our Design Manual

Transcription

our Design Manual

Main Index | Introduction | Hydraulics | MP200 | Super Span | Structural Design | End Treatments | Installation
Main Index
Asset International
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Email: [email protected]
INTRODUCTION
HYDRAULIC DESIGN
MULTIPLATE MP 200
MULTIPLATE SUPER-SPAN
STRUCTURAL DESIGN
(including BD12/01)
END TREATMENTS
MULTIPLATE INSTALLATION PROCEDURES
© Asset International 2013 - all rights reserved
Main
Introduction
MULTIPLATE CORRUGATED
STEEL BURIED STRUCTURES
Background to Usage
APPLICATIONS
Culverts / Storm Sewers
Vehicular,Pedestrian & Livestock
Underpasses
Utilities and Other Applications
ECONOMIC CONSIDERATIONS
Next
•Main
Hydraulic Design
INTRODUCTION
Introduction - Page 1
Page 2
Page 3
CULVERT & CHANNEL HYDRAULICS
OPEN CHANNEL FLOW THEORY
Flow Theory - Page 1
Page 2
•Next
CULVERTS - INLET CONTROL
Inlet Control - Page 1
Page 2
Page 3
Page 3
CULVERTS - OUTLET CONTROL
Page 1 Page 5
Page 2 Page 6
Page 3 Page 7
Page 4 Page 8
SUMMARY - CULVERT SIZING
WORKED EXAMPLE
Example - Page 1
Page 2
SEWER DESIGN
Sewer Design - Page 1
Page 2
Main
MULTIPLATE MP 200
INTRODUCTION
SHAPE AND SIZE RANGE
PROFILE DATA:
Pipe
Pipe Arch
Underpass
Arch (BD12/01 Compliant)
Arch (Other)
Vertical Ellipse
Horizontal Ellipse
PHYSICAL PROPERTIES
COMPONENTS:
Plates
Nuts and Bolts
Arch Seating Channel
Alternative Arch Seating
SPECIFICATION
Next
Multiplate
SUPER-SPAN
INTRODUCTION
PROFILE DATA:
Horizontal Ellipse
Low Profile Arch
High Profile Arch
ACCESSORIES:
Thrust Beams
SPECIFICATION
Main
Next
•Main
Structural Design
•Next
DESIGN METHODS
Design - BD12/01
DURABILITY
LIVE LOAD STANDARDS:
Highway Loading - UK (page 1)
(page 2)
(page 3)
Railway Loading - UK (page 1)
(page 2)
Highway & Railway Loading -USA
HEIGHT OF COVER TABLES
•Main
END TREATMENTS
•Next
INTRODUCTION and TYPICAL DETAILS
SKEW AND BEVEL DETAILS
COLLAR AND RING BEAMS
INSTALLATION
PROCEDURES
GENERAL REQUIREMENTS
BASE PREPARATION:
Flat Bedding
Shaped Bedding
SPECIAL GROUND
CONDITIONS:
Rock Foundations
Soft Foundations
•Main
•Next
BACKFILL
Trench and Embankment Conditions
Material Selection
Backfill Placement
Good and Bad Backfill Practices
Notes on Excavation and Backfill
Multiple Structures
Backfill Summary
MULTIPLATE ASSEMBLY:
Unloading and Handling
Assembly Procedure and
Methods
Bolt Tightening
Multiplate
SUPER-SPAN
Index
Next
Introduction
ASSET MULTIPLATE Super-Span products are long span
corrugated steel buried structures developed to safely, effectively
and economically cover wider spans than are normal for this type of
construction. The special feature of Super-Span structures is that
they utilise a cast in situ concrete 'Thrust-Beam' to generate the
maximum available lateral ground from the adjacent compacted
backfill.
All Super-Span structures are designed to customer requirements
by ourselves on a design and supply basis.
There are many thousands of Super-Span structures worldwide, the first of many in this country being installed
under the A1(M) in 1971. An ASSET MULTIPLATE Super-Span structure can be designed and constructed in a
fraction of the time taken for other forms of construction such as reinforced concrete.
All our Super-Span structures utilise our MP200 material the material properties of which can be found in the
MP200 section of this manual.
The only item not included in the MP200 section of the manual is the 'Thrust-Beam', which is fully detailed later in
this section.
Multiplate
SUPER-SPAN
Index
Next
The following diagrams show typical shapes and sizes of
ASSET MULTIPLATE Super-Span structures.
Other profiles are available upon request.
Index
Multiplate
SUPER-SPAN
Next
PROFILE DATA: Horizontal Ellipse
This table lists a small selection of available sizes.
Please contact ASSET International for further
information.
All dimensions are to inside of corrugation
ANGLE A1 ALWAYS = 80 DEGREES
OTHER DIMENSIONS ARE TO INSIDE OF
CORRUGATIONS.
INTERNAL DIMENSION
RADII
STEP
STRUCTURE
Min. Step REFERENCE
Top
Radius
Side
Radius
R1 (m)
R2 (m)
23.58
24.74
25.93
4.177
4.345
4.514
1.720
1.720
1.720
0.97
1.01
1.05
25-E-13
26-E-13
27-E-13
4.826
4.984
6.015
27.13
29.62
38.38
4.682
5.019
5.019
1.720
1.720
2.393
1.09
1.17
1.17
28-E-13
30-E-13
30-E-18
7.898
8.475
8.114
5.063
6.300
5.141
30.90
41.76
32.20
5.187
5.187
5.355
1.720
2.528
1.720
1.21
1.21
1.25
31-E-13
31-E-19
32-E-13
8.787
8.330
9.004
6.585
5.220
6.664
45.28
33.52
46.92
5.355
5.524
5.524
2.662
1.720
2.662
1.25
1.29
1.29
32-E-20
33-E-13
33-E-20
8.547
9.220
8.763
5.299
6.743
5.378
34.87
48.58
36.24
5.692
5.692
5.860
1.720
2.662
1.720
1.33
1.33
1.37
34-E-13
34-E-20
35-E-13
9.436
8.979
9.653
6.822
5.456
6.900
50.26
37.63
51.97
5.860
6.029
6.029
2.662
1.720
2.662
1.37
1.41
1.41
35-E-20
36-E-13
36-E-20
9.196
9.869
9.412
5.535
6.979
5.614
39.05
53.70
40.49
6.197
6.197
6.365
1.720
2.662
1.720
1.44
1.44
1.48
37-E-13
37-E-20
38-E-13
Max Span
Max Rise
End Area
(m)
(m)
(m2)
6.599
6.816
7.032
4.590
4.669
4.748
7.248
7.681
8.162
(m)
10.085
9.628
10.302
7.058
5.693
7.137
55.45
41.95
57.22
6.365
6.533
6.533
2.662
1.720
2.662
1.48
1.52
1.52
38-E-20
39-E-13
39-E-20
9.845
10.518
10.999
5.771
7.215
8.247
43.44
59.02
70.98
6.702
6.702
6.702
1.720
2.662
3.336
1.56
1.56
1.56
40-E-13
40-E-20
40-E-25
10.061
10.735
11.216
5.850
7.294
8.326
44.95
60.85
73.03
6.870
6.870
6.870
1.720
2.662
3.336
1.60
1.60
1.60
41-E-13
41-E-20
41-E-25
10.374
10.951
11.432
6.135
7.373
8.404
48.72
62.69
75.10
7.038
7.038
7.038
1.855
2.662
3.336
1.64
1.64
1.64
42-E-14
42-E-20
42-E-25
10.590
11.648
10.807
6.214
8.483
6.293
50.32
77.19
51.94
7.207
7.207
7.375
1.855
3.336
1.855
1.68
1.68
1.72
43-E-14
43-E-25
44-E-14
11.865
11.600
12.273
8.562
7.609
9.053
79.31
68.37
86.87
7.375
7.543
7.543
3.336
2.662
3.605
1.72
1.76
1.76
44-E-25
45-E-20
45-E-27
Index
Multiplate
SUPER-SPAN
Next
PROFILE DATA: Low Profile Arch
information.
RADIUS R2 ALWAYS = RADIUS R3
CORRUGATIONS.
INTERNAL DIMENSION
Max
Span
(m)
Rise
(m)
Bottom
Span
(m)
RADII
End
Area
Side
Top
Radius
Radius
(m)
R1 (m)
R2/R3
(m)
ANGLE
STEP
Min.
AngleA3
Step
(DEG)
STRUCT.
REF.
(m)
6.095
6.311
6.528
2.233
2.272
2.311
6.032
6.248
6.465
10.90
11.47
12.04
4.009
4.178
4.346
1.316
1.316
1.316
12.55
12.55
12.55
1.04
1.08
1.12
24-A-5-1
25-A-5-1
26-A-5-1
6.744
6.690
7.393
2.351
2.390
2.469
6.681
6.897
7.330
12.63
13.23
14.46
4.514
4.683
5.019
1.316
1.316
1.316
12.55
12.55
12.55
1.16
1.20
1.27
27-A-5-1
28-A-5-1
30-A-5-1
7.609
8.018
8.235
2.508
2.756
2.795
7.546
7.965
8.182
15.09
17.52
18.23
5.187
5.356
5.524
1.316
1.586
1.586
12.55
10.46
10.46
1.31
1.35
1.39
31-A-5-1
32-A-6-1
33-A-6-1
8.451
8.667
8.884
2.834
2.874
2.913
8.398
8.615
8.831
18.94
19.67
20.40
5.692
5.861
6.029
1.586
1.586
1.586
10.46
10.46
10.46
1.43
1.47
1.51
34-A-6-1
35-A-6-1
36-A-6-1
9.100
9.701
9.918
2.953
3.634
3.673
9.047
9.573
9.790
21.15
28.37
29.28
6.197
6.366
6.534
1.586
2.124
2.124
10.46
14.10
14.10
1.55
1.59
1.63
37-A-6-1
38-A-8-2
39-A-8-2
10.134
10.350
10.567
3.713
3.752
3.791
10.006
10.222
10.439
30.20
31.13
32.08
6.702
6.871
7.039
2.124
2.124
2.124
14.10
14.10
14.10
1.67
1.71
1.75
40-A-8-2
41-A-8-2
42-A-8-2
10.783
10.999
11.216
3.831
3.870
3.910
10.655
10.871
11.088
33.04
34.01
34.99
7.207
7.375
7.544
2.124
2.124
2.124
14.10
14.10
14.10
1.79
1.83
1.86
43-A-8-2
44-A-8-2
45-A-8-2
Index
Multiplate
SUPER-SPAN
Next
PROFILE DATA: High Profile Arch
information.
RADIUS R3 ALWAYS = RADIUS R1
CORRUGATIONS.
INTERNAL DIMENSIONS
Max
Span
(m)
Total
Rise
(m)
RADII
ANGLE STEP
Bottom
Span
End
Area
Top/Side
Radius
Corner
Radius
(m)
(m2)
(m)
(m)
Angle A3
(DEG)
Min.
Step
STRUCT.
REF.
(m)
6.287
6.504
6.720
3.795
3.839
3.883
5.583
5.828
6.069
20.47
21.42
22.37
4.009
4.178
4.346
1.586
1.586
1.586
24.19
23.22
22.32
0.94
0.98
1.02
24-A-6-7
25-A-6-7
26-A-6-7
6.936
7.153
7.585
3.925
3.968
4.052
6.308
6.547
7.018
23.33
24.31
26.28
4.514
4.683
5.019
1.586
1.586
1.586
21.50
20.73
19.35
1.06
1.10
1.17
27-A-6-7
28-A-6-7
30-A-6-7
7.801
8.019
8.788
4.094
4.135
5.398
7.252
7.486
7.926
27.28
28.30
40.55
5.187
5.356
5.356
1.586
1.586
2.663
18.73
18.14
23.14
1.21
1.25
1.25
31-A-6-7
32-A-6-7
32-A-10-9
8.235
8.451
9.220
4.177
4.218
5.484
7.718
7.949
8.407
29.32
30.36
43.20
5.524
5.692
5.692
1.586
1.586
2.663
17.59
17.07
21.78
1.29
1.33
1.33
33-A-6-7
34-A-6-7
34-A-10-9
8.668
9.437
8.884
4.259
5.526
4.300
8.180
8.647
8.410
31.41
44.55
32.46
5.861
5.861
6.029
1.586
2.663
1.586
16.58
21.15
16.12
1.37
1.37
1.41
35-A-6-7
35-A-10-7
36-A-6-7
9.653
9.100
9.869
5.569
4.340
5.611
8.885
8.638
9.121
45.90
33.53
47.26
6.029
6.197
6.197
2.663
1.586
2.663
20.57
15.69
20.01
1.41
1.45
1.45
36-A-10-9
37-A-6-7
37-A-10-9
9.509
4.361
9.174
34.91
6.366
1.855
13.17
1.49
38-A-7-6
10.089
9.725
5.653
4.401
9.357
9.399
48.64
35.98
6.366
6.534
2.663
1.855
19.48
12.83
1.49
1.53
38-A-10-9
39-A-7-6
10.302
10.687
9.942
5.694
5.659
4.441
9.592
10.248
9.263
50.02
50.97
37.07
6.534
6.534
6.702
2.663
3.201
1.855
18.99
14.88
12.51
1.53
1.53
1.57
39-A-10-9
39-A-12-7
40-A-7-6
10.518
10.158
10.736
5.736
4.481
5.777
9.825
9.847
10.059
51.41
38.18
52.82
6.702
6.871
6.871
2.663
1.855
2.663
18.51
12.21
18.06
1.57
1.61
1.61
40-A-10-9
41-A-7-6
41-A-10-9
11.120
10.374
10.952
5.740
4.521
5.819
10.703
10.071
10.291
53.72
39.29
54.23
6.871
7.039
7.039
3.201
1.855
2.663
14.16
11.91
17.63
1.61
1.65
1.65
41-A-12-7
42-A-7-6
42-A-10-9
11.336
11.529
10.591
5.780
7.308
4.561
10.929
10.184
10.294
55.11
72.13
40.42
7.039
7.039
7.207
3.201
3.471
1.855
13.82
25.25
11.64
1.65
1.65
1.69
42-A-12-7
42-A-13-13
43-A-7-6
11.168
11.552
11.745
5.860
5.820
7.352
10.522
11.154
10.430
55.65
56.51
73.93
7.207
7.207
7.207
2.663
3.201
3.471
17.22
13.50
24.66
1.69
1.69
1.69
43-A-10-9
43-A-12-7
43-A-13-13
10.807
11.384
11.768
4.601
5.901
5.861
10.517
10.752
11.379
41.55
57.09
57.92
7.375
7.375
7.375
1.855
2.663
3.201
11.37
16.83
13.19
1.73
1.73
1.73
44-A-7-6
44-A-10-9
44-A-12-7
11.961
11.216
11.601
7.396
4.847
5.942
10.675
10.932
10.983
75.74
45.39
58.54
7.375
7.544
7.544
3.471
2.124
2.663
24.10
11.12
16.45
1.73
1.76
1.76
44-A-13-13
45-A-8-6
45-A-10-9
11.985
12.178
5.901
7.440
11.605
10.920
59.36
77.56
7.544
7.544
3.201
3.471
12.90
23.56
1.76
1.76
45-A-12-7
45-A-13-13
Multiplate
SUPER-SPAN
ACCESSORIES: Thrust Beams
Index
Next
Multiplate
SUPER-SPAN
Index
Next
SPECIFICATION
ASSET MULTIPLATE SUPER-SPAN SPECIFICATION GUIDE
Please refer to the MP 200 section of this manual as the Specification Guide given there also applies to ASSET
MULTIPLATE SUPER-SPAN material.
