load rating of a steel composite girder...
TRANSCRIPT
Load Rating of a Steel Composite
Girder Bridge
Luis J. Vila, Ph.D.
Structural Engineer, GM2 Associates, Inc.
MIDAS 2016 Elite Engineers Webinar Series
April 07, 2016
2
Presentation Outline
Introduction
Modeling Aspects
Construction Stage Analysis
Live Load Analysis
Load Rating
Analysis of Expansion Joint
3
Introduction
Bridge location
4
Introduction (Cont’d)
Bridge location
5
Introduction (Cont’d)
Bridge 00032, Stamford, CT
MNRR
I 95
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Introduction (Cont’d)
Built in 1958
Rehabilitation work since: joints replacement, substructure
strengthening, widening
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Introduction (Cont’d)
Bridge 00032 overview:
17 spans carrying I95 over MNRR and local roads
1065 ft long
16 Steel Composite Girder Spans
Main span over MNRR
• - Composite and Non-composite
Floorbeams
• - Steel Through Girders
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Introduction (Cont’d)
Span 7: I95 over Metro-North Railroad (MNRR)
Steel Through Girders
Composite and Non-composite Floorbeams
NB Traffic
SB Traffic
Diagonal Expansion Joint
11 ft
200 ft Span
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Defining Bridge Geometry
Import geometry from Microstation or AutoCAD
Bridge Wizard (e.g. Steel composite, PSC, Cable Stayed, Suspension)
Define each node and element
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Steel Composite Girder Modeling
Material:
• - SRC
Section:
• -Composite
• -Ds/Dc=0
Weight of concrete
applied as distributed
load
Definition of Steel Composite
Girder Geometric and Material
Properties
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Steel Through Girder Modeling
Built-up Section
• - 2 Web Plates
• - 6 Plates for Flanges
• - Longitudinal Stiffeners
Modeled using Midas Civil General
Section Designer Tool
• -Import shape from
Microstation or AutoCAD
• - Determines Section Properties
of Built-up Section
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Steel Through Girder Modeling
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Concrete Deck Modeling
Deck Dummy Elements
• -Weightless concrete
• -Provide transverse connection
between floorbeams
• -Transverse distribution of live
loads and composite dead loads
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Diagonal Expansion Joint Modeling
Diagonal Expansion Joint
Compression only link
Rigid elastic link
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Construction Stage Analysis
Composite stage
Non-composite stage
Composite Section for Construction
Stage
Stage 1: Steel Only
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Construction Stage Analysis (Cont’d)
Stage 3: Composite Action
Stage 2: Concrete Pour
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Live Load Analysis
Live Load Analysis for Load Rating:
• -Design (HL93)
• -CT Permit
• -CT Legal
Traffic Lane Definition
• -Traffic Lane Optimization
Center (Default) Left Right
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Live Load Analysis (Cont’d)
Traffic Lanes
• -Forward and backward moving load
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Live Load Analysis (Cont’d)
Live Load Analysis Results
• -Moment Diagrams
Non-Composite Floorbeam
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Live Load Analysis (Cont’d)
Live Load Analysis Results
• -Displacement Results for HL93 Truck
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Load Rating
Strength Limit State: Service Limit State: Fatigue Limit State:
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Load Rating (Cont’d)
Fatigue Limit State
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Load Rating (Cont’d)
Parameters for Fatigue Rating
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Load Rating (Cont’d)
Fatigue Limit State
• -Rating Results
If RF < 1.0 => Check for finite fatigue life
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Analysis of Expansion Joint
Analysis of Expansion Joint Under Live Load
NB Traffic
SB Traffic
Corrosion of floorbeam below expansion joint due to active water
leakage
Damaged deck due to repeated impacts against top flange of floorbeam
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Analysis of Expansion Joint (Cont’d)
Span 7 over MNRR
Planking for floorbeam
inspection
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Analysis of Expansion Joint (Cont’d)
South Side of Non-Composite floorbeam North Side of Non-Composite floorbeam
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Analysis of Expansion Joint (Cont’d)
Deck deterioration along joint
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Analysis of Expansion Joint (Cont’d)
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Analysis of Expansion Joint (Cont’d)
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Analysis of Expansion Joint (Cont’d)
Determine the location of the truck when deck detaches from top
flange
• -MIDAS Civil Moving Tracer Tool
Location of truck causing maximum and minimum displacement of
deck
• -Two locations of trucks causing a gap between deck and top flange
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Analysis of Expansion Joint (Cont’d)
Moving Load Tracer
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Analysis of Expansion Joint (Cont’d)
Moving Tracer Results
Maximum (upward) displacement at midspan
Minimum (downward) displacement at midspan
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Analysis of Expansion Joint (Cont’d)
Case 1: Maximum (upward) displacement of deck at expansion joint
Through
Girder
(South)
Pier 6 Pier 7
Deck
Joint 16 kips wheel load4 kips wheel load
N
Through Girder
(North)
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Analysis of Expansion Joint (Cont’d)
Deck
Joint
Through
Girder (South)
Through
Girder
(North)
gap
Case 1: Maximum (upward) displacement of deck at expansion joint
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Analysis of Expansion Joint (Cont’d)
gap
gap
Case 1: Maximum (upward) displacement of deck at expansion joint
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Analysis of Expansion Joint (Cont’d)
Through
Girder (South)
Through Girder
(North)Pier 6 Pier 7
Deck
Joint16 kips wheel load
N
4 kips wheel load
Case 2: Minimum (downward) displacement of deck at expansion joint
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Analysis of Expansion Joint (Cont’d)
Deck Joint
Through
Girder (South)
Through Girder
(North)
gap
gap
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Conclusion
midas Civil advantages
• -User friendly
• -Graphic user interface
• -Fast and accurate bridge modeling
• - General section designer
Load Rating Method
• -Composite girders/floorbeams (midas Civil)
• -Non-composite floorbeam (spreadsheet using results
from midas Civil)
• -Through girders (spreadsheet using results from midas
Civil)
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Questions?