Australian Capital Territory Current Regulations Australian Capital Territory Current Regulations(1) The stresses imposed or developed in any member, component, part, or attachment, of any crane, hoist, lift, scaffolding, plant or gear shall be computed and after inclusion of all relevant increases consequential to section 125 and the other sections as may be applicable shall not exceed the relevant and appropriate maximum prescribed by this regulation.
(2) If the member, component, part or attachment is of timber, the stress imposed or developed in it shall not exceed the relevant and appropriate maximum shown in table 126.1, or any other stress that may be more specifically prescribed elsewhere in this regulation.
Table 126.1 Maximum permissible stresses for timbers
* Generally termed ‘horizontal shear'.
† Hardwood includes only Australian hardwoods of
approximately the same strength and reliability as spotted gum.
(3) Table 126.1 applies if more specific provision is not made in this regulation.
(4) If the member, component, part or attachment is of any other material, the stress imposed or developed in it shall not exceed that prescribed by section 122 (4) to (23), and amplified in relation to certain commonly used materials by table 126.2:
Table 126.2 Physical properties of materials
* As determined by rotating bar test on 10 million cycle basis.
† As determined by reciprocating bar test on 10 million cycle basis.
‡ If approved by chief inspector.
(5) If the stresses include those due to wind loads, they may exceed the maximum mentioned by 25% provided—
(a) that the increase is solely due to wind loading; and
(b) that the strength of the structure so determined will not be less than it would have been if wind loading had been disregarded.
(6) If a mild steel member of H, T or I section is used as a beam or cantilever, the stress imposed or developed in the tension flange shall not exceed 12 tons per square inch.
(7) The stress imposed or developed in the compression flange of a cantilever shall not exceed that prescribed for a beam of twice the length of the cantilever; each half length of the beam shall be assumed loaded with identical loading and incidence of loading to that on the cantilever.
(8) The beam thus loaded will have a central reaction equal in magnitude to twice the algebraic sum of the loads on the cantilever, and the position of the point of application of this reaction shall determine whether the beam load is applied to the compression flange, or tension flange, or centroid of the beam section.
(9) If the principal external loading is concentrated and is applied to the compression flange of a beam of the section, the stress imposed or developed in the flange shall not exceed the lesser of the following stresses:
(a) 14 4 / 10 tons per square inch, or
(b)
that determined by the formula 
tons per square inch.
(10) In subsection (9):
"b" means the least breadth of the compression flange that can be measured within a distance of 1 / 4 of the span of the beam of the section at which the stress is determined.
"d" means the overall depth of the section of the beam at which the stress is determined, exclusive of any track rail laid on it.
"l" means the maximum length of compression flange that is not supported laterally by adequate external means.
"t" means the thickness of the compression flange measured as provided for flange thickness of Australian Standard Beam Sections by Australian Standard Specification No AI—1940, for structural steel.
(11) If the compression and tension flanges of a beam are of different sections, or if the beam is of the single plate web girder type, the flange thickness "t" must be determined from the formula—
t =
.
(12) In subsection (11):
"b"—see subsection (10).
beam about its minor rectilinear axis, provided that if the compression and tension flanges are of different section.(13) I y must be taken as equal to twice the moment of inertia of the compression flange about the aforesaid axis, and provided that if the compression flange of an Australian Standard Beam Section is not compounded, t may be determined as prescribed in this section for the standard beam section.
(14) Track rails need not be included when determining flange thicknesses, t .
(15) If the principal external
loading is concentrated and is applied at the centroid axis of the beam, the
formula 
tons per square inch may be substituted for the formula stated in subsection (9) (b).
(16) If the principal
external loading is concentrated and is applied to the tension flange of the
beam, the formula 
tons per square inch may be substituted for the formula stated in subsection (9) (b).
(17) These maximum stresses are permissible only for beams or cantilevers of mild steel conforming to Australian Standard Specification No A.I—1940, ‘Rolled Steel Sections for Structural Purposes'.