•Main
Structural Design
•Index
•Next
DESIGN
Corrugated Steel Buried Structures (CSBS) have been in service
since the late nineteenth century and have manufactured in the UK
since 1954.
Since the 1960's the design has been based on the Ring
Compression Theory, where structures are considered as flexible
soil / steel rings in compression.
Until the mid 1980's standard U.K. practice was to undertake
structural design using the design procedures developed by the
American Iron and Steel Institute (AISI) with modifications to suit
national loading requirements.
It is current standard UK practice to design CSBS to the Highway Agency Department Standard BD 12/01.
This standard is still based on the Ring Compression Theory and also includes durability calculated to
provide a 120 year design life.
Use of BD12/01 is mandatory for all CSBS under motorways and trunk roads within the UK and is used for all
low and medium cover applications by ASSET.
BD12/01 does not cover the use of corrugated steel buried structures in the repair of other types of
structures, e.g. as a liner for failing brick arch structures. However, in these situations, Asset International
can provide specialist advice and will carry out the design of such an application as a departure from the
standard.
For special applications such as aggregate tunnels and high fill situations BD12/01 is generally inappropriate
and the AISI design method is used.
The AISI method is still commonly used for many non UK applications.
•Main
Structural Design
Design - BD12/01
Typical Fill Requirements for Minimum Excavation Option
1. TRENCH CONDITION
•Index
•Next
2. PARTIAL TRENCH CONDITION
•Main
Structural Design
•Index
•Next
DURABILITY
It is standard UK practice to design corrugated steel buried structures to BD12/01 which requires a design life of
120 years.
The relevant properties of the surrounding soil and ground water, the effluent flowing through the structure, the
availability for maintenance of the interior surfaces and protection provided by additional protective coatings are
all considered and assessed. The most severe condition will be used in the design.
Calculations are then carried out to determine the thickness of extra or sacrificial steel that is required to achieve
the design life.
It is possible to vary the design life of a structure to suit special requirements within the methodology of BD
12/01.
In some cases durability is not a consideration e.g. temporary or short working life structures.
Environments that are deleterious to steel and zinc such as environments having pH values less than 5 or
greater than 9, chlorine concentrations greater than 250 ppm and sulphate concentrations greater than 0.6g/l as
SO4 should be avoided.
Secondary protective coatings shall be applied to all galvanised steel surfaces by utilising a paint system within
BD35. Aplication of such a paint system should be in accordance with BA27.
It is not intended that the life of this minimum secondary protective coating shall be taken into account when
calculating sacrificial steel requirements. Where it is intended to take the life of the secondary protective coating
into account, that coating must carry a current BBA certificate. At the time of publishing, the secondary coatings
used by Asset do not yet carry BBA certification. However, it is Asset's intention to pursue such certification.
For culvert applications, anti-abrasion invert protection is a requirement. i.e. a concrete slab or a proprietary
invert protection system (clause 8.14 to 8.20 of BD12/01 refers).
•Main
Structural Design
•Index
•Next
Highway Loading - UK
Generally, the definitions as specified by BS 5400 are:
Basis of HA and HB highway loading
Type HA loading is the normal design loading for Great Britain, where it represents the effects of normal
permitted vehicles other than those used for the carriage of abnormal indivisible loads.
For loaded lengths up to 30 m, the loading approximately represents closely spaced vehicles of 24 t laden weight
in each of two traffic lanes. For longer loaded lengths the spacing is progressively increased and medium weight
vehicles of 10 t and 5 t are interspersed. It should be noted that although normal commercial vehicles of
considerably greater weight are permitted in Great Britain their effects are restricted, so as not to exceed those of
HA loading, by limiting the weight of axles and providing for increased overall length.
In considering the impact effect of vehicles on highway bridges an allowance of 25% on one axle or pair of
adjacent wheels was made in deriving HA loading. This is considered an adequate allowance in conditions such
as prevail in Great Britain.
This loading has been examined in comparison with traffic as described for both elastic and collapse methods of
analysis, and has been found to give a satisfactory correspondence in behaviour.
HB loading requirements derive from the nature of exceptional industrial loads (e.g. electrical transformers,
generators, pressure vessels, machine presses, etc) likely to use the roads in the area.
HA loading is normally taken as a combination of Uniformly Distributed Load (UDL) and Knife Edge Loading
(KEL) as described in BS 5400. However, this concept is more suited to complex bridge structures than to
ASSET buried steel structures and, consequently, UDL and KEL are recommended in the DTp Standard BD
12/01 as not to be used. Instead, the Standard recommends the adoption of the Single Nominal Wheel Load
alternatively described in paragraph 6.2.5. of BS 5400.
This is a single 100 M wheel exerting a
pressure of 1111.1111 kN/m' over a square
area with 0.300 m sides. The pressure is
dispersed downwards at a gradient of 2:1.
Although the pressure is dispersed over a twodimensional area, only a onedimensional cross
section of the pressure cone need be
considered, as shown, since the design of the
structure is based upon a single metre length
of the culvert at right angles to the cross
section.
•Main
Structural Design
•Index
•Next
Highway Loading - UK (cont)
HB loading must be taken into account where a highway is liable to be used by exceptional industrial loads such
as transformers, generators, pressure vessels, machine presses, etc. The HB unit is considered to be a 4-axle
transporter with each axle carrying 10 kN distributed on to four wheels, such that each wheel is pressing down
with a force of 2.5 M. 25 units would be a wheel load of 62.5 M and 45 units a wheel load of 112.5 M. The
drawing below shows the wheel and axle distribution for HB loading together with the pressure cone 'footprints'
at different depths below the highway surface. BS 5400 allows for variable separation of the axle pairs, but we
consider that for buried steel structures, the 6 m separation will provide the most concenti-ated load, and will thus
provide the ,worst case' condition.
It is therefore necessary to establish in the first instance whether the road over the structure is to be used only by
normal HA loadings, or whether HB loadings are to be experienced as well. If HB loadings are to be experienced,
then the technical approving authority must decide whether the minimum 25 units or more, up to the normal
maximum of 45 units of HB loading must be catered for. It is generally acceptable to adopt 45 units of HB loading
for ASSET buried steel structure design, whenever there is doubt as to the potential utilisation of the highway.
45 HB is a sixteen wheel load, with each 112.5 kN wheel exerting a pressure of 1111.1 kN/M2 over a square
area with 0.3182 m sides. The pressure is dispersed downwards at a gradient of 2:1.
Note that area changes are allowed for at 0.68 m when four wheels overlap.
1.48 m when two axles overlap.
5.68 m when four axles overlap.
Live load design, therefore, either caters for HA alone or HA plus HB. The diagram on the previous page
indicates how HA and HB (45 units) disperse downwards and the areas over which they act.
HB loading usually governs except in occasional circumstances when less than 45 units are considered.
•Main
Structural Design
•Index
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Highway Loading - UK (cont)
For determining the design vertical live load pressure, dispersal of the wheel loads may be assumed to occur
from the contact area on the carriageway to the level of the crown of the buried structure at a slope of 2 vertically
to 1 horizontally. This pressure is subsequently to be assumed as acting over the whole span. Wheel loads not
directly over the structure shall be considered if their dispersal zone falls over any structure. Braking loads and
temperature effects may be ignored.
•Main
Structural Design
•Index
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Railway Loading - UK
British Standard BS5400: Part 2:
1978 is referred to for live loading, including allowance for dynamic effects.
The distribution of stresses due to live loading for buried structures is not referred to in BS5400. Therefore the
same method of dispersal as adopted by the Department of Transport for highway loading on buried structures is
adopted. (Department of Transport, Technical Memorandum (Bridges) No. BE1/77 - Standard Highway
Loadings).
RU Loading
RU loading allows for all combinations of vehicles currently running or projected to run on railways in the
continent of Europe, including the United Kingdom, and is to be adopted for the design of bridges carrying main
line railways of 1.4 m gauge and above.
The type RU loading acting on two tracks on the rail, sleeper and ballast arrangements shown below, will
produce vertical stresses within the subgrade as indicated on the graph opposite.
•Main
Structural Design
•Index
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Railway Loading - UK (cont)
Dynamic Effects The standard railway loading specified is an equivalent static loading and should be multiplied
by appropriate dynamic factors to allow for impact, oscillation and other dynamic effects, including those caused
by track and wheel irregularities. The dynamic factors given in Table 15 of BS5400 are used. The dynamic factor
is multiplied by the static vertical stress. The vertical stress due to embankment, sleeper and rail loading is then
added to the dynamic stress on the crown of the buried pipe PV.
Example
Assume a 2.48 metre diameter MultiPlate
Pipe, with a cover of 2.78 metre from
crown of pipe to underside of sleeper.
(Assume ballast depth B = 0.375m).
From the graph of vertical stress due to
static loading, the vertical stress due to
static loading, the vertical stress at crown
of pipe, Pv1 = 39.2 KN/m2.
Dynamic Factor I:
S = T +( Hc - B) + (2B tan 5o)
S = 2.48 + (2.78 - 0.375) + (0.75 tan 5o)
S = 4.95m
Therefore L =4.95 + 3.0 = 7.95m
Therefore
I = 0.73 +
S = T + (Hc-B) + (2B tan
L = S + 3.0
5o)
Dimension L
<3.6
From geometry of pipe size and
position, S and L are calculated.
The dynamic factor (bending) is
then determined from:
3.6 to 67
7.95-0.2
= 0.73 + 2.16
= 0.73 + 0.78
2.78
I = 1.51
Therefore dynamic live load
Pv2 = I x Pv1
= 1.51 x 39.2
Pv2 = 59.19 KN/m2
Dynamic
Factor
2.0
0.73 +
2.16
L-
>67
0.2
1.0
2.16
Dead load pressure, assuming the
embankment height to rail level to allow for
weight of sleeper plus rails.
Pv3 = 18.85 (2.78 + 0.367)
Pv3 = 59.32 KN/m2
Therefore total pressure of crown of pipe
Pv = ( Pv2 + Pv3)
Pv = (59.19 + 59.32) = 118.51 KN/m2
•Main
Structural Design
USA Highway andRailway Loading
Summary of USA Highways and Railway Loading
•Index
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•Main
Structural Design
•Index
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Height of Cover Tables - UK
The tables below show height of cover limits in metres for both ASSET MP200 structures. These
limits are based upon the UK Highways Agency design method BD 12. The calculation takes into account the
maximum allowable corner bearing pressure of 300Kn/m2 and assumes HA and 45 units of HB loading.
