bridge-manual-3rd-edition-appendix-d.pdf

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Page D2

The NZ Transport Agencys Bridge manual SP/M/022

Third edition, Amendment 0

Effective from May 2013

D GeneralUse of the criteria in this appendix will be subject to approval of the road controlling

authority.

a. Note that this appendix provides minimum design standards.These criteria cover one-lane bridges on lightly trafficked roads. The criteria shall

only be used where all the following criteria are met:

i. the traffic count is less than 100 vehicles per day (vpd)ii. the road cannot become a through routeiii. the alignment is such that speeds are generally below 70km/hiv. use of the route by logging trucks is unlikely, andv. no significant overloads are expected to occur or the bridge can be bypassed.

b. Following each clause title below, is the number of the clause in the main body of thisdocument which is modified by this appendix. Where no modification is detailedbelow, the original clauses shall apply in full.

D2 Specific requirementsD2.1Basis of design(2.1.3)

For wind, floodwater and earthquake actions the importance level may be taken as 1,

except for any bridges that span other roads or railways for which the bridge shall be

designed for the importance level of the road or railway crossed.

D2.2Geometricrequirements (2.2) The specific requirements of appendix A may be waived but the following width limitsapply:a. Bridges without handrails or traffic barriers: 3.0m minimum, 3.7m maximum

between kerbs or wheel guards.

b. Bridges with pedestrian barriers: 3.0m minimum, 3.7m maximum between kerbs orwheel guards, 3.7m minimum between pedestrian barriers.

c. Bridges with traffic barriers: 3.7m minimum, 4.3m maximum between guardrails.Pedestrian barriers may only be omitted where it is acceptable under the Building code(1)

to do so. Where required, pedestrian barriers shall satisfy the Building code(1)

requirements as a minimum.

Since agricultural vehicles up to 3.7m width may use a public road without permit, the

choice of type and height of side protection should be made after consideration of the

actual vehicles using the road, and the clearance to any overhanging portions of the

vehicles.

D2.3Traffic loads -gravity effects (3.2)

a. For design of both main members and decks, the HN design load may be replaced by0.85 HN. The dimensions of the loaded areas remain the same as for full HN load.

HO load need not be considered.

b. Areas of deck where wheels cannot normally travel, due to dimensional limitations orphysical barriers need not be designed for the wheel loads of (a) above, but shall be

designed for one 15kN wheel load, using the same contact area as an HN wheel,placed anywhere on the deck.


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D2.3 continued c. Note that the uniformly distributed part of the reduced HN load is expected to beadequate to cover the effect of all routine stock load.

D2.4Combinationof load effects (3.5)

Tables 3.1 and 3.2 shall be replaced by tables D1 and D2 respectively.

Table D : Load combinations and load factors for the serviceability limit state

Hza

lotun

Prestressing shortening and

secondary effectsP 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Notapplicable

1.00

1.00

Shrinkage and creep effects SG 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temperature effects, overall and/or

differentialT - 1.00 1.00 - - 0.3

3-

0.3

3-

1.00

ta v Collision loads CO - - - - - - - 1.00

- -

Eroma o

hWind load WD - - - 1.00 - - 1.00 - 1.00 -

Earthquake effects EQ - - - - - 1.00 - - - -

we

Water ponding PW

- - - -1.00

-1.00

- - -

Floodwater pressure and buoyancy,

with scour FW

- - - -1.00

-1.00

- - -

r nary water pressure anbuoyancy (to be taken as due to theflow with an ARI of 1 year) O

W1.00

1.00

1.00

1.00

-1.00

-1.00

1.00

1.00

S

Settlement S 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Ground water GW

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

Earth pressure E1

.00

1

.00

1

.00

1

.00

1

.00

1

.00

1

.00

1

.00

1

.00

1

.00

Tac

hza Centrifugal effects of traffic loads C 1.00 - 1.00 1.00 1.00 - - - - -

Horizontal effects of traffic loads H - - 1.00 1.00 1.00 - - - - -

vc Normal live load (gravity effects)

with dynamic load factor L 1.35

-1.35

1.35

1.35

- - - - -

Cuo Locked-in forces due to erection

sequenceE 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Construction loads, including loads

on an incomplete structure C - - - - - - - - 1.00

1.00

Self weight Dead load and superimposed deadload

D 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Combination 1A 1B 2A 2 2 3A 3 3 4 5A 5

Lsm

Primarynormal

trafficcases

Secondarynormaltraffic

cases

Primarylateralload

cases

Trafficoverloadcase

Constructioncases

Notes: Where the effect of a possible reduction in permanent load is critical, replacement of the permanent load by 0.9 x permanent load shall beconsidered.

