First Smart Highway Bridge in Canada

by S. H. RizkaIla and G. Tadros

The Beddington Trail/Centre Street, Calgary, Alberta, Canada, is the first prestressed

concrete highway bridge built in Canada pretensioned by Carbon Fiber Reinforced Plastic, FRP,

tendons. It is also the first bridge which has utilized a structurally integrated optical sensors

system to monitor the behaviour. The bridge is completed and was opened to traffic on

November 5, 1993. The project involved the cooperation from the following experts in the

private sector, government and universities:

• The City of Calgary (Chris Wade, P.Eng. and Amit Guha-Thakurta)

• Strait Crossing Incorporated (Dr. G. Tadros, P.Eng.)

• Graham Construction Ltd.

• Con-force Structures Ltd, Canada (Leon Grant, P.Eng.)

• Mitsubishi Kasei, Japan

• Tokyo Rope Mfg. Co. Ltd., Japan

• University of Toronto Institute for Aerospace Studies (Dr. R. Measures, Dr. T. Alavie and

Dr. R. Maaskant)

• University of Manitoba (Dr. S. Rizkalla and A. Abdelrahman)

• External Affairs and International Trade Canada

• National Research Council of Canada (Industrial Research Assistant Program)

The bridge is a two span continuous skew bridge 75 feet (22.83 m) and 63 feet (19.23 m)

spans consisting of 13 bulb-Tee section precast prestressed concrete girders in each span. Two

different types of carbon fiber plastic, FRP, tendons were used to pretension six precast concrete

girders, typical of those shown in Figure (1). Carbon fiber composite cables, CFCC, 5/8"

FIRST SMART HIGHWAY BRIDGE IN CANADA Ri::Jwlla & Tadros. 1994

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(15.2 mm) in diameter, produced by Tokyo Rope, Japan were used to pretension four girders

while the other two girders were pretensioned using two 3fa" (8 mm) diameter Leadline rods

tendons, produced by Mitsubishi Kasei. Distribution of the CFCC cables and Leadline tendons

within the bottom flange, is shown in Figure (2). Continuity of the two spans was achieved by

post-tensioned steel tendons extended along the entire length of the bridge.

Fiber optic Bragg grating strain and temperature sensors were used to monitor the

behaviour during the construction and under serviceability conditions. The 4-channel Bragg

grating fiber laser sensing system was developed at the University of Toronto Institute for

Aerospace Studies. 1

Before construction of the bridge, an experimental program was conducted at the

Structural Engineering and Construction R&D Facility, University of Manitoba, to examine the

behaviour of a 1:3.3 scale model beams pretensioned by the same types size and anchorage of

the two different tendons used for the bridge girders. The tests also used the same optic sensor

as used for the bridge in addition to electric resistance strain gauges to compare the results.

Tests results of the structural behaviour and optical sensors are discussed in detail in separate

papers.2,3

Structural Design

Flexural design of the girders, using carbon fibre reinforced plastics, CFRP, tendons was

based on the strain compatibility and the materials characteristics of the CFCC, Leadline rods

and the concrete. The material characteristics of CFRP is perfectly linearly elastic up to failure

with a guaranteed tensile strength of 250 ksi (1750 MPa) and 285 ksi (1970 MPa) for the CFCC

cables and Leadline rods respectively. The elastic models of CFCC and Leadline rods were

20,000 ksi (137 GPa) and 21,000 ksi (147 GPa) respectively. The girders were designed to

provide identical behaviour to the other girders pre tensioned by steel tendons under service

loading conditions as shown in Figure (3). This design resulted in higher flexural strength of

the girders pretensioned by CFRP, however, less deflection at ultimate in comparison to the

girders pretensioned by conventional steel strands.

Special detail was implemented in the structural details to provide safety precaution

features in the unlikely event of possible distress of the CFRP. Holes were provided at the

thickened web at the end of the girders, as shown in Figure (4), to be used to bolt steel brackets

FIRST SMART HIGHWAY BRIDGE IN CANADA Rizkalla &: Tadros. 1994

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on each side of the web to support external prestressing system, if needed, at the bottom flange

of the girder to compensate any possible losses of the pretension system. The failure mechanism

of the bridge ensured also that the catenary action provided by the steel tendons, used to provide

the continuity over the middle support, is sufficient to carry the self weight of the bridge.

Due to the high bond characteristics of the CFRP, which could result in shorter transfer

length and consequently possible split cracking, spiral reinforcements were provided at the end

of the girders for each cable as shown in Figure (5).

