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The construction of the steel box girder by up-down
support and casting concrete at the negative moment area
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This method's purpose is improving stiffness
necessary to negative moment area by shear connector installed and
casting concrete on the bottom of the negative moment area of the
steel box to steel box girder.
Otherwise, improving stiffness
necessary for taking off tension force when design load applied
by using the up-down method, compressive stress installed on the
negative moment area of upside of deck plate concrete.
This method is more extend a span of bridge
than existed steel box bridge and case of making nonprismatic section
of the positive-negative moment area, most extend a span of bridge.
Otherwise prevent a decay in the steel box by being installed concrete
at the bottom of the negative moment area and obtain effect that
obsorbed noise or shake.
And reduce a fault of welding area
by changing top and bottom flange thick into relatively simple.
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The procedure of construction
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(1) The manufacturing and construction
of 2 span steel box girder bridge
The drawing
shows the procedure and details of construction.
1 is lifting-up
support, 2 is lifting-down support, 3 points slab concrete
and 4 indicates concrete that is cast in lower part of the
steel box girder at the range of negative moment.
A. The state of lifting-up
inner support after casting and curing concrete in
lower part of the steel box girders at the 50% range
of negative moment in condition of setting steel box
girder over 2 span |
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B. The state of setting in
condition of lifting-down support after casting and
curing concrete over full span in condition of lifting-up
support |
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(2) The manufacturing and construction
of 3 span steel box girder bridge
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The dynamic effects of 3 span is
same as them of 2 span.
A. The state of lifting-up
support after connecting 2 spans first among 3 spans
and then casting and curing concrete in lower part of
the steel box girder at the negative moment range of
the first inner support |
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B. he state of lifting-down
inner support that was lifted up after casting and curing
concrete over full span except left-hand parts of the
third support in condition of lifting-up the first inner
support |
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C. The state of lifting-up
support to induce compression stress to concrete in
lower part of the steel box girder after casting and
curing concrete in lower part of the steel box girder
at the negative moment range of the right-hand support |
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D. The state of setting to
support in condition of lifting-up right-hand
support after casting and curing concrete in remaining
span |
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(3) The
manufacturing and construction of steel box girder bridge more than
4 span
The
steel box girder bridge more than 4 span can be constructed by iterating
above procedure and be applied to method of reinforcing rigidity.
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