HEIGHT OF COVER TABLE MP200
Steel Thickness (mm)
Diameter/Span (m)
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
3.0 mm
(10bits/m)
Min Max
0.65 13.4
0.65 11.5
0.65 9.0
0.65 7.3
0.7
6.1
0.8
5.1
4.0 mm
(10bits/m)
Min Max
0.65 15.4
0.65 15.7
0.65 13.3
0.65 11.0
0.7
9.3
0.8
8.0
0.9
7.0
1.0
6.1
5.0 mm
(10bits/m)
Min Max
0.65 15.4
0.65 15.7
0.65 15.7
0.65 15.7
0.7 13.5
0.8 11.7
0.9 10.3
1.0
9.2
1.1
8.3
1.2
7.5
1.3
6.8
1.4
6.2
6.0 mm
(15bits/m)
Min Max
0.65 15.4
0.65 15.7
0.65 15.7
0.65 15.7
0.7 15.7
0.8 15.7
0.9 15.0
1.0 13.2
1.1 12.2
1.2 10.7
1.3
9.5
1.4
8.3
1.5
7.2
7.0 mm
(20bits/m)
Min Max
0.65 15.4
0.65 15.7
0.65 15.7
0.65 15.7
0.7 15.7
0.8 15.7
0.9 15.7
1.0 15.7
1.1 14.3
1.2 12.7
1.3 11.3
1.4
9.9
1.5
8.7
1.6
7.6
8.0 mm
(20bits/m)
Min Max
0.65 15.4
0.65 15.7
0.65 15.7
0.65 15.7
0.7 15.7
0.8 15.7
0.9 15.7
1.0 15.7
1.1 15.7
1.2 14.3
1.3 12.6
1.4 11.1
1.5
9.7
1.6
8.5
HEIGHT OF COVER TABLE MP100
Steel Thickness (mm)
Diameter/Span (m)
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
1.5 mm
(10bits/m)
Min
Max
0.65
9.6
0.65
7.5
0.65
6.0
0.65
4.9
0.65
3.9
2.0 mm
(10bits/m)
Min
Max
0.65
11.2
0.65
8.8
0.65
7.1
0.65
5.9
0.65
4.9
0.65
4.0
0.65
3.2
0.65
2.1
2.5 mm
(10bits/m)
Min
Max
0.65
14.0
0.65
11.1
0.65
9.1
0.65
7.6
0.65
6.5
0.65
5.6
0.65
4.8
0.65
4.1
0.65
3.5
0.65
2.8
3.0 mm
(10bits/m)
Min
Max
0.65
15.7
0.65
15.7
0.65
14.0
0.65
11.9
0.65
10.4
0.65
9.1
0.65
8.1
0.65
7.2
0.65
6.5
0.65
5.9
0.65
5.4
3.5 mm
(10bits/m)
Min
Max
0.65
15.7
0.65
15.7
0.65
14.1
0.65
12.0
0.65
10.4
0.65
9.1
0.65
8.1
0.65
7.3
0.65
6.6
0.65
5.9
0.65
5.4
0.65
4.9
•Main
END TREATMENTS
•Index
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INTRODUCTION and TYPICAL DETAILS
The design of a buried structure under an
embankment must consider the end treatment
most suitable for the particular structure.
Obviously, the function of the structure and its
geographical location are major factors in
reaching a decision.
For example, the end treatment of a culvert
under an unsurfaced access road in
mountainous country might well differ from that
required for a similar culvert under a motorway.
If the structure is an underpass for vehicles or
pedestrians, the end treatment might well differ
from that where the underpass is required for the
passage of livestock.
If the structure is a culvert, then the designer
could consider erosion, undermining, hydrostatic
forces, debris, energy dissipation or fish
passage amongst other effects.
Multiplate corrugated steel structures have many advantages in overcoming end treatment problems when
compared with other forms of construction, not least being the inherent flexibility of the structures.
A wide variety of end finishes can be fabricated in our factory to suit specific site conditions.
ASSET can supply skewed ends, bevelled ends, skew / bevelled ends, part bevelled ends and other
combinations providing the designer with a wide choice. For example the designer may opt for plain ends
with or without headwalls; ends full or part bevelled tied to a concrete ring beam, stone pitching or gabions.
Many other possibilities exist which may be applicable for a specific installation.
•Main
END TREATMENTS
•Index
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SKEW AND BEVEL DETAILS
Severe skews and bevels are not recommended for Multiplate structures. For skews in excess of 15 degrees
special end treatments should be designed with skew ends in excess of 45 degrees not being recommended.
To avoid confusion when specifying cut end skews, the designer should specify a 'skew number' which is the
angle between the axis of the embankment and the centre-line of the culvert, measured in a clockwise direction.
Skew Details
Bevel Details: - For all bolted plate structures except Super-Span.
Bevelled ends are usually specified to match the slope of the embankment. This slope must be clearly stated
when ordering bevelled ends. Orders should make clear that the specified slope relates to the horizontal.
The culvert invert slope should be detailed on the order if more than 2% as with steep invert slopes the two ends
of a culvert may have to be bevelled differently to match the symmetrical slopes of the embankment.
The length of Multiplate structures relates to the 'net laying length' (refer to MP200 sections) of the
structure as manufactured and is measured from centre of bolt hole to centre of bolt hole at either end of a
structure.
It should be remembered when ordering Multiplate that the actual structure extremities will extend a distance
beyond the centre of the bolt holes dependent upon the structure corrugation.
•Main
END TREATMENTS
•Index
•Next
COLLAR AND RING BEAMS
The practical positioning of anchor bolts and
stirrups is easy to envisage where the collar is
vertical.
However, detailed positioning on a skewed end, or
on a bevel with a sloping collar, is more difficult,
since the corrugations run vertically.
Therefore, bolts are set in a measured distance
from the cut edge with a 470mm vertical step, but
placed on the nearest corrugation crest or trough,
so that the bolts project radially from the structure.
NB. Plate layout diagrammatic only
INSTALLATION
PROCEDURES
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GENERAL
This chapter presents information of fundamental importance
regarding installation and construction procedures including base
preparation, unloading and assembly, and placement and
compaction of backfill.
A well situated, properly bedded, accurately assembled and
carefully backfilled corrugated steel structure will function properly
and efficiently over its entire design life. Although smaller structures
may demand less care in installation than larger ones, reasonable
precautions in handling base preparation, assembly and backfilling
are required for all sizes of structures.
Because of their strength, lightweight and modular construction, ASSET Multiplate corrugated steel structures
can be installed quickly, easily and economically.
The flexible steel shell is designed to distribute loads throughout its periphery and into the backfill. Flexibility
allows a degree of unequal settlement and dimensional change that could cause failure in a rigid structure.
This advantage is further enhanced when a corrugated steel structure is installed on a well prepared
foundation with a well-compacted, stable backfill placed around the structure.
Adherence to these requirements satisfies design assumptions and ensures a satisfactory installation.
During design reasonable care during installation is assumed; indeed the selection of steel thickness and
associated design criteria are based on this assumption. Just as with concrete or other structure types,
careless installation of corrugated steel structures can undo the work of the designer.
Minimum cover requirements are required for corrugated steel structures under highway or other live loadings.
These are based on fundamental design criteria, as well as long term experience.
However, it must be emphasised that such minimum cover may not be adequate during the construction
phase, because of the possibility of high live loads from construction traffic.
Therefore when construction equipment which produces higher live loads than those for which the pipe has
been designed is to be driven over or pass too close to the structure, it is the responsibility of the contractor to
provide any additional cover needed to avoid possible damage to the pipe.
INSTALLATION
PROCEDURES
•Main
•Index
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BASE PREPARATION: Flat Bedding
Pressures developed in the structure wall by the weight of the backfill and live loads are transmitted both to the
side fill and the strata underlying the pipe. The supporting soil beneath the pipe, generally referred to as the
foundation, must provide a reasonable uniform resistance to the imposed pressures, when viewed along both
longitudinal and transverse lines. Requirements when soft foundations or rock foundations are encountered are
discussed later in this section.
Bedding is defined as that portion of the foundation in contact with the bottom or invert of the structure.
Depending upon the size and type of structure, the bedding may either be flat or shaped. With flat bedding the
pipe is placed directly on the fine-graded upper portion of the foundation. Soil must then be compacted under the
haunches of the structures in the first stages of backfilling.
For structures with invert plates exceeding 3700mm in radius, the bedding should be shaped to the approximate
profile of the bottom portion of the structure. Alternatively, the bedding can be shaped to a shallow 'Vee' shape.
Shaping the bedding provides a more uniform support for the relatively flat bottoms of pipe-arches and avoids
creating zones that are difficult to compact under large structures. The shaped portion need not extend across
the entire bottom of the structure, but must be wide enough to permit compaction of backfill under the remainder
of the structure.
INSTALLATION
PROCEDURES
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•Index
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BASE PREPARATION: Shaped Bedding
The diagrams above illustrate the shaped bedding of a pipe-arch. Note that the soil adjacent to the corners of a
pipe-arch must be of excellent quality and well compacted to support the higher pressures that can develop at
these locations.
Whether the bedding is flat or shaped, the upper 50 to 100mm layer should be composed of relatively loose
material so that the corrugations can seat in the bedding. This is usually referred to as a compressible bedding
lift. The material in contact with the structure should not contain gravel larger than 75mm, frozen soil, chunks of
highly plastic clay, organic matter, or other deleterious material.
INSTALLATION
PROCEDURES
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SPECIAL GROUND CONDITIONS: Rock Foundations
If rock ledges are encountered in the foundation, they may create hard points that tend to concentrate loads on
the pipe. Such load concentrations are undesirable since they can lead to distortion of a structure. Large rocks or
ledges must be removed and replaced with suitable compacted fill before preparing the pipe bedding.
When the pipe foundation makes a transition from rock to a compressible soil, special care must be taken to
provide for reasonable uniform longitudinal support so as to minimise longitudinal settlement.
Illustrated below are typical treatments for a transition zone.
INSTALLATION
PROCEDURES
•Main
•Index
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SPECIAL GROUND CONDITIONS: Soft Foundations
Evaluation of the construction site may require subsurface exploration to detect undesirable foundation materials,
such as soft compressible soil or rock ledges. Zones of soft material give uneven support and can cause the pipe
to shift and settle non-uniformly after the embankment is constructed.
These materials should be removed and replaced with suitable compacted fill to provide a continuous foundation.
The extent of soft material removed should be such that the column of fill adjacent to the structure has at least as
good a foundation as that beneath the structure.
The depth and width of soft material removed will depend on the quality of the existing soil, the size of the
structure and the load to be carried.
SKETCH DEMONSTRATING THE
PRINCIPLE OF A YIELDING FOUNDATION.
Note: If replacement material in Zone A is of less depth
and less compacted than the replacement materials in
Zone B and C, the side columns of fill above Zones B
and C will tend to offer support to the central column of
earth which overlies the flexible structure.
Load on the structure is thereby reduced and any
tendency to deform is greatly diminished.
The heavy arrows show the support tendency.
INSTALLATION
PROCEDURES
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•Index
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MULTIPLATE ASSEMBLY: Unloading and Handling Multiplate
Assembly of ASSET Multiplate is straightforward provided our basic recommendations are followed.
This should include careful reading and understanding of the assembly instructions before any plates are laid out
or connected to each other.
Unloading and Handling Multiplate
Plates for Multiplate structures are shipped nested in bundles complete with all bolts and nuts necessary for
assembly. Included with the shipment are detailed assembly instructions.
Bundles are normally 2 tonne maximum weight for ease of handling. Normal care in handling is required to keep
plates clean and free from damage by rough treatment.
Early reference to the assembly instructions is advised so that the plates needed first are readily accessible and
those following can do so without unnecessary rehandling of bundles.
All bundles are tagged with a reference number which enable identification of the plates in the bundle from the
packing list included with the assembly instructions. Each bundle's contents are listed with details of plate length,
width, radius and whether the individual plate is uncut or cut.
The identifying mark of a plate will be shown in the packing list and the accompanying plate layout drawing will
give its unique position in the structure.
INSTALLATION
PROCEDURES
•Main
•Index
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MULTIPLATE ASSEMBLY: Assembly Procedure and Methods
Assembly Procedure
The first essential is to read and understand the assembly instructions provided.
All Multiplate structures are supplied with typewritten assembly instructions together with a diagrammatic sketch.
This sketch, sometimes referred to as a 'bullseye' sketch, shows the positions of each plate in the 'rings' of the
structure and the recommended sequences of plate laying where 'plate by plate' assembly procedure is followed.
For all but the simplest structures, we provide an additional plate layout drawing unique to the structure which
must be followed exactly using the 'bullseye' sketch only as a guide to the order of plate assembly.
Unless the plate layout drawing is followed exactly with regard to the positioning of plates with reference to the
invert centreline then there is risk of elbows, bevels, etc. begin incorrectly angled in the structure.
Having studied the assembly instructions and drawings, there are generally two approaches to the actual
assembly method:
1. Plate-by-plate assembly
2. Component sub-assembly (or prefabrication of units).
Plate-by-Plate Assembly
This is commonly used for the assembly of Multiplate pipe structures as distinct from pipe-arch structures,
although the pre-assembly method can be used for assembly of large diameter pipes. When assembling pipes
by the plate-by-plate method, the procedure is to lay out and bolt together a considerable number of invert plates
which are then followed by side plates. The side plates are placed alternatively on either side of the invert to
maintain balance, and top or roof plates follow.
The single most important thing to remember when assembling Multiplate is to assemble the structures with as
few bolts as possible initially until several rings are closed. When several rings have been assembled, work can
proceed with placing and tightening all remaining bolts. During assembly, only a few bolts should be placed in
the longitudinal seams. Two bolts near each end and two near the centre of the plates are quite sufficient and
these bolts should be tightened with a hand wrench only (not an air impact wrench). Circumferential bolts should
all be positioned and tightened to hold adjacent plates together.
Nuts may be placed inside or outside the structure. It is a good idea to put all nuts in the lower half of the
structure on the inside and on the outside in the upper half to facilitate the use of air wrenches.
