1964_BUILDING_(CONSTRUCTION)_REGULATIONS — Page 64

B 64

[Subsidiary]

CAP. 123]

Building (Construction) Regulations

[1985 Ed.

F

бы +

For

does not exceed unity at any point,

where f

the calculated axial tensile stress:

F,

total permissible axial stress in tension;

fot

the maximumy resultant tensile stress due to bending about both principal axes; and

Grillage beams.

L.N. 294/76.

Effective length of columns and

struts.

F

= total permissible tensile flexural stress in

extreme fibres of beams and girders.

(3) In paragraphs (1) and (2) "total permissible" means, in relation to any stress, the maximum permissible stress specified in regulation 97 or 98 (as the case may be) plus, where applicable, the increase on the maximum permissible stress permitted in respect of wind load under regulation 99.

101. The maximum permissible stresses in grillage beams (other than hollow compound girders) may exceed the stresses specified in Table XX by 33} per ceht where-

(a) the beams are entirely embedded in concrete not inferior to

that designated Grade IIIA in regulation 19; and

(b) the beams are spaced apart so that the distance between

the edges of adjacent flanges is not less than 75 mm; and

(c) the thickness of the concrete cover on the top of the upper flanges and at the outer edges of the sides of the outermost beams and at the ends is not less than 100 mm; and

(d) the concrete is properly compacted solid around all beams.

102. For the purpose of regulation 98. the effective length of a column or strut shall be that specified in Table XXV for the type of column or strut specified in that Table.

TABLE XXV

Effective length of columns and struts

Type of column or strut

Properly restrained at both ends in position and

direction

Properly restrained at both ends in position and

at I end in direction

Properly restrained at both ends in position but

not in direction

Properly restrained at end in position and direction and at the other end partially restrained in direction but not in position

Properly restrained at 1 end in position and direction but not restrained at the other end

2

Effective length (L = length

of column or strut between centres of restraining members)

0.7 L

0.85 L

L

1.5 L

2.0 L

Note: The effective length of a column or strut of a type not specified in this Table

shall be determined to the satisfaction of the Building Authority.

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