Bridge Engineering Case Studies

Case Study 1: Making your life easier with SAM-LEAP5: Composite Results

Deriving moments and shears for a box beam modelled as a set of plate finite elements can be very difficult, as you transform and sum all the relevant forces at a section. SAM-LEAP5's "Composite Member" feature makes this process very easy. More

Case Study 2: Integrated Bridge Design

"Integrated Bridge Design" is a technique in which the two major numerical processes in bridge design are brought together. This means that the process of code checking structural components ("Design") and the process of analysing the structure for moments and shears ("Analysis") communicate in a very structured way. This leads to great increases in productivity for bridge designers, saving them both time and effort. More

Case Study 3: SAM-LEAP5's Innovative Load Optimisation Process

How quickly can you define a set of load combinations that will give the live load bending moment envelope for one of the box beams shown in the finite element model below? Using SAM-LEAP5's innovative optimisation process together with the composite results facility (see Case Study #1) you can do the optimisation in less than a minute. More

Case Study 4: Fast-Track Design for Project Proposals

When designing bridges for project proposals, you need to be sufficiently accurate to ensure both that your price is keen and the structures are adequate. And you usually need to do this within a very tight deadline. Here is a fast-track technique for achieving all these goals: in fact one engineer recently said that he would be able to do 6 schematic designs in a day, rather than his normal single bridge per day, and still meet his quality standards. More

Case Study 5: Secondary Moments Arising from Post-Tensioning

For post-tensioned bridges there are several analysis problems to overcome: - The definition of the cable profiles, especially in decks that are curved in plan. The calculation of the losses such as friction, wobble, elastic shortening, jacking releases etc. Calculation of the moments and forces induced into the structure by the cable. SAM-LEAP5 now has a facility that addresses all of these issues. More

Case Study 6: Temperature Effects on Integral 3D Structures

In many cases, the effect of temperature on 3D structures can yield surprisingly different results than those obtained from a simplified 2D model. Having the ability to model a structure with 3D shell finite elements as well as simple 2D frames, as is the case in SAM-LEAP5, can prove extremely beneficial. More

Case Study 7: Modelling Plastic Behaviour in Remedial Work

When widening a bridge, it is sometimes appears that the existing superstructure needs to be strengthened, especially if the analysis uses elastic methods. This can be expensive, but may not be necessary if it is realised that "elastic" models do not account for the true post-elastic behaviour of materials at the ultimate limit state. More

Case Study 8: Cost-effective design of pre-tensioned beams

What are the factors that affect the cost of precast pre-tensioned bridge beams, and how easy is it to design according to an optimised cost criteria? Two examples are presented here which demonstrate that the answer is not always what it may seem. More

Case Study 10: Live load optimisation for assessment to BD 86/04

When carrying out an assessment using BD 86 the main problem is the large number of vehicle configurations that need to be analysed. An initial assessment is generally carried out to establish "reserve factors" for each of the five SV type loads for each design detail being considered. This is done for both normal and slow speeds, which affects the dynamic amplification factor applied and the unloaded length in front and behind the vehicle. The analysis should also be carried out for SV cases with and without associated lane loading and for both Ultimate and Serviceability limit state conditions. The associated load can be either standard HA loading or convoys of any of the Appendix D vehicles. More

Case Study 11: Central; Motorway Junction - Auckland

Commonly referred to as "Spaghetti Junction", the Central Motorway Junction (CMJ) in Auckland, New Zealand, is where the Southern, North Western and Northern Motorways converge, just west of the city centre. Built in the 1970s, the CMJ needed a much-needed upgrade. More

Case Study 12: A26 Toome Bypass - River Bann Bridge

The River Bann Bridge is a landmark 98m span bowstring arch bridge, and with a distance between unbraced arches of 28m is the largest bridge of its type in the British Isles. It carries the dual carriageway of the A6 Trunk Road, which connects Belfast to Londonderry over the Lower River Bann and forms the main structure on the Toome Bypass. More

Case Study 13: Dockland Light Railway - City Airport Expansion

On 2 December 2005 the City Airport extension to the Docklands Light Railway (DLR) network was opened to the public, two weeks ahead of schedule. Halcrow were the designers for the civil, structural, rail, and communications systems on the project. More

