Masonry - ICE Manual of Structural Design: Buildings - page 389

M id moment in wall due to eccentricity of the fl oor connection
to the wall.
Taken as the fi rst fl oor load acting at an eccentricity of t/6.

M

md

e e00 6.2 0

=

md

+ ++ =+ e =+ e0++ 6. ++ 6.2

e e e ++ e ini ++

init mk hm k e0 k e0

e init

hm

N

mid

e

mk

6.2mmt 0mt 5

e

mk mk =

= 2 0.0 0.0 6 6 = 6.2m 6.2mmt ≥ mt ≥ 0 mt 5 mt mt

20 100
6

×

0 0mt 0 mt mt 0 mt

M id = 333 kNmm/m

t

=

Annex G

Annex G provides values of φ m , based on E values
as a function of f k .
For E = 1000f k fi gure G.1 is used

N id Design value at top (or bottom) of wall = 51.0 kN
e he eccentricity due to horizontal loads = 0 kN

Figure G.1

e init eccentricity due to initial imperfections,

taken as h/450 = 6.2mm

Clause 5.5.1.1

For this example φ m is approximately equal to 0.61
Limiting value of φ min is given as = 0.61 (based on middle).
Compressive resistance:

M 333

51

id

0 6.2 where... 0.05t 5mm e = = +

i = + id

e e += += e e ini +=

init

++ ++ 0

=

i he he

e init

N

id

005

= 12.9 12.9 12.9 mm ≥ 0 . 005 5 t t mm

06 1 1 0 × × 10 ×× 1000 12 0

×× ×

Ntf

0 . 06 1 ×× ×× 10 ×× ×× 1000 × 12

N N N NNt == N Nt == Nt

06 . 06 06 1 ×× 100 100 ×× 100 ×× 100 ×× ×× 1000 1000 × 12 12 . . 12 0

73 k k Nm N ok k N Nm

= 73 k kNm Nm N Nm NNm NNm >

E
Nm No No

Nt == Ntf == Nt == Ntf == fi

RD Nt RD Nt d d d

==

d

= 73 k k kNm Nm

E
Nm No Nm N Nm Nm >

E No D No D No E

73 kNm Nm N Nm

1000

/

Reduction factor at top/bottom of wall =

1000

A three-storey building is constructed in load-bearing masonry
construction. An internal partition is constructed using 21 5mm
wide blockwork (15 N in M4 mortar).
The height of the lowest storey is 4 m high. The fl oors of the
construction are precast concrete and sit on either side of the
internal wall (see Figure 20.14 and 20.15 ).
The wall carries the following loads:

t 12 12.9

12 e

i

φ i 0.74

=12 = 12 =12 = 12 =

100

Small plan area factor check is applicable where the cross sec-
tional area of the wall is less than 0.1 m 2 , with the modifi cation
factor given below:
Area = 0.1 × 1.0 = 0.1 m 2 ≥ 0.1 m 2
∴ (0.7 + 0.3A) = 1.0

Equation 6.3

Above fi rst fl oor = 46 kN/m Gk and 20 kN/m Qk
First fl oor = 16 kN/m Gk and 14 kN/m Qk (8 kN/m Gk and
7 kN/m Qk on each side)
SW of wall below fi rst fl oor = 14 kN/m
Check the resistance of the inner and outer leaves.
Basic requirement:

Eccentricity at the middle of the wall, e m

M
N

e

md

Equation 6.6 0.05t

≥

= + e mk = mk =

md

+ ++

e =+ e e e e ++ e e ini ++

init

e

mk

e mk mk e

hm k mk hm

e init

mid

M id assumed to be a point of contrafl exure, therefore = 0 kNm
N id Design value at top (or bottom) of wall = 50 kN
e m

Clause 6.1.2.1
Equation 6.1 & 6.2

eccentricity due to vertical loads N ED ≤ N RD = N ED ≤ φtf d

M
N

md

0 e =

md

=

Loading:

m

mid

e he eccentricity due to horizontal loads = 0 kN
e init eccentricity due to initial imperfections, taken as

N ED-innerleaf = (1.35 Gk + 1.50 Qk) = 92 kN/m
N ED-innerleaf-fi rstfl oor = (1.35 Gk + 1.50 Qk) = 21 kN/m
N ED-innerleaf-fi rstfl oor = (1.00 Gk ) = 8 kN/m
>N ED-innerleaf-SW = (1.35 Gk ) = 19 kN/m

h/450 = 6.2 mm

BS EN1990

e k eccentricity due to creep, given as

Equation 6.8
Clause 6.1.2.2

h

Total N ED at base of wall = 152 kN/m

ef

0 00. φ φ ∞ te e =

k

m

∞

t

ef

Assumptions / Specifi cation requirements:
Masonry unit

Table NA.7

φ w = 1.5, fi nal creep coeffi cient for aggregate
concrete blocks

Category I

Masonry Group Group 1 (<25% voids)

However as slenderness is less than 27, creep
may be ignored.

NA to BS
EN1996:1

Construction classifi cation Class 2

Design masonry resistances

As e m = 0, e k = 0