(18) For a beam or cantilever of the same type but of steel conforming to British Standard Specification No 548—1934, ‘High Tensile Structural Steel for Bridges, etc, and General Building Construction', or British Standard Specification No 968—1941, ‘High Tensile (Fusion Welding Quality) Steel for Bridges, etc, and General Building Construction', the stress imposed or developed in the tension flange shall not exceed 15 tons per square inch, and in the compression flange of the beam, the lesser of the following stresses:
(a) 17 6 / 10 tons per square inch; or
(b) that determined by the formula stated in subsection (9) (b) or the alternative provided in subsection (15) or (16).
(19) If a member of H, T or I section is used as a beam and the principal external loading is applied to the compression flange, and if the loading is evenly distributed throughout the span of the beam and is greater in magnitude than any concentrated loading that may be simultaneously applied, the stress imposed or developed in the flange shall not exceed the lesser of the following stresses—
(a) 14 4 / 10 tons per square inch, or
(b) that determined by the formula 
tons per square inch.
(20) In subsection (19):
"b"—see subsection (10).
"d"—see subsection (10).
"l"—see subsection (10).
"t"—see subsection (10).
(21)
If the external loading is applied at the centroid axis of the beam,
the formula 
tons per square inch may be substituted for that stated in subsection (19)
(b), and if the loading is applied to the tension flange of the beam, the
formula 
tons per square inch may be so substituted.
(22) These maximum stresses are permissible only for beams or cantilevers of mild steel conforming to Australian Standard Specification No A.I.—1940, ‘Rolled Steel Sections for Structural Purposes'.
(23) For a beam or cantilever of the same type, but of steel conforming to British Standard Specification No 548—1934, ‘High Tensile Structural Steel for Bridges, etc, and General Building Construction', or British Standard Specification No 968—1941, ‘High Tensile (Fusion Welding Quality) Steel for Bridges, etc, and General Building Construction', the stress imposed or developed in the tension flange shall not exceed 15 tons per square inch, and in the compression flange of the beam, the lesser of the following stresses:
(a) 17 6 / 10 tons per square inch; or
(b) that determined by the formula stated in subsection (19) (b) or the alternative provided in subsection (21).
(24) The computed deflection of a steel beam in the direction of either the major or minor rectilinear axis of any cross-section shall not exceed 1 / 380 part of the span of the beam.
(25) The computed deflection at the extremity of a steel cantilever shall not, when measured in the direction of either the major or minor rectilinear axis of any cross-section, exceed 1 / 190 part of the length of the cantilever.
(26) For the purpose of computing the deflections, the modulus of elasticity of steel shall be deemed to be 13 000 tons per square inch.
(27) In computing deflections it shall be necessary to increase the forces producing the deflections in the way provided by section 125.
(28) Forces shall be considered to act simultaneously, and the horizontal forces referred to in section 124 shall be included.
(29) The maximum vertical shearing stress in the webs of rolled steel joists, channels or plate-web girders of mild steel conforming to Australian Standard Specification No A.I—1940 ‘Rolled Steel Sections for Structural Purposes' shall not exceed 6 tons per square inch.
(30) If the members are of steel conforming to British Standard Specification No 548—1934, ‘High Tensile Structural Steel for Bridges, etc, and General Building Construction', or British Standard Specification No 968—1941, ‘High Tensile (Fusion Welding Quality) Steel for Bridges, etc, and General Building Construction', the maximum vertical shearing stresses in the webs shall not exceed 7 1 / 4 tons per square inch.
(31) The shearing stresses mentioned in subsections (29) and (30) are permissible only if the ratio—
does not exceed 83 for the mild steel or 75 for the high tensile steel members.
(32) For the purposes of web-shearing computations the depth of web of a rolled steel joist or channel may be taken as the full depth of the joist or channel, and the depth of web of a plate girder may be taken as the depth of the girder, measured between the centroid axes of the respective compression and tension flanges.
(33) If the ratios of depth to web thickness mentioned in subsection (31) are exceeded, the maximum vertical shearing stress shall not exceed that determined by the formula—
(34) For subsection (33), the value of K shall be
selected from table 126.3 in conformity with, and as appropriate to the
ratio 
where d 1 is the longer and d the lesser rectilinear dimensions of the panels into which the web is divided by effective stiffeners, measured in the vicinity of the stress assessed.
