SUNSHINE SKYWAY BRIDGE

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1 SUNSHINE SKYWAY BRIDGE Retrofit of the Post-Tensioned Precast Transition Pier Columns on the Sunshine Skyway Bridge Presented by: Antonio Ledesma, P.E. May 7, 2012

2 SUNSHINE SKYWAY BRIDGE, FLORIDA

3 Presentation Outline 1. INTRODUCTION 2. SKYWAY STRUCTURAL SYSTEM 3. SKYWAY CONSTRUCTION METHODS 4. PREVIOUS REHABILITATION OF HIGH-LEVEL APPROACH COLUMNS 5. PRECAST SEGMENTAL TRANSITION PIERS 6. REPAIR OPTIONS 7. CONSTRUCTION

Introduction The Sunshine Skyway Bridge is

Bay. In May 1980, a major ship impact caused the

4 Introduction The Sunshine Skyway Bridge is located on the west central coast of Florida. Part of I-275 linking Tampa/St. Petersburg to Bradenton/Sarasota across Tampa Bay. In May 1980, a major ship impact caused the collapse of the southbound main span. Sunshine Skyway Bridge St. Petersburg

5 Sunshine Skyway Bridge NORTH LOW LEVEL TRESTLE SPANS (4283 ) NORTH HIGH LEVEL APPROACH (2430 ) MAIN SPAN (4000 ) SOUTH HIGH LEVEL APPROACH (2430 ) SOUTH LOW LEVEL TRESTLE SPANS (8738 ) Total Bridge length: 4.14 miles

6 High Level Approaches and Main Span Unit

7 Structural System High Level Approaches HIGH LEVEL APPROACH HIGH LEVEL APPROACH Total length: 4,860 ft Post-Tensioned Precast Segmental Box Girders (Span-by-Span) Post-Tensioned Precast Segmental Columns

8 Structural System Main Span Unit MAIN SPAN UNIT Total length: 4,000 ft Post-Tensioned Precast Segmental Box (Balanced Cantilever)

9 Precast Segmental Substructure Bearing pad PT anchorage Column cap Transition point External Tendon Segment joint (typ) Internal tendon Precast footing shell Grout pad Cast-in-place concrete Precast concrete strut Tremie seal concrete

10 Previous Rehabilitation of Approach Piers PE Duct Couplers Poor detail of vertical tendon couplers

11 Column 133 NB SE Tendon September 2000 Corroded strands in the zone of 2 ft below the column cap (11 out of strands were failed)

12 Failed strands as a result of severe corrosion

13 Previous Rehabilitation of Approach Piers

14 Previous Rehabilitation of Approach Piers

15 Previous Rehabilitation of Approach Piers Core holes in footing and grout PT bars in place Top of Footing Place reinforcing

16 Previous Rehabilitation of Approach Piers Concrete pumped from top of deck Placing concrete inside column

17 Transition Piers Between HLA and Main Unit

18 Transition Piers 106 (6 S) and 117 (6 N)

19 Expansion Joint Segment at Transition Pier

20 As-Built Transition Columns Tie-Down Tendons Hollow Columns Filled with Concrete for Vessel Impact

Transition Pier Analysis Do we need to repair the transition pier columns? How to repair columns with concrete already placed inside segments?

21 Transition Pier Analysis Do we need to repair the transition pier columns? How to repair columns with concrete already placed inside segments? What is the purpose of the tie-down tendons Vessel Impact Load Case Hurricane Wind Load Case Impact of vessel impact risk analysis Repair options

22 Transition Column Inspection Column 117 SB Top view of interior column

23 Transition Column Inspection Column 106 SB Poorly done duct couplers

24 Transition Column Inspection Column 117 SB

25 Transition Column Inspection Column 117 NB Tendon T4 E (spiral cracked duct)

26 Transition Column Inspection Column 106 SB Cracked PE duct in 6 gap beween top of pier cap and transition segment

27 Transition Column Inspection Column 117 SB View at column transition point

28 Transition Column Inspection Column 117 SB Void

29 Transition Column Inspection Column 117 SB View of T1 W (cracked duct and void)

30 Purpose of Tie-Down Tendons 4 looped tendons (8 vertical tendons) 2-17x0.5 Tendons extend into superstructure EOR used tie-down tendons for vessel impact and hurricane wind analysis Tie-Down Tendons

