1964_BUILDING_(CONSTRUCTION)_REGULATIONS — Page 84

B 84

CAP. 123]

Building (Construction) Regulations

[1985 Ed.

[Subsidiary]

TABLE XXXIV

Bending moment coefficients for slabs spanning in 2 directions at right angles simply supported on 4 sides

2

3

5

7

8

9

10

11

lly

1.0

1.2 1.3 1.4

1.5

1.75

2.0 2.5 3.0

Xx

0.062

*

0.074 0.084 0.093 0.099 0.104 0.113 0.118 | 0.122 | 0.124 0.062 0.061 0.059 0.055 0.051 0.046 0.037 0.029 0.020 0.014

(4) In the case of slabs restrained on 4 sides-

(a) where the corners of a slab are prevented from lifting and adequate provision for torsion in accordance with sub- paragraph (e) is made, the bending moments shall be assumed to have the values given in sub-paragraph (c); (b) slabs are considered as being divided in each direction into middle strips and edge strips as shown in Diagram 1, the middle strip having a width of 3 of the width of the slab and each edge strip having a width of § of the width of the slab, except that, for slabs for which the ratio of the sides 1/1, exceeds 4.0, the middle strip in the short direction shall be taken to have a width of 1,-/, and each edge strip a width of 12

I

DIAGRAM 1

Division of slabs into

middle and edge strips

FOR SPAN Ix

Ly

FOR SPAN ly

Ly

EDGE STRIP

EDGE STRIP

MIDOLE STRIP

EDGE STRIP

MIDOLE STRIP

EDGE STRIP

T

T

(c) the maximum bending moments per unit width in the middle strip of a slab shall be calculated by the following equations:

Ms

By w12 Bx

M

Bwl2

where-M, and M, are the maximum bending moment on strips of unit width in the direction of spans /, and /, respectively:

11'

is the total load per unit area;

1

is the length of the longer side;

is the length of the shorter side:

Band B, are coefficients given in Table XXXV.

TABLE XXXV

Bending moment coefficients for rectangular panels supported on 4 sides with provision for torsion at corners

Short span coefficients B