CLIENT'S REQUIREMENTS
1. A bridge to carry a new three-lane highway across a series of existing rail tracks and sidings located in a major urban area in the North of England. The vertical alignment of the new highway is constrained by the clearances required above the railway and by the presence of an existing highway viaduct which the new highway has to pass beneath. The horizontal alignment of the new highway bridge is fixed due to the close proximity of two leaf piers supporting the existing viaduct, which the new road has to pass between. These constraints are illustrated on Figure 1. Both the new highway and the existing ground are horizontal (i.e. they have a gradient of 0% ).
2. The new bridge is to have three traffic lanes with a total width between kerbs of 11.0 m. In addition, a 2.0 m wide footway is to be provided at each side of the highway.
3. The required minimum clearance to the overhead viaduct must be achieved for the completed new bridge. The minimum clearance to the existing railway must be achieved at all times during construction and for the completed new bridge.
4. Erection of the main superstructure elements for the spans over the railway must take place during rail possessions. Once these elements have been erected, further work on the bridge superstructure over the rail tracks and sidings can be carried out at any time, provided that full protection is provided to prevent any items of the works or plant falling onto the tracks.
5. Rail track possessions can be allowed as follows:
Main tracks: Any weekend, between 22:00 hrs Saturday evening and 14:00 hrs Sunday afternoon.
Sidings: Any weekend, between 20.00 hrs Friday evening and 07.00 hrs Monday morning. In addition, closures of the sidings can be arranged (if necessary) for two non-consecutive periods each of two weeks duration.
6. A minimum horizontal clearance of 4.5 m shall be provided between any rail and the face of any piers or abutments to the new bridge above ground level, to avoid the need to design these elements for accidental impact.
IMPOSED (VARIABLE) LOADING
7. Vertical traffic loading 10.0 kN/m2
Note: alternatively, where local wheel effects are likely to be more critical, a 100 kN wheel load applied to a plan area of 0.3 m x 0.3 m shall be considered.
Longitudinal loading 750 kN (horizontal load applied at highway surface or via the bridge bearings, where these have been provided).
Lateral wind loading 2.0 kN/m2 (acting on a max. vehicle height of 2.5m)
All the above loads are characteristic (unfactored) values.
SITE CONDITIONS
8. The characteristic temperature range = 50ºC.
9. Typical ground conditions:
Existing ground level - 2.0 m Made ground. SPT (N) values vary between 1 and 5.
2.0 m - 7.0 m Alluvium. Sand and Gravel. SPT (N) values vary between 10 and 20.
7.0 m - 12.0 m Soft Clay. Cu = 25 kN/m2.
Below 12.0 m Firm to Stiff Clay. Cu = 75 kN/m2.
Groundwater was encountered in the alluvium during the ground investigation. The firm to stiff clay was proven to a depth of 30.0 m below existing ground level.
10. Detailed design of any wingwalls required for the abutments or any intermediate supports (although these must be shown on your drawings). Detailed design of any vehicle containment parapets. Detailed consideration of collision load effects and any stresses caused by temperature differences between the highway surface and the deck soffit.
SECTION 1 - CONCEPTUAL DESIGN
Prepare a design appraisal with appropriate sketches indicating two distinct and viable solutions for the proposed bridge including the foundations for the end and any intermediate supports. Indicate clearly the functional framing, load transfer and stability aspects of each scheme. Identify the solution you recommend, giving reasons for your choice.
SECTION 2 - DETAILED DESIGN
For the solution recommended in Section 1:
2.1 Detailed Design Calculations
Prepare sufficient design calculations to establish the form and size of all the principal structural elements for the new bridge. You are required to produce calculations for all the principal structural members including a typical section of the bridge superstructure (including any beams and deck slab, as appropriate) and one of the end supports and its foundations. You are NOT required to produce detailed design calculations for any intermediate supports. Calculations are also required to show that the structure remains stable during all stages of construction.
2.2 Drawings and Construction Process
a). Prepare general arrangement plans, sections and elevations to show the dimensions, layout and disposition of the structural elements and critical details for estimating purposes. All drawings must be suitably annotated giving details of material specifications and any special construction sequences, as appropriate.
b). Prepare a detailed method statement (including supporting risk assessments) for the safe construction of the bridge and an outline construction programme in the form of a bar (or Gantt) chart.
SECTION 3 - PRESENTATION
Up to 10 marks will be awarded based on the quality of the presentation of the written work. This includes the layout and structure of the report as well as correct spelling, grammar and referencing. (Marks for the quality of presentation of the calculations and the drawings are included in the marks awarded for 2.1 and 2.2, respectively).
SECTION 4 - PROGRESS & ORIGINALITY
Up to 10 marks will be awarded based on the progress made throughout the study period (this will be assessed primarily during the small group-based tutorial sessions) and on the degree of originality demonstrated in the design work.
Attachment:- Design Brief.rar