As long as all nuts and bolts are positioned and tightened, it does not matter - structurally - which way round the
bolts are placed.
It is important that the curved side of the nut is placed against the plate (like the wheel nuts on a car). Final bolt
placement and tightening should always be kept at least one full ring behind plate assembly.
Avoid placing too many side plates before closing the top or roof to prevent the structure 'spreading'.
When starting assembly on the prepared bed and throughout the whole assembly, it is important that the bed
itself is uniform in gradient; that invert plates are individually checked for correct position of invert centreline and
that the structure is kept plumb and on line as assembly proceeds.
It also advisable to keep a check on the rise and span dimensions of the structure during assembly and
backfilling.
Component Sub-Assembly
This can be used for the assembly of larger structures of all shapes and all pipe-arches and arches.
As arches rest in unbalanced channels in previously constructed abutments plate-by-plate assembly would
involve propping until rings are complete.
The quickest method for arch assembly to is to pre-assemble each full ring on the ground frequently resting on
its 'side'. All nuts are placed on the outside of the arch but left loose. Each pre-assembled ring is then lifted on to
the abutments, shingle lapping with its neighbouring ring. Obviously it is essential that both unbalanced changes
are laid true to line and gradient at the correct distance apart. They must also be angled correctly (as shown on
the contract drawings) depending on the rise / span ratio of the arch specified. The short leg of the channel is to
the inside of the abutment and the anchoring lugs in the base of the channel should be bent down at right angles
and twisted through 90 degrees before pouring the abutment concrete. It should also be noted that unbalanced
channel lengths always correspond with the net plate lengths, i.e., multiples of 3 metres and 2 metres. This
results in the plates at the end of the structure protruding beyond the ends of the unbalanced channel by 50mm
at each end of the structure.
On medium size and large arch structures when pre-assembling rings, it may be helpful to adopt the 'strength
and squeeze' technique to facilitate bolt placement when shingle lapping rings.
Pipe-arches are commonly assembled using a combination of component sub-assembly and plate-by-plate
methods.
All pipes-arches have comparatively large radius inverts and as proper placement and compaction of backfill can
be a problem it is usual to lay this type of structure on a shaped bed.
When laying pre-assembled invert sections on a shaped bed a problem can arise with placement of the
circumferential seam bolts which connecting these sections on the bed. This is overcome using the spring clips
provided by means of which the circumferential seam bolts on the ring are positioned ready to receive the next
ring.
The procedure for pipe-arches is to pre-assemble invert sections lying on their sides making sure to place all
nuts inside. These pre-assembled rings are then connected together on the shaped bed with the aid of the spring
clips discussed above and all bolts tightened up. It is important to note that attention must be paid to the width of
the pre-shaped bedding which must be kept clear of the seams which connect corner plate to invert plates.
Having placed all the invert plates and tightened up all the nuts, it is usual to place corner plates equally on both
sides plates-by-plate.
Avoid placing too many corner plates to prevent the structure 'spreading' and do not tighten invert / corner seams
at this stage. Then position side and top plates one at a time, or in pre-assembled sections equally to both sides
of the structure, closing the crown as soon as possible to avoid structure spread. Bolt placement and tightening
may then proceed, always keeping at least one full ring behind plate assembly.
The assembly of vertical and horizontal ellipse shaped structures is similar to the procedure for pipes.
In all Multiplate structures, except arches, the aim should always be to achieve a 'staircase' effect when the
structure being assembled is viewed from one side. This effect is achieved by having a closed ring at the starting
end with side plates gradually stepping down to invert plates only at the advanced end. As soon as a ring is
closed, it should be checked for span and rise (or diameter) and adjusted if necessary before proceeding further.
This 'staircase' method of assembly should be adopted in preference to any other method of assembly except for
arch structures.
INSTALLATION
PROCEDURES
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•Index
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MULTIPLATE ASSEMBLY: Bolt Tightening
Recommended torque values are in the range 135Nm to 270Nm.
Placing of all the bolts and tightening up to full torque should never proceed without at least one full ring existing
between this operation and the assembly crew.
When tightening bolts to full torque, always work from the centre of seams towards the plates corners. Do not
insert corner bolts until all other are placed. Alignment of bolt holes is easier when bolts are loose.
The bolts should all be torqued to a maximum of 270 Nm and bolt tightening should proceed from one end of
the structure progressively ring by ring.
Good Fit of Plates - one to another is more important than precise torque figures
Backfilling will inevitably cause torque variation, usually a tendency towards slight decrease. The degree of
torque change is a function of metal thickness, plate match and change of structure shape during backfilling. This
is normal and not a cause for concern should checks be made at a later stage.
Assembly of Multiplate Super-Span Structures
The foregoing procedures apply equally to Multiplate Super-Span structures. Continual monitoring of structure
shape is most important in Multiplate Super-Span installation.
Advice on all aspects of assembly and backfilling is available from our staff as required.
INSTALLATION
PROCEDURES
•Main
•Index
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BACKFILL: Trench and Embankment Conditions
Trench Condition
In trench installation, the trench should be kept as narrow as possible but sufficiently wide to permit tamping
under the haunches of the structure. Generally trench width will range from 500mm to 800mm greater than the
span of the structure. For structures above 1.50 metre span or where mechanical tamping equipment is to be
used, greater trench width may be required.
Excavations for multiple installations must take into account the additional width required for spacing between
structures. Side walls should be as vertical as practical, at least to an elevation above the top of the structure.
Embankment Condition
For structures in embankments, the area of controlled backfill should extend to at least one diameter or span on
each side of the structure.
INSTALLATION
PROCEDURES
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BACKFILL: Material Selection
Backfill should be selected in accordance with the requirements of The Department of Transport Manual of
Contract Documents for Highway Works - Volume 1 - Specification for Highway Works - clause 623.
Alternatively, backfill material should preferably be granular to provide good structural performance and be free
from large stones, organic or frozen material. This select structural backfill material should conform to one of the
following classifications of soil from AASHTO Specifications M-145 Table 2.
INSTALLATION
PROCEDURES
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BACKFILL: Backfill Placement
Backfill material should be placed in horizontal uniform layers not exceeding 200mm in thickness before
compaction, and should be brought up equally on both sides of the structure.
Pipe-arches require that the backfill at the corners be of the best material and especially well compacted.
Each layer of backfill should be compacted to 90% of maximum density at optimum moisture content as
determined by British Standard 1377 and in accordance with the requirements of the Department of Transport
Manual of Contract Documents for Highway Works - Volume 1 - Specification for Highway Works - clause 623.
Tamping can be done with hand or mechanical equipment, tamping roller or vibrating compactors, depending
upon field conditions. More important than method is that it be done carefully to ensure a thoroughly compacted
backfill without excessive distortion of the structure.
Particular care should be taken in backfilling arches to avoid peaking or rolling during the backfill operation.
Protection from Construction Traffic
For adequate protection from heavy construction equipment, it may be necessary to temporarily locally increase
the height of cover over a structure.
How much additional fill is needed depends upon the wheel loads of equipment used, distribution, and frequency
of loading.
INSTALLATION
PROCEDURES
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•Next
BACKFILL: Good and Bad Backfill Practices
Good Backfilling Practice
To ensure that no pockets of uncompacted fill are placed next to the structure, it is necessary to ensure that all
equipment runs parallel to the length of the structure.
Poor Backfilling Practice
The possibility of pockets of uncompacted fill or voids next to the structure can arise with equipment operating at
right angles to the structure.
INSTALLATION
PROCEDURES
•Main
•Index
•Next
BACKFILL: Notes on Excavation and Backfill
1) Excavation shall be carried out in accordance with the contract except that additional excavation will be
required to remove pockets of soft soil, loose rock and any voids shall be filled with 6K lower bedding material.
2) Lower bedding material class 6K ( 20mm down ) shall have its top surface shaped during compaction to
match the structure profile when the bottom radius is greater than 3700mm.
When the radius is less than 3700mm the lower bedding shall be compacted in layers to a depth of span/10 and
a layer of uncompacted class 6L ( sand ) 50mm deep placed 1000mm wide along the centre of the structure. (
This will allow access for positioning bolts in the invert longitudinal seams on multiplate structures. ) The lower
bedding under the structure shall be well compacted using a suitably sized length of timber. Lower bedding shall
extend a width 800mm ( 500mm for structures up to 3m span ) beyond the span on each side of the structure
and 300mm beyond each end of the structure.
Lower bedding shall extend to a depth such that it supports the bottom radius ( rb ) of the structure or 20% of the
circumference for round pipes.
The depth of lower bedding shall be increased by 300mm if rock is encountered at the base of the bedding. Also
if the height of cover is greater than 8m then the depth shall be increased by another 40mm for each metre of
cover to a maximum additional depth of 600mm.
3) Surround material class 6M ( 75 down ) shall extend a span either side of the structure for embankment
construction and 800mm ( 500mm for structures up to 3m ) for trench conditions. Structures in part trench / part
embankment may use a combination of backfill widths. Surround material shall extend to a height of span/5 or
1m ( 650mm for structures up to 3m span ) whichever is the greater above the crown of the structure or to the
formation level if lower.
INSTALLATION
PROCEDURES
•Main
•Index
•Next
BACKFILL: Multiple Structures
Multiple Structures
When two or more structures are laid parallel, the space between structures in normally one half diameter or
span, with a minimum of 600mm and maximum 1000mm. These spacings should be treated as minimum
recommendations, as the spacings may need to be increased to leave sufficient room for mechanical compaction
equipment to operate, and for tamping the fill under the haunches of the structures.
Minimum Clearance Between Conduits
SHAPE
PROFILE
SPAN S
UP TO 2 m
1. CIRCULAR
PIPES
MINIMUM VALUE
OF b
HALF S OR 600 mm
WHICHEVER IS
GREATER
GREATER THAN 2m 1 m
UP TO 3 m
2. PIPE ARCHES
AND
UNDERPASSES
THIRD S OR 600 mm
WHICHEVER IS
GREATER
GREATER THAN 3m 1.0 m
3. ARCHES
ALL SIZES
0.6 m
INSTALLATION
PROCEDURES
BACKFILL: Summary
The key points in the backfilling operations are:
1. Use good quality backfill material.
2. Ensure adequate compaction under haunches.
3. Maintain adequate width of backfill.
4. Place backfill material in thin uniform layers.
5. Balance fill either side as fill progresses.
6. Compact each layer before adding next layer.
7. Maintain design shape.
8. Do not allow construction equipment over the structure, without
adequate protection, until minimum depth of cover is achieved.
9. Place and compact backfill parallel to structure.
•Main
•Index
•Next
Index
MULTIPLATE MP 200
Next
INTRODUCTION
ASSET International are a Quality Assured Company to BS EN ISO 9002: 1994 - Certificate No FM 12306.
ASSET MP200 is made in compliance to BBA Certificate No 91/59 and has Highway Agency Type Approval
Certificate No. BE 1/1/97.
ASSET MP200 meets all the requirements of the relevant parts of the Specification for Highway Works Part 2
Series 600 and Part 6 Series 2500 (6th edition) and Notes for Guidance on the Specification for Highways Works
Part 2 Series NG600.
ASSET MP200 structures are available in a wide range of shapes and sizes to suit a wide range of applications.
ASSET MP200 can be additionally protected with a variety of secondary coatings.
ASSET MP200 is normally designed in accordance with the Highway Agency Departmental Standard BD 12/01
for the Design of Corrugated Steel Buried structures.
ASSET sells a computer programme to assist the sizing of structures and structural calculations.
Index
MULTIPLATE MP 200
Next
MP200 is manufactured in the range of shapes and sizes shown in the table below. All MP200 steel plates are
fabricated with corrugations 200mm pitch x 55mm depth.
PROFILE
SHAPE
SIZE RANGE
0.8m - 8.0m
Culverts, Underpasses,
Service, Recovery Tunnels,
Piling or Back Shutters.
Span
1.0m - 8.0m
Culverts, Tunnels or Re-lining
where headroom is limited.
Span
Underpasses beneath
embankments for pedestrians,
Diameter
Round Pipe
Low Profile Pipe
Arch
Underpass
1.0m - 8.0m
Span
Vertical Ellipse
Horizontal Ellipse
Arch
SOME TYPICAL USES
livestock or vehicles, culverts.
1.0m - 8.0m
Culverts, Underpasses, Service
Tunnels or Vehicle Tunnels
Span
1.0m - 8.0m
Culverts or Tunnels where
headroom is limited.
Span
1.0m - 8.0m
Culverts, Tunnels or Re-lining
Note:
All the above structures may be used for lining failing structures by either assembling inside the failing structure
where working space permits or hauling the assembled MP200 structure in from outside where working space is
insufficient. Grout connections can be provided to assist filling the annular space between the new lining and the
failing structure.
All these structures may be used for extending existing structures.
Larger sizes than those shown are available. Please contact ASSET International Ltd. for further advice.
Other shapes are available for special applications.
Index
MULTIPLATE MP 200
Next
PROFILE DATA: Pipe
All dimensions are to the inside of corrugations.
