Load Rating of Post-Tensioned

Cast-in-place Concrete Segmental

Bridge

Ken Lee and Nyssa Beach

H-09-U: SH 82 over Maroon Creek, Aspen CO

Buttermilk Ski ResortH-09-U

Project Overview – CDOT Load Rating

• First of two task orders to rate Colorado structures

that are either missing load ratings or in need of

updated load ratings.

• 20 structures rated in the first task order

• Load ratings included:– Cast-in-place post tensioned segmental structure (Maroon Creek – Midas)

– 10-span curved welded plate steel girder (AASHTOWare BrR)

– Multi-cell cast-in-place post tensioned box girder (AASHTOWare BrR)

– 8-span spliced post-tensioned concrete U-girder (Bentley Consplice)

– 3-span welded plate girder steel slant leg (Midas)

– Concrete Arch Culvert (SAP2000)

Bridge Overview – Maroon Creek Bridge

Bridge Overview – Maroon Creek Bridge

Completed in 2005

3 Spans (170ft. – 270ft. – 170ft.)

Bridge width = 73’-0”

Typical Box Depth = 13’-6” along

Bridge Width = 73’-0”

Fully Integral at Piers

Bridge Overview – Maroon Creek Bridge

Bridge Overview – Maroon Creek Bridge

Bridge Overview – Maroon Creek Bridge

Bridge Overview – Maroon Creek Bridge

Challenging aspects of Bridge Design

• Transverse and Longitudinal Analyses

• Construction Stages

• Time-dependent Behavior

• Interaction of Transverse Bending and Longitudinal

Shear in Webs

• Geometry

• Prevention of Substructure Flexural Crack

• Load Ratings

Main Topics

• Longitudinal Analysis and Design

• Construction Stages

• Time-dependent Behaviors

• Load Ratings

Modeling of Maroon Creek Bridge

Connectivity and BCs

Modeling of Maroon Creek Bridge

Creep/Shrinkage: CEB-FIP (1978)

Time-dependent Material and Behavior

Creep Coefficient

Modeling of Maroon Creek Bridge

Tendon Profiles

Modeling of Maroon Creek Bridge

Tendon Properties (low relaxation)

Modeling of Maroon Creek Bridge

Jacking Force

Modeling of Maroon Creek Bridge

17- Load Cases

Load Combination

20 Load combinations

Temperature and Structural Behavior

TG [AASHTO 3.12.3]

Why Construction Stage Analysis is crucial?

M under Selfweight wo/ CS – 3 span continuous

M under Top PT w/ CS– Cantilevers and closure pour

Why Construction Stage Analysis is crucial?

M under Top PT wo/ CS – Secondary PT included!!

M under Top PT w/ CS – No Secondary PT Effect

Construction Stage Analysis- Total 11 CSs.

360days for Bridge Completion

Construction Stage Analysis

Assign Groups to Each Construction Stage

Construction Stage Analysis

Construction Stage Analysis

360 days at Bridge Completion and 10 years for CR/SH

Construction Stage Analysis

Summation of CS

Summation of CS

Reaction

DL+ER+Secondary PT+Secondary CR+Secondary SH

Deformation

DL+ER+Primary PT+Primary CR+Primary SH

Force

DL+ER+Primary PT+Secondary PT+Secondary CR+

. Secondary CR

Evaluation of Post-Analysis: Const. Stages

Evaluation of Post-Analysis: After Completion

Tendon Stress Limits

Evaluation of Post-Analysis: Tendon Loss

Midas Design Feature

Longitudinal Reinforcing

Midas Design Feature

Shear and Torsional reinforcing

Load Rating

Design Vehicles – HL93 / 9 Legal / CDOT Permit

Define Rating Cases

Load Rating

Summary of Ratings in Strength

Summary

• Load Rating = 1.3

• Construction Stage Analysis is crucial

• Verification of Behavior of Time-dependent material

• Evaluation of Post-Analysis

• Midas Design Features for Seg. PT Concrete Bridge

• Capability of Midas Load Rating for Seg. PT Concrete

Bridge

Acknowledgement