ACI expansion joint spacing 2

[ramihabchi]

hello,
ACI 224.3R-95 recommend table 1.2 as a rule of thumb and national academy of science criteria (fig 3.6) as analytical way to determine maximum expansion joint spacing.As I understood from the code
These methodes give the adequate joint spacing to have acceptable lateral deflection due to thermal loads.what I can't find if these spacing also permit to neglect thermal loads in structure analysis/design (for example considering thermal stresses taken into account in safety factors of design).What do you think?

 

[r13]

Is this concerning an isolate element such as slab on grade (SOG)? Or the expansion joint between two framing systems? In general, if an element is allowed free to expand/shrink (no restrain), I think you can ignore the thermal load in the design. But you have to apply the thermal load to the framing members, because it causes additional force on the connections due to volume change. The expansion joint here accommodates the frame movement only.

 

[ramihabchi]

Not an isolated element.It is an elevated slab.In ACI 224 a method for single story structure given by Martin and Acosta,clearly say that no need to include thermal load in analyzing the structure as it is already safely taken into account in strength design by the load factors.
I need to know if the same applies for other methods that could be applied on multistory structure.

 

[r13]

ASCE7 has dropped T (thermal effect) in it's load combination. Check ACI, if there is no such combination, then do not worry about it. I don't know how they calculate and incorporate the safety factor into structural element though. Also note, according to ASCE7-10 section 2.3.5 'where applicable, the structural effects of load T shall be considered in combination with other loads'.

 

[HTURKAK]

Temperature ,shrinkage and creep effects may be ignored in building type structures whose
lateral dimension does not exceed 40m and the frames are not substantially restrained by shear walls
ACI 318 -14 ' : R5.3.6 Several strategies can be used to accommodate movements due to volume change and differential settlement.Restraint of such movements can cause significant member forces and moments, such as tension in slabs and shear forces and moments in vertical members. Forces due to T effects are not commonly calculated and combined with other load effects. Rather, designs rely on successful past practices'

ASCE 7-16 ' T = cumulative effect of self-straining forces and effects arising from contraction or expansion resulting from environmental or operational temperature changes, shrinkage, moisture changes, creep in component materials, movement caused by differential settlement, or combinations thereof'

ASCE 7-16 ':2.3.4 Load Combinations Including Self-Straining Forces and Effects. Where the structural effects of T are expected to adversely affect structural safety or performance, T shall be considered in combination with other loads. The load factor on T shall be established considering the uncertainty associated with the likely magnitude of the structural forces and effects,the probability that the maximum effect of T will occur
simultaneously with other applied loadings, and the potential adverse consequences if the effect of T is greater than assumed.The load factor on T shall not have a value less than 1.0.'

 

[ramihabchi]

Thank you for your answers.
I need to know if respecting the limit of the graph of national academy of science(attached) permits to avoid including thermal effect in analysis/design

https://files.engineering.com/getfi...54a-a1d207c0404b&file=IMG_20200201_192040.jpg