SLIDE 1 Construction of Laboratory and Field Demonstration Modified Beam-in-Slab Bridges Construction of Laboratory and Construction of Laboratory and Field Demonstration Modified Field Demonstration Modified Beam Beam-
in-
Slab Bridges
- T. F. Konda, F. W. Klaiber,
T.J. Wipf
Iowa State University Bridge Engineering Center
SLIDE 2 Iowa’s Deficient Off System Bridges Iowa’s Deficient Off System Iowa’s Deficient Off System Bridges Bridges
Approximately 30% of Off System
Structures are Deficient
Limited Replacement Funding Develop Alternative Designs
SLIDE 3 Alternative Replacement Designs Alternative Replacement Designs Alternative Replacement Designs
Design Requirements
– Lower Cost – Constructible by County Forces – Accommodate Recycled Materials – Require Minimal Maintenance
SLIDE 4 Alternative Replacement Designs Alternative Replacement Designs Alternative Replacement Designs
Beam-in-Slab Bridge (BISB) System
– Conservatively Designed – In Service For 25 Years + – Exists only in Iowa?
SLIDE 5 Beam-in-Slab Bridge System Beam Beam-
in-
Slab Bridge System
W 12 Girders, 24 in.
Steel Confining Straps Plywood Concrete
SLIDE 6 Beam-in-Slab Bridge System Beam Beam-
in-
Slab Bridge System
Conclusions to BISB Testing
– Structurally Adequate System
Advantages
– Easy to Construct – Cost Competitive
Limitations
– Lack of Efficiency – Limited Span Length
SLIDE 7 Increasing Applicability Increasing Applicability Increasing Applicability
Increase the Efficiency of the System
– Develop Composite Action – Reduce Self Weight of the Section
SLIDE 8 Composite Action Composite Action Composite Action
Use of Alternative Shear Connector (ASC)
SLIDE 9 Reduce Self Weight With Arched Section Reduce Self Weight With Reduce Self Weight With Arched Section Arched Section
Advantages
– Wider Girder Spacing – Deeper Girder Sections – Longer Spans – Reduced Reinforcement
Complication
– Forming the Section
SLIDE 10 Formwork Investigation Formwork Investigation Formwork Investigation
Various Materials and Configuration
– Polyethylene Pipe – Arched Plywood – Corrugated Metal Pipe (CMP) – Custom Rolled Corrugated Section
SLIDE 11
Custom Rolled Corrugated Sections Custom Rolled Corrugated Custom Rolled Corrugated Sections Sections
SLIDE 12 Laboratory Testing Laboratory Testing Laboratory Testing
Specimen # 1 (Preliminary Section)
– Investigate Feasibility
#4 ASC Reinforcement 2” x 1/4” Strap 21” Radius, 42”
W 21 x 62 Girders 84” 8” 8” 2.5” 45” 19.5” Concrete
SLIDE 13 Laboratory Testing Laboratory Testing Laboratory Testing
Specimen # 2 & # 3
– Investigate Punching Shear
SLIDE 14 Laboratory Testing Laboratory Testing Laboratory Testing
Specimen # 4
– Investigate Load Distribution – Investigate Flexural Failure Mode
SLIDE 15 Demonstration Bridge Demonstration Bridge Demonstration Bridge
Design Based on:
– AASHTO LRFD Bridge Design Specification – Laboratory Testing Results
6 – W27 x 129 Girders Outfitted with ASC Custom Rolled Corrugated Sections
SLIDE 16
Demonstration Bridge Demonstration Bridge Demonstration Bridge
SLIDE 17
Demonstration Bridge Demonstration Bridge Demonstration Bridge
SLIDE 18
Demonstration Bridge Demonstration Bridge Demonstration Bridge
SLIDE 19
Demonstration Bridge Demonstration Bridge Demonstration Bridge
SLIDE 20
Demonstration Bridge Demonstration Bridge Demonstration Bridge
SLIDE 21 Conclusions Conclusions Conclusions
BISB System
– Alternative Replacement – Span Limited to 50 ft due to Structural Inefficiencies
Modifications to Improve Efficiency of
Design
– ASC and Transverse Arched Section – Increase Span Length to 75 ft – Improved Use of Materials
SLIDE 22
Acknowledgements Acknowledgements Acknowledgements
– Sponsor: Iowa Department of Transportation, Highway Division and the Iowa Highway Research Board – Tama County Engineer and Bridge Crew – ISU Research Laboratory Manager – Numerous ISU undergraduate students