Table 126.3
|
ratio |
1.0
1.2
1.4
1.5
1.6
1.8
2.0
2.5
3.0
K
9.42
8.0
7.3
7.1
7.0
6.8
6.6
6.3
6.1
5.35
(35) If vertical shearing stresses are low and the depth of web is less than 132 times the web thickness for mild, or 120 times the web thickness for high tensile steels as mentioned in subsections (29) and (30), the following compressive stresses shall not be exceeded at any section of the web:
(a) for such mild steel—8 tons per square inch;
(b) for such high tensile steel—9 tons per square inch.
(36) If relationships of web depths to thicknesses mentioned in subsection (35) are exceeded, the compressive stress in the web shall not exceed that determined by the formula—
(37) For subsection (36), the value of K shall be
selected from table 126.4 in conformity with, and appropriate to the
ratio
with the same meaning as mentioned in subsection (34).
Table 126.4
|
ratio |
0.4
0.5
0.6
0.67
0.75
0.8
0.9
1.0
1.5
2.0
3.0
8
K
23.9
21.1
19.8
19.7
19.8
20.1
21.1
21.1
19.8
19.7
19.8
19.7
(38) The stress at the bottom of the Whitworth thread of a bolt or tie rod or other threaded member of mild steel shall not exceed—
(a) 8 000 pounds per square inch for threads up to and including 1 / 2 an inch in diameter;
(b) 12 000 pounds per square inch for threads 5 / 8 of an inch in diameter;
(c) 16 000 pounds per square inch for threads 3 / 4 of an inch in diameter;
(d) 20 000 pounds per square inch for threads 7 / 8 of an inch in diameter;
(e) 24 000 pounds per square inch for threads 1 inch in diameter;
(f) 25 000 pounds per square inch for threads 1 1 / 8 inches in diameter;
(g) 26 000 pounds per square inch for threads 1 1 / 4 inches in diameter;
(h) 27 000 pounds per square inch for threads 1 3 / 8 inches in diameter;
(i) 28 000 pounds per square inch for threads 1 1 / 2 inches and over in diameter.
(39) The stress in a compression member, or strut, of mild steel shall not exceed that shown in table 126.5, relevant and appropriate to the ratio of slenderness of the member.
(40) If the member is of high tensile structural steel, the stress shall not exceed that shown in table 126.6 relevant and appropriate to the ratio of slenderness of the member.
(41) The ratio shall be determined by dividing the greatest length of member that is not supported effectively against lateral deflection, by the least radius of gyration of any cross-section of the member within the central 1 / 2 of the length of the member.
(42) If 1 end of the member is fixed and the other end free, the ratio of slenderness shall be determined by dividing twice the length of the member by the least radius of gyration of any cross-section within 1 / 2 of the length of the member of the fixed end.
Table 126.5 Maximum stresses permissible in mild steel* compression members or struts subject only to concentric axial loading
* Mild steel conforming to Australian Standard Specification No A1—1940, ‘Rolled Steel Sections for Structural Purposes'. Column ‘B' is applicable to members of angle, tee or tube section, and to members of latticed, battened or other framed construction.
Permissible stresses for intermediate ratios of slenderness
should be interpolated.
Table 126.6 Maximum stresses permissible in high tensile* steel compression members or struts subject only to concentric axial loading
* High tensile steel conforming to British Standard Specification No 548—1934, ‘High Tensile Steel for Bridges, etc., and General Building Construction', of British Standard Specification No 968—1941, ‘High Tensile (Fusion Welding Quality) Steel for Bridges, etc., for General Building Construction'. Column ‘B' is applicable to members of angle, tee, or tube sections and to members of latticed, battened or other framed construction.
Permissible
stresses for intermediate ratios of slenderness should be interpolated.
(43) If the radius of gyration of the cross-section of a compression member or strut of metal or alloy is less near the ends of the member than in the vicinity of the half-length of the member, the radius of gyration of a cross-section at the half-length shall for the purpose of assessing the slenderness ratios, be reduced in the ratio—
.