31 EOR Original Design Scenario 2100 k 1900 k Vessel Impact Load k Design Load Pier cannot withstand full force; inelastic scenario was used to satisfy requirement

in AASHTO (piers outside of limit are designed for

32 Vessel Impact Risk Analysis 3*LOA = 2310 ft CL Channel Limit analysis to 3*LOA limit as specified in AASHTO (piers outside of limit are designed for minimum vessel impact) 8 piers on either side of the channel

33 Aerial View of Sunshine Skyway Bridge First two piers are very well protected, eliminate from risk analysis Conservatively ignore protection of remaining piers

34 Vessel Impact Risk Analysis 1350 k 2000 k Transition Pier 4000 k Protected

35 Wind Load on Bridge Wind Pressure Service Level Ultimate Strength 80 psf 177 mph 250 mph 60 psf 153 mph 217 mph

Wind defined as 1.6 x Wind @ 80% of Ultimate Strength M u = 1.

36 Check Uplift at Bearings Service Level Wind (153 mph) No Uplift at Bearings Tie-Down Tendons Not Required M top Wind Ultimate Wind defined as 1.6 x 80% of Ultimate Strength M u = 1.6 x Moment / 0.8 M top = 7725 kip-ft M base = kip-ft M base

37 Analysis Summary Proposed Vessel Collision Load = 2000 k Actual Column and Foundation Capacity = 2250 k Collapsed Column Scenario would not be required Tie-down tendons not required for vessel collision or hurricane wind load cases

38 Transition Pier Repair Potential Options for Lower Column Repair Option 1: Repair the columns from the inside (coring 55 deep concrete) Option 2: Repair the columns from the outside (using a cofferdam)

39 How do you repair the columns? Hollow Columns Filled with Concrete for Vessel Impact

40 Repair Option 1: Core Holes Inside Column Lower Column Repair: Core 5 φ holes through filled column and footing 28-1 ¾ φ unstressed PT bars Grout bars in place

41 Repair Option 2: Core Holes Outside Column 1 Concrete Shell 1 Concrete Shell Cofferdam

42 Repair Option 2: Core Holes Outside Column Steel Cofferdam (need split form for repair) Precast Dumb-Bell Precast Concrete Strut Precast Dumb-Bell And Steel Cofferdam During Construction

43 Repair Option 1 Chosen: Core Holes Inside Column Column Buttresses Upper Column: 24-1 ¾ φ Bars 5 φ Cored Holes Lower Column: 28-1 ¾ φ Bars

44 Upper Column Repair: Reinforced Column Buttresses Upper Column Repair: Core 5 φ holes through 2 thick lower segments and pier cap 4 column buttresses 24-1 ¾ φ unstressed PT bars

45 Upper Column Repair: Remove External Tendons Upper Column Repair: After column buttresses in place, strip external ducst, add anchorage plates to tendons and encapsulate in concrete to form an anchorage block Cut and remove external tendons Lower tendons to remain and will provide redundancy to lower column repair PT bars connecting pier cap to transition segment added at Department s request

Cost Estimate Option 1: Repair from inside (coring concrete) Estimated Total: $ 3 million Option 2: Repair from outside (w/ cofferdam) Estimated Total: $ 4 million Construction

46 Cost Estimate Option 1: Repair from inside (coring concrete) Estimated Total: $ 3 million Option 2: Repair from outside (w/ cofferdam) Estimated Total: $ 4 million Construction Time : 9 months to 12 months. Original Contract Amount: $2.2 million Original Construction Time: 1 year Unforseen conditions will increase total dollar amount and contract time.

47 Construction Photos Core Drill 5 diameter, 5 long steel tubing

48 Construction Photos Cleaning out core holes for lower column repair Core holes in thickened section For upper column buttress bars

49 Construction Photos Preparing and finishing column buttresses

50 Construction Photos Removal of external tendon ducts and addition of anchorage clamps

51 Removal of external PT tendon tie-down and installation of PT bar tiedown Construction Photos

52 Current Project Status 2 columns completed, 2 ongoing Estimated completion: Summer, 2012

53 Thank you. Contact: Antonio Ledesma, P.E.

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