Combinations 3A and 3C only apply to the design of deck joints and elastomeric bearings and to consideration of stability of the structure.


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Table D2: Load combinations and load factors for the ultimate limit state

Hza

lotun

Prestressing shortening and

secondary effectsP 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Notapplicable

Notapplicable

1.00

1.00

1.00

Shrinkage and creep effects SG 1.10(1.0

0)

1.10

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

1.00

1.00

1.00

1.20

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

Temperature effects, overall and/or

differential T - 1.38

1.2

0

- - 0.33

- 0.33

- 1.0

0

-

ta v Collision loads CO - - - - - - - 1.50

- - -

Eroma

ohWind load WD - - - 1.00 - - 1.00 - 0.3

3- -

Earthquake effects EQ - - - - - 1.00 - - - - 0.33

we

Water ponding PW

- - - -1.00

-1.00

- - - -

Floodwater pressure and buoyancy,

with scour FW

- - - -1.00

-FL

- - - -

r nary water pressure anbuoyancy (to be taken as due to the

flow and ARI of 1 year)

OW

1.10

1.10

1.20

1.20

-1.25

-1.25

1.20

1.20

1.20

S

Settlement S 1.10(1.0

0)

1.10

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

1.00

1.00

1.00

- - -

Groundwater GW

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

Earth pressure E 1.49(1.35)

1.49

(1.35)

1.20

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

1.25

1.25

1.25

1.20

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

Tac

hza Centrifugal effects of traffic loads C 1.84 - 1.20 1.20 1.20 - - - - - -

Horizontal effects of traffic loads H - - 1.20 1.20 1.20 - - - - - -

vc Normal live load (gravity effects)

with dynamic load factor L 1.84

-1.20

1.20

1.20

- - - - - -

Cuo Locked-in forces due to erectionsequence E 1.

10

(1.00

)

1.10

(1.00

)

1.20

(1.00

)

1.20

(1.00

)

1.20

(1.00

)

1.00

1.00

1.00

1.20

(1.00

)

1.20

(1.00

)

1.20

(1.00

)

Construction loads, including loads

on an incomplete structure C - - - - - - - 1.32

1.32

1.32

Self weight Dead load and superimposed deadload

D 1.10(1.0

0)

1.10

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

1.00

1.00

1.00

1.20

(1.0

0)

1.20

(1.0

0)

1.20

(1.0

0)

Combination 1A 1B 2A 2 2 3A 3 3 3D 4 5A 5 5

Lsm

Primarynormal

trafficcases

Seco

ndarynormaltraffic

cases

Primarylateralload

cases

Tra

fficoverloadcase

Co

nstructioncases

Notes: Where the effect of a possible reduction in a permanent load is critical, use of the lower bracketed load factors shall be considered.Combination 3D applies only to the design of footbridges.

FLshall be as defined in 3.4.8(a)


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D2.5Reinforcedconcrete and

prestressed

concrete - General

(4.2.1)

Design shall be in accordance with NZS 3101.1&2 Concrete structures standard(2), as

amended by 4.2.1, with the following further provisos:

a. Crack widths (clause 2.4.4.2)Crack widths under the application of load combination 1A as defined in table D1

shall not exceed the limits specified in table D3 unless alternatively the requirementsof NZS 3101(2)clause 2.4.4.1(a) are satisfied.

Table D3:Crack width limitsExposure classification Crack width limit

Reinforced concrete

Prestressed concreteA2, B1, B2

0.40mm

0.30mm

Reinforced concrete

Prestressed concreteC

0.30mm

0.20mm

b. Permissible service load stress ranges in prestressed reinforcement (clause19.3.3.6.2(a) and (b))

The stress range due to infrequent live loading by clause 19.3.3.6.2(b) shall be taken

as that applicable to live loading acting on lightly trafficked rural bridges.


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D3 References

(1) Parliamentary Counsel Office (1992) Building Regulations 1992. Schedule 1

The building code. Wellington.

(2) Standards New Zealand NZS 3101.1&2:2006 Concrete structures standard.

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