Polygon Shear Design Shear Forces

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MaFiAMaX

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TBDY 2018 Figure 7.12 Shear design shear force Hello everyone, There is an article 7.6.6.1 about calculating the shear design moment. Figure 7.12 a and b are explained with the description made here. The graphic shown as 7.12 c about the curtain cut is not explained in any article. Does anyone know the purpose of this graph?
 
Re: TBDY 2018 Figure 7.12 Curtain design shear force Hello; The purpose of this graph is to calculate the curtain design shear forces. Two graphs for design bending moments and a graph for design shear forces are given in Figure 7.12 under the title of TBDY Section 7.6.6 Design Bending Moments and Shear forces. At the same time, since the Design Shear Force calculation is explained in article 7.6.6.3 it means that Figure 7.12 (c) should be used. Figure 7.12(c) (Design Shear force graph) is used in the designs of shear walls with high ductility level found in all examples (BA1, BA2 and BA3) described in the Turkey Building Earthquake Code Training Manual. There is also a similar calculation in the curtain design shear force calculation in Eurocode mixed systems. Best regards...
 
Re: TBDY 2018 Figure 7.12 Shear force of curtain design Hello Mr. Oğuzcan, Thank you for your reply. In EC8, it explains this issue in clause 8 of 5.4.2.4. In TBDY 2018, in article 7.6.6.3, to be increased with certain coefficients; The shear force obtained from the moment capacity and the shear force obtained from the analysis are calculated and the smaller one is taken into account. In other words, it is not explicitly stated that an adverb like this will be used. I think the problem is that our regulation has formulas derived from EC and ACI 318. Could they not have included the clause about it when they put this 7.12(c)? In DBYBHY 2007, this correction was made only for design moments.
 
Re: TBDY 2018 Figure 7.12 Curtain design shear force Hello; There is no clear statement that the 7.12(c) chart will be used in TBDY 2018. However, as I explained above and in the published "TBDY Training Manual", it means that this graphic should be used. Comparing the shear force obtained from the moment capacity and obtained from the analysis and considering the smaller one is explained in article 7.6.6.3. When the material is applied as you say, very small shear forces appear on the upper floors. I am attaching the photo of the Design shear force graph calculated for the curtains in the Training Manual. Best regards...
 
In the group curtain shear safety calculation, Mp (moment capacity) value in TBDY Equation 7.16 is made by considering the whole polygon section. The cutting capacity is calculated on the basis of the arm. Considering the shear force coming to the curtain group as a whole, this shear force is distributed to the arms. Shear strength resistance is also found with the transverse reinforcements in the curtain arms. The arms shown in pink in the attached pictures share the shear force equally and the shear strengths of the curtain arms (P1X1 and P1X2) are calculated according to the reinforcements inside the arms. Similarly, the shear force on the curtain arm shown in blue is compared with the calculated shear strength in the texts (P1Y1) shown in the same color.
 
Re: TBDY Sample Book Curtain Design Cutting Forces Hello Mr. Oğuzcan; First of all, thanks for this reminder. In some control authorities, modeling such as polygonal column for group curtains is insistently requested. Programs that model in this type of polygon column logic do not calculate and control the shear force separately for the curtain arms, but for the entire section. With this reminder, it turns out that the models to be made in the polygon column logic are actually wrong. Best regards.
 
Polygon modeling will not be wrong if one looks at the cutting forces and evaluates the remaining verifications as polygons. While analyzing the project with foreign software, while looking at the curtain capacity, the polygon is a single pier, but a different model arm is assigned for the cutting forces. I guess that's what the regulations want.
 
I started to think that increasing the shear force of the curtain after Hw/3 as in Figure 7.12 (c) is against the logic of CURTAIN CUTTING STRENGTH CALCULATION. Namely; 1-We calculate the shear force coming from the analysis to the curtain. We multiply that by 1.2*D or 1.4*D. This increase is a precaution taken for the ductile operation of the curtain. There is no problem with that. Let's call this Ve1. 2- Based on the moment capacity of the shear wall, we calculate a shear force (equation 7.16) depending on this capacity. Let's call this Ve2. What does the regulation say? Consider the smaller of these Ve1 and Ve2 you found as the design shear force. Why is that? Because; Scenario 1: Let Ve1=100 kN, Ve2=200 kN. A maximum of 100 kN will come from the earthquake anyway, so there is no point in taking 200 kN. Scenario 2: Let Ve1=200 kN, Ve2=150 kN. That is, the scenario where the moment capacity of the curtain is almost the same as the incoming moment. At this time, due to the moment you get from the curtain, it will already carry a maximum shear force of 150 kN. Therefore, you will design according to 150 kN. Now after these scenarios, the shear force greater than Ve1 and Ve2 is taken into account on the upper floors where the curtain is less difficult. Especially, in the building that does not comply with the rigid basement rule, the Vbase is very large due to the basement floor mass. When you plot the graph with half of this Vbase at the top, you calculate abnormal shear forces.
 
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