INTERNAL
Dia (m)
STRUCTURE
Area REFERENCE
(m2)
INTERNAL
Dia (m)
Area (m2)
STRUCTURE
REFERENCE
17.55
18.68
19.26
20.44
21.04
64
66
67
69
70
1.74
1.81
1.96
2.03
2.36
2.57
3.02
3.25
24
25
27
28
4.73
4.88
4.95
5.10
5.18
2.11
2.26
2.33
2.48
2.56
3.49
4.01
4.28
4.84
5.14
29
31
32
34
35
5.25
5.40
5.48
5.63
5.70
21.66
22.91
23.55
24.85
25.52
71
73
74
76
77
2.63
2.78
2.86
3.01
3.08
5.44
6.08
6.41
7.10
7.46
36
38
39
41
42
5.77
5.92
6.00
6.15
6.22
26.19
27.56
28.27
29.69
30.42
78
80
81
83
84
3.16
3.31
3.38
3.53
3.61
7.83
8.58
8.98
9.79
10.21
43
45
46
48
49
6.30
6.45
6.52
6.67
31.16
32.65
33.41
34.97
85
87
88
90
6.75
6.82
6.97
7.05
7.20
35.75
36.55
38.17
38.99
40.67
91
92
94
95
97
7.27
7.35
7.50
7.57
7.72
41.52
42.38
44.12
45.01
46.80
98
99
101
102
104
7.79
47.71
105
3.68
3.83
3.90
4.05
4.13
10.64
11.52
11.91
12.91
13.39
50
52
53
55
56
4.20
4.35
4.43
4.58
4.65
13.88
14.88
15.40
16.46
17.00
57
59
60
62
63
7.87
48.63
106
Index
MULTIPLATE MP 200
Next
PROFILE DATA: Pipe Arch
information.
All of these profiles conform to BD12/01
All dimensions are to inside of corrugation.
INTERNAL DIMENSION
INTERNAL RADII
Span
Rise
Area
Top
Corner Bottom
(m)
(m)
(m2)
R1(m)
R2(m)
1.93
1.53
2.31
1.00
2.28
2.64
1.72
1.85
3.12
3.79
2.89
3.38
2.00
2.17
3.48
3.84
SUBTENDED ANGLES
STRUCT
REF
Top
Corner Bottom
R3(m)
A1(deg)
A2(deg) A3(deg)
0.60
1.35
130.4
85.5
58.6
10-4-6
1.15
1.38
0.60
0.60
2.76
2.14
160.1
133.2
85.5
85.5
29.0
55.8
14-4-6
14-4-9
4.53
5.60
1.47
1.85
0.60
0.60
3.32
2.57
152.8
121.7
85.5
85.5
36.2
67.3
17-4-9
17-4-13
2.63
2.77
7.17
8.19
1.76
1.99
0.85
0.85
3.01
2.80
158.3
140.3
76.5
76.5
48.7
66.7
21-5-11
21-5-14
3.71
4.08
4.56
2.79
2.93
3.12
8.21
9.29
10.82
1.86
2.07
2.42
0.85
0.85
0.85
4.12
3.50
3.21
171.3
153.7
132.1
76.5
76.5
76.5
35.7
53.3
74.9
24-5-11
24-5-14
24-5-18
4.23
4.72
5.09
5.55
3.29
3.48
3.62
3.82
11.10
12.80
14.15
16.04
2.12
2.39
2.63
3.00
1.05
1.05
1.05
1.05
4.62
3.91
3.69
3.58
175.6
155.7
141.7
124.6
74.8
74.8
74.8
74.8
34.8
54.7
68.7
85.8
28-6-12
28-6-16
28-6-19
28-6-23
4.79
5.14
5.61
5.95
3.82
3.96
4.16
4.31
14.47
15.92
17.96
19.56
2.40
2.59
2.89
3.13
1.28
1.28
1.28
1.28
4.25
3.99
3.85
3.81
172.1
159.2
143.2
131.9
71.9
71.9
71.9
71.9
44.0
56.9
72.9
84.2
31-7-14
31-7-17
31-7-21
31-7-24
5.44
5.93
6.29
6.75
4.18
4.38
4.52
4.72
17.98
20.13
21.82
24.18
2.73
3.01
3.24
3.59
1.28
1.28
1.28
1.28
5.04
4.61
4.46
4.36
171.0
155.2
144.1
130.2
71.9
71.9
71.9
71.9
45.1
60.9
72.0
85.9
35-7-17
35-7-21
35-7-24
35-7-28
179.1
163.5
152.5
138.7
71.9
71.9
71.9
71.9
37.0
52.6
63.6
77.4
38-7-17
38-7-21
38-7-24
38-7-28
6.67
6.06
5.63
5.44
129.0
173.9
163.1
149.5
139.9
71.9
71.9
71.9
71.9
71.9
87.1
42.2
53.0
66.6
76.3
38-7-31
42-7-21
42-7-24
42-7-28
42-7-31
1.28
1.28
1.28
7.05
6.35
6.05
170.5
157.0
147.4
71.9
71.9
71.9
45.6
59.1
68.7
45-7-24
45-7-28
45-7-31
1.28
7.54
166.3
71.9
49.8
49-7-28
5.65
6.16
6.53
7.01
7.35
4.35
4.54
4.68
4.88
5.03
19.61
21.84
23.60
26.03
27.94
2.83
3.10
3.32
3.66
3.93
1.28
1.28
1.28
1.28
1.28
6.16
5.35
5.05
4.84
4.76
6.44
6.83
7.33
7.70
4.76
4.90
5.10
5.24
24.24
26.07
28.62
30.61
3.22
3.44
3.75
4.01
1.28
1.28
1.28
1.28
7.03
7.56
7.93
5.07
5.26
5.41
28.01
30.64
32.69
3.52
3.83
4.08
7.84
5.48
33.46
3.94
Index
MULTIPLATE MP 200
Next
PROFILE DATA: Underpass
information.
INTERNAL
DIMENSION
INSIDE RADII (m)
SUBTENDED ANGLES
STRUCT.
REF
Span
Rise
Area
Top
Corner
Bottom
Top
Corner
Bottom
(m)
(m)
(m2)
R1(m)
R2 (m)
R3 (m)
A1
(deg)
A2
(deg)
A3
(deg)
2.35
2.14
3.97
1.173
0.87
1.592
190.20
60.00
49.80
17-4-6
2.66
2.97
2.37
2.54
4.89
5.95
1.329
1.486
0.87
0.87
2.496
2.238
208.00
186.60
60.00
60.00
32.00
53.40
21-4-6
21-4-9
2.88
3.19
2.55
2.71
5.78
6.80
1.442
1.597
0.87
0.87
3.902
3.902
219.50
198.70
60.00
60.00
20.50
41.30
24-4-6
24-4-9
3.48
3.93
2.96
3.17
7.97
9.72
1.741
1.963
0.87
0.87
4.444
3.412
212.90
189.10
60.00
60.00
27.10
50.90
28-4-9
28-4-13
4.31
3.35
10.67
2.066
0.87
4.250
199.20
60.00
40.80
31-4-13
4.41
4.76
3.59
3.75
11.99
13.69
2.203
2.378
0.87
0.87
6.019
4.839
211.10
195.70
60.00
60.00
28.90
44.30
35-4-13
35-4-16
4.95
3.93
14.71
2.476
0.87
5.989
204.20
60.00
35.80
38-4-14
5.15
5.60
5.96
4.28
4.48
4.64
16.76
19.27
21.50
2.577
2.801
2.982
1.09
1.09
1.09
8.143
5.996
5.382
216.90
199.80
187.80
60.00
60.00
60.00
23.10
40.20
52.20
42-5-14
42-5-18
42-5-21
5.80
6.16
4.67
4.82
20.56
22.79
2.902
3.079
1.09
1.09
7.238
6.235
206.70
194.90
60.00
60.00
33.30
45.10
45-5-18
45-5-21
6.01
6.34
6.81
5.02
5.18
5.38
23.02
25.17
28.41
3.006
3.171
3.405
1.32
1.32
1.32
9.453
7.513
6.431
217.30
206.10
192.10
60.00
60.00
60.00
22.70
33.90
47.90
49-6-16
49-6-19
49-6-23
6.84
6.92
7.27
5.46
5.67
5.83
27.30
30.37
32.98
3.241
3.459
3.634
1.54
1.54
1.54
8.795
7.157
6.579
214.10
200.70
191.10
60.00
60.00
60.00
25.90
39.30
48.90
52-7-17
52-7-21
52-7-24
7.20
7.54
5.92
6.07
32.65
35.28
3.599
3.768
1.54
1.54
8.743
7.760
207.80
198.50
60.00
60.00
32.20
41.50
56-7-21
56-7-24
7.41
7.75
6.10
6.26
34.39
37.06
3.703
3.873
1.54
1.54
10.37
8.827
212.80
302.50
60.00
60.00
27.20
36.50
59-7-21
59-7-24
Index
MULTIPLATE MP 200
Next
PROFILE DATA: Arch (BD12/01 Compliant)
information.
INTERNAL DIMENSION
RADII
Span
Rise
Area
Radius
(m)
(m)
(m2)
R1 (m)
SPAN
SUBTENDED
ANGLES
Bottom
Span
Subtended
Angle
(m)
A1 (deg)
Rise/Span
Ratio
2.00
1.41
2.37
1.00
1.82
228.90
0.71
2.50
1.74
3.65
1.25
2.30
226.20
0.70
3.00
1.96
4.88
1.00
2.86
215.40
0.65
3.50
3.50
2.28
2.61
6.65
7.68
1.75
1.75
3.33
3.05
215.40
238.50
0.65
0.74
4.00
4.00
2.50
2.93
8.25
9.88
2.00
2.00
3.88
3.54
208.70
238.60
0.62
0.73
4.50
4.50
2.82
3.15
10.50
11.91
2.25
2.25
4.35
4.12
209.40
227.40
0.63
0.70
5.00
5.00
3.03
3.48
12.47
14.59
2.50
2.50
4.88
4.60
204.70
226.20
0.61
0.70
5.50
5.50
5.50
3.36
3.70
4.12
15.21
16.99
19.10
2.75
2.75
2.75
5.36
5.16
4.77
205.60
220.30
239.90
0.61
0.67
0.75
6.00
6.00
6.00
3.57
4.02
4.35
17.55
20.16
21.94
3.00
3.00
3.00
5.89
5.64
5.36
202.00
219.90
233.40
0.60
0.67
0.72
6.50
6.50
6.50
3.90
4.24
4.67
20.78
22.92
25.55
3.25
3.25
3.25
6.337
6.19
5.84
203.00
215.40
232.00
0.60
0.65
0.75
7.00
7.00
4.11
4.57
23.48
26.58
3.50
3.50
6.89
6.67
200.00
215.40
0.59
0.65
7.00
4.89
28.74
3.50
6.42
227.00
0.70
7.50
7.50
7.50
7.50
4.44
4.78
5.22
5.54
27.20
29.71
32.83
34.98
3.75
3.75
3.75
3.75
7.37
7.12
6.90
6.59
201.10
211.80
226.20
237.00
0.59
0.64
0.70
0.74
8.00
8.00
8.00
5.10
5.44
5.87
33.86
36.39
39.50
4.00
4.00
4.00
7.69
7.46
7.08
212.10
222.00
235.60
0.64
0.68
0.73
Index
MULTIPLATE MP 200
Next
PROFILE DATA: Arch (Other)
information.
These profiles do not conform to BD12/01
INTERNAL DIMENSIONS
RADII
Span
Rise
Area
Radius
(m)
(m)
(m2)
A1 (m)
SPAN
SUBTENDED
ANGLES
Bottom
Span
Subtended
Angle
(m)
R1 (deg)
Rise/Span
Ratio
2.50
0.90
1.65
1.32
2.50
143.20
0.36
3.00
1.11
2.44
1.57
3.00
146.00
0.37
3.50
1.45
3.82
1.78
3.50
158.60
0.41
4.00
4.00
1.23
1.66
3.50
4.99
2.24
2.04
4.00
4.00
126.20
158.60
0.31
0.41
4.50
4.50
1.44
2.00
4.65
6.85
2.48
2.26
4.50
4.50
130.50
166.60
0.32
0.44
5.00
5.00
1.80
2.21
6.59
8.39
2.63
2.52
5.00
5.00
143.20
165.70
0.36
0.44
5.50
5.50
2.01
2.54
8.10
10.74
2.89
2.76
5.50
5.50
144.60
170.80
0.37
0.46
6.00
6.00
2.36
2.75
10.51
12.65
3.09
3.01
6.00
6.00
152.60
169.90
0.39
0.46
6.50
6.50
6.50
2.13
2.75
3.08
9.99
12.40
15.49
3.54
3.34
3.25
6.50
6.50
6.50
133.10
153.30
173.90
0.33
0.39
0.47
7.00
7.00
7.00
2.34
2.90
3.29
11.84
15.28
17.77
3.79
3.57
3.50
7.00
7.00
7.00
135.00
158.60
172.90
0.33
0.41
0.47
7.50
7.50
7.50
2.70
3.11
3.61
14.82
17.54
21.09
3.95
3.82
3.75
7.50
7.50
7.50
143.20
158.60
175.80
0.36
0.41
0.48
8.00
8.00
8.00
8.00
2.45
3.91
3.45
3.82
14.01
17.04
20.92
23.75
4.48
4.21
4.04
4.00
8.00
8.00
8.00
8.00
126.20
143.90
163.30
174.90
0.31
0.36
0.43
0.48
Index
MULTIPLATE MP 200
Next
PROFILE DATA: Vertical Ellipse
information.
