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State of the Arts of Hybrid structures consisting of steel and concrete in Japan

Kazuo OHGAKI *

* Dr. Engineer, Kawasaki Heavy Industries, Ltd., Tokyo, Japan; ohgaki_kazuo@khi.co.jp

AbstractHybrid structures consisting of steel and concrete have been adopted for the construction of various structures. Thecomposite construction in Japan has not only been adopted for the roadway bridges but also been adopted for variousstructures such as the foundation, the vessel, the harbor structure and so on. This reason is an economic advantage ofthem. Furthermore, hybrid structures consisting of CFT has been studied recently. This structural type is nowincreasing for the pursuit of the economy, rationalization of structures and efficiency of construction now. In this paper,the present state of hybrid structures consisting of steel and concrete in Japan is introduced, and particularly the jointsystem in each structure is focused on.

Keywords: Hybrid structure, Shear connector, CFT girder

1. IntroductionThe composite construction in Japan has not only been

adopted for the roadway bridges but also has beenadopted for various structures such as the foundation, thevessel, and the harbor structure, etc. This reason is aneconomic advantage obtained from its lightnesscompared to the concrete structure. Therefore, it is saidthat these composite structures are rational ones underearthquake attack. Another reason is that the compositestructures are more advantageous than steel structurefrom a viewpoint of economic.

Around a half of the contents of this paper consists ofthe citation from the report of the committee of "RecentProgress of Hybrid Structures” set up by “Committee onHybrid Structures of JSCE”. Primarily I show compositestructures, in which there are two plate girder bridgesthat has wide span pre-stressed concrete slab, and PCbox girder bridges with the steel corrugated web. Acharacteristic part explained is joint systems between thecorrugated steel web and the concrete slab for thesecomposite bridges. Next I explain, as an applicationexample, the PC hybrid truss bridge consisting of thesteel pipes used for the web member. Moreover, as thejoint system between concrete slab and steel pipe, thesystem consisting of the double tube is explained.

The investigation result of each structural type for thejoint systems between steel and concrete slab are shownin this paper. This investigation includes the shearconnectors being used for various kinds of compositestructure.

Finally, the steel deck plate girder with CFT for thelower flanges is shown as an example. The limit statedesign method was applied to this bridge. These arepresented in this paper.

.2. Recent hybrid structures and joint systems2.1 Composite two girder bridge

The target is squeezed to the roadway bridges wherethe hybrid structures were developed, and preferablybeing used in Japan. The trend is described about theconstruction case for the recent hybrid structures and thejoint systems between steel and concrete. In the roadwaybridges, there are a lot of cases that the hybrid structuresare adopted, especially in the expressway, and the onethat steel and concrete were combined in a structuralcross section is called a composite structure, and on theother hand, the one that steel and concrete werecombined in a structural member is called a mixedstructures, and generally these are called hybridstructures. The most general hybrid structure in the

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expressway bridge is a two plate girder bridge that haswide span (6-11m) in the concrete slab. For thecomposite plate girder bridges, in the latter half of 1990's,the steel rational plate girder bridges come to be adoptedas a standard structural form of the steel bridges byrationalizing construction and so on. For the concreteslabs, PC slabs are adopted with the increase of the spanof the concrete slabs, and for the durability of theconcrete slabs. In this kind of bridge, the headed stud hasbeen adopted for the connection between steel andconcrete, and the composite action is generally expectedunder the live load. The examples are shown in Figure1and Figure2. Figure1 indicates the case of 6m in spanlength of concrete slab, and Figure2 indicates the case of11m in span length of concrete slab.

2.2 PC box girder bridges with the corrugated steel webThe technology of PC box girder bridges with thecorrugated steel web shown in Figure3 was introducedfrom France, and it was adopted in the expressway for

the first time in 1999 in Japan, and around 100 bridgeshave been constructed so far. The construction cases ofthis type bridge are shown in Figure 4 and Figure 5.

