Amendments-IRC 112-2011.pdf

Amendment No. 1/August, 2013/IRC:112-2011 to IRC:112-201 IRC:1 12-2011 1 “Code of Practice for Concrete Road Bridges”

  C    R    I

S. No.

Clause No.

1

Clause 10.1 Page No. 80

2

Clause 10.3.1  Notation

For

Add following sub Para:

For concrete of grades higher than M60, the shear strength shall be limited to that of strength grade M60 for design purpose.

 f  ywd  = Design strength of web reinforcement used to resist shear limited to 0.8 f yk /gm.

Page : 86 Page: 87

v1 is a strength reduction factor.

2. If design stress of shear reinforcement is  below 80 percent percen t of  f  yk  value of v1 can be taken as : v1 = 0.6

= 0.9 –

10.3.3.2:

Members with vertical Shear reinforcement Page No. 91

resist shear =

 f  yk 

v1 = v is a strength reduction factor for concr ete cracked in shear, given in Eq. 10.6.

Delete

for  f ck  ≤ 80 MPa

 f ck 

> 0.5

250

3

 f  ywd  = Design strength of web reinforcement to γm

1. Value is given by v1  ≈  v . Where v is given by Eq. 10.6.

Page: 88

Read

for  f ck  > 80 MPa

 f  ywd  = Design strength of web reinforcement used to resist shear limited to 0.8  f  ywk 

Delete

 f  ywd  is the design strength of web reinforcement

to resist shear =

 f  yk  γm

v1 is a strength reduction factor for concrete cracked in shear:

v1 = v is a strength reduction factor for concr ete cracked in shear given in Eq 10.6.

v1 = 0.6

for  f ck  ≤ 80 MPa

Delete

> 0.5 for  f ck  > 80 MPa

Delete

v1 = 0.9 –

 f ck 

250

If  v  v 1 = v, then value of 0.67  f  yk  can be used.

INDIAN HIGHWAYS, OCTOBER 2013

Delete

49

AMENDMENT TO IRC:112-2011

S. No.

Clause No.

For

4

5.3.2.5

The bridge or any of its components shall not loose its capacity to carry design loads  by virtue of its materials reaching fatigue limits due to its loading history.

Read

  C    R    I

Limit State of Fatigue Page No. 21

The bridge or any of its components shall not lose its capacity to carry design loads by virtue of its materials reaching fatigue limits due to its loading history. For carrying out Note :  For structures designed as per this fatigue verification, specialist literature may Code, the effects of fatigue due to action of  be referred. live loads on concrete need not be taken into However, fatigue veri fication is not necessary account, unless otherwise specified. for the following: a) For Reinforced concrete structures when the stress in the tensile reinforcement is less than 300 MPa under Rare Combination of Serviceability Limit State as against 0.8 f y specified in clause no. 12.2.2.

 b) For prestressed concrete structures under the frequent combination of action and  prestressing force, only compressive stresses occur at the extreme concrete fi bers, under Serviceability Limit State.

S. No.

Figure No. & Page No.

5.

Figure 6.1 (b) (Page 29)

For

Read

f yk 

(b) Hot Rolled/Heat Treated HYSD Steel

50

---

(b) Hot Rolled/Heat Treated HYSD Steel

INDIAN HIGHWAYS, OCTOBER 2013

AMENDMENT TO IRC:112-2011 Amendment No. 1/ IRC:112-2011 / January 2014 To IRC:112-2011 “Code of Practice for Concrete Road Bridges” S. No

1

Clause No. & Page No.

3

 f  pk   characteristic tensile strength of  f  pk   characteristic tensile strength of  prestressing steel  prestressing steel which is same as  f  p corresponding to breaking load given in the relevant IS codes listed in Table 18.2

6.2.2 Note: (2) Value of εuk   shall be taken from the Value of εuk   shall be taken as the uniform Fig.6.2 standard governing the manufacture of elongation given in the standard governing reinforcement. the manufacture of reinforcement. (Page 30)

10.4.4

(Page 103)

4

Read

  C    R     I 3.2.2

(Page 12)

2

For

15.3.1.2

(Page 163)

The design punching shear resistance The design punching shear resistance shall (MPa) of slab may be calculated as  be assessed at the basic control perimeter, follows: according to Clause 10.4.2. The design  punching shear resistance (MPa) of slab may  be calculated as follows:

The minimum cover for post tensioned ducts shall not be less than maximum of the outer diameter of ducts or 75 mm.

