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AS 3600-2001 Amdt 2-2004 Concrete structures

AS 3600/Amdt 2/2004-10-28

STANDARDS AUSTRALIA

Amendment No. 2

to

AS 3600—2001 Concrete structures

REVISED TEXT

The 2001 ed ition of AS 3600 is amend ed as follows; the amend ments should be inserted in the appropriate places.

SUMMARY: This Amendment applies to the Clauses 7.1.1, 7.2.1, 7.2.2, 7.2.3, 7.3.1, 7.3.2, 7.3.4, 7.4.1, 7.5.1, 7.6.2, 7.6.8.1, 7.6.8.3, 8.1.8.4, 8.6.1, 9.2.4, 9.4.1, 19.2.1.1 and Tables 2.3 and 7.3.2. Published on 28 October 2004.

Page 23 Table 2.3

Add the following Note under Table 2.3:

NOTE: Refer to Clauses 7.2.1, 7.3.1 and 7.6.8.3 when using Class L reinforcement.

Page 59 Clause 7.1.1(e)

Delete ‘For reinforced or prestressed structures’ and replace with the following: ‘(e) For reinforced or prestressed concrete beams, slabs or structures—’

Page 62 Clause 7.2.1 1 Delete ‘and’ from Item (e).

2 Delete ‘.’ from Item (f) and replace with ‘; and’. 3

Insert the following new Item to the Clause:

‘(g) where Class L reinforcement is used as the main reinforcement the design

capacity of the beam or slab, calculated in accordance with Sections 8 or 9, is reduced by not less than 20%.’

Page 62 Clause 7.2.2

Delete Item (a)(i) and replace with the following:

‘(i) Two spans only ...................................................................F d L n 2/9 Class N; or

.......................................................................F d L n 2/8 Class L.’

Page 62 Clause 7.2.3

Delete Item (b) and replace with the following:

‘(b) In interior spans..........................................................................F d L n 2/16 Class N; or ............................................................................F d L n 2/14 Class L.’

AMDT No. 2 OCT 2004

AMDT No. 2 OCT 2004

AMDT No. 2 OCT 2004

AMDT No. 2 OCT 2004

AMDT No. 2 OCT 2004

e d t o M r S a m u e l G u e r v i l l e o n 15 F e b 2006. P e r s o n a l u s e l i c e n c e o n l y . S t o r a g e , d i s t r i b u t i o n o r u s e o n n e t w o r k p r o h i b i t e d .

Page 63 Clause 7.3.1 1 Insert ‘and the corners are prevented from lifting ’ after ‘four sides ’ in the first paragraph.

2 Delete ‘and ’ from Item (b).

3 Delete ‘.’ from Item (c) and replace with ‘;’. 4

Insert the following new Items to the Clause:

(d) where Class L reinforcement is used as the main reinforcement, the design

capacity of the slab, calculated in accordance with Section 9, is reduced by not less than 20%; and (e)

slabs incorporating Class L mesh are continuously supported on walls.’

Page 63 Clause 7.3.2

Delete the text of Clause 7.3.2 and replace with the following: ‘The design bending moments in a slab shall be determined as follows:

(a) The positive design bending moments at mid-span, M *x and M *y on strips of unit

width spanning L x and L y , respectively, shall be calculated from the following equations:

M *x = βx F d L x 2 M *y = βy F d L x 2

where F d is the uniformly distributed design load per unit area factored for strength, and βx and βy are given in — (i)

Table 7.3.2(A) for slabs with Class N reinforcement (bars or mesh) as the main flexural reinforcement; and

(ii) Table 7.3.2(B) for slabs with Class N reinforcement (bars or mesh) or Class L

mesh as the main flexural reinforcement and no moment redistribution can be accommodated at either the serviceability or strength limit states. The moments, so calculated, shall apply over a central region of the slab equal to three-quarters of L x and L y respectively. Outside of this region, the requirement for strength shall be deemed to be complied with by the minimum strength requirement of Clause 9.1.1. (b)