Figure 1. OTSURO River Bridge(Slab span length 6m)

Figure 2. WARASHINA River Bridge

(Slab span length 11m)

Concrete upper slab

Corrugated

steel web

Deviator

Concrete lower slab

Inner PC cable

Corrugatedsteel web

Outer PC cable

Inner PC cable

Figure 3. Structure of PC box girder with corrugatesteel web

Figure 4. KOKAWAUCHI River Bridge

Figure 5. TOYOTA C-Ramp Bridge

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2.3 Extradosed PC box girder bridgeIn recent years, application has been extended to

Extradosed PC box girder bridge and cable-stayed PCbridge that especially used the corrugated steel for theweb, and it leads to the span extension by lightening ofthe superstructures. The typical cases are shown inFigure 6 and Figure 7.

2.4 Joint systems between the corrugated steel web andthe concrete slab

A characteristic part is a joint system between thecorrugated steel web and the concrete slab for thesecomposite bridges. In this structure, it is necessary totransfer the shear force acting at the interface betweenthe corrugated steel and the concrete slab. Therefore thejoint system between the corrugated steel and theconcrete slab is basically important to attain the completecomposite performance for this structure. In the firststage into which the technology of the bridge structure to

Figure 6. HIMI-YUME Bridge

Figure 7. OMI-OTORI Bridge

鋼棒合接

孔筋鉄

筋鉄横通貫

ブェウ板鋼形波Corrugated

steel web

Hole for

reinforcement

Reinforcement

Corrugated steel web

Penetrated reinforcement

(a) Direct embedding in concrete

フランジプレート

貫通鉄筋Ｕ字鉄筋U-formed reinforcement

Flange

Angle

U-formed reinforcement

Penetratedreinforcement

Angle

Corrugated steel web

Flange plate

(b) Angles welded to the flange plate

Penetrated

Penetrated

reinforcemen

Flange rlate

Perforated steel

Corrugated steel webCorrugated steel web

Perforated steel plate

Penetrated hole

Penetratedreinforcement

Flange plate

(c) Twin perforated steel plate

Penetrated

reinforcement

Headed stud

Penetrated

reinforcement

Flask formedperforatedsteel plate

Headed stud

(d) Flask formed perforated steel plateand headed stud

Figure 8. The type of joint system of thecomposite PC box girder bridge withthe corrugated steel web

Penetrated reinforcement

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use the corrugated steel web was introduced from France,the headed stud was used for the joint system betweenthe corrugated steel web and the concrete slab. In theexpressway bridge in Japan, the horizontal shear forceacting on the interface between the corrugated steel andthe concrete slab in the longitudinal direction of thebridge is large, and also the influence of fatigue by thewheel load increases. Therefore, the joint systems shownin Figure8 have been employed recently. As a result ofthese examinations, the perforated-bond plate of flasktype was developed in the lower slab. In recent years, thetwin perforated-bond plate has been adopted for theupper slab, otherwise the directly embedding system isadopted for the lower slab pursuing further economy.

2.5 PC hybrid truss bridgeNext, PC hybrid truss bridge developed is introduced.

This type of bridge is shown in Figure 9 and Figure 10.

2.6 Joint systems between the steel pipe and the concreteslab

These bridges are adopted for the continuous rigidframe type structure for the first time in the world, andthe maximum span length is 119m, and the bridge scaleis the world's largest as the PC hybrid truss bridge. Thesteel pipe is used for the web truss member, andlightening is attempted. Moreover, as the joint systemsbetween concrete slab and steel pipe, the joint systemconsisting of the double tube and that consisting of twingusset shown in Figure11 and Figure12 were developed.

The joint system using the double tube is composed ofthe steel pipe with rib on the outside surface, the holedsteel pipe with rib on the inside and outside surfacewhich is arranged on that outside, and the steel plate thatis connected with that both outside steel pipes.

