RF-CONCRETE Members – Online Manual Version 5

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RF-CONCRETE Members – Online Manual Version 5

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2.1.3 Shear Forces Between Web and Flanges of T-Beams

Shear Forces Between Web and Flanges of T-Beams

The longitudinal shear stress vEd,f at the junction between flange and web is determined by the longitudinal force difference Δ Fd,f in the flange's governing part according to EN 1992-1-1, clause 6.2.4 (3), equation (6.20).

vEd,f = Fd,fhf · xf 

where

Table 2.1

hf

flange thickness at junction

Δxf

considered length

ΔFd,f

longitudinal force difference in flange over length Δx

The maximum value that may be assumed for the length Δxf is half the distance between the maximum and the zero point of moments. Where concentrated loads are applied, the distance between the concentrated loads should not be exceeded.

The determination of Δ Fd,f is done optionally with a control available in the module details according to two different methods that are described below.

1. Simplified method via inner lever arm z = 0.9d without considering Mz,Ed

Table 2.1

for compression flanges

for tension flanges

where

Table 2.1

zs

distance between centroid of cross-section and tension reinforcement

z

lever arm of internal forces 0.9 d

beff,i

width of adjacent flange (compression flange) or width of reinforcement distribution in adjacent flange (tension flange) considering the Distribute reinforcement evenly over complete slab width option (see Figure 3.30)

beff

flange width

Asa

reinforcement exposed in connected tension flange

As

total area of tension reinforcement

2. Calculation of Fd from general stress integration in partial areas of cross-section

The required tension flange reinforcement due to shear forces per unit length asf may be determined according to equation (6.21).

asf  vEd,f · hfcot θf · fyd 

where

Table 2.1

1.0 ≤ cot θf ≤ 2.0

inclination of concrete compression strut for compression flanges

1.0 ≤ cot θf ≤ 1.25

inclination of concrete compression strut for tension flanges

fyd

design yield strength of reinforcement

At the same time, the compression struts in the flange must be prevented from failing, which is ensured if the following requirement is met:

vEd  ν1 · fcd · sin θf ·cos θf 

Equation 2.6 EN 1992-1-1, Eq. (6.22)

where

Table 2.1

fcd

design value of concrete strength

ν1

reduction factor for concrete strength in case of shear cracks

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