The minimum cover for post tensioned ducts shall not be less than 75 mm. Local reduction in cover at externally jointed locations of ducts is acceptable.

(local reduction in spacing at externally jointed locations of ducts is acceptable).

5

16.9 (1)

(Page 186)

Deep beams can be designed using Deep beams (span/depth ratio less than 3) appropriate elastic models or by plastic can be designed using appropriate elastic methods. models or by plastic methods.

INDIAN HIGHWAYS, FEBRUARY 2014

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AMENDMENT TO IRC:112-2011 Amendment No. 2/IRC:112-2011/August, 2014 To IRC:112-2011 “Code of Practice for Concrete Road Bridges” S. No. Clause No. & Page No

1.

6.4.2.7 Table 6.9 (Page 47) Age at loading to(days)

For

Read

Table 6.9 Final Creep Coefcient [φ (70 yr)] of Concrete at age of t = 70 years.

Table 6.9 Final Creep Coefcient [φ (70 yr)] of Concrete at age of t = 70 years

Notional Size 2Ac/u (in mm) 50

150

600

Dry atmospheric conditions (RH-50%)

50

150

Age at loading to (days)

600

Notional Size 2Ac/u (in mm) 50

Humid atmospheric conditions (RH-80%)

150

600

Dry atmospheric conditions (RH-50%)

50

150

600

Humid atmospheric conditions (RH-80%)

1

5.50

4.60

3.70

3.60

3.20

2.90

1

6.00

4.95

4.05

3.95

3.50

3.15

7

5.50

4.60

3.70

2.60

2.30

2.00

7

4.20

3.45

2.85

2.75

2.45

2.20

28

3.90

3.10

2.60

1.90

1.70

1.50

28

3.20

2.65

2.20

2.10

1.90

1.70

90

3.00

2.50

2.00

1.50

1.40

1.20

90

2.60

2.10

1.75

1.75

1.50

1.35

365

1.80

1.50

1.20

1.10

1.00

1.00

365

2.00

1.60

1.30

1.30

1.15

1.05

Note :

1.

The above table is applicable for M35 grade concrete. For lower grades of concrete the coefcients may be multiplied  by

45  f  cm 2.

2.

For higher grades of concrete the coefcient may be worked out using equations given in Annexure A-2 .

10.2.2.2(2) Fig 10.4 (Page 84)

Fig. 10.4 Shear Components of Increased Tension in Bonded Prestressing Tendons and Forces in Chord Members Inclined w.r.t. Axis of the Element

Fig. 10.4 Shear Component for Members with Inclined Chords

3.

10.2.3(3) & (4) (Page 84 and 85)

3 In the elements of variable depth, where V Ed’ MEd’  and N Ed are concurrently acting forces, the design shear force V Ed from sectional analysis shal l be reduced by the favourable contribution from any inclined compression chord, tension chord and incli ned  prestressing tendons in case of bonded tendons as shown in Fig. 10.4. Any unfavourable contributions, depending on direction of inclination of chords and the prestressing tendons shall be added to VEd, in Fig. 10.4, V NS = V Ed – V pd – V ccd – V td with appropriate signs.

4.

10.3.1 (Page 85)

VRd  - The shear resistance of a member with shear VRd  - The shear resistance of a member with shear reinforcement = V RdS + Vccd + Vtd reinforcement = Minimum of (V Rds; VRd.max) + Vccd + Vtd

50

3 In the elements of variable depth, where V Ed, MEd  and NEd are concurrently acting forces, the design shear force V Ed from sectional analysis shall be reduced by the favourable contributi on from any inclined compression chord and tension chord as shown in Fig. 10.4. Any unfavourable contributions, depending on direction of inclination of chords, shall be added to V Ed. In Fig. 10.4, V NS = VEd – Vccd – Vtd .

INDIAN HIGHWAYS, OCTOBER 2014

AMENDMENT TO IRC:112-2011 5.