INTERNAL
DIMENSIONS
SIDE
TOP/BOTTOM
STRUCT. REF
Span
Rise
Radius
Angle
Radius
Angle
Area
(m)
(m)
R2 (m)
A2 (m)
R1 (m)
A1 (deg)
(m2)
1.223
1.705
2.096
2.617
2.979
3.460
3.851
4.373
4.734
5.215
5.607
6.128
6.489
6.970
1.655
2.307
2.8369
3.5410
4.030
4.682
5.210
5.915
6.404
7.056
7.585
8.290
8.779
9.430
0.996
1.579
1.784
2.111
2.547
3.214
3.399
3.693
4.163
4.848
5.024
5.300
5.787
6.484
94.60
58.60
74.20
88.10
73.10
58.10
66.80
76.00
67.40
58.00
63.90
70.70
64.80
57.90
0.448
0.746
0.861
0.995
1.230
1.517
1.635
1.782
2.004
2.287
2.406
2.558
2.775
3.057
85.40
121.40
105.80
91.90
106.90
212.90
113.20
104.00
112.60
122.00
116.10
109.30
115.20
122.10
1.56
3.14
4.67
7.19
9.44
12.92
15.88
20.30
23.98
29.36
33.74
40.05
45.16
52.44
7-3
7-7
10-7
14-7
14-10
14-14
17-14
21-14
21-17
21-21
24-21
28-21
28-24
28-28
Index
MULTIPLATE MP 200
Next
PROFILE DATA: Horizontal Ellipse
information.
INTERNAL
DIMENSIONS
SIDE
TOP/BOTTOM
Span
Rise
Radius
Angle
Radius
Angle
Area
(m)
(m)
R1 (m)
A1 (m)
A2 (m)
R2 (deg)
(m2)
1.514
2.133
2.609
3.245
3.709
4.329
4.805
5.441
5.905
6.524
7.001
7.637
8.101
8.720
1.369
1.930
2.391
2.936
3.356
3.916
4.348
4.923
5.343
5.903
6.334
6.909
7.330
7.890
0.596
0.907
1.082
1.303
1.541
1.842
2.019
2.248
2.478
2.777
2.954
3.186
3.413
3.711
64.50
100.50
84.70
70.70
85.70
100.70
92.00
82.80
91.30
100.70
94.80
87.90
93.80
100.80
0.786
1.156
1.383
1.695
1.969
2.347
2.571
2.878
3.157
3.538
3.761
4.064
3.346
4.720
115.50
79.50
95.30
109.30
94.30
79.30
88.00
97.20
88.70
79.30
85.20
92.10
86.20
79.20
1.61
3.24
4.82
7.43
9.75
13.34
16.39
20.96
24.75
30.30
34.83
41.35
46.62
54.12
STRUCT.
REF
3-7
7-7
7 - 10
7 - 14
10 - 14
14 - 14
14 - 17
14 - 21
17 - 21
21 - 21
21 - 24
21 - 28
24 - 28
28 - 28
Index
MULTIPLATE MP 200
Next
PHYSICAL PROPERTIES
Seam Strengths kN/m
Steel
Thickness
Section Moment
Area
of Inertia
Section
Modulus
Radius of
Gyration
Steel
Thickness
10
Bolts/M
15
Bolts/M
20
Bolts/M
t (mm)
(mm2/m)
(mm4/mm)
(mm3/mm)
(mm)
(mm)
2.75
3248
1242
43.00
19.55
2.75
582
657
719
*3.00
3544
1356
46.77
19.56
*3.00
667
738
827
3.25
3840
1471
50.52
19.58
3.25
752
819
934
*4.00
4729
1819
61.67
19.61
*4.00
961
1264
1368
4.75
5618
2171
72.66
19.66
4.75
1255
1428
1784
*5.00
5915
2289
76.29
19.67
*5.00
1354
1561
1915
5.50
6509
2526
83.51
19.70
5.50
1584
1872
2221
*6.00
7103
2766
90.68
19.73
*6.00
0
1996
2402
6.25
7400
2886
94.25
19.75
6.25
0
2049
2479
*7.00
8293
3251
104.88
19.80
*7.00
0
0
2859
*7.75
9187
3621
115.41
19.85
*7.75
0
0
3188
Notes:
Steel thickness marked (
* ) in bold are preferred thicknesses.
Seam strengths for MP200 as approved by the Highways Agency.
Index
MULTIPLATE MP 200
Next
COMPONENTS: Plates
MP200 structures are built up from a combination of plate sizes, involving two lengths and four width variations,
combinations of which permit structures to be supplied in a wide range of span/rise ratios and 1.0 metre bottom
length increments as standard.
The 'length' of a plate is taken as being in the same direction as the longitudinal axis of the structure and the
'width' of the plate is at right angles to that axis. The corrugations run circumferentially around the structure.
Standard bolt hole punching allows for 10 bolts per metre of longitudinal seam. This can be increased to 15 or 20
bolts per metre, if required by structural design.
All dimensions in mm unless otherwise indicated
Optional 15 bolts/m
Hole Configuration
for MP200
Optional 20bolts/m
Hole Configuration
for MP200
Index
MULTIPLATE MP 200
Next
COMPONENTS: Nuts and Bolts
Bolt head may be placed on corrugation crest or trough whichever is deemed most convenient by the installer.
On underpass structures, however, many specifiers call for all bolt heads to be placed inside the structure to
avoid projecting bolt shanks.
HEADWALL ANCHOR BOLT
Index
MULTIPLATE MP 200
Next
COMPONENTS: Arch Seating Channel
MP200 seating channel is designed to be cast into concrete footings, and also to allow for the bolting of plates in
their correct positions. It is asymmetrical in cross-section, and has casting lugs pre-punched along the base.
The asymmetrical channel must be angled to match the arch base, and therefore will have to be set into the
concrete in any one of the different basic configurations as shown.
In Case 1, care should be taken in designing the concrete footings, so that the concrete surface does not impede
access for inserting and tightening bolts.
In Case 2, which is the 'neutral case', concrete can be level on both sides of the channel, at a cast-in depth of
50mm.
In Case 3, care should be taken that sufficient concrete is maintained at point 'A', so that the stresses from the
arch thrust forces can be properly absorbed without spalling or failure.
Index
MULTIPLATE MP 200
COMPONENTS: Alternative Arch Seating
Next
Index
MULTIPLATE MP 200
Next
SPECIFICATION
General
MP200 corrugated galvanised steel bolted segmental structures are manufactured in accordance with BBA
Roads and Bridges Certificate No 91/59.
Material
MP200 culverts shall be made from steel:
Grade HR4 to BS 1449: Section 1.1: 1991
Tolerance to BS EN 10051: 1992
Minimum yield strength of 229/mm2.
Fabrication
Standard plates are pressed, punched, curved and then hot dip galvanised to BS EN ISO 1461: 1999.
Average zinc thickness shall be 0.053mm on steel thickness up to and including 4.00mm and 0.064mm on steel
thickness above 4.00mm.
Plates supplied shall be a combination of circumferential widths to provide the specification profile of the
structure and in net laying lengths to provide the specified structure length.
Cut edges of special plates shall be free from notches, gouges, oxides or dross. Where possible all fabrication
shall be performed before hot dip galvanising. All special plates shall be marked to correspond to the assembly
drawing.
Corrugations
The corrugation shall form smooth continuous curves and tangents with dimensions 200mm pitch by 55mm
depth, tolerance ±5%. When installed the corrugations shall form circumferential rings about the longitudinal axis
of the structure.
Dimensions (Diameter, Span and Rise)
Dimensions for Diameter for single radius structures and Span and Rise for multi-radius structures are in metres
and are subject to a tolerance of ± 5%.
Bolt Holes
Bolt holes diameter shall be 25mm, tolerance ±1mm.
Bolts holes shall be punched on a corrugation crest or valley and on the edges of the plates so as to enable
structure assembly.
Bolt holes on the longitudinal plates edges shall staggered in two rows 50mm apart, furnished to accommodate
10, 15 or 20 bolts / metre.
Bolt holes on the circumferential plate edges shall be at 235mm centre to centre.
Accessories
All MP200 accessories shall be hot dip galvanised to BS EN ISO 1461:1999.
Bolts shall be 20mm diameter and conform to BS 6104 : Part 1: 1981: Grade 10.9
Nuts shall be 20mm diameter and conform to BS 6104 : Part 2: 1981: Grade 10.9
Bolt lengths shall be sufficient to ensure a full thread in the nut when the plates are drawn together.
Anchor nuts and bolts shall conform to BS 3692 Grade 4.8.
Arch seating channels shall be minimum 5mm thick
Repair of Damage
Damage to galvanised coatings shall be made good in accordance with BS 729:1980 by the use of zinc rich
paint.
Inspection
Subject to prior notification all materials and relevant Quality Assurance records can be inspected at the works
during or after manufacture.
•Main
Hydraulic Design:
INTRODUCTION
The importance of the following three considerations cannot be emphasised too strongly because
they draw the designer's attention to all the fundamental elements which have to be confronted
before embarking on the detailed hydraulics calculations for culvert or sewer.
First, in considering the hydraulic design of pipes and pipe-arch structures it is vitally important,
before all else, to differentiate between two basic types of conduit
(1) CULVERTS
(2) LONG PIPELINES (e.g. storm water sewers or stream enclosures).
If the structure in question is classed as a culvert, then culvert hydraulics formulae are applicable.
If the structure is of sufficient length to be classed as a long pipeline or sewer then sewer
hydraulics formulae should be applied. (Pages 3.25-3.26). As a guideline, a conduit over 100
metres in length in which a uniform flow pattern can develop might be classed as a sewer rather
than a culvert.
Secondly, it must be recognised that both culverts and sewers can operate under two basic types
of flow conditions, namely
(1) INLET CONTROL
(2) OUTLET CONTROL.
Under INLET CONTROL, the important factors are:
(1) Cross sectional area of the culvert barrel.
(2)Hydraulic efficiency of the inlet (related to the inlet geometry)
(3) Depth of headwater or amount of ponding.
Under OUTLET CONTROL, the important factors in addition to those for inlet control are:
(1) Elevation of the tailwater in the outlet channel.
(2) Slope, roughness and length of the conduit barrel.
Thirdly, it is important to bear in mind that the capacity required for any drainage structure is
governed by three very vital factors:
(1) Runoff.
(2) Debris.
(3) Maintenance.
•Index
•Next
•Main
Hydraulic Design:
INTRODUCTION (cont)
In any formula used to calculate runoff, several factors are involved which are only rough
approximations. Also, unless regular maintenance is carried out on clearing debris, conduit
capacity can be seriously reduced. By comparison to the scale of error which these factors can
induce, pipe wall roughness is a comparatively minor consideration.
In the pages following, the hydraulics of culverts and sewers (or long pipe-lines) are considered in
some detail. Before embarking on this we think it would be helpful and wise to discuss some
characteristics and deficiencies of culverts in particular and to make some comments thereon.
A reputable authority on the design of culverts from the Highway Engineer's viewpoint listed the
following desirable features:
Characteristics of Good Culvert Design
(a) The culvert, together with its appurtenant entrance and outlet structures, should properly take
care of water, bed-load and floating debris at all stages of flow.
(b) It should cause no unnecessary or excessive property damage.
(c) Normally it should provide for transportation of the material without detrimental change in flow
pattern above and below the structure.
(d) It should be designed so that future channel and highway improvement can be made without
too much loss or difficulty.
(e) It should be designed to function properly after fill has caused settlement.
(f) It should not cause objectionable stagnant ponds.
(g) It should be designed to accommodate increased run-off occasioned by anticipated land
development.
(h) It should be economical to build, hydraulically adequate to handle design discharge,
structurally durable and easy to maintain.
(i) It should be designed to avoid excessive poncling_ at entrance, which may cause property
damage, accumulation of'drift, culvert clogging, saturation offills or detrimental upstream deposits
of debris.
(j) Entrance structure should be designed to screen out material which will not pass through the
culvert, reduce entrance losses to a minimum, make use of the velocity of approach in so far as
practical, and by use of transitions and increased slopes as necessary, facilitate channel flow
entering the culvert.
(k) The design of culvert and outlet should be effective in re-establishing tolerable, non-erosive
channel flow within the right-of-way or within a reasonably short distance below the culvert.
(l) The outlet should be designed to resist undermining and washout.
(m) Culvert dissipaters (at outlet) if used should be simple, easy to build, economical and
reasonably selfcleaning during periods of heavy flow.
(n) Where culverts will be used by humans, cattle or fish, necessary provisions should be made.
(o) Culverts should not be death-traps for children.
The same authority listed culvert design deficiencies which are:
Common Culvert Deficiencies
(1) Poor functioning or damage to road or property due to faulty location of culverts.
(2) Barrel failures due to load or to differential foundation settlement.
(3) Barrel failures due to erosion or corrosion.
(4) Damage to roadway, outlet features, or to downstream properties due to excessive velocities.
(5) High maintenance costs due to clogging or channel silting.
(6) Inadequate facilities to catch drift which will not pass through culvert.
(7) Inadequate size.
(8) Culvert shape not in agreement with channel shape.
(9) No provision for maintenance access to ends of structure.
(10) Failure to anticipate future roadway widenings or improvements changing channel run-off
characteristics.
(11) Poorly designed inlets or poorly designed outlets.
Conclusions
•Index
•Next
It is important to understand the difference between inlet and outlet control flow conditions.