(44) In subsection (43):
the member. is 1 / 4 of the length of the member from either end.(45) If a steel member is subject to simultaneous axial compression and transverse stress it shall be designed as a beam, or if free at 1 end, a cantilever, in which the maximum transverse stress is determined by the formula—
( |
+ fx + fy
)
tons per square inch
where, in relation to the section under consideration:
c is a constant, having the value 18 for mild steel, or 22 for high tensile structural steel.
f is the maximum axial compressive stress.
fp is the maximum permissible axial compressive stress as prescribed in this section for the same member if assumed subject solely to axial stress.
fx and fy are the maximum transverse stresses due to external flexural forces acting or resolved about the respective principal rectilinear axes.
(46) The stress in a compression member or strut of timber shall not exceed that shown in table 126.7, relevant and appropriate to the ratio of slenderness of the member, and to the kind of timber and its sectional dimensions.
(47) The ratio of slenderness shall be determined by dividing the greatest length of member that is not supported effectively against lateral deflection, by the diameter of the greatest inscribed circle of any cross-section of the member within the central half of the length of the member.
(48) If 1 end of the member is fixed and the other end free, the ratio of slenderness shall be determined by dividing twice the length of the member by the diameter of the greatest inscribed circle of any cross-section of the member within half the length of the member of the fixed end.
Table 126.7 Maximum stresses permissible in timber compression members or struts subject only to concentric axial loading
|
maximum permissible stress in lb/in 2 |
|---|
Permissible stresses for intermediate ratios of slenderness should be interpolated.
Refer to s 131 about quality of timber.
* Hardwood includes only Australian
Hardwoods of approximately the same strength and reliability as Spotted Gum.
(49) If a timber member is subject to simultaneous axial compression and transverse stress it shall be designed as a beam, or if free at 1 end, a cantilever, in which the maximum transverse stress is determined by the formula—
( |
+ fx + fy
)
pounds per square inch
where, in relation to the section under consideration:
c is a constant, having the value 8000 for ironbark or other Australian hardwood timbers, or 3600 for Douglas fir (Oregon pine).
f is the maximum axial compressive stress.
fp is the maximum permissible axial compressive stress as prescribed in this section for the same member if assumed subject solely to axial stress.
fx and fy are the maximum transverse stresses due to external flexural forces acting or resolved about the respective principal rectilinear axes.
(50) If the cross-section of a timber compression member or strut is less near the ends of the member than in the vicinity of the half-length of it, the diameter of the inscribed circle referred to in subsections (47) and (48) shall, for the purpose of assessing the slenderness ratio, be reduced in the ratio—
where:
the half-length of the member. least section that is 1 / 4 of the length of the member from either end.(51) The computed early deflection of a timber beam in the direction of either the major or minor rectilinear axis of any cross-section shall not exceed 1 / 380 part of the span of the beam.
(52) The computed early deflection at the extremity of a timber cantilever shall not when measured in the direction of either the major or minor rectilinear axis of any cross-section, exceed 1 / 190 part of the length of the cantilever.
(53) The computed early deflection of a timber beam used for scaffolding or shoring purposes, shall not exceed 1 / 150 part of the span of the beam, provided that the computed early deflection of platform planks of bricklayers' or similar heavy scaffoldings shall not exceed 1 / 60 part of their span, and that the computed early deflection of platform planks of decorators' or similar scaffoldings of the lightest type shall not exceed 5 1 / 2 inches.
(54) For the purpose of computing the deflections the modulus of elasticity of the constituent timber shall be deemed to be—
(a) for ironbark—1 300 tons per square inch; and
(b) for other hardwoods—1 050 tons per square inch; and
(c) for Douglas fir (Oregon pine)—715 tons per square inch.
(55) In computing deflections it shall be necessary to increase the forces producing the deflections in the way provided by section 125.
(56) Forces shall be considered to act simultaneously and the horizontal forces referred to in section 124 shall be included.
(57) The thickness of a timber beam or cantilever shall not be less than 1 / 4 of the depth of the beam or cantilever.
(58) If 1 bridge beam only of an overhead traveller crane is supported laterally by effective bracings, the other bridge beam may be considered to derive from it a measure of lateral support per medium of the crab frame and its track wheels, provided the wheels have double flanges and together with their supports and fastenings are considered by the chief inspector to be suitable for the purpose.
