Accurate calculation of the shear resistance of slabs
The calculation of the resulting shear force was calculated in the past according to the following formula:
\[{{v}_{d,max~}}=\sqrt{{{v}_{x}}^{2}+{{v}_{y}}^{2}}\]
Then, the force was applied to all analyzed angles between the x-axis, and directions were checked. In most cases, the shear and interaction checks were overly conservative.
As shown in the figure above, the corresponding normal force is zero for the angle of 90°. The compressive normal force influences the design shear resistance VRd,c, respectively, the value of σcp according to EN 1992-1-1 6.2.2 (1).
In IDEA StatiCa RCS, additional angles correspond to the direction of the resultant shear force (26.6°), the perpendicular angle (116.6)°, and the angle of the concrete strut. These angles are assigned a corresponding shear force as well as other internal forces.
A shear check's governing (extreme) angle is now different (26.6°). The results are more accurate with proper VRd,c respectively σcp values.
This method accurately determines the direction of shear force and conducts code checks accordingly, aligning with the corresponding internal forces. You can find more information on how the internal forces are recalculated in the Theoretical Background for RCS - 2D sections.
If you are interested in designing concrete slabs and would like to know more about Baumman theory implemented in IDEA StatiCa RCS, try our webinar: Baumann's method for design of concrete shells in practice.
Released in IDEA StatiCa patch 23.1.2.