10.3.3 (Page 90)

Memb ers requ ir in g d esi gn s hear rei nforcement

Members requ iri ng des ig n s hear rein fo rcemen t (VRdc < VED)

6.

10.3.3.2 (Page 90)

For members with vertical shear reinforcement the shear For members with vertical shear reinforcement, the shear resistance VRd is the smaller value of .. resistance is the smaller value of …...

7.

10.5.2.1(4) T  /T   + V  Ed /V  Rdmax < 1.0  Ed   Rdmax Eq. 10.47 VEd is the design transvers force (Page 108)

T  Ed /T  Rdmax + V  Ns/V  Rdmax < 1.0

8.

16.5.4 (1) In certain cases, (e.g. clear cover to main reinforcement being (Page 180) larger than 50 mm and in webs) it may be necessary to provide surface reinforcement, either to control cracking or to ensure adequate resistance to spalling of the cover.

In certain cases, (e.g. clear cover to main reinforcement being larger than 75 mm and in webs) it may be necessary to provide surface reinforcement, either to control cracking or to ensure adequate resistance to spalling of the cover.

9.

17.1 (6) Where longitudinal reinforcement is curtailed (e.g. in tall piers) Where longitudinal reinforcement is curtailed potential of (Page 192)  potential of for mation of hinge shal l be avoided just b eyond the formation of hinge shall be avoided just beyond the point of  point of curtai lment. curtailment. Not more than 1/3 of longitudinal reinforcement available at the section shall be curtailed.

ERRATA TO IRC:112-2011 Errata No. 3/IRC:112-2011/August, 2014 To IRC:112-2011 “Code of Practice for Concrete Road Bridges” S. No. Clause No. & Page No.

For

Read

1.

10.3.3.3(8) Fig. 10.6 (Page 93)

2.

11.3.2.2(4) (Page 116)

C = 10 (π2)

C =10 (≈ π2)

3.

18.8.9(1) (Page 228) 2nd line

Clause 18.8.8(4)

Clause 18.8.8(3)

4.

Annexure-A2 Eq-A2-27 (Page 239)

 β RH  = 1.55

INDIAN HIGHWAYS, OCTOBER 2014

 β RH  = 1.55

51

AMENDMENT TO IRC:112-2011 Amendment No. 1/IRC:112-2011/January, 2015 IRC:112-2011 “Code of Practice for Concrete Road Bridges” S. No.

Clause No. & Page No.

For

Read

1.

6.4.2.7(1) (Page 46)

Creep of concrete depends, on the stress in the concrete, age at loading and duration of loading in addition to the factors listed in Clause 6.4.2.6(1). As long as the stress in concrete does not exceed 0.36 f ck creep may be assumed to be proportional to the stress.

Creep of concrete depends , on the stress in the concrete, age at loading and duration of loading in addition to the factors listed in Clause 6.4.2.6(1). As long as the stress in concrete does not exceed 0.36 f cm (t 0) creep may be assumed to be proportional to the stress.

2.

6.4.2.7(2) (Page 47)

The values given in Table 6.9 can be considered as final creep co-efficient for design for normal weight concrete, subject to condition that the compressive stress does not exceed 0.36  f  ck  at the age of loading and mean temperature of concrete is between 10ºC and 20ºC with seasonal variation between – 20ºC to 40ºC. For temperature greater than 40ºC the coefficient given may be increased by 10 percent in absence of accurate data. In case the compressive stress exceeds 0.36 f ck , at loading, non-linear creep shall be considered.

The values given in Table 6.9 can be considered as final creep co-efficient for design for normal weight concrete, subject to condition that the compressive stress does not exceed 0.36  f  cm  at the age of loading and mean temperature of concrete is between 10ºC and 20ºC with seasonal variation between – 20ºC to 40ºC. For temperature greater than 40ºC the co-efficient given may be increased by 10 percent in absence of accurate data. In case the compressive stress exceeds 0.36 f  cm (t 0), at loading, non-linear creep shall be considered.

3.

