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Steel-Free Concrete Bridge Deck
The Need
Steel-free concrete replaces reinforced concrete in bridge decks and similar structures in marine environments and in northern climates having snow and ice. It is to eliminate the source of deterioration, the steel reinforcing bars in slabs exposed to deicing salts. Eliminating corrosion makes concrete deck slabs virtually maintenance-free, which makes life cycle costs of steel-free concrete decks much lower than reinforced concrete decks.
The Technology
Shear connectors make the steel-free concrete deck composite with the steel girders that support it. Top flanges of girders attempt to displace outward when a truck drives across the deck. External transverse steel straps below the bridge deck and between the bridge girders prevent this outward displacement by providing a lateral restraining force to the girder and concrete deck. In response, compressive membrane forces develop in the concrete deck. Ultimate load can be greater than the load at which the same deck would fail if it were reinforced conventionally. In fact, the tension capacity of the steel straps in the steel-free deck replaces conventional reinforcing steel. The external steel straps can be inspected and maintained in a similar fashion to steel girders.
The Benefits
The benefits from implementing this system are:
- Improvement of quality and durability by eliminating corrosion caused by de-icing salts
- Maintenance and repairs without the normal disruption of traffic
Status
Two versions are available: 1. The cast-in-place version 2.The pre-cast ArchPanelTM version.
The cast-in-place deck slab is now in the Canadian Highway Bridge Design Code (CHBDC), currently in the press. Japan is reviewing the technology. Meeting with American Association State Highway Transportation Officials (AASHTO) Code Committee are in progress.
Points of Contact
- Dr. Aftab A. Mufti, P.Eng. President ISIS Canada, The University of Manitoba, Administrative Centre, 227 Engineering Building, Winnipeg, Manitoba, Canada R3T 5V6 Phone: 204 474 8506 Fax: 204 474 7519 E-mail: muftia@cc.umanitoba.ca
Refrences
- News Release, 2000 Nova Award Nominations
Disclaimer Statement
Neither the Construction Industry Institute nor Purdue University in any way endorses this technology or represents that the information presented can be relied upon without further investigation.