General
Multi-span Bridge
Prestressing Strands
100
This is the most conservative depth-to-span ratio for use in bridge design
- 0.045
- 0.05
- 0.055
- 0.04
What is 0.055?
100
In a multi-span continuous PS/PC bridge, negative moments occur at these locations.
- the piers
- the abutments
- the girder at mid-span
- all of the above locations
What are Piers?
100
what event causes cambering?
- cutting of the prestressing strands
- the concrete shrinking
- jacking the strands
- concrete curing
Cutting of the prestressing strands
300
By tailoring internal stresses and inducing bending stress, this technique allows girders to achieve longer spans
What is prestressing
300
This is the stage in construction when a multi-span bridge becomes structurally continuous.
- after the deck is poured
- after vehicles begin driving over it
- when rebar is placed in it
- after the deck hardens
after the deck hardens
300
The additional concrete poured to account for cambering is called what??
- haunch
500
This failure mode is typically not considered during curing
and fabrication of precast girders at the plant, since it develops later under service conditions after installation.
- Web cracking from detensioning strands
- Tensile failure causing concrete to crush
- Fatigue failure due to repetitive live loads
- Fatigue failure due to repetitive live loads
500
This is the KEY reason multi-span bridges are more structurally efficient than single-span bridges of the same total length.
- continuity and moment redistribution
- transverse reinforcement at piers
- reduced shear forces at interior supports
- increased stiffness due to additional supports
Continuity and moment redistribution
500
For prestressed concrete girders, designers must estimate the prestressing force that the strands apply on the concrete section. The designer will typically accomplish this by specifying the initial jacking stress (fpj) as well as total prestress losses which includes this... what is
Loss due to shrinkage (∆fpSR)
Loss due to concrete creep (∆fpCR)
Loss due to strand relaxation (∆fpR)
All the above
All of the above