(59) In such case the strength of the unbraced beam may be determined by placing the fully-loaded crab at whatever position is productive of the greatest critical stress.
(60) The maximum stress then resulting at any section of the unbraced beam shall not exceed the maximum stress permissible for the same beam when the laterally unsupported length is deemed to be 3 / 4 of the actual span.
(61) The lateral deflection due to all loads other than those applied by the crab wheels shall not exceed 1 / 2 an inch, when calculated on the assumption that the crane is brought evenly to rest from its maximum travelling speed in a distance of 5 feet.
(62) Other deflections with the crab at any position shall not, however, exceed those elsewhere prescribed for beams by this regulation.
(63) The ratio of slenderness of a tension member shall not exceed 300.
(64) The ratio shall be determined as though the member were a compression member.
(65) After being increased as prescribed by subsection (67), the torsional stress imposed or developed in any spring made from carbon spring steel shall not exceed the relevant and appropriate maximum stress shown in table 126.8.
(66) It shall not be necessary to increase the computed forces on, or moments in, a spring in the way otherwise prescribed by section 125, unless alternation occurs, and in such case the provisions of section 122 shall apply.
Table 126.8 Maximum torsional stresses permissible in springs of carbon spring steel (in pounds per square inch)
|
diameter in inches of greatest circle that may be inscribed within the least section that is relevant of the material of which spring is made |
classification of part of crane, hoist, plant, or scaffolding in which spring is employed | ||
|---|---|---|---|
| |
4 |
3 |
2 or 1 |
| not exceeding 0.085 |
60 000 |
75 000 |
93 000 |
| above .085 and no exceeding 0.185 |
55 000 |
69 000 |
85 000 |
| above 0.185 and not exceeding 0.32 |
48 000 |
60 000 |
74 000 |
| above 0.32 and not exceeding 0.53 |
42 000 |
52 000 |
65 000 |
| above 0.53 and not exceeding 0.97 |
36 000 |
45 000 |
56 000 |
| above 0.97 and not exceeding 1.5 |
32 000 |
40 000 |
50 000 |
(67) To compensate for errors consequential to computation of only torsional stresses in helical or volute springs, the computed torsional stress in any helical or volute spring shall be increased in the ratio W , the Wahl factor, shown in table 126.9 as relevant and appropriate to the relationship:
R =
.
(68) In subsection (67):
inches.d is the diameter in inches of the greatest circle that may be inscribed within the least section that is relevant of the material of which the spring is made.
Table 126.9 Compensating ratios, W, or Wahl factors, for stresses in helical or volute springs
|
|
|---|
2.0
2.06
4.2
1.38
7.6
1.19
2.1
1.98
4.3
1.37
7.8
1.19
2.2
1.90
4.4
1.36
8.0
1.18
2.3
1.84
4.5
1.35
8.5
1.17
2.4
1.79
4.6
1.34
9.0
1.16
2.5
1.75
4.7
1.34
9.5
1.15
2.6
1.71
4.8
1.32
10.0
1.14
2.7
1.68
4.9
1.32
10.5
1.14
2.8
1.64
5.0
1.31
11.0
1.13
2.9
1.60
5.2
1.30
11.5
1.12
3.0
1.58
5.4
1.28
12.0
1.12
3.1
1.56
5.6
1.27
12.5
1.11
3.2
1.53
5.8
1.26
13.0
1.11
3.3
1.51
6.0
1.25
13.5
1.11
3.4
1.49
6.2
1.24
14.0
1.10
3.5
1.48
6.4
1.24
14.5
1.10
3.6
1.46
6.6
1.23
15.0
1.10
3.7
1.44
6.8
1.22
16.0
1.09
3.8
1.43
7.0
1.21
17.0
1.08
3.9
1.42
7.2
1.21
18.0
1.08
4.0
1.40
7.4
1.20
19.0
1.07
4.1
1.39
Note See also s (69) and s (70) about limiting
values of R.
(69) Springs in which the ratio R referred to in subsection (67) is less than 6 shall not be used unless specifically approved by the chief inspector.
(70) If practicable, R shall be made equal to nine.
(71) The value of "G", the modulus of torsional rigidity shall, for carbon spring steel, be deemed to be 5 100 tons per square inch.
General