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and stud shear connectors were applied. Design was conducted
so as to produce full shear connection in view of strength.
The characteristics of the composite section are depicted in
Fig. 1(a). The bridge is a 2-span continuous composite girder
with spans of 15 m for a total span of 30 m (Fig. 1(b)).The fabrication of the composite girder prototype proceeds
as follows. Firstly, the precast decks manufactured in the
factory are transported to the prototype bridge plant. Once the
girders are positioned, the decks are lifted and installed on the
girders. At that time, in the case of the prototype, the installation
of the decks was performed on the girders equipped in advance
with the shear connectors. In such case, the assembling may
be delicate because of the lack of space due to the presence of
the shear connectors and loop joints. As a measure to solve this
problem, the shear connectors can be welded to the girder at
the shear pocket locations using a stud welder after installation
of the decks on the girder and with the shear connectors not
welded to the girders. However, such methods require sufficient
space for the shear pockets, and the process may also be delicate
when space cannot be secured. Especially, the enlargement of
the shear pockets may generate adverse results in the deck
because of the difficulty to arrange the reinforcing bars, which
makes it difficult to enlarge indefinitely the space of the shear
pockets. As another measure, shear connectors in the form of
screw-bolt can be considered.
On the other hand, once the installation of the decks is
completed, the transverse reinforcement shall be arranged in
the overlapping sections of transverse loop joints (Fig. 2(a)
and (b)). As illustrated in Fig. 2(b), six main reinforcements
have been arranged at the top and bottom of the overlapping
sections of transverse loop joints for the prototype. After the
arrangement of bars, concrete is cast in the shear pockets
and transverse joints, and curing is performed. As shown in
Fig. 2(a), the edge of the shear pockets has been rounded to
minimize the effects of stress concentration. The fabrication of
the two-girder continuous composite bridge is completed with
the end of curing (Fig. 2(c)).
2.3. Loading and measurement locations
For all the tests, loading was applied at both mid-spans
(Fig. 3(a)) considering the contact surface of the wheel load
(Fig. 3(b)). A location of loading with respect to the nearest
joints was about 600 mm. The first loading was applied up to
360 kN and then fatigue loading test proceeded. Lastly, static
loading was applied up to 900 kN. The fatigue load of 1.5 Hz
cycles was applied using a dynamic actuator with capacity of
500 kN. Minimum and maximum load of the test were 3.9 kN
and 360 kN, respectively.
The deflection of the test bridge has been measured
by means of LVDT disposed at both loaded mid-spans as
illustrated in Fig. 3(c). In the sectional direction, deflections
were measured both in the bottom of the girder and in the
decks. After the development of cracks has been verified using
Omega gauges, the crack width was measured at the bottom of
the decks in the loaded sections and at the top of the decks in
the internal support sections. Considering that the distribution
of relative slip between the girder and the deck occurs anti-
symmetrically with respect to the center of the internal support,
measurements were performed only for the span of one girderFig. 2. Fabrication of continuous composite bridge with loop joint
prefabricated slabs.
at locations (SL1–SL6) indicated in Fig. 3(c) [6]. The strain
of the girders was measured by sticking strain gauges at mid-