Case Study 14: A1 River Tyne Bridge - Scotland

The A1 between London and Edinburgh was in March 2004 upgraded by the opening of the 13.7km Haddington to Dunbar Expressway. A key aspect of this scheme was the construction of a post-tensioned concrete bridge across the River Tyne valley. In keeping with the location, the Scottish Executive required that the crossing be of striking form; resulting in a 217m long three span structure, with a centre span of 89.4m and slender raking piers fully encastré with the deck and the foundations. More

UK & Ireland Case Studies

Devon County Council Miller's Crossing

A new route between Exwick and Exeter City Centre has been created exclusively for pedestrians and cyclists. The main feature of the route is the Miller's Crossing Bridge spanning the River Exe, adjacent to the Mill on the Exe Inn and Blackaller Weir. More

Doncaster North Bridge Relief Road Viaduct

Bullen Consultants in Durham UK, have been using the SAM-LEAP5 integrated bridge analysis and design software for the past twelve months on a number of bridge design and assessment schemes. These vary from a 15 span 620m long composite steel/concrete viaduct, using a ladder deck construction in Doncaster, to a number of assessments of multi span simply supported pre-stressed post-tensioned concrete bridges on the A1 Darrington to Dishforth DBFO project for the Highways Agency. More

Australia & New Zealand Case Studies

Pacific Motorway Package 1

Pacific Motorway Package 1 was one of five major design packages for the 43Km eight lane upgrade of the existing Pacific Highway between Logan, south of Brisbane, and Nerang near the Gold Coast. Package 1 consisted of 4.8 km of eight lanes of motorway, service roads and three major interchanges at Logan Motorway, Beenleigh North and Beenleigh South. A total of 16 bridge structures where required for the works including a large span single cell post-tensioned box girder and a variety of "super-T" and "deck unit" concrete bridges. More

Brisbane Airport Rail Link Project

Brisbane Airport Rail Link is an 8.5 km elevated spur line linking new stations at Brisbane Airport's domestic and international terminals with the city and the Gold Coast. The structure is typically constructed using precast prestressed concrete girders up to 38m span, which are supported on precast piles and in-situ concrete piers. Other major crossings included two crossings of Schulz Canal and the Gateway Arterial Roads where spans up to 55m were achieved using post-tensioned cantilever piers and "drop in" spans. More

Charles Grimes Bridge

The Charles Grimes Bridge crosses the Yarra River in Melbourne's central business district. The project required the demolition of the existing twin bridge structures, to be replaced by two new bridges with complex horizontal and vertical geometry. Realignment was required as part of the changed traffic network in and around Melbourne Docklands. More

Brisbane Inner City Bypass

The Inner City Bypass is a new transport route linking Hale Street at Paddington with Kingsford Smith Drive at Hamilton and will provide a new route for motorists travelling across Brisbane. The bypass will be 4.5 kilometres long with six lanes between Hale Street and the Campbell Lutwyche Interchange, followed by four lanes for the remainder to Kingsford Smith Drive. Major structures include a new interchange at Normanby, a 'landbridge' over the railway line at Yorks Hollow, and a 400m long tunnel under the RNA Showgrounds. Railway overpasses include a major viaduct at Abbotsford Rd, and several bridges and another tunnel in soft soil at Breakfast Creek. More

Port of Brisbane Motorway

The Port of Brisbane Motorway was the biggest single road project under construction in Queensland during 2002. Innovative engineering solutions and a focus on quality resulted in successful project delivery ahead of time, well under budget and with minimal disruption to the environment and community. More

Oyster Channel Bridge

The Oyster Channel Bridge near Yamba was constructed in 1937 and is being widened to provide an improved carriageway width and a pedestrian footpath. The project is funded by the Roads and Traffic Authority of NSW. During the project conceptual design phase, a requirement to strengthen the existing bridge superstructure was identified. A proposal for strengthening using carbon fibre reinforced polymer (CFRP) laminates was proposed and included in the preliminary project cost estimates. More

CMJ Scheme, Auckland

Commonly referred to as "Spaghetti Junction", the Central Motorway Junction (CMJ) in Auckland, New Zealand, is where the Southern, Northwestern and Northern Motorways converge, just west of the city centre. The area is a geometrically complex system of motorways and connecting ramps at multiple levels, carrying around 200,000 vehicles per day, all within a very restricted area. Built in the 1970s, the CMJ is now receiving a much-needed upgrade. Stage 1 of the upgrade was completed in December 2004, and Stage 2 is in progress. More

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