Discharge of Conditions_P_2016_00474 Approval in Principle - AIP Nurton Bridge

27 Pages·2016·0.41 MB·English

BRANSTON LOCKS DEVELOPMENT

NURTON BRIDGE

SCC STRUCTURE REFERENCE NUMBER: - B3933

APPROVAL IN PRINCIPLE

REVISION (1.0)

JANUARY 2016
Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

1. NAME OF SCHEME

1.1 Type of highway

Road number (TBC), 10.8 metre wide single carriageway crossing the Trent and Mersey
canal west of Burton, east of Tatenhill village.

1.2 Permitted traffic speed

30 mph (48 kph) – Proposed

1.3 Existing restrictions

None.

2. SITE DETAILS

2.1 Obstacle crossed

Trent and Mersey Canal

3. PROPOSED STRUCTURE

3.1 Description of Structure and working life

The proposed structure is to be a road bridge crossing the Trent and Mersey Canal,
providing access to a new development called Branston Locks.

The new bridge is to consist of a single span reinforced concrete deck supported on
reinforced concrete cap beam and sheet pile abutments. The widened carriageway cross
section will consist of a 10.8 metre wide single carriageway with a 3.5 metre wide
combined foot/cycle way to the south side and a 2.5 metre wide footway to the north side.
All services will be carried in the footways of the new structure.

The clear span of the bridge between abutment faces will be approximately 16.130
metres, with a 16.5 degree skew.

The wingwalls are to comprise of sheet piles and are to be structurally separate from the
abutment sheet piles. Following consultation and outline approval by the Canal and River
Trust, (CRT), the exposed faces of both the wingwalls and abutments are to be clad in
masonry to match as closely as possible the adjacent Branston Canal Bridge.

3.2 Structural Type

The single span integral bridge is to be cast onto reinforced concrete capping beams
supported by load bearing sheet piled abutments. The structure is to have a design
working life is to be 120 years (working life category 5).

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Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

Superstructure – Composite concrete deck consisting of ‘TY11’ series precast beams and
cast insitu reinforced concrete forming a traditional filler beam deck. The spaces between
the ‘TY11’ beams will accommodate services prior to forming the filler beam deck.

Substructure – Cast insitu reinforced concrete cap beam and sheet pile foundations.
Approach retaining walls either side of bridge to be sheet pile walls clad in masonry and
sloped embankments.

3.3 Foundation Type

The sheet piles forming the abutments are to be designed to provide vertical support to
the bridge deck, and lateral resistance to earth pressure, thermal and longitudinal loads.
Allowance for corrosion of the sheet piles will be made with reference to standard
published wastage rates for steel in contact with soil.

Sheet piles will be toed into Mercia rock mass approximately 11.0m below existing bridge
Towpath level.

3.4 Span Arrangements

The clear straight span between abutment walls will be approximately 16.13 metres,
(16.830 metre skew span). Based on precast beam manufacturer’s guidance a minimum
length of 500mm should be included to accommodate the integral bridge bearings. Based
on a 950mm cap beam width it is intended to use a minimum bearing distance of 500mm
for each bearing.

Thus the bridge deck will have a single straight or square span of approximately 16.83
metres, skew angle of 16.5º, (difference of 16.5º normal to the foundations), and a skew
span of 17.5 metres.

3.5 Articulation Arrangements

Integral deck and abutment is to have no expansion joints or bearings. Global thermal,
braking and traction effects are to be resisted by the soil behind the abutment sheet piles,
which will be designed for increased K* lateral pressure in accordance with BA 42/96 –
Design of Integral Bridges. The transition between the approach embankment and the
bridge deck will be formed using a proprietary geogrid in two layers within the compacted
fill. The geotextile will be fixed to the back of the piles using a bodkin connection below
cap beam level. The geotextile transition will maintain the retained soil stability while the
structurally integral bridge superstructure/abutment is allowed to move via flexure of the
sheet piles.

3.6 Proposed classes / levels

3.6.1 Consequence class

Consequence class to be CC2 (Medium) in accordance with Table B1, BS EN 1990; 2002.

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Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

3.6.2 Reliability class

Reliability class to be RC2 : KFI = 1.0

3.6.3 Inspection level

Inspection level to be IL2 in accordance with Table B5, BS EN 1990 ; 2002

3.7 Road restraint system type

Parapets are to be a minimum of 1.1 metre high, (1.4 metre high for combined cyclist /
pedestrian footway), concrete normal containment N2, level B impact severity level.

