Presentation is loading. Please wait.

Presentation is loading. Please wait.

Structural Slab Analysis

Similar presentations


Presentation on theme: "Structural Slab Analysis"— Presentation transcript:

1 Structural Slab Analysis
Design Assumptions Loadings Proposed Slab Options

2 Structural Slab Analysis
Assumptions Check whether 300mm thick slab is sufficient in temporary and permanent conditions. For the time being, assume there are not hazards in the tunnel (e.g. spillage of aggressive chemicals, stray current corrosion etc.) In the permanent case, Vibration Loading from dipole is not considered. Accidental Loading (e.g. fire only, helium release event not considered) Design according to the EuroCodes Durability checks according to EC2 e.g. standard crack width criteria (0.3mm) All factors as recommended by general EuroCodes (not National Annexes) Max speed of the vehicles < 10km/h (Temporary Case)

3 Structural Slab Analysis
Fire Design Assumptions Fire characteristic curve: ISO 834 Requested fire resistance: Class R60 Tabular method for the definition of the minimum thickness of the concrete structures and the minimum rebar cover.

4 Structural Slab Analysis
Loading Parameters Indicative layout from ILC TDR

5 Loadings

6 Loadings

7 Option 1a: Cast In-situ Concrete
Proposed Construction Sequence: Step 1: Fix rebars in both walls Install movable shutter Concrete Step 2: Fix rebars in the slab 2 1 1 This Option To Be Analysed

8 Option 1a: Cast In-Situ Concrete
Worked examples: Barcelona Metro (Spain) Type 1 Cross section with cast in-situ mass concrete Gantry on rollers (Crossrail) Concreting on site Movable shutter

9 Option 1b: Cast In-situ Mass Concrete and Pre-stressed Slab Unit
Proposed Construction Sequence: Step 1: Fix rebars in the thick wall Install movable shutter Fix bars in hollow concrete units Concrete Step 2: Install pre-stressed slab panels Fix connection rebars Concrete the topping 2 1 1

10 Option 1b: Cast In-situ Concrete Slab
Worked examples: Over-head crane to lift pre-stressed units Barcelona Metro (Spain) Type 1 Mortarless Concrete Block Wall Concreting on site Movable shutter

11 Option 1c: Cast In-situ Mass Concrete and Pre-stressed Slab Unit
Proposed Construction Sequence: Step 1: Fix rebars in thick wall Install movable shutter Fix bars in hollow concrete units Concrete Step 2: Fix corbel bars Cast concrete 3 2 1 1 Step 3: Install pre-stressed slab panel Fix connection rebars Concrete the topping Worked examples as for Solution 1b

12 Summary on Options 1a, 1b, and 1c
Pros: Robust mass concrete under Dipole prevents vibration issues Especially for Solution 1c, where the safe area envelope is shifted Typical RC-concrete Not innovative material = reasonable price Good fire performance of RC-elements Individually designed passive resistance of concrete (cover, polyfibres). Gantry directly behind the TBM including: Formwork on rails/rollers Crane for lifting pre-cast units Cons: Thick Elements Rebars due to Thermal Cracking Slow construction progress due to on-site concreting For Options 1b and 1c, the process accelerated by providing pre-stressed units Corbel construction

13 Solution 1d: Pre-fabricated Concrete Units

14 Solution 1d: Pre-fabricated Concrete Units
(Slow Construction) Worked examples: SMART tunnel (Malaysia) Airport Link tunnel (Australia)

15 Solution 1d: Pre-fabricated Concrete Units
(Slow Construction) Pros: Typical pre-stressed RC-units Not innovative material = reasonable cheap Good fire performance of RC-elements Culvert-laying gantry directly behind the TBM Cons: Thick Elements Multiple Short Spans Slow construction progress due to cast in-situ topping Corbel construction

16 The following options are for information only since they don’t meet the key objective of providing stiff, robust and vibration-free support for the dipole. However, they present innovative techniques and some individual ideas can be implemented into the final solution.

17 Option 2: Steel or Pre-stress Frames
(Moderately Quick Construction)

18 Option 2: Steel or Pre-stress Frames
(Moderately Quick Construction) Worked Example: Intermediate pre-stressed concrete slab units Barcelona Metro (Spain) Section Type 2 Over-head crane lifting the units

19 Option 2: Steel or Pre-stress Frames
(Moderately Quick Construction) Pros: Quick construction Frames assembled in a factory Long span of the main frames Optimised usage of steel Simple connections (i.e. pinned) Limited zones of mass fillings By both sides of the frame only Limited areas of concrete mass fill Easy to construct concrete block walls No shutter needed Cons: A lot of concreting on site Slab toppings and mass concrete Slow construction progress Fire protection layer needs to be sprayed/cast Temporary bracing (if steel frames used)

20 Option 3: UHPFRC* Slab Units
(Quick Construction) * Ultra-High Performance Fibre-Reinforced Concrete

21 Option 3: UHPFRC* Slab Units
(Quick Construction) Worked Example: Airport Link tunnel (Australia) Separated culvert-laying gantry from the TBM backup

22 Option 3: UHPFRC* Slab Units
(Quick Construction) Pros: Quick construction Prefabricated units “ready-to-use” Small amount of concreting on site In the joints only Long span of the main frames Optimised usage of concrete Thin units due to very strong concrete Simple connections (i.e. pinned) Limited zones of mass fillings On side only Limited areas of concrete mass fill Easy to construct concrete block walls No shutter needed Cons: Very expensive material Fireproofing tests need to be done Individual design approach Full scale fire tests Very smooth top surface Wearing Surface material to be installed Corbel Construction * Ultra-High Performance Fibre-Reinforced Concrete

23 Option 3: UHPFRC* Slab Units
Very high compressive strength MPa Examples: Steel fibres added to achieve ductile behaviour Low W/C ratio Available on French market (DUCTAL, BSI/CERACEM, BCV) Comparison of a UHPFRC slab and a conventional concrete slab Physical and mechanical characteristics UHPFRC (example) UHPFRC slab (example) * Ultra-High Performance Fibre-Reinforced Concrete


Download ppt "Structural Slab Analysis"

Similar presentations


Ads by Google