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structural members under service loads.
Recently, an experimental test on a full-scale model of a
steel and concrete composite plate girder with prefabricated
slabs under hogging moments was cautiously conducted and
observed in order to study crack control [7]. From the study,
it was concluded that initial crack spacing of the slab in the
composite girder with prefabricated slabs can be wider than
those of general RC beam structures. Also, it is considered
that crack widths of the composite girder with prefabricated
slabs were more enlarged in weak surfaces of construction
joints. Moreover, the crack spacing is decisively influenced by
transverse reinforcement spacing. Therefore, it is necessary to
consider the existence of construction joints and the influence
of transverse reinforcement spacing on the crack spacing in the
calculation of crack width.
In this study, an experimental test on a full-scale model of
a continuous composite two-girder bridge with prefabricated
slabs was cautiously conducted and observed in order to study
crack control. The bridge is a 2-span continuous composite
girder with spans of 15 m for a total span of 30 m. The design
of the deck has been conducted considering the real dimensions
applied for highway bridges. Girder spacing of 2.5 m has been
designed taking into regard the deck span of ordinary multi-
girder composite bridges.
Static loading test has been conducted to observe the elastic
and cracking behaviour. After a survey of the crack width
developed at the bottom of the decks located in the loaded
sections and at the top of the decks near the internal supports,
fatigue load was applied one million times, followed by static
loading test up to 900 kN, the maximum capacity of the
actuator. Deflection, relative slip, crack widths and moment
curvature curve of the composite section under static and
fatigue loadings were observed. Crack distributions and crack
spacing were viewed. The composite section behaviour of the
precast deck with loop joints was confirmed. Test results were
analyzed by finite element analysis and design methods. The
flexural stiffness of the composite section is compared with that
of the proposals in EUROCODE 4-2 [4] and discussed.
2. Experimental works
2.1. Bridge prototype
The thickness of the deck has been determined so as
to satisfy the minimum thickness specifications [9] and
on the basis of previous research results [7,8] on joint
details. Transverse pre-tension was introduced in the transverse
direction of the deck. Pre-tension level was determined so that
the deck resists the bending moment produced by the dead
load during the transport and the transverse bending momentdeveloped in the deck due to design live load. Twenty four
tendons of diameter 12.7 mm were arranged transversely in
each prefabricated slab. Transverse pre-tension appears to be
required especially in case of transverse long precast decks.
Diameter of transverse reinforcement was 13 mm. The ratio of
longitudinal reinforcement was 1.28% of which diameter was
16 mm.
Vertical stiffeners have been disposed at regular intervals
in the girder in order to prevent shear buckling of the web
plate, and cross beams have been installed at the supports.
Except near the interior support, spacing of vertical stiffeners
is three times the girder height because the tension-field action
is assured. Horizontal stiffeners are not installed anywhere. The
thickness of vertical stiffeners was 14 mm. The dimensions of
the precast deck are illustrated in Fig. 1(c), and a total of 15
decks with width of 2.04 m were installed transversely on the
girders. Three shear connectors per shear pocket were disposed