Design Considerations and Efficient Construction of HSR Structures

1. Design Considerations and Efficient Construction of HSR Structures Gonzalo de Diego Barrenechea March 4, 2011

2. 1. World HSR Development

3. SPANISH EXPERIENCE • World HSR rank [expected by end of 2010] • 1st China: 1,929 miles [3,105 km] • 2nd Japan: 1,352 miles [2,176 km] • 3rd Spain: 1,200 miles [1,932 km] • Spain has more than 24 years of HSR experience (first construction started 1986) • More than US$ 85 billion invested in HSR since the 90s • Estimated construction cost: US$ 20 million/km for new lines • Only China and Spain designed HSR infrastructure for 220 mph [350 km/h] operations  Speed matters • AECOM-Spain (legacy INOCSA) has provided HSR design services for more than 625 miles (1,000 km) [including PE-15%, PE-30%, and Final Design] HSR Structures

4. 2. Loads And Actions ConsideredDuring HSR Structural Design

5. LOADS AND ACTIONS HSR Structures

6. 2.1 Vertical and Horizontal Loads

7. VERTICAL & HORIZONTAL LOADS VERTICAL • Static analysis: UIC-71 load model • Dynamic analysis: Specific model for HSR  HSLM (High Speed Load Model) [for trains exceeding 200 km/hr- 125 mph] HORIZONTAL • Traction & breaking forces are significant • Centrifugal forces increase significantly in curved structures. • Combined response of the structure and track • Longitudinal forces over track (acceleration, starting, breaking) • Different deformation between deck & slab • Resulting load transfer between track and ballast through fixings HSR Structures

8. 2.2 DynamicEffects

9. DYNAMIC EFFECTS • Static stresses and deformations induced in a bridge are increased and decreased under the effects of moving traffic by: • Rapid rate of loading due to the speed of traffic crossing the structure and the inertial response  Specific Dynamic Analysis  IMPACT COEFFICIENT [ v > 220 KM/H- 125 mph] • Passage of successive loads with uniform spacing which can excite the structure and under certain circumstances create RESONANCE (where the frequency of excitation matches a natural frequency of the structure) • Variation in wheel loads resulting from track or vehicle imperfections. • These stresses and deformations might cause fatigue so a proper fatigue analysis should also be done. HSR Structures

10. 2.3 AerodynamicEffects

11. AERODYNAMIC EFFECTS • Passing trains  Aerodynamic effect • Must be taken into consideration when designing structures adjacent to railway tracks. • Aerodynamic effect  Wave alternating pressure and suction • At 300 km/hr this pressure can be up to 6 times that at 120 km/h HSR Structures

12. 2.4 Combined Response

13. COMBINED RESPONSE OF STRUCTURE AND TRACK TO VARIABLE ACTIONS • Track • Superstructure (a single deck comprising two spans and a single deck with one span shown) • Embankment • Rail expansion device (if present) • Longitudinal non-linear springs reproducing the longitudinal load / displacement behaviour of the track • Longitudinal springs reproducing the longitudinal stiffnes K of a fixed supporte to the deck taking into account the stiffness of the foundation, piers and bearings etc. HSR Structures • Continuous rails + discontinuities in the support to the track (e.g between bridge structure and embankment)  structure of the bridge (bridge decks, bearings and substructure) + track (rails, ballast, etc) JOINTLY resist the longitudinal actions due to traction or braking. • Where continuous rails restrain the free movement of the bridge deck • Deformations of the bridge deck (e.g due to terminal variations, vertical loading, creep and shrinkage )  produces longitudinal forces in the rails and in the fixed bridge bearings. • Continuous bridges require rail expansion devices

14. 3. Efficient Structure Construction

15. SPANISH EXPERIENCE • Know-how evolves  maximum bridge span increases  optimum bridge typology evolves HSR Structures

16. 3.1 PrecastBeam Bridges

17. PRECAST BEAM BRIDGES • Beams produced at the factory  transported to the site • Once beams are on deck  concrete slab is applied • Usual height/span ratio: 1/14 • Typology: • Double T beams  no longer in use due to lack of torsion stiffness  Track warping problems • U shaped beams  in use (below) • Bridge type: • Mostly applied to simply – supported bridges. Also valid for continuous structure • Constructive methods: • Cranes • Beam launching • Transversal shifting • Lifting • Maximum span: 35 m (exceptionally 40 meters) HSR Structures

18. 3.2 Slab Bridges

19. SLAB BRIDGES • Pre-stressed  best beam depth/span ratios [1/16 – 1/20] • Appropriate for urban-semiurban areas • Types • Depending on slab depth • Depth < 90 cm.  solid slab • Depth > 120 cm  voiled slab • Depth 90 cm – 120 cm  varies • Depending on span • < 30 meters: constant depth slab • Span 30-50 meters: variable depth slab • Construction method  Conventional centering HSR Structures

20. 3.3 Pre-Stressed Box

21. PRE-STRESSED BOX • Most widely used: monocelular – double track • Box dimensions depend on bridge dimensions HSR Structures

22. 3.4 ConstructiveMethods

23. CONSTRUCTIVE METHODS (SPAN) HSR Structures

24. SIMPLY SUPPORTED VS. CONTINUOUS STRUCTURE • Significant vertical loads + high speed  Dynamic effects • Need to impose strict deformation limits for: - Rotation - Settlement • To increase comfort & safety and reduce fatigue HSR Structures

25. 3.5 Special HSR Bridge Typology

26. Rombach Type Bridge: Viaducto del SOTO (Spain) • Designed: INOCSA – AECOM Spain • Continuous structure • Length: 1,755 meters • Span No.: 22 • Pier height: 77.5m • Spans: center (132m arch), sides (52.5m), others (66m). HSR Structures

27. Thank You gonzalo.dediego@aecom.com March 4, 2011