The external exposed faces of the parapets are to be brick faced and the parapets will be
topped with reconstituted stone copings.

Road restraint barriers are also required on the approaches and departures to the bridge,
consisting of N2 containment and W2 working width. The N2 road restraint barrier
transition to parapets is to be confirmed.

As the road speed will be less than 50 mph in accordance with TD19/06 an in-house
assessment has been undertaken to verify the Vehicle Road Restraint System
requirements. The internal faces of the parapets are to be brick faced and the parapets
will also include stone copings.

3.8 Proposed Arrangements for Maintenance and Inspection

3.8.1 Traffic management

Inspection and future maintenance to the bridge deck surface is to be by single way
working controlled by temporary traffic signals or stop/go boards in accordance with
Chapter 8 of the Traffic Signs Manual. Inspection and future maintenance to the bridge
deck soffit and abutments may require permission from the Canal and River Trust.

3.8.2 Access

Access to the deck soffit is to be by a platform mounted a boat, underbridge inspection
vehicle, scaffolding or ladder. All will require permission from the Canal River Trust.

3.9 Sustainability issues considered – Materials and finishes

Deck: Composite pre-stressed precast concrete TY11 beams and insitu reinforced
concrete deck, protected by sprayed waterproofing, indicator mesh and topped with
bitmac road and kerb construction.

Concrete to the deck and superstructure to be strength class class C40/50 IIA (6-20% fly
ash) or IIB-S (21-35% ggbs) to B.S. 8500-1:2006. Exposure classes considered – XD1 to
deck soffit and XD3 to parapets.
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Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

Abutments : S240GP PU32 sheet piles, with sections coated in two coats of cut back
bitumen emulsion, and otherwise surmounted with a concrete capping beam, integral with
deck slab. All visible faces clad in masonry class B engineering brick to match nearby
Branston Canal Bridge. The PU32 sheet piles may be upgraded with additional steel
sections as required during the detailed design to meet required pile stiffness
requirements.

Wingwalls : S240GP PU32 sheet piles, with sections coated in two coats of cut back
bitumen emulsion. All visible faces clad in masonry class B engineering brick to match
nearby Branston Canal Bridge.

Concrete to the abutments and foundations to be C32/40 IIA (6-20% fly ash) or IIB-S (21-
35% ggbs) to B.S. 8500-1:2006. Mass concrete fill to be ST1 to BS8500. Exposure
classes considered –XC2 to foundations, and XD3 to abutments.

Reinforcement to be grade B, Fy=500N/mm² type B or C to comply with B.S. 4449:2005

Finishes - The finishes to the concrete surfaces are to be as follows :-
Foundation buried formed surfaces – F1
Foundation buried unformed surfaces – U1
Abutment walls exposed surfaces – F3
Abutment walls hidden surfaces – F1
Deck – vertical exposed surfaces – F3
Deck – vertical hidden surfaces – F1
Deck – horizontal exposed surfaces – U3
Deck – horizontal hidden surfaces – U1
Deck – surfaces to receive waterproofing – U5

All exposed concrete surfaces are to be impregnated in accordance with DMRB standard
BD 43/03.

Waterproofing – The deck slab will be waterproofed using a permitted waterproofing
system in accordance with clause 2003 of the Specification for Highway Works and to the
requirements of BD 47/99. Where required to protect the waterproofing system indicator
mesh will be used.

3.10 Risks and hazards considered for design, execution, maintenance and demolition.
Consultation with and/or agreement from Principal Designer.

The risks and hazards to both the general public and the workforce during the
construction, operation and maintenance of the bridge will be fully considered in the
Design Risk Assessment and reviewed regularly during the detailed design phase.

The key risks considered are :-

• Working at height
• Working over and adjacent to water
• Stability of structures during construction
• Safety of pedestrians during construction
• Construction methods
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Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

• Safety during maintenance
• Vehicle impact on the bridge superstructure and substructure
• Services over and under the bridge.
• Stability of canal and infrastructure.

