Design a Wall

Question 1

How to Design a Wall

Answer 1

1. Robustness
2. Loads
3. Capacity
4. Design Options

Question 2

Robustness

Answer 2

• confinement
• containment
• boundary elements
• shear

Question 3

Loads

Answer 3

• tension shifted moment diagram
• linear to allow for higher mode responses
• jd = lw

Question 4

Capacity

Answer 4

• coupling effect accounts for 40-60%

Question 5

Design Options

Answer 5

• conventionally reinforced

- diagonally reinforced cage

Question 6

conventionally reinforced

Answer 6

• only appropriate for small EQ forces and displacements
• more appropriate for slender coupling beams
• performs very badly under large shear

Question 7

diagonally reinforced cage

Answer 7

• detail diagonal cages as mini columns (<= 6db)
• extend at least 1.5 Ld into wall for anchorage
• wedges of concrete not required for strength so services
• require basketing to stop diagonal wedges falling out (anchor 100 - 150 mm)

Question 8

containment

Answer 8

• extra ties in web for containment of core and preventing buckling of long. bars
• <= lw/3 or 300
• ensures load path maintained when concrete crushed up and prevents falling out

Question 9

confinement

Answer 9

• lots of stirrups to confine core
• increase compressive strain (0.008)
• also increases ductility, compressive strength and prevents inward buckling

Question 10

boundary elements

Answer 10

• end sections of wall: 0.15 lw
• designed like columns (min 8 bars and h/4 spacing)
• more steel in boundary elements than middle
• ensure multiple cracks and fan cracking
• lumping steel for yielding and elongation of bars
• cracking steel run full height
• enlarged BEs
• staggered lapping

Question 11

shear

Answer 11

• horizontal spacing lw//3, 3t, 450
• vertical spacing lw/5, 3t 450
• limit nominal shear stress to prevent diagonal compression failure in PPHZ (< 0.2 f’c or 8 MPa)