Shearwall Modeling

4.5.3. Modeling of Reinforced Concrete Hollow Shearwalls

4.5.3.1 - Reinforced concrete curtains are vertical carrier system elements that generally work as cantilevers .

4.5.3.2 - Rectangular reinforced concrete walls are structural system elements defined as at least 6 (six) ratio of length in section to thickness .

4.5.3.3 - In reinforced concrete walls with cross-section shape I, T, L, U or C, at least one wall arm in each direction will meet the condition given in 4.5.3.2 . Otherwise, the carrier system element will not be counted as a curtain in that direction. However, the condition given in 4.5.3.2 may not be applied in case of a curtain arm (or parts) of a tie-beam curtain that meets 4.5.4.5 of the curtain arm (or arms) in I, T, L, U or C section walls .  

4.5.3.4 - Shear frame models in which the wall end regions defined for the reinforced concrete design of the wall section in Chapter 7 are modeled like a column, and the body region between them as a very rigid beam, will not be used for walls. 

4.5.3.5 - Modeling techniques in which curtain arms are modeled and calculated separately for walls with cross-section shape T, L, U or C shall not be used for curtains .

4.5.3.6 - Reinforced concrete walls will be modeled by one of the methods given in 4.5.3.7 and 4.5.3.8 .

4.5.3.7 - Reinforced concrete walls with rectangular cross-section shape I, T, L, U or C shall be modeled with shell finite elements containing degrees of freedom for both in-plane and out-of-plane displacements . 

(a)   All 6 degrees of freedom shall be considered at the joints of shell finite elements. 

(b)   Finite element dimensions shall be chosen in such a way that the internal force distribution is calculated with sufficient accuracy. 

(c)   Effective cross-section stiffnesses for in-plane and out-of-plane behavior shall be determined in accordance with 4.5.8 .

(d) For walls with rectangular cross-section shape, I, T, L, U or C, the resultant of the forces of the finite element node, the equivalent rod cross-section effects at the cross-section gravity center (bending / torsion moments, shear forces, axial force), based on the reinforced concrete section calculation. ) will be obtained as. The bending moment obtained in this way at the wall base shall be used as the curtain base overturning moment M _DEV in 4.3.4.5 , 4.3.4.6 and 4.3.4.7 .

4.5.3.8 - Walls with a rectangular cross-section shape, I, T, L, U or C, can be modeled as an equivalent rod finite element whose axis passes through the center of cross-section gravity, where the ratio of the largest curtain arm length to the total wall height in the plan does not exceed 1/2 . In this case; 

(a) The  dependent degrees of freedom at the joints of the wall pieces at the floor levels with the beam and / or slab finite elements in the plan shall be connected kinematically to the 6 independent degrees of freedom at the main node, which will be defined at the cross-section gravity center, in a way to provide the three-dimensional rigid body motion condition . 

(b)  Effective cross-section stiffness for bending and shear of walls modeled as equivalent bars shall be determined according to 4.5.8 .

(c)  Based on the reinforced concrete section calculation, the rod section effects (bending / torsion moments, shear forces, axial force) are obtained directly at the section center of gravity. The bending moment obtained at the wall base will be used as the curtain base overturning moment M _DEV in 4.3.4.5 , 4.3.4.6 and 4.3.4.7 .