3.11 Estimated cost of the proposed structure together with other structural forms
considered (including where appropriate proprietary manufactured structure) and
the reasons for their rejection (including comparative whole life costs with dates of
estimates)

Estimated capital cost of the proposed structure only (including preliminaries and
temporary works, but not including service diversions) is £1.7 million.

a. Upgrade and Widening of Existing Branston Canal Bridge

Description Upgrade and widening of existing Branston Canal Bridge
Cost £1.8M August 2015 (Spons price database book with inflation factor)
Duration 30 weeks
Summary The upgrade and widening of this bridge and approaches would require
unacceptable disruption to highway and canal users due to long diversions
this option was rejected for social and political reasons.

b. New Steel Beam and Concrete Composite Deck Slab Bridge

Description New steel beam and concrete composite deck slab Bridge.
Cost £1.5M August 2015 (Spons price database book with inflation factor )
Duration 26 weeks
Summary Scheme rejected on practical construction issues by Canal River Trust
based on scheme archive information because of the need to support
formwork over the canal in order to cast insitu parapet plinths.

c. New All Steel Bridge.

Description New all steel beam Bridge using steel deck and parapets.
Cost £1.3M August 2015 (Spons price database book with inflation factor)
Duration 20 weeks
Summary Scheme rejected due to aesthetic issues as bridge would span over canal
conservation area and would not blend with existing environment.

d. New Filler Beam Deck with Reinforced Concrete Spread Foundations.

Description New Filler Beam Deck and RC Spread Foundations
Cost £2.5M August 2015 (Spons price database book with inflation factor)
Duration 34 weeks
Summary Scheme rejected due to high water table, 0.9m from existing ground level
which would require extensive temporary and drainage works. Also due to
soft layers of soil stratum at depth which will increase the risk of long term
settlement of this form of construction.
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01.doc
Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

3.12 Proposed arrangements for execution

3.12.1 Traffic Management

Vehicular and pedestrian access along the new road and over the canal will not be
maintained during the construction of the bridge. The Construction Programme for the
works is to be discussed by the Main Contractor with the Canal and River Trust in order to
agree canal and towpath closures requirements to suit.

3.12.2 Service Diversions

No existing services are to be diverted, new services will be laid through bridge deck but
this has yet to be agreed.

3.12.3 Interface with existing structures

The canal embankments adjacent to the bridge will be sheet piled prior to construction of
the bridge proper subject to agreement with the Canal and River Trust. The new sheet
piled abutments and wingwalls will be set back approximately 4.0 metres from the existing
canal embankments to prevent any surcharge loading.

4. DESIGN CRITERIA

4.1 Actions

4.1.1 Permanent actions

Normal weight reinforced concrete, density γ = 25.0 kN/m³
Hot rolled asphalt, density γ = 23.0 kN/m³

4.1.2 Snow, wind and thermal actions

Snow loading is not to be considered.

Wind loading in accordance with Section 8 of BS EN 1991-1-4 and NA to BS EN 1991-1-4.

Thermal actions considered in accordance with Section 6 of BS EN 1991-1-5 and NA to
BS EN 1991-1-5, adopting Approach 2 for determination of vertical temperature difference
component.

4.1.3 Loading relating to normal traffic under AW regulations and C&U regulations

Load Models 1 & 2 in accordance with BS EN 1991-2 ; 2003 and associated National
Annex.

4.1.4 Loading relating to General Order traffic under STGO regulations

Load Model 3 – SV100 vehicle in accordance with the UK NA to BS EN 1991-2 ; 2003
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01.doc
Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

4.1.5 Footway or footbridge live loading

Load Model 4 – 5 kN/m2 in accordance with BS EN 1991-2 ; 2003

4.1.6 Loading relating to Special Order Traffic, provision for exceptional abnormal
indivisible loads including location of vehicle track on deck cross section.

Not applicable

4.1.7 Accidental actions

Accidental actions on the bridge deck to be in accordance with clause 4.7.3 of BS EN
1991-2 and NA to BS EN 1991-2

The abutments are beyond 4.0 metres of the canal embankments so do not need to be
designed for accidental loading due to boat impact.

4.1.8 Actions during execution

For the purpose of temporary works design, density of fresh concrete to be taken as γ =
26 kN/m³.

4.1.9 Special rules for combination of actions

No special requirements

4.1.10 Any special action not covered above

Fatigue verification to be carried out using Fatigue Load Model 3 of BS EN 1991-2

4.2 Heavy or high load route requirements and arrangements being made to preserve
the route, including any provision for future heavier loads or future widening

Not applicable

4.3 Minimum headroom provided (including allowance for vertical sag compensation
and maximum deflection of structure)

Minimum headroom to be 2.700 metres above towpath, (including allowance for deflection
of deck and settlement of supports), based on guidance from the Canal and River Trust.