On the other hand, the joint system having two gussetsstructurally leads to a big joint system because the gussetplate is so big. Two friction joint systems with the high

Figure 9. Outside view of hybrid truss bridge(SARUTA River Bridge)

Figure 10. Inner view of hybrid truss bridge(TOMOE River Bridge)

Figure 11. Joint system consist of the double tube

Holed steel pipe with rib Steel pipe with rib

Steel pipeConnection plate

Figure 12. Joint system consist of twin gusset

Gusset plate

Penetrated reinforcement

and Perforated steel plateSteel truss member

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tension bolts were used for connection systems betweentruss members and the upper chord slabs. By this system,the height of gusset plates was reduced, resulting in thedecrease of the number of the bolt. The gusset part wasarranged in a concrete beam with a combination of shearmechanisms such as PBL. In this bridge, two gussetsystems was adopted in the joint part where the highaxial force for the truss member is subjected, and thedouble tube joint system is adopted in other joint parts.

3. Investigation result of hybrid structuresThis investigation for establishing the design

technique was carried out by Subcommittee on theRecent Progress of Hybrid Structures in JSCE. Thequestionnaire survey was requested from thesubcommittee to the engineer or the designer of thesehybrid structures. With respect to the content of thequestionnaire, it was an outline of the structure, meritsof adoption of the hybrid structures, a design methodand so on. In addition, the opinion of a structuralproblem and the performance-based design methodbeing advanced in JSCE was expressed.

The classification of the investigated each structuralform is shown in Table1. In this investigation, thenumber of the hybrid rigid frame type bridge, thecomposite plate girder bridge (The PC box girder bridgeusing corrugated steel web is included) and thecomposite slab bridges is comparatively large. In theseinvestigations, the merits of the adopted hybrid structuresare shown in Figure13. The reason for a lot of merits thatare given from Figure13 is the economy. The resistanceof the earthquake increases by improvement of thestructure. Furthermore, a construction period of thesehybrid structures can be shortened.

The investigation result of each structural type for thejoint systems between steel and concrete slab are shownin Figure14. Various joint systems in various structureswere adopted. This reason is the one basically adopted inconsideration of a structural characteristic, construction,and the economy, etc. In the composite plate girderbridge, it is understood that the headed stud is generallyused. The perforated-bond plate is preferably used to PCbox girder bridges using the corrugated steel web

Table 1. The investigated each structural form

Classification

① Composite girder bridge (corrugated steel web bridge )

② Composite slab bridge

③ Hybrid structure(truss bridge , arch bridge)

④ Hybrid structure(cable stayed bridge)

⑤ Mixed structure, Steel reinforced concrete girder

⑥ Hybrid structure(rigid ramen bridge)

⑦ Fiber reinforced plastics girder , Steel stiffened timber bridge

⑧ Others

included in the composite plate girder bridge. Moreover,

the block dowel (Section steel shear connector) isadopted in the railway bridges. There are various jointsystems for the composite slab, because these slabs weredeveloped in each company.

(a)Composite plate girder bridge (PC box girderbridge using corrugated steel web is included)

(b)Composite slab bridge

(c)Hybrid structure(rigid ramen bridge)Figure 14. Joint system of each hybrid structures

91

68

46

46

56

36

29

17

0 10 20 30 40 50 60 70 80 90 100

①.Cost performance

②.Constructability

③.Seismic performance

④.Lightness

⑤.Shortening

⑥.Maintenance

⑦.Sosio economicimpact

⑧.Others

Figure 13. Merits of hybrid structures

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3

5

4

6

0 5 10 15 20

Headed studs

Perforated-bond plate

Block dowel

Bond, Friction

Others

9

11

1

3

8

0 5 10 15 20

Headed studs

Perforated-bond plate

Block dowel

Bond, Friction

Others

15

8

5

1

2

0 5 10 15 20

Headed studs

Perforated-bond plate

Block dowel

Bond, Friction

Others

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4. CFT girder bridge4.1 Structural summary

The CFT girder bridge developed by Kawasaki HeavyIndustries is the new type of composite structure. CFT isused for the lower flange of the steel deck plate girderbridge, as can be seen in Figure15. CFT is a concretefilled steel tube and has superior plastic deformationproperties in a compression stress state. Hence, we usedCFT for a lower flange subjected to compressive force.The stiffness of the main girder increases and a long spanconstruction can be attained compared to the normalplate girder.

