overlapping armor

[Dario1982]

Good morning, everyone. I wanted to ask a question: I am drawing the wall armor of a dissipation chamber for a drainer channel. since the chamber has the shape "to gallery", therefore also the two closing walls have such shape. therefore the armoring of the wall (I have a mesh 20 x 20 cm of horizontal and vertical needles) are all variables by force of things.. However, since the wall is curved, I cannot give it variability from the minimum to the maximum. not to draw iron for iron, I thought to draw one of the same long edges and then to increase the overlap with the central one. My question is: the minimum overlap is obviously binding (in my case is 1.20 m) but is the maximum overlap? or is there no limit? Thank you so much!

 

[Betoniera]

Good morning, everyone. I wanted to ask a question: I am drawing the wall armor of a dissipation chamber for a drainer channel. since the chamber has the shape "to gallery", therefore also the two closing walls have such shape. therefore the armoring of the wall (I have a mesh 20 x 20 cm of horizontal and vertical needles) are all variables by force of things.. However, since the wall is curved, I cannot give it variability from the minimum to the maximum. not to draw iron for iron, I thought to draw one of the same long edges and then to increase the overlap with the central one. My question is: the minimum overlap is obviously binding (in my case is 1.20 m) but is the maximum overlap? or is there no limit? Thank you so much!

Of course there is.
in dm 14-01-2008 (technical construction standards) is indicated the resistance of concrete adherence to bars.
for a concrete class c 25/30 (rck = 300 kg/cm2), the resistance is 23 kg/cm2.
the old legislation on admissible voltages (dm 16-01-1996) provided anchorages of 20 diameters per compressed area and 40 diameters per ten area.
therefore, without making any calculation always remember a minimum overlap of 40 diameters
Hi.

 

[studio.avarino]

from a strictly normative point of view, I do not think there is a maximum to be respected for the overlap of the irons. the problem could exist in the fact that, when the overlap exceeds the minimum, the steel area to be considered is no longer that of one armor but that of the two overlapping armours, as each one is able to develop the maximum resistance having a length of anchorage that allows it to reach the fy. This may not be important (I have an even greater "capacity" than that required) but it may also bother, for example if it involves having to consider very high last stresses that, in case of resistance hierarchy, are almost annoying (they force to "oversize" other parts of the structure). Therefore the question is simple, not just the answer that, in my opinion, depends on the structural element considered and the connections of this with others.
to clarify: If I arm a beam and want the crisis for cutting to be later than that for bending, doubling the longitudinal armor (because I make "exaggerated" overlaps) puts me in trouble because it forces me to review all the brackets and, even, it could make impossible the cutting sizing (because it goes in crisis the dot in cls).

 

[Cristallo]

apart from considerations more than correct of avarino, remains a moral problem (the executive enterprise will laugh behind you if you do overlays from 3m only to indicate a finite measure on a drawing) and one of economic type (the work will cost an extra tot only because you want to indicate a number on a sheet).
It is so beautiful the "tot=var" and will give work to another that these need to develop one by one...

 

[Betoniera]

hi avarino, hi crystal
I am pleased that the forum also discusses some structures.
avarino has made a more general speech than mine, stating that an increase of armor within the critical areas can compromise the hierarchy of resistances.
It is true, but this is true for the frames composed of beams and pillars, whose knots represent critical areas.
In this case we talk about walls where, I think, we cannot talk about critical areas (except for sect buildings).
It is also true that dm 2008 does not provide a minimum, nor a maximum for overlaps. Article 4.1.2.1.1.4 is limited to the tangential resistance of steel-calcestruc-adhesion. This resistance implicitly provides the calculation rule the anchor which, of course, is function of the shooting and characteristics of the materials.
However, it is equally obvious that, for practical purposes, one cannot even make a calculation for each iron resumption.
Here is then that the old "rule" of the admissible tensions of the 40 diameters will be good in 99% of the cases and, above all, it is understandable by the geometra that must draw the irons.
it will then be the task of the engineer strutturista to verify and possibly give more precise indications in the knot or in critical situations.
For example, that adhesive voltage should be calculated for anchoring the tyrants in the base plates of steel structures.
orbene, the tension of adherence is different depending on the fact that the background is straight or shaped. so things get complicated and it turns out quite difficult for a designer to respect "only" the norm. you need an excellent understanding between designer and strutturist, otherwise it is very easy to do work not in norm.
Hi.

 

[studio.avarino]

I am pleased that in the forum you discuss also some structures

Also to me, I do only construction and civil design, in the forum I feel "in minority"! every now and then it is interesting to discuss structures in a definitely more friendly and peaceful environment of others in which these themes are addressed!
returning to the question, besides the already suggested tot=var is so beautiful l tot=xx÷xxx, certainly works excellently only in cases of variable profile with linear law but, as they say, "and in the yard that nothing must do? !"

 

[Cristallo]

"and in the yard nothing has to do? !"

Well, it depends on the desire in the yard.
I have developed distinct armours to be sent to ferrier for a bottom insole of a gallery, in which varying the axle and the insole quota all the needles were variable.
we have established a step of 5cm and I have developed all the iron combinations to install (length stretch about 3km)
but I do not belong to the executive enterprise, neither to the d.l., nor to the designer... of the series (they) will want to wash jumps on me! :biggrin:

 

[studio.avarino]

He's gonna be working on me!

Right! If you don't find them made by others, you have to develop them. I think this is a good way to allow the desire to work on jumping on the right people. I understand that everyone can also think that the right people are others.. .

p.s. at the end of the fair, someone will have paid you the "infamous" job you did, or not?

 

[Dario1982]

thank you very much to all for the very technical and interesting answers! I do not know whether there is a way to determine the "delta" between iron and other but I do not believe. at the end we solved by working on "beams" of irons in which the minimum overlap was that required, and the maximum one was a little higher but without exaggerating

 

[Cristallo]

p.s. at the end of the fair, someone will have paid you the "infamous" job you did, or not?

Of course I do. I didn't do it for free.