Shearwall Design For Flexure and Axial Force
- oğuzcan hadim
- Zeynep Aladağ
Shearwalls with High Ductility Level
In the wall or group wall design with high ductility level, there are various increments obtained by using these internal force diagrams as well as internal forces calculated under the combined effect of vertical loads and earthquake loads. In TBDY 2018 Section 7.6.6 , it is stated how the values of wall design bending moments and design shear forces should be calculated.
According to TBDY Section 7.6.6.1 ;
In walls meeting the H w / l w > 2.0 condition, the design bending moments are considered as a constant value along the critical wall height (H cr ) . This constant value is taken equal to the bending moment calculated according to Section 4 at the wall base. Above the section where the critical wall height ends, a linear moment diagram parallel to the line combining the moments calculated at the base and top of the wall is applied (TBDY Figure 7.12) .
Design bending moments in all sections of walls with H w / l w ≤ 2.0 shall be taken equal to the bending moments calculated under the combined effect of vertical loads and earthquake loads ( bending moments calculated according to TBDY Section 4 ).
Sample
The design bending moment values will be calculated under the 0.9G '+ Ey + 0.3Ex-0.3Ez loading combination for the wall group named GP1 of the 8-storey building with a plan height of 3m below.
In the first step , a moment diagram is drawn under the loading combination 0.9G '+ Ey + 0.3Ex-0.3Ez . In Figure 1a, with the blue lines , the M3 moment diagram of the GP1 group curtain under the combined effect of vertical loads and earthquake loads under 0.9G '+ O + 0.3Ex-0.3Ez loading combination is shown.
Moment value was found as 434.47 tfm at the lower end of the ground floor curtain. This value will be used as the design bending moment value along the critical wall height (H cr = 4.25m) . In the section above the section where the critical wall height ends, a line is drawn from the moment value (434.47 tfm) at the lower end of the ground floor curtain to the moment value (29.43 tfm) at the top end of the top floor. Then, a line parallel to this line is drawn from the section where the critical wall height ends, and the design bending moment diagram shown in Figure 1b is obtained in the middle. The curtain design is made using this moment diagram.
Shearwalls with Limited Ductility Level
Walls with limited ductility level will be dimensioned and reinforced according to the internal forces caused by the combined effect of vertical loads and seismic loads as stated in Section 7.10 of TBDY . In this case, the design bending moment value is the internal force values resulting from the loading combinations.
Icons
H cr = Curtain critical height
H w = Total curtain height measured from top of foundation or ground floor slab
l w = Length of the curtain or tie-beam curtain piece in plan
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