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In this study, an experimental test on a full-scale model of a two-span continuous composite two-girder bridge with prefabricated slabs was
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cautiously conducted and observed in order to study crack control. In the testing, a first loading was applied up to 360 kN and then fatigue loading
test proceeded. Lastly, static loading was applied up to 900 kN. From the test results, it is confirmed that the two-girder continuous composite
bridge with loop joints prefabricated slabs shows composite section behaviour for both strength and stiffness under static and fatigue loads.
Although, in negative moment regions, cracks concentrated at the cast interface of the joints between decks above the internal support and the
initial crack spacing is constituted by the distance between joints, crack widths can be controlled appropriately within an allowable crack width
in the decks and transverse joints of the composite bridge with prefabricated slabs on an interior support under service loads. Moment curvature
relationship or the flexural stiffness by Eurocode 4-2 is still useful for the estimation of the effective stiffness considering tension stiffening effects
in the composite bridge with loop joints prefabricated slabs.7389
2007 Published by Elsevier Ltd
Keywords: Crack control; Continuous composite two-girder bridge; Prefabricated slabs; Loop joint; Transverse joint; Static and fatigue loads; Composite section
behaviour; Negative moment region; Crack width; Flexural stiffness of composite section1. Introduction
Steel and concrete composite bridges are very attractive
solutions for short and medium span bridges. However, for steel
and concrete composite continuous bridges, when a concrete
slab is in tension and a lower flange of a steel girder is in
compression under hogging moments, there are shortcomings
in view of durability and strength. Especially, concrete cracking
affects the durability and service life of bridges. Therefore,
crack control is an important issue in steel and composite
continuous bridges. There are two approaches for dealing with
concrete cracking in composite bridges: one is to prevent
cracking using prestressing methods and the other is to allow
the formation of cracks but limit their widths to acceptablevalues. Prestressing methods, however, are inconvenient and
doubtful due to prestress losses by the long-term behaviour
of concrete. Therefore, it is considered that the control of
crack width without prestressing is the more economical and
interesting solution.
Some previous researchers have studied the cracking of
the decks in composite bridges such as the influence of
reinforcement ratios, diameter and spacing on crack spacing
and crack widths. Also, it is necessary to notify local weakening
of the tensile capacity of a concrete slab caused by shear
connectors or transverse reinforcement since these factors may
influence the crack spacing and widths [5,7,10,12].
A precast concrete deck could be very attractive because
the system can ensure the quality of concrete decks, improve
working environments for the workers, and reduce man
hours outdoors and traffic disruption. A shorter construction
time could be an important factor in choosing precast deck
bridges. A precast deck bridge has two types of connection:
shear connection between steel girder and precast deck, and
transverse joint between precast panels.However, in order to apply precast decks to continuous
composite bridges, the tensile behaviour of precast decks or
transverse joints between slabs in hogging moment regions
should be confirmed in view of serviceability and durability.
Particularly, stiffness of the composite section during cracking
should be evaluated precisely, because it is very important to
estimate crack widths, deflection and stress ranges applied to