The cables were located at three different layers to also provide significant safety and

ductility to the bridge since any possible distress will take place gradually from the bottom layer

to the second and the third layer, thereby providing sufficient warning effect. The bridge is

continuously monitored using the built in optical sensors and electric resistance strain gauges.

Collected data on the performance will also provide sufficient warning effect to avoid any

possible accumulation of serious distressing, therefore helping engineers to take appropriate

actions.

Construction Details

Prestressing of CFRP were adapted to practice of the precasters by using couplers to

couple the CFCC and Leadline rods to conventional steel strands as shown in Figure (6.a, b) for

the CFCC and Leadline respectively. Use of couplers were useful to minimize the length of

CFRP tendons. The couplers were staggered to allow use of the same spacing used for the

conventional steel tendons. The couplers system simplified the tensioning process by allowing

the precasters to use the same jacking system typically used for steel tendons without any

modifications. Details of the coupling system is shown in Figure (7). The CFCC and the

Leadline rods were delivered to the precast plant in approximately 2 meter diameter rolls as

shown in Figure (8) The Leadline rods were cut at the site, and two rods were used for each

tendon. The CFCC were delivered precut to the specified length with 300 mm die cast at each

end to distribute the stresses at the anchorage zone. Construction of the bridge and handling of

the girders at the site were typical as shown in Figure (9). The completed bridge is shown in

Figure (10).

FIRST SMART HIGHWAY BRIDGE IN GlNADA Rizkaila & Tadros. 1994

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--------- --

Optic Sensing System

A 4-channel Bragg grating fibre laser sensor system, developed by University of Toronto

Institute for Aerospace Studies, was used at different locations along the bridge girders

pretensioned by the CFRP. This system involves 4 independent Bragg grating tuned fiber lasers

that are multiplexed in order to be pumped by one semiconductor laser. Each fiber laser was

attached to the surface of the tendon to serve as a sensor. The sensors were connected, through

a modular system, to a laptop computer used at the construction site to record the measurements

at different stages of construction and after the completion of the bridge as shown in Figure (11).

The optic sensor system measures the absolute state of strain rather than a strain relative

to an initial calibration value such as the case for the electric resistance strain gauges and

mechanical gauges.

ACKNOWLEDGMENTS

The writers gratefully acknowledge the financial support provided by the National

Research Council - IRAP program, Science and Technology Canada and External Affairs

Canada, who made it possible to complete this project. Special thanks is owed to Mr. A.

Abdelrahman for his assistance during fabrication, testing of the specimens and the preparation

of this paper.

REFERENCES

1. Measures, R., T. Alavie, R. Maaskant, M. Ohn, S. Karr, S. Huang, D. Glennie, C. Wade,

G. Tadros and S. Rizkalla. 1993. Structural Integrated Fiber Optic Strain Sensing of

Composite Prestressing Tendons Within a New Road Bridge, Proceedings of the Second

Canadian International Conference on Composites, Ottawa, September 27-29, 1993.

2. Abdelrahman, A.A., c.J. Wade, S.H. Rizkalla and G. Tadros. 1993. First Concrete

Highway Bridge in Canada Prestressed by Carbon Fibre Tendons, FIP Symposium 1993,

Kyoto Japan, October 17-19.

3. Abdelrahman, A.A., G. Tadros and S.H. Rizkalla. Test model for the first Canadian smart

highway bridge. Submitted to ACI Journal, December 1993.

FIRST SMART HIGHWAY BRIDGE IN CANADA Rizjcalla & Tadros, 1994

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LIST OF FIGURES

Figure (1) Typical precast concrete girder pretensioned by carbon fibre reinforced plastics

Figure (2.a) Distribution of CFCC tendons within the bottom flange of the girder

Figure (2.b) Distribution of Leadline tendons within the bottom flange of the girder

Figure (3) Behaviour of the short span girder pretensioned by steel, CFCC, and Leadline

tendons

Figure (4) Holes in the thickened web at the end of the girders

Figure (5) Spiral reinforcement provided at the end zone

Figure (6.a) Couplers for CFCC strands

Figure (6.b) Couplers for Leadline rods

Figure (7) Details of the coupling system

Figure (8) Rolls of Leadline rods.

Figure (9) Construction of the bridge

Figure (10) The completed bridge

Figure (11) Fibre optical measuring devices used for the bridge

FIRST SMART HIGHWAY BRIDGE IN CANADA RiVealla &: Tadros. 1994

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THE AUTHORS

Dr. Sami H. Rizkalla, Ph.D., P.Eng., is a Fellow of ACI and Associate Dean of Engineering,

Professor of Civil Engineering and Director of the Structural Engineering and Construction R

& D Facility at the University of Manitoba. He is currently a member of ACI Committee 440

FRP reinforcement, ACI Committee 550 precast concrete and ACI chapter activities committee.

