The deck of a concrete arch may be an open grid of precast or steel I-beams or a continuous prestressed-concrete box girder or ribbed slab. A box girder offers flexural and torsional stiffness at the deck level that reduces arch bending and simplifies deck construction, while a ribbed slab is easier to cast.
Continuous box girders and ribbed slabs can be incrementally launched over the arch or can be cast span-by-span with an MSS. Launching saves labor and allows the use of longer approach spans without the increasing cost, weight and complexity of the MSS. Launching also avoids loading the arch with the weight of the MSS, which increases bending in the arch and in the deck and the need for temporary stay cables.
The flexural stiffness of a deck designed for longer approach spans relieves bending in the arch generated by staged deck construction, and horizontal cables connecting the spandrel columns to the launch abutment minimize arch bending due to launch gradient and friction. Safer work conditions, stationary logistics, one learning curve for main span and approaches, and an inexpensive casting facility are additional advantages.
With extensive illustrations and case studies, Launched Bridges (2-day class) provides exhaustive coverage of the design, construction, technology and industry trends of steel and prestressed-concrete bridges built by incremental launching. You will learn under which circumstances is bridge launching a competitive solution, will explore the other construction methods for medium-span steel and prestressed-concrete bridges, and will compare alternatives in preparation of successful value engineering sessions.
The class explains how to control self-weight bending and shear during launch with launch noses, temporary piers and front cable-stayed systems, and provides exhaustive coverage of their design for optimized interaction with the deck. It discusses the Reduced Transfer Matrix method for parametric launch stress analysis with a spreadsheet, web stability and lateral torsion-flexure buckling of steel girders, and launch post-tensioning, deck segmentation and the organization of the casting facilities for prestressed-concrete bridges.
For both types of bridges, the class explores geometric launchability criteria, launch bearings and guides, thrust systems and how to control the movements of the deck in uphill and downhill launching. Richly illustrated with almost 300 photographs of case studies, the class is constantly top-rated for material and presentation.
The class delivers a unique wealth of knowledge, learning and insights extracted from three decades of design and construction of launched bridges and my three books on the topic. Integrated by the bestseller Bridge Construction Equipment (2013, ICE Publishing), the second edition of Bridge Launching (2014, ICE Publishing) and many eBooks of the Bridge Engineering eManuals project, the class provides exhaustive coverage of the topic. Addressing the needs of bridge owners, designers and constructors, the class provides an exciting occasion for face-to-face interaction with other bridge professionals and participating in a true learning experience.
- Launch of steel and PC bridges
- Alternative construction methods
- Geometry requirements
- Launch bearings and guides
- Thrust force and launch techniques
- Control and correction of launch stresses
- Analysis of launch stresses
- Incremental launching of steel bridges
- PC bridges: deck segmentation
- PC bridges: casting stages
- PC bridges: launch and integrative post-tensioning
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Photo: courtesy Prof. Leonhardt.