An outlet control designed culvert will tend to be on a flat gradient and will tend to flow generally
full or part full for part or all of its length. It will be designed almost certainly, to have a fully
submerged inlet at anything approaching peak flow conditions and frequently will have a
submerged outlet. Such a culvert runs severe risks of blockage from floating debris and could
also cause extensive damage downstream if discharging like a fire hose. In severe storm
conditions, upstream ponding is likely to increase dramatically with resulting property damage
apart from the very real risk of over-topping and loss of the whole embankment.
•Main
Hydraulic Design:
INTRODUCTION (cont)
It has to be remembered also, that calculations done to estimate the amount of water arriving at
the upstream end of a culvert are fraught with approximations. It must, then, be reasonable to
allow extra crosssectional area in the conduit to cope with the hazards of severe flooding andlor
timber, brushwood, rubbish, dead animals and low standards of maintenance.
An inlet control designed culvert will tend to be a larger conduit on a slightly steeper gradient
though not necessarily so. Its outlet end will discharge freely and never be submerged. Any
drastic increase in the amount of water arriving at the upstream end will be dealt with comfortably,
provided the inlet end itself will admit the extra flow.
TO SUM UP CULVERT DESIGN
Based upon our experience, which extends to75 years, it is Asset's opinion that over 95% of all
culverts are and SHOULD BE DESIGNED FOR INLET CONTROL conditions of flow. There is no
doubt that any culvert designed to flow under outlet control conditions runs a risk of causing
property damage (with resulting ciaims) and possibly a risk of failure.
DESIGN APPROACH
It is generally considered that there are two basic types of flow found in hydraulic culverts:
1) Flow with INLET CONTROL, and 2) Flow with OUTLET CONTROL.
In simple terms, inlet control means that varying conditions on the inlet side of the culvert affect
the amount of water flowing through. This is because the cross sectional area of the culvert barrel
is sufficiently large, and the outlet so free, that it can transport away all the water that can enter
through the inlet, even if the inlet is totally inundated and under hydraulic pressure. Thus it is
variations in the inlet condition that govern the flow rate in the culvert.
Conversely, outlet control means that the gradient of the pipe is so flat and the outlet so
encumbered that variations in conditions at the outlet affect the amount of water which can enter,
and thus can vary the flow capacity of the culvert.
For each type of control, different factors and formulae are used to compute the hydraulic
capacity of the culvert. Under inlet control, the cross-sectional area of the culvert barrel, the inlet
geometry and the amount of headwater or ponding at the entrance are of primary importance.
The roughness and length of the barrel have no effect on the capacity of the culvert. Outlet control
involves the additional consideration of the elevation of the tailwater in the outlet channel and the
gradient, roughness and length of the culvert barrel.
It is difficult in many instances to predict the type of flow likely to occur for any given discharge
and culvert installation. The type of flow or the location of the control is dependent on the quantity
of flow, roughness of the culvert barrel, changes in alignment, obstructions, sediment deposits,
type of inlet structure, flow pattern in the approach channel and other factors. In some instances
the flow control changes with change in discharge and occasionally the control fluctuates from
inlet control to outlet control and vice versa for the same discharge. Thus, to design culverts, it is
necessary to have an understanding of both types of flow, so that calculations can be made for
each type and the final design based upon the more adverse flow condition.
The following tabular and nomographic methods for selecting culvert sizes under different
conditions, are based upon systems developed by the U.S.A. Bureau of Public Roads. They have
been supplemented where necessary, and have been aligned specifically to the range of Asset
MULTI-PLATE structures of circular and PIPE-ARCH cross section.
•Index
•Next
•Main
Hydraulic Design:
CULVERT & CHANNEL HYDRAULICS
Modern road design concepts are based upon the aims of maximising cost-effectiveness of effort,
and minimising construction costs. This invariably necessitates construction based on a 'cut-andfill' concept. Material excavated from cuttings is used to fill the valleys and other low points along
the route. Consequently, earth embankments are almost invariably the cheapest type of valley
crossing which can be designed. In exceptional cases, elevated structures in the form of viaducts
can be adopted - for example, for aesthetic purposes, or perhaps to overfly areas of particular
ground problems such as unstable mine shafts.
Nonetheless, when a valley is to be crossed by an earth embankment for the purpose of carrying
a road or railway line, provision must be made for any river or drainage system to pass beneath
the embankment safely. The serious potential consequences of inadvertantly blocking the valley's
drainage, necessitates that any such drainage scheme must be properly designed. In particular,
this includes an assessment of the required normal flow conditions, as well as the extreme 'worst
case' conditions which are acceptable during time of flood.
In essence, culverts can either perform as simple open channels, or as pressure pipes,
depending upon the quantity of water passing through. Naturally, when water flows are low, the
culvert pipe acts as a simple open channel, but as inflow volumes rise, the pipe itself becomes
increasingly full.
The water level of the upstream side of the culvert can become sufficiently high that the inlet
mouth of the culvert becomes completely submerged. This is a normal phenomenon, and is an
essential part of a design, in the interests of economy. If this did not occur during occasional
storm conditions, then the selected culvert would be far too large and expensive for the vast
majority of its working life.
The point at which the culvert turns from open channel flow to pressure pipe flow will depend
upon the diameter, length and gradient of the pipe, and on the physical conditions at the outlet
side. If, for example, in a steep valley, flooding cannot occur on the downstream side of the
embankment, then full-bore flow may never be established. Conversely, in lowland areas, where
roads are carried on culverted embankments, flooding may occur on the downstream side,
submerging the outlet mouth of the culvert, and generating pressure pipe flow driven by a
differential water head as the upstream water level increases.
The embankment design detail may have to cater for upstream water ponding during storm
conditions. Prior to the design of the embankment, therefore, a study must be made of the
meteorological, physical and dimensional conditions of the catchment area. Such a study
provides the guidance for typical day-to-day flow capacity requirements, and expected storm runoff accumulation under exceptional conditions.
The objective of the hydraulic design is therefore to determine the most economic dimension that
can provide the passage of a designed discharge without exceeding the allowable head of water
which will build up on the upstream side of the embankment. It is Asset's view that designers
should attempt to design culverts to flow under inlet control at all times, thus avoiding the inherent
technical problems associated with 'full-bore' flow, large area water collection on both sides of the
embankment and correspondingly high water levels.
In practical terms, during the design of the embankment, soil mechanics considerations become
intrinsically involved with the hydraulic design of the culvert, as a cyclical and somewhat iterative
series of assumptions, modifications, and calculations are made to obtain the appropriate balance
between the various constraints.
•Index
•Next
•Main
Hydraulic Design:
•Index
•Next
The major components of a culvert normally include the inlet structure, the pipe barrel itself, the
outlet structure, and an outlet flow energy dissipator where necessary.
Inlet structures protect embankments from erosion, and are designed to increase the rate of
acceptance of flow of any given culvert cross-section. Outlet structures are designed to both
improve the outflow hydraulics, and to protect the outlet environment from scouring. When
considering the acceptability of concentrated flow into the down stream channel, it may be
desirable to design and install a turbulence-generative device to extract energy from the water
before releasing it from the culvert system.
The hydraulic operation of culverts may be classified into four categories:
1 . Flow with unsubmerged inlet.
2. Inlet submerged, but pipe only partially filled.
3. Inlet submerged, pipe completely filled, but free discharge at outlet.
4. Submerged inlet and outlet.
In addition, there are the special conditions pertaining at the transition points between the above
clearly-defined cases.
SOME THEORETICAL CONSIDERATIONS OF FLOW IN AN OPEN CHANNEL
In order to ensure adequate cleansing and flow, a culvert is usually laid at a slightly steeper
gradient than the average of the stream channel in which it is being inserted. It thus normally
comprises a hydraulic flow environment as illustrated below.
The water flow geometry in such an open channel is a function of the velocity, the slope and cross-section of the
channel and the roughness of the channel walls.
Hydraulic Design:
(cont)
At point A the water is streaming calmly with subcritical velocity. Roughness and possible
changes in crosssectional area are of primary importance in determining water flow and depth in
the channel. Any abrupt reduction in slope in section A would increase the water depth and
reduce the velocity of the water simply because of the loss of fall. Similarly, any sharp increase in
gradient causes velocity to increase and water depth to decrease accordingly. This occurs at the
inlet mouth of the culvert, as shown opposite. Therefore, the water flowing in section A is flowing
under OUTLET CONTROL since it is flowing at less than the critical velocity, and therefore any
change in outlet conditions induces an upstream effect on the water in section A.
It is interesting to note that the inlet structure of the culvert pipe actually comprises the OUTLET
CONTROL point of the upstream section of the system.
In section B, where the gradient is so great that the water is flowing with supercritical velocity, a
change of the slope would not affect the water flow. Any induced flow deceleration cannot
produce upstream-effects when the down-stream velocity is supercritical. The circumstances at
the entrance of the culvert are the important factors for the water flow, and consequently the flow
within the culvert, whilst super-critical, is controlled by the inlet conditions, and is thus under
INLET CONTROL.
Somewhere between the points A and B the water flow increases to a critical velocity and a
critical depth, dc
Thus:
dc x g = V2
v=
and subsequently
(dc x g)
v = mean velocity (m/sec)
where
g = gravitational acceleration (9.81 m/sec2)
dc = critical depth (m)
The critical velocity is the same as that for the propagation of a small surface wave. When the
velocity of the water flow reaches such a speed that any induced surface wave cannot travel
against the flow, the velocity is critical, becoming supercritical with any further increase.
If the flow velocity within the culvert is below critical speed, then any hydraulic effect or change at
the exit of the culvert will propagate upward through the culvert, and consequently the culvert flow
conditions will be under OUTLET CONTROL.
Note that the control changes from outlet control to inlet control when the velocity changes from
subcritical to supercritical.
As shown in the diagram above, if the external channel flow velocity is subcritical (as is often the
case), water depth increases rapidly, causing the development of a'hydraulic jump' at point C.
This results in a useful loss of energy due to the generation of strong turbulence. The high exit
velocity and the subsequent induced turbulence may cause localised erosion. This should be
catered for, where necessary, in the design of the exit structure. The water flow will continue
calmly at subcritical velocity after the hydraulic jump.
•Main
•Index
•Next
•Main
Hydraulic Design:
INLET CONTROL
•Index
•Next
CULVERTS FLOWING WITH INLET CONTROL
As described previously, inlet control means that the discharge being effected by the culvert is controlled at the
culvert entrance by the depth of the headwater (HW), the entrance geometry and the type of inlet (head wall,
wing walls, etc.).
Sketches of inlet-control flow are shown below.
PROJECTING END - UNSUBMERGED
This is the classical concept of inlet controlled flow, where the culvert gradient is sufficient to induce a
supercritical flow velocity throughout its entire length.
When the hydrostatic head at the entrance is less than 1.2 x D, air will break into the barrel, and the culvert will
flow under no pressure. Due to the sudden reduction in water area at the entrance, the water usually enters the
culvert in a supercritical condition. The critical depth is passed through at the entrance to the barrel.
PROJECTING END - UNSUBMERGED
Since the culvert slope and the barrel wall friction determine the flow condition in the culvert (open channel
flow), cases can occur where the absorption of energy by wall friction reduces the flow velocity below the critical
velocity within the culvert barrel. This happens where the rate of energy dissipation is higher than can be gained
from the barrel slope, so that the depth of flowing water increases in the downstream direction. Depending on
the tail water level, the supercritical flow may convert to subcritical flow through a hydraulic jump within the
barrel. The assessment of such a possible condition is not dealt with here, but can be addressed through the
attached bibliography list, and solved by the application of water surface profiles developed for open channel
design.
•Main
Hydraulic Design:
INLET CONTROL (cont)
•Index
•Next
PROJECTING END - SUBMERGED
TWhere the headwater height is greater than 1.2 x D, but the in-barrel velocity is supercritical with a free
discharge at the outlet, a partially-full pipe flow condition will normally result, as shown above.
The discharge being effected by the culvert will simply depend upon how much water is forced into the entrance
by the hydraulic head. The culvert is still flowing under INLET CONTROL, and the discharge can be calculated
by
Q = Cd x A x Sq. Root (2 x g x h)
Where h is the hydrostatic head above the centre of the orifice and A is the cross-sectional area. Cd is the
coefficient of discharge; common values varying from 0.62 for square-edged inlet structures, to 1.0 for well
rounded ones.
In the light of the above theoretical analyses, it is most important to recognise that UNDER INLET CONTROL,
THE ROUGHNESS AND LENGTH OF THE CULVERT BARREL AND OUTLET CONDITIONS ARE NOT
FACTORS IN DETERMINING CULVERT CAPACITY.
There is therefore no advantage in specifying smooth wall structures into such designs, and under inlet control
conditions, where corrugation roughness can be ignored, the inherent advantages of continuous flexible ASSET
structures makes them considerably more attractive than any other type of culvert.
As explained above, for inlet controlled conditions, culvert design is reduced to the determination of the expected
excess water height on the upstream side of the embankment, for any given water flow through the entrance.To
reduce numerical calculations,the following nomograms have been developed to give headwater discharge
relationships for culverts flowing with inlet control through a range of headwater depths and discharges. In
particular, they include the case of non-circular pipe-arch sections which are more difficult to quantify
numerically.
•Main
Hydraulic Design:
INLET CONTROL
Nomograph No. 1
MULTIPLATE PIPE CULVERT WITH INLET CONTROL
Nomograph No. 1
Inlet control nomograph for corrugation steel pipe culverts. Where possible it is recommended
that HW/D is kept to a maximum of 1.5 and preferably to no more than 1.0.