Minimum lateral clearance to abutment wall faces from the canal embankments to be 2.0
metres, based on guidance from the Canal and River Trust.

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01.doc
Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

4.4 Authorities consulted and any special requirements

Staffordshire County Council
Canal and River Trust
Statutory Undertakers
East Staffordshire Borough Council
Environment Agency

4.5 Standards and documents

4.5.1 List of relevant documents from the TAS

See attached schedule, Appendix A, (TAS September 2015)

4.5.2 Additional relevant standards and publications

• CIRIA Report C660 – Early-age thermal crack control in concrete

• SCI Publication 163 Integral Steel Bridges – Design Guidance

• SCI Publication 180 Integral Steel Bridges – Worked Example

• Technical Guide 13 Integral Concrete Bridges to EC2: Worked Example

• RFCS-CT-2005-00042 Design of Integral Abutment Bridges with small and medium
spans

• EUR 24224 EN - Economic and durable design of composite bridges with integral
abutments

• Guidance from Canal and River Trust as and when required see 4.7.

4.6 Proposed departures from Standards and documents given in 4.5.

Although not part of the bridge design a Departure from standard for the Vehicle Restraint
System, (VRS), is proposed on the south east approach to accommodate an adjoining
pedestrian ramp and stair access. The VRS will be reduced in length from 30m to
approximately 15m. The VRS departure is to be submitted separately to the bridge design
with a CAT 0 design and check certificate for the VRS foundation designed to BD70/03.

4.7 Proposed methods for dealing with aspects not covered by Standards and
documents in 4.5

Where standards and documents stated in 4.5 do not accommodate the design then
Canal and River Trust standards will be used as guidance.

4.8 List of record of options and choices (for Category 2 or 3 checks)

None
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01.doc
Technical Approval of Highway Structures January 2016

Client / Scheme: Structure: Engineers:
Staffordshire County Council Nurton Bridge (B3933) SCC / Amey
New Development Branston Locks Development
_____________________________________________________________________________________

5. STRUCTURAL ANALYSIS

5.1 Methods of analysis proposed for superstructure, substructure and foundations.

Superstructure

The deck superstructure will be modelled as a two dimensional (2D) plane frame grillage
using computerised analysis software package STRAP. Applied loading will be
apportioned to the grillage members using the STRAP pre-processor software for bridge
decks. The STRAP Bridge Module will be utilised to analyse the deck in accordance with
the Eurocodes using the relevant Dynamic Load Models.

A torsionless grillage analysis will be used to model the bridge in both the pinned
supported and fixed end states to obtain the worstcase parameters, (flexure, shear and
deflection), for the design of the bridge deck as a conservative approach.

Substructure

Substructure and foundations will be analysed using propriety soil structure interaction
software Prosheet provided by Arcelor Mittal for preliminary design, which is similar to
software packages utilised by SCI 163 “Integral Steel Bridges – Design Guidance” to
establish boundary stiffness parameters. Detailed design will utilise simple elastic hand
calculations and computer spreadsheets, using output data from the fixed end
superstructure grillage in conjunction with all relevant loads determined for braking,
thermal movement and accidental load effects will be utilised to develop a design
envelope of load effects. Consideration will be given in the design of the effect of the
staged construction sequence.

As a detailed check on the above approach the structure will be modelled via STRAP as a
plane frame, ( goal post portal structure ), using suitable spring supports to simulate soil
stiffness parameters. This Winkler Spring Model approach is also valid in accordance with
SCI 163 “Integral Steel Bridges – Design Guidance”.

5.2 Description and diagram of idealised structure to be used for analysis.

See Appendix C, idealised structure diagrams for deck analysis and foundation design.

5.3 Assumptions intended for calculation of structural stiffness.

Gross element stiffness will be used and element properties will be based on uncracked
sections. The following properties will be used in the calculation of element stiffness :-
Esteel = 205 kN/mm² , Econc = 31 kN/mm² (concrete grade C40/50 short term).

For thermal deformation, settlement, shrinkage and effects of creep, a reduced stiffness
corresponding to the cracked section is to be used.

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