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Long spans-difficult engineering challenge due to
- Available construction technology and structural materials
- Forces of nature such as gravity, earthquakes, and strong winds
- Harsh working environment
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Slab Bridges
- Easy to construct
- short spans
- High self-weight
- Material: Reinforced or prestressedconcrete
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Voided Slab Bridges
- Voids introduced to reduce self weight
- May adopt solid section near supports (larger shear)
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Beam-and-Slab Bridges
- Beams uniformly spaced across the bridge’s width
- Columns at each pier
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Box Girder Bridges
- Hollow box shape (rectangle / trapezoid / triangles)
- Strong in torsion
- freeway overpasses
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truss bridges
- rigid joints at openings, stronger than the triangles
- only tension and compression develops
- force develop along the members
- wires cannot take compression
- statue of liberty
-
arch bridge –type
deck, through, half-through
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arch bridge –eg
- ChaotianmenBridge - longest arch bridge (main span: 552 m)
- Sydney Harbor Bridge- Tallest steel arch bridge
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Suspension Bridges-eg
- Golden Gate Bridge
- Tsing Ma Bridge- longest suspension bridge
- Bitan Suspension Bridge
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Suspension Bridges
- Cable, suspenders and anchorages under tension
- Towers under compression
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Cable-stayed Bridge-type
- Fan cable stays and harp cable stays
- A-frame, H-frame
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Cofferdams is…..made of ….;building procedures; it can be easily damaged due to…
- Temporary enclosure standing in water to create a dry environment to proceed with work;
- Sheet pile
- Must be built before Building the bridge & when water is shallow, start with building the frame, then drive the sheeting around the parameter by using a vibratory hammer, then pump out the water and drive the foundation piles;
- Pump out the water
- Overflooding (not much higher than water level) AND
- Strong currents and soil mud shifting out can bend the cofferdam
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