The negative design bending moments at a continuous edge shall be taken as — (i)

1.33 times the mid-span values in the direction considered when they are taken from Table 7.3.2(A); or

(ii) αx or αy times the mid-span values in the direction considered when they are

taken from Table 7.3.2(B), where the value of αx or αy is also taken from Table 7.3.2(B) for the appropriate case. If the negative moment on one side of a common support is different from that on the other side —

(A) the unbalanced moment may be redistributed (in proportion to the stiffness of

span L x in the adjacent panels) if Class N reinforcement (bars or mesh) are the main flexural reinforcement; or (B) the slab shall be reinforced on both sides of the support for the larger support

AMDT No. 2 OCT 2004 AMDT No. 2 OCT 2004

e d t o M r S a m u e l G u e r v i l l e o n 15 F e b 2006. P e r s o n a l u s e l i c e n c e o n l y . S t o r a g e , d i s t r i b u t i o n o r u s e o n n e t w o r k p r o h i b i t e d .

(c) The negative design bending moment at a discontinuous edge, where there is a

likelihood of restraint, may be taken as —

(i)

0.5 times the mid-span values in the direction considered when they are taken from Table 7.3.2(A); or

(ii) 0.8 times the mid-span values in the direction considered when they are taken

from Table 7.3.2(B).

Page 63 Clause 7.3.4

Add the following after ‘…in Figure 7.3.4’ ‘, provided — (a)

the reactions apply directly when all edges are continuous;

(b) when one edge is discontinuous, the reactions on all continuous edges are increased

by 10% and the reaction on the discontinuous edge can be reduced by 20%; and (c) when adjacent edges are discontinuous, the reactions are adjusted for elastic shear

considering each span separately ’

Page 64 Table 7.3.2

Replace table designation ‘TABLE 7.3.2’ with ‘TABLE 7.3.2(A)’.

Page 64 Table 7.3.2

Insert new Table 7.3.2(B) as follows:

AMDT No. 2 OCT 2004

AMDT No. 2 OCT 2004 AMDT No. 2 OCT 2004

e d t o M r S a m u e l G u e r v i l l e o n 15 F e b 2006. P e r s o n a l u s e l i c e n c e o n l y . S t o r a g e , d i s t r i b u t i o n o r u s e o n n e t w o r k p r o h i b i t e d .

TABLE 7.3.2(B)

ELASTIC BENDING MOMENT COEFFICIENTS FOR RECTANGULAR SLABS

SUPPORTED ON FOUR SIDES

Short span coefficients (βx and αy )

Values of L y /L x

Edge condition

1.0 1.1 1.2 1.3 1.4 1.5 1.75

2.0 >2.0

Long span coefficients

(βy and αy ) for all values of L y /L x 0.021 0.025 0.029 0.032 0.034 0.036 0.039 0.041 0.042 0.020 1 Four edges cont i nuous

2.31 2.22 2.14 2.04 2.06 2.03 2.00 2.00 2.00 2.69 0.027 0.030 0.033 0.035 0.037 0.039 0.041 0.042 0.042 0.024 2 One short edge discontinuous

2.20 2.14 2.10 2.06 2.04 2.02 2.00 2.00 2.00 2.29 0.024 0.028 0.034 0.038 0.043 0.047 0.056 0.061 0.070 0.028 3 One long edge discontinuous

2.22 2.17 2.09 2.03 1.97 1.93 1.86 1.81 1.80 2.46 0.032 0.035 0.037 0.038 0.039 0.040 0.042 0.042 0.042 0.024 4

Two short edges discontinuous

2.09 2.05 2.03 2.01 2.00 2.00 2.00 2.00 2.00 — 0.024 0.028 0.035 0.042 0.049 0.056 0.071 0.085 0.125