4.2 The comparison with the conventional bridge formI assumed the 3-span continuous girder bridge with a

span length 100+125+100m to examine the economy ofthis bridge. Three types of structures designed are a steeldeck plate box girder bridge, composite truss bridge andsteel deck plate girder bridge with CFT. These designedbridges for comparison are shown in Figure16. Acomparison result with respect to steel weight,deadweight and the number of steel plates is given inTable2. The steel deck plate girder bridge with CFT hassmaller steel weight and the number of steel platescompared to those of steel deck plate box girder bridges,and it will give an advantage in economy.

Table 2. The comparison with the conventional bridge

Item

Steel deckplate box

girder bridge

composite trussbridge

CFT girderbridge

Steel weight 1,650tf 1,250tf 1,500tf

deadweight 2,700tf 5,100tf 2,900tf

number of

steel platesmost many few

4.3 The design method of main girderThe limit state design method was applied to the

design of the steel deck plate girder bridge with CFT. Inthe limit state, it was defined that CFT member reachesplasticity as shown in Figure17. With respect to theultimate strength of this newly developed bridge system,it has been confirmed by an experiment.

Figure 15. The CFT girder bridge

CFT

Steel deck plate

Concrete

Steel tube

Figure 16. Compared design bridges

(a) Steel deck plate box girder bridge

(b) Composite truss bridge

(c) Steel deck plate box girder bridge with CFTCFT CFT

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4.4 An application example to Kobe new transportationsystem

The CFT girder bridge shown in Figure18 wasdesigned for the construction for the second stage of theKobe new transportation Port Island Line. On theoccasion of construction, the wind-resistant stability wasexamined by the wind tunnel test, the concrete fillingperformance was examined and confirmed and theinspection method of the filling degree confirmationsystem by infrared photography was established.

5. Concluding remarksExamples of steel-concrete composite structures were

introduced. The continuous composite two girder bridges,the PC box girder bridges with the corrugated steel web,the extradosed PC box girder bridges and PC hybrid trussbridge were shown as construction example of hybridstructures. Furthermore, I explained the joint systemsbetween the steel members and the concrete slabs.

In addition, the investigated result on shear connectorsthat have been adopted for various composite structureswere shown. The shear connector design document ofvarious composite structures was also offered.

Finally, I introduced an application example of theCFT girder bridge. The result of comparative design, theapplication of limit state design method to the maingirder and the adoption of this type of bridge for Kobenew transportation system were introduced.

6. AcknowledgmentThe first half of this paper is from the result obtained

in “The Present Conditions Investigation Subcommittee”of “The Hybrid Structure Committee” of Japan Societyof Civil Engineering. I thank these cooperators verymuch.

ReferencesJSCE Subcommittee on the Recent Progress of Hybrid

Structures; (2008). “Survey and Analysis on theCurrent Situation of Hybrid Structures(Toward theAdvance of Performance-Based Design Method ofHybrid Structures)”, Hybrid Structures Reports 02

Uehira K., Ito S. (2008). “Recent Progress ofHybridStructures and Its Design Methods in Japan”,EASEC-11, Building a Sustainable Environment,Taipei, TAIWAN

Kawasaki Technical Review; (2005). “New Style Bridge:First “Steel Deck CFT Girder Bridge” in Japan”,No.157, pp.10-15.

σt

σc

σy

σy

Figure17. The design method of main girder

Ultimate limit state

steel deck plate

web plate

CFT

plastic

Fullplastic

Using limit state

Tension

Compression

(a)side view

CFT CFT

(b)photograph

Figure18. The CFT girder bridge in Kobe new

transportation system