He is Chairman of the Structural Engineering Division of the Canadian Society for Civil

Engineering and a Fellow of ASCE and CSCE. His current research field is in the use of

advanced composite materials for civil engineering applications and he is a board member of the

Canadian network in this field. Besides being the author of a large number of technical papers,

he is co-author of four technical books in the fields of structural engineering and advanced

composite materials.

Dr. GamiI Tadros, Ph.D., P.Eng.,is an ACI member, graduated from Cairo University with

a B.Sc. (Honours) in 1962 and a Ph.D. in 1970 from the University of Calgary, Canada. He

is a Advanced Engineer with Strait Crossing Inc., with his main activity being bridge design and

construction. He has designed bridges with deck areas over 400,000 m2• Gamil has published

extensively in the field of bridge design and construction. He has won numerous awards and

is a member of CSCE, ACI, PCI, ASCE and IABSE.

FIRST SMART HIGHWAY BRIDGE IN CANADA Ri;:kalla & Tadros. 1994

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--------~- ~ -

Figure (1) Typical precast concrete girder pretensioned by carbon fibre reinforced plastics

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PAGE 7

Cl Ln

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60 4- [S! 50 130 4- [S! 50 60

26- 015 TOKYO ROPE CO. crcc COMPOSITE CABLES, STRAIGHT

DEBONO 6 CABLES FOR 2000 IN FROM EACH END OF GIRDER.

Figure (2.a) Distribution of eFee tendons within the bottom flange of the girder

FIRST SMART HIGHWAY BRIDGE IN CANADA Rizkalla & Tadros, 1994

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-.--,-,-------rr---_~~ _________ JL_

-~~---------ir-CI~ = = = = = ~I~

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EACH END OF GIRDER. 60 4 @l 50 130 4 @l 50 60

52- 08 LEAD LINE CO. CFRP COMPOSITE CABLES, STRAIGHT

Figure (2.b) Distribution of Leadline tendons within the bottom flange of the girder

FIRST SMART HIGHWAY BRIDGE IN CANADA Rizkalla & Tadros. 1994

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. . .

. . . ........ -i- -_ ......... ---:- .. _ ...... --- -:- .. -_ .. --- --, --- .. _- -- -r-" -- .. _ .. _-

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I , 19.230

Figure (3) Behaviour of the short span girder pretensioned by steel, eFee, and Leadline tendons

FIRST SMART HIGHWAY BRIDGE IN CANADA Rizkalla & Tadros, 1994

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\ .i:F;;; 0 Ln 11Ire:~~O:':'::::----'O 1"'"""'_0 - N --- ----.Ln - ___ .0 ____

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, -- - ...... .--- =---

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1650 4-00 4-00 9 -50 oIA. HOLES THROUGH GIRDERS

EACH C/W 85 oIA. X 40 DEEP RECESS AT EACH END.

2$40 l500 "_.

Figure (4) Holes in the thickened web at the end of the girders

FIRST SMART HIGHWAY BRIDGE IN CANADA RilJcalla & Tadros, 1994

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Figure (5) Spiral reinforcement provided at the end zone

FIRST SMART HIGHWAY BRIDGE [I"~ CAf..',JI'A

Rizkalla & Tadros 1994

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Figure (6<a) Couplers for CFCe strands

FIRST SMART HIGHWAY BRIDGE r~ (A,\'ALM Rillcalla & Tadros, 1994

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------ - -- - -

Figure (6.b) Couplers for Leadline rods

FIRST SMART HIGHWAY BRIDGE TN CANADA Rizkalla & TadrllS. 1994

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Figure (7) Details of the coupling system

FIRST SMART HIGHWAY BRlljGE IN CANADA RiVcalla & Tadros. 1994

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Figure (8) Rolls of Leadline rods.

FIRST SMART HIGHWAY BRIDGE IN CANADA

RitJcalia & Tadros. 1994 PAGE 16

Figure (9) Construction of the bridge

FIRST SMART HIGHWAY BRiDGE T.\ ,_.-!'\ADA

Rizkalla & Tadros I Q91

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Figure (10) The completed bridge

FIRST SMART HIGHWAY BRflJGE IN CANADA Riz/calla & Tadros. 1994

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· .

Figure (11) Fibre optical measuring devices used for the bridge

FIRST SMART HIGHWAY BRIDGE IN CANADA Rizkalla & Tadros. ]99./

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