0.039

5 Two long edges discontinuous — — — — — — — — — 2.31 0.031 0.03

6 0.041 0.046 0.050 0.053 0.060 0.064 0.070 0.034 6

Two adjacent edges

discontinuous

2.13 2.07 2.01 1.87 1.92 1.89 1.83 1.80 1.80 2.13 0.039 0.044 0.048 0.052 0.055 0.058 0.063 0.066 0.070 0.035 7

Three edges discontinuous (one long edge continuous)

2.04 1.97 1.93 1.89 1.86 1.84 1.80 1.80 1.80 — 0.033 0.039 0.047 0.054 0.061 0.067 0.082 0.093 0.125

0.046

8

Three edges discontinuous (one short edge continuous)

— — — — — — — — — 2.12 0.044 0.052 0.059 0.066 0.073 0.079 0.091 0.100 0.125 0.049 9 Four edges d i scont i nuous

— — — — — — — — —

Page 64 Clause 7.4.1

Insert the following new Item (i) to the Clause: (i)

Class L reinforcement is not used as the main flexural reinforcement.

Page 67 Clause 7.5.1

Replace the first sentence with the following:

Provided that Class L reinforcement is not used as the main flexural reinforcement, this Clause applies to the analysis of reinforced and prestressed framed structures incorporating two-way slab systems having multiple spans including —

Page 69 Clause 7.6.2

Third paragraph, delete ‘, except that the following simplifications may be used:’ and replace with ‘. Provided Class L reinforcement is not used, the following simplifications may be applied:’

Page 71 Clause 7.6.8.1 Delete the last paragraph.

AMDT

No. 2 OCT 2004

AMDT No. 2 OCT 2004

AMDT No. 2 OCT 2004

AMDT No. 2 e d t o M r S a m u e l G u e r v i l l e o n 15 F e b 2006. P e r s o n a l u s e l i c e n c e o n l y . S t o r a g e , d i s t r i b u t i o n o r u s e o n n e t w o r k p r o h i b i t e d .

Page 71 Clause 7.6.8.3

Delete the text of Clause 7.6.8.3 and replace with the following:

Where linear elastic analysis is used and it is intended to use Class L reinforcement, then the following applies: (a) Beams or one-way slabs and supports Reinforcement shall be provided to carry the elastic distributions of stresses at all locations.

(b)

Two-way slab systems The analysis shall model the slabs as a system of plates and supports. Reinforcement shall be provided to carry the elastic distributions of stresses (including calculated torsions) at all locations within the slab system.

Where Class L reinforcing steel is used as the main reinforcement, the effects that relative foundation movements, variations in loading arrangements and accidental loadings can have on the strength of beams and slabs shall be assessed and the design capacity of the member, calculated in accordance with Section 8 or 9, reduced by not less than 20%.

Page 77 Clause 8.1.8.4(a)

Delete reference to ‘Clause 13.1.2.3’ and replace with ‘Clause 13.2.2’.

Page 89 Clause 8.6.1

Delete the text of Clause 8.6.1 and replace with the following:

For the purpose of this Clause the resultant action is considered to be primarily tension when the whole of the section is in tension, or primarily flexure when the tensile stress distribution within the section prior to cracking is triangular with some part of the section in compression.

Cracking in reinforced beams subjected to tension, flexure with tension, or flexure, shall be deemed to be controlled if the appropriate requirements in Items (a) and (b), and either Item (c) for beams primarily in tension or Item (d) for beams primarily in flexure, are satisfied. For regions of beams fully enclosed within a building except for a brief period of weather exposure during construction, and where it is assessed that crack control is not required, only Item (b) need be satisfied.

(a) The minimum area of reinforcement in a tensile zone of a beam shall comply with

Clause 8.1.4.1. (b)

The distance from the side or soffit of a beam to the centre of the nearest longitudinal bar shall not exceed 100 mm. Bars with a diameter less than half the diameter of the largest bar in the section shall be ignored. The centre-to-centre spacing of bars near a tension face of the beam shall not exceed 300 mm. For T-beams and L-beams, the reinforcement required in the flange shall be distributed across the effective width.