Table No. 11.1

 Note : Positional restraints are given for dir ections at  Notes : right angles to the member  1. Positional restraints are given for directions at right angles to the member. 2. Cases 1 to 5 shows superstructure held in position which means the deck is held in position at some location other than the pier under consideration (say typically either at another pier or at the abutment). 3. In case of any floating deck on elastomeric  bearings (simply supported or continuous), Case 7 will be applicable. 4. For a continuous deck fixed at any pier/abutment, Case 7 applies for the design of fixed pier/ abutment. For design of other piers in the longitudinal direction, Case 4 applies for piers with elastomeric bearings and Case 5 applies for  piers with free metallic bearings.

 Note below Table (Page 114)

4.

11.3.2.2(1) (Page 115)

Add at the end of the Clause. The effect of imperfection may be represented by an eccentricity in mm,

limited to 50 mm l o is the height of pier in mm.

INDIAN HIGHWAYS, MAY 2015

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AMENDMENT/ERRATA TO IRC:112-2011 S. No.

Clause No. & Page No.

For

Read

5.

12.2.1(2) (Page 120)

Where compressive stress in concrete under quasi-permanent loads is within 0.36 f  ck , linear creep may be assumed. In case compressive stress exceeds 0.36 f  ck , non-linear creep shall be considered, for which Annexure A-2 may be referred.

Where compressive stress in concrete under quasi-permane nt loads is within 0.36 f  cm(t 0), linear creep may be assumed. In case compressive stress exceeds 0.36 f  cm(t 0), non-linear creep shall be considered. For stress level in the range of 0.36  f  cm(t o) < σc ≤ 0.48 f  cm(t o) the non-linearity of creep may be taken into account using the following equation:

ϕ  (t ,  t o) is the non-linear creep coefficient. σ 

ϕ (t ,  t o) is the linear creep coefficient.

k  = σ 

6.

12.3.4(3) Under Eq. 12.9 (Page 127)

c is the clear reinforcement.

cover

to

the

is the strength ratio.

longitudinal c is the clear cover to the longitudinal reinforcement. Wherever the clear cover exceeds 50 mm a value of 50 mm shall be used in the calculation.

Errata No. 1/ IRC:112-2011/January, 2015 IRC:112-2011 “Code of Practice for Concrete Road Bridges” S. No.

Clause No. & Page No.

For

Read

1.

6.4.2.2(3) (Page 39)

To avoid irreversible damage like local cracking (eg. due to early age prestressing) the achievement of early age strength shall be verified by testing. It is to be noted that the field testing results based on small number of samples are a measure of the mean value of early age strength and not of the characteristic value of early age. The values thus obtained should be reduced by 1.645 x (standard deviation for the grade of concrete). The value of the standard deviation to be used for early age is required to be established by testing at least 30 numbers of samples at site, unless it is know from  past experience. Refer Secti on 18 for details .

To avoid irreversible damage like local cracking (eg. due to early age prestressing) the achievement of early age strength shall be verified by testing. Refer Section 18 for details.

2.

11.3.1(3) First line (Page 115)

Stress – strain relationships for concrete given in In so far as material non-linearity is concerned, stress – Annexure (A2.7) and for steel given in Section 6 strain relationships for concrete given in Annexure A2-7 (Fig. 6.2 and 6.4) may be used. and for steel given in Section 6 (Fig. 6.2 and 6.4) may  be used.

3.

11.3.1(4) Last line (Page 115)

In the absence of more refined models, creep may be taken into account by modifying all strain values in the concrete stress-strain diagram using effective E value as per Clause 6.4.2.5.4 (iii).

In the absence of more refined models, creep may be taken into account by modifying all strain values in the concrete stress-strain diagram using effective E value as  per Clause 6.4.2.5(4) (i ii).

4.

15.2.5.1(3) (d) Last line (Page 156)

For splicing of bars in beams and columns the stirrups or links provided for other considerations can be taken into account to satisfy the requirement of (2) and its spacing shall not exceed 150 mm.

For splicing of bars in beams and columns the stirrups or links provided for other considerations can be taken into account to satisfy the requirement of (b) and their spacing shall not exceed 150 mm.

5.

15.2.5.6.1 (10)

n1 = 1 and n 2 = 2

n1 = 2 and n 2 = 2

Fig 15.6 (under RHS sketch) (Page 160)

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INDIAN HIGHWAYS, MAY 2015