimal place? For $350 you think you could have sprung for the extra ink. Check out the the W14X22 (d=13.7, 13 3/4) vs the W14X43 (d=13.7, 13 5/8) its the same decimal depth with different fractional depths. Now I'm having to check everyone of the sections against the manual value. On a side note: What's up with the manual's only rounding the depth of the member to 0.1" (See WF's)? I use to be able to run a simple macro that could take all the decimal dimensions, convert them to the detailing dimension, and write to a text file. I like to write spreadsheets that can reproduce the manual's numbers, or at least be able to understand why I'm not getting their numbers. #Calculating flexture modulus full#I wish they would run a full example that would show their reasoning that reproduces the same number in the tables.Īny help explaining this would be great. I figure that they are somehow manipulating the radius of the bend differently for different thickness-or something. I'm willing to do this, I just don't seem to be able to reproduce the table. They state that if you want a more precise answer that you can take only compression side out, calculate a new S(eff) with a shifted neutral axis. easier) and show that the HSS8x8x3/16 works for the moment they are requireed to resist. They caculate S(eff) conservatively (i.e. However, they are testing for a required moment. The CD of examples that came with the manual actually runs the HSS8x8x3/16. Once the section goes past the non-compact region, I'm having difficulty determining the rational to get the same results shown in Table 3-13 of the new manual. There is a fair amount of tubes that do not met the requirements.
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