(c) For beams primarily subject to tension, the calculated steel stress (f scr ) shall not

exceed the maximum steel stress given in Table 8.6.1(A) for the largest nominal diameter (d b ) of the bars in the section, and under direct loading the calculated steel stress (f scr.1) shall not exceed 0.8f sy . (d) For beams primarily subject to flexure, the calculated steel stress (f scr ) shall not

exceed the larger of the maximum steel stresses given in —

(i)

Table 8.6.1(A) for the largest nominal diameter (d b ), of the bars in the tensile zone; and

AMDT No. 2 OCT 2004

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e d t o M r S a m u e l G u e r v i l l e o n 15 F e b 2006. P e r s o n a l u s e l i c e n c e o n l y . S t o r a g e , d i s t r i b u t i o n o r u s e o n n e t w o r k p r o h i b i t e d .

(ii) Table 8.6.1(B) for the largest centre-to-centre spacing of adjacent parallel bars

in the tensile zone. Under direct loading the calculated steel stress (f scr.1) shall not exceed 0.8f sy . Bars with a diameter less than half the diameter of the largest bar in the section shall be ignored when determining spacing.

NOTE: Design bending moments M *s and M *s.1 at the serviceability limit state will normally be estimated using elastic analysis. Significant errors may result if they are determined from the design bending moments M * at the strength limit state when the amount of moment redistribution is unknown; for example, if plastic methods of analysis are used for strength design.

Page 99 Clause 9.2.4(b)

Delete the equation in Item (b) and replace with the following:

()[]

2**

v uo .min .u 2/0.1/2.1a V uM V V +=

Page 103 Clause 9.4.1

Delete the text of Clause 9.4.1 and replace with the following:

Cracking in reinforced slabs subject to flexure shall be deemed to be controlled if the appropriate requirements in Items (a), (b), (c) and (d) are satisfied. For areas of slabs fully enclosed within a building except for a brief period of weather exposure during construction and, where it is assessed that crack control is not required, only Item (a) and Item (b) need be satisfied.

(a) The minimum area of reinforcement in a tensile zone of a slab shall comply with

Clause 9.1.1. (b) The centre-to-centre spacing of bars in each direction shall not exceed the lesser of

2.0D s or 300 mm. Bars with a diameter less than half the diameter of the largest bar in the cross-section shall be ignored. (c) The calculated steel stress (f scr ) shall not exceed the larger of the maximum steel

stresses given in —

(i)

Table 9.4.1(A) for the largest nominal diameter (d b ) of the bars in the tensile zone; and

(ii) Table 9.4.1(B) for the largest centre-to-centre spacing of adjacent parallel bars

in the tensile zone, and, when determining spacing, bars with a diameter less than half the diameter of the largest bar in the section shall be ignored. (d)

The calculated steel stress f scr.1 shall not exceed 0.8f sy .

NOTE: Design bending moments M *s and M *s.1 at the serviceability limit state will normally be estimated using elastic analysis. Significant errors may result if they are determined from the design bending moments M * at the strength limit state when the amount of moment redistribution is unknown; for example, if plastic methods of analysis are used for strength design.

Page 142 Clause 19.2.1.1

Insert the following after the last paragraph:

‘Class L reinforcement shall not be substituted for Class N reinforcement unless the structure is redesigned.’

AMDT

No. 2 OCT 2004 AMDT No. 2 OCT 2004

AMDT No. 2 OCT 2004

e d t o M r S a m u e l G u e r v i l l e o n 15 F e b 2006. P e r s o n a l u s e l i c e n c e o n l y . S t o r a g e , d i s t r i b u t i o n o r u s e o n n e t w o r k p r o h i b i t e d .