Masonry Internal Wall Design

Question 1

How is ultimate applied load, F (per metre length of wall), calculated?

Answer 1

Floor dead load + Floor live load + Roof dead load + Roof live Load + block self weights

Question 2

How is the clear height of a wall panel calculated?

Answer 2

Height - thickness of floor (or roof)

Question 3

How is effective height reduction factor calculated?

What value should it not exceed? If it does exceed this value, what do you do?

Answer 3

0.5 x (total height / clear height)

Should not exceed 0.75, if it does, take the value as 0.75

Question 4

How is effective height (Hef) calculated?

Answer 4

Effective height factor x clear height

Question 5

What needs to be calculated for cavity walls after the effective height?

Answer 5

Effective thickness (Tef)

Question 6

After cavity effective thickness is calculated, what must be calculated?

Answer 6

Slenderness ratio (Hef / Tef)

Question 7

What must the slenderness ratio (Hef / Tef) not exceed?

Answer 7

27

Question 8

What must be calculated after the slenderness ratio?

Answer 8

Area reduction factor

Question 9

What is the area reduction factor equal to?

Answer 9

If the area is greater than 0.1m2 it is 1.0, if it is less than this then it is (0.7 + 3A)

Question 10

How is capacity reduction factor obtained?

Answer 10

Using one of the three equations from table M8

Question 11

How is F/A calculated?

What units should it be in?

Answer 11

The ultimate force per metre length calculated first

Divided by

1m width x thickness

N/mm2

Question 12

What should be calculated after F/A?

Answer 12

Masonry design strength required, Fd

Question 13

Using the required design strength calculated, what must be calculated next?

What table must be used?

Answer 13

Masonry characteristic strength, using the required masonry strength multiplied by the partial safety factor in table M5

Question 14

Where is mortar strength found and what mortar strength should be specified?

Answer 14

Table M1, start with M6 typically

Question 15

What table is used to choose a suitable grade of block?

Answer 15

Table M4

Question 16

How is the required masonry compressive strength calculated?

Answer 16

Using the mortar value you specified and the Fk value (masonry characteristic strength), use interpolation to find Fb

Question 17

How do you check the interpolated values?

Answer 17

Using equations in table M3

Question 18

How is the actual compressive strength calculated?

Answer 18

Fb / shape factor (from table M2)

Question 19

How is the shape factor obtained?

Answer 19

Using the dimensions of the block specified in the question, the shape factor is obtained from table M2

Question 20

What is the formula for interpolation?

Answer 20

Y = Y1 + (X - X1) x ((Y2 - Y1) / (X2 - X1))

Question 21

How do you check for wind loading?

Answer 21

1. Divide the total ultimate design load per metre by the partial factor for safety of live loads (Ned)
2. Calculate load ratio (alpha)
3. Use interpolation of table M6
4. Calculate min thickness (t) and then check wall thickness exceeds this

Question 22

What Eurocode is used for masonry?

Answer 22

EC5

Question 23

During the calculation for effective thickness, what is…

t1?

t2?

Answer 23

t1= thickness of brickwork outer skin

t2= thickness of blockwork inner skin

Question 24

When using external walls, what must you multiply the load by in calculations?

Answer 24

2

Question 25

When using internal walls, what must you multiply by in the load calculations?

Answer 25

4

Question 26

In internal wall calculations, what is Tef equal to?

Answer 26

The thickness of the blockwork (if single skin)

Question 27

For external walls restrained at the top and bottom, what should the effective height factor not exceed? For internal walls where the wall is not the end wall and has rotational restraint, what should the effective height factor not exceed?

Answer 27

External - 1.0 Internal - 0.75