Huge Difference in ETABS vs Tekal Structural Designer 3

[Al Jazari]

I have been using ETABS for ages, and the results are always books perfect. I was introduced to Tekla Structural Designer, i like the interface and many aspects about it, but one thing is amazing me, The huge difference in deflections between ETABS and TSD, am i doing something wrong ? or is TSD getting it completely wrong ?

both the models are here. i have verified forces again and again but the difference is huge in both software.
tekla : 1.8in
ETABS : .14in

Link

ETABS

 

[Al Jazari]

and not so far off are ETABS result as well.

 

[IRstuff]

"modification" factors == "fudge" factors?

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[sticksandtriangles]

Why does the Tekla model have (2) differing deflections at same x coordinate nodes (if I am reading the output correct)?
Looks like at the roof, the one further with a larger Y coordinate moves 1.3 inches vs the other one which moves 1.6 inches.

S&T

 

[jhardy1]

Tekla Structural Designer "Modification Factors" apparently allow for long-term vs short-term concrete behavior:

The accuracy of determination of the second-order effects for concrete structures is dependent upon a reasonable estimation of the concrete long term properties. Consequently design codes can require that analysis stiffness adjustment factors are applied (as the appropriate properties to use in analysis are load and time dependent).

These modification factors can be applied for each of the different materials from the Modification Factors page of the Analysis Options dialog. (which is located on the Analyse toolbar).

For non-concrete members it is also possible that you will want to apply an adjustment to material properties for various other investigations. One suggested example is the assessment of structures subject to corrosion. Another classic requirement in this regard relates to torsion, it is common engineering practice to assume that if it will work without assuming any torsional strength, then torsion can be ignored.

https://teklastructuraldesigner.sup...esigner-2019i/en/sta_useofmodificationfactors

I would hazard a guess that the OP had (perhaps accidentally) activated the default long-term second-order analysis in TSD, and hence displacements were being magnified; it is not clear to me whether the OP was using first-order or second-order analysis in ETABS.

http://julianh72.blogspot.com

 

[IRstuff]

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

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[johnie134]

Hi IRstuff, not promoting anything

 

[bkal]

Hi,

do not be offended, but as some software is units aware and some is not, are you sure that the units are correct (I've done this mistake a few times myself). The difference (1.8in vs 14in) is just too big to be explained by subtleties if element definitions.

 

[Al Jazari]

the problem was solved, and i have pasted the issue above. If you start trying this new software you might run into this issue.