•Index
•Next
•Main
Hydraulic Design:
INLET CONTROL
Nomograph No. 2
MULTIPLATE PIPE CULVERT WITH INLET CONTROL
Nomograph No. 2
Inlet control and headwater depths for pipe arch culverts. Headwater depth should be kept low
because pipe-arches generally are used where headroom is limited.
•Index
•Next
•Main
Hydraulic Design:
OUTLET CONTROL
If the gradient of a culvert is insufficientto generate a flow velocity equal to or greater than the
critical velocity, then downstream effects will be transmitted upstream through the culvert, and
theculvert is flowing under outlet control.
Culverts flowing with outlet control can flow with the culvert barrel full or part full as shown in the
following figures.
•Index
•Next
•Main
Hydraulic Design:
OUTLET CONTROL (cont)
The calculation procedures given here provide methods for the accurate determination of
headwater depth for the flow conditions shown in the first three cases. With regard to the last
figure shown opposite, being a non-full flow condition, the given solution for headwater depth
decreases in accuracy as the headwater decreases towards 0.75D. It is invalid where HW<0.75D.
The head H or energy required to pass a given quantity of water through a culvert flowing with
outlet control is:
H = Hv + H e + H f
or
H=
V2 +
2g
ke x V2
2g
+
2gL x V2
K2 X R4/3
simplified for full flow to
H=
1 + ke + 2gL
K2 x R4/3
x
V2
2g
......... (3.2)
•Index
•Next
•Main
•Index
Hydraulic Design:
•Next
The figure on page 3.15 shows the terms of equation 3.2, where
H = loss of energy = energy required to pass a given quantity of water through a culvert
flowing in outlet control (m)
Hf = friction loss (m)
Hv = V2 = velocity head (m)
2g
He = ke x v2 = entrance loss (m)
2g
ke = entrance loss coefficient as shown below.
L = length of culvert (m)
K = Manning's coefficient (m1/3/sec)
G = gravitational acceleration (m/sec2)
R = hydraulic radius (m)
v = mean velocity in the culvert barrel (m/sec)
TYPE OF INLET
Projecting from fill (no headwalls)
Headwall, or headwall and wingwalls square edge
End-section conforming to fill slope
Bevelled Ring
ke
0.9
0.5
0.5
0.25
The equation for H can be readily solved using the full flow nomograms 5 and 6.
Because of the low velocities in most entrance pools, the upstream velocity is considered to be
negligible, and thus the headwater depths obtained using charts can sometimes be slightly higher
tjian might occur in practice.
The headwater depth, HW, can be expressed by
HW = H + ho - (L x So)
...........(3.3)
where: ho is equal to the tailwater depth TW, when the outlet is submerged.
L is the culvert length.
So is equal to the slope gradient of the culvert invert. If gradient = 0.4%, then So = 0.004.
When ho is less than D or the waterflow so small that the tailwater elevation is below the top of the
culvert (figures on previous pages), equation 3.3 is not valid.
To get an approximate answer in these cases, ho is the greater of the two values:
TW depth
or
0.5 (dc + D)
dc , is the critical water depth at the outlet for a given water flow, and can be taken from charts A
and B on the following pages.
•Main
Hydraulic Design:
CHART A
•Index
•Next
•Main
Hydraulic Design:
CHART B
•Index
•Next
•Main
Hydraulic Design:
•Index
•Next
For a different Manning's coefficient (Kx), from that (K), shown on the chart, use the length scales shown with an
adjusted length Lx calculated by
Lx = (K)2 x L
(Kx)2
Manning's coefficient can be taken from the following graph:
•Main
Hydraulic Design:
NOMOGRAM 5
•Index
•Next
•Main
Hydraulic Design:
NOMOGRAM 6
•Index
•Next
•Main
Hydraulic Design:
SUMMARY of CULVERT SIZING
SUMMARY OF PROCEDURE FOR SELECTION OF CULVERT SIZE
Step 1 List design data (See suggested tabulation form below)
Step 2 Choose type of culvert.
Step 3 Assume inlet control and determine the headwater depth HW.
Step 4 Assume outlet control and calculate HW according to equation 3.3.
H can be taken from charts A and B.
ho is the greater of the two values TW and 0.5 (dc + D).
Step 5 Compare the results of HW derived from steps 3 and 4. If the calculation under the
assumption of inlet control gives the greater headwater level, then the water flow in
the culvert is under inlet control.
Step 6 Determine the outlet velocity, thus making it possible to estimate the danger of erosion.
With inlet control the velocity is calculated using Manning's formula:
V = K R2/3 So1/2
With outlet control the velocity is:
v = Q
Ao
Ao is the cross sectional area of flow in the culvert barrel at the outlet.
•Index
•Next
•Main
Hydraulic Design:
WORKED EXAMPLE
•Index
•Next
WORKED EXAMPLE (See partially completed hand-written tabulation form below.)
Step 1 Design discharge 0 = 16 m3/s
Allowable headwater AHW = 3.2 m
Tailwater TW = 2.0 m
Slope S = 0.4%
Length L = 100 m
Step 2 Choose a circular pipe with projecting end (Column C on nomogram l.)
Step 3 INLET CONTROL CALCULATION
Assume HW = 1.5
D
From nomogram 1, D = 2.43 m
HW = 1.5 x D
= 1.5 x 2.43
= 3.65 m AHW
Now on nomogram 1, assume D = 2.74 m
Therefore, HW = 1.1
D
HW = 1.1 x 2.74
= 3.01 m AHW
(This is slightly less than the permitted maximum of 3.2 rn, and is therefore acceptable.)
•Main
Hydraulic Design:
WORKED EXAMPLE (cont)
•Index
•Next
Step 4 OUTLET CONTROL CALCULATION
Since D = 2.74 m, K can be read off the graph at
page 6 as K. = 47.5
It can be seen that nomogram 5 gives K = 31.8
for a diameter of pipe = 2.74 m. This is arrived at
by examination of the Manning's Coefficient
table on that nomogram, and interpolating
between 31.2 and 32.1.
Length correction on the nomogram is necessary:
Lx = (31.8)2 x 100
(47.5)2
= Approximately 45 m
On Nomogram 5, Connect L = 45 m and D = 2.74 m.
Read off H = 1.27 m for a 16 cumec flow.
From chart A, read off dc = 1.80 m
0.5 (dc + D)
= 0.5 (1.80 + 2.74)
= 2.27 m
ho = 2.27 m
.........(3.3)
HW = H + ho - (L x So)
= 1.27 + 2.27 - (100 x 0.4 ) = 3.14 m
100
Step 5 HW from step 4 (OUTLET CONTROL)
is greater than
HW from step 3 (INLET CONTROL).
Therefore, the culvert is flowing under outlet control.
Step 6 v = Q
Ao.
=
16
5.25
= 3 m/s
This is quite a high velocity, and therefore some protection
against erosion might be necessary.
•Main
Hydraulic Design:
SEWER DESIGN
•Index
•Next
SEWER DESIGN
The Manning and Kutter equations are the more common flow equations used today. These formulae are based
on fluid resistance as it applies to the turbulent flow conditions most often experienced in storm sewers.
Both the Manning and Kutter Formulae are widely used in open channel flow calculations, but the Manning
Formula may also be applied to closed conduit and pressure flows.
Nomogram 7 may be used for estimating steady uniform flows for pipes flowing full, using the Manning Equation.
In cases where pipes are only flowing partly full, the corresponding hydraulic ratios may be determined from
Charts C and D.
NOMOGRAM 7 - Solution of Manning's Formular for Sewer Pipes Flowing Full
•Main
Hydraulic Design:
SUMMARY
•Index
•Next
Introduction:
Index
Background to Usage
Next
ARMCO Culverts were firstly installed in the United Kingdom in 1913,
having been developed in the USA in 1896. Since that time,
corrugated steel pipe has become a major construction material
throughout the world.
ARMCO construction and drainage products were first approved for
use by the Department of Transport in 1954 and have subsequently
been installed on numerous sites throughout the United Kingdom.
ASSET International as successors to ARMCO Ltd. in the United Kingdom, have continued to serve the market
to ensure that they remain at the forefront of the corrugated steel construction products industry.
ASSET International's corrugated buried steel products have Highways Agency approval and BBA certification
for all products in this manual contained within the Highways Agency Design Manual for Roads and Bridges.
When designed, constructed and installed in accordance with Highways Agency requirements, a 120 year design
life is specified; an independent testament to the proven durability of corrugated steel buried structures.
The continuing promotion of good engineering practice has instigated the publication of this updated design
manual, which has been prepared to provide engineers, at all stages of a project, with useful guidance and
assistance in the use of corrugated steel buried structures.
Perhaps even more impressive than the durability to these structures is the variety of applications and shapes
developed over past decades. Simple arches and circular culverts have developed into pipe-arch and underpass
shapes and these in turn have been joined by the impressive 'Super-Span' structures for such applications as
major highway and railway crossings.
Introduction
•Main
•Index
•Next
In assessing the feasibility of using a buried corrugated steel structure to meet a particular need for a conduit, it
is first necessary to examine the end use.
These functions can be broadly categorised as:CULVERT / STORM SEWER * VEHICULAR * PEDESTRIAN / LIVESTOCK * UTILITY
The distinction between culverts and storm sewers is made mostly on
the basis of length and types of inlets / outlets. A culvert is defined as
an enclosed channel serving as a continuation of and/or a substitute
for an open stream, where that stream meets an artificial barrier such
as a roadway or embankment of any kind. A storm sewer on the
other hand, is a collection system for storm and surface water,
exclusive of domestic and industrial wastes and is usually a series of
tangent sections with manholes or inlets at all various points.
A culvert may also be classified as a type of bridge. Normally, the rigid definition of a bridge requires that the
deck of the structure also be the roadway surface, and simply an extension of the roadway. The use of
corrugated steel buried structures alters this conventional definition.
Full round pipe is suitable for many applications, but a pipe-arch profile may be more suitable where there is
limited headroom.
This low wide pipe-arch profile is hydraulically more efficient at low water levels than a round pipe.
Many bridges have been identified as being in need of repair and maintenance. These structures can often be
replaced or strengthened quickly and economically with corrugated steel buried structures.
Introduction:
APPLICATIONS
Index
Next
Vehicular Underpasses
Conventional structures for rail and vehicular underpasses have
traditionally been of concrete or steel construction.
In the late 1960's, developments were made which involved adding
stiffening members to corrugated steel bolted plate products which
permitted the use of larger spans. This concept made it possible to
achieve the economies and speed of construction of corrugated steel
with clear spans in excess of twelve metres, a size range often
suitable for road or rail underpasses.
The range of shape and sizes available in Multiplate MP200 and Multiplate 'Super-Span' profiles is given later on
in this manual.
In the years since their introduction, this range of structures have proven their ability to meet cost-effectively the
needs of many applications road and rail projects, particularly as bridge replacements where a rapid, economic
solution is required.
Pedestrian / Livestock Underpasses
Pedestrian underpasses find their principle use in protecting people
who would otherwise be forced to cross dangerous roads.
Safety is not the only advantage. Where an institution is divided by a
busy road, a buried corrugated steel underpass is often the most
convenient and economical solution.
Similarly, large farms can also be divided by a road, requiring livestock to make repeated, dangerous crossings.
A cattle pass under the road is often the most satisfactory solution to this problem.
Corrugated steel underpasses can be made attractive and functional by suitably selected end treatments, interior
painting, lighting and paving.
Where speed of installation is of the essence - in order to reduce closure time of an existing road for instance the structure can be pre-assembled, either complete or in two halves and lifted into position onto a prepared bed.
Introduction:
APPLICATIONS
Index
Next
Utilities
Utilities must often pass below or between buildings or beneath
embankments or other surface obstacles. Good engineering practise
calls for placing utilities within a conduit to protect amongst other
things against direct loading, impact, corrosion, temperature
extremes, sabotage or vandalism.
A conduit large enough to walk through provides better access for inspection and repair. Brackets, hangers or
cushioning bases are easily installed. Existing utility lines can also be encased with two piece sections of
corrugated steel conduit bolted together.
Other Applications
Stockpile Reclaim Tunnels
For many years, corrugated steel products have been used for
materials recovery tunnels. These can range from comparatively
small sizes of about three metre diameter up to vehicular size tunnels
where road or rail vehicles pass through the tunnel to load from
hoppers placed at intervals along the tunnel roof.
Introduction
Index
Next
ECONOMIC CONSIDERATIONS
Corrugated steel has been used for many years for a wide range of
important functions in every sector of construction. It is a material for
which design parameters have been developed and correlated to
decades of actual experience. Using proved techniques, the engineer
confidently can select the corrugated steel product and design that is
right for his particular job.
The decision to select any particular material or alternative should be on careful analysis. It is fundamental
responsibility of the engineer to make the right choice on the basis of fact. To evaluate corrugated steel products
objectively for specific uses calls for a value analysis approach on the part of the engineer. When given this type
of consideration, corrugated steel will frequently justify selection in the best interest of the client.
Some of the benefits to be gained by the use of corrugated steel structures are:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Strength and durability.
Ability to accommodate differential settlement.
Resistance to disjointing.
Quick straight forward design process.
Lightweight; minimising foundation requirements.
Ease of handling during construction.
Low tech assembly procedures.
Speed of manufacture.
Speed of installation.
Ready for use immediately after backfilling.

our Design Manual

Transcription

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