Beanbag1
Structural
- Mar 12, 2014
- 21
Hello,
The following scenario and question is for structural engineers who design bridges:
Designing a multi span bridge over a creek, say 12 spans each 40-ft for total 480-ft. Each span substructure is comprised of concrete cap supported on pipe piles. The cap and top of piles is approximately 10-feet above the water and the creek bed (mudline) is 10-feet below the waterline, with pile fixity located approximately 10-feet below the mudline. The superstructure is a concrete deck supported on I-beams that are simply supported on each bent. Each I-beam has a hinge bearing (fixed) at one end and a roller bearing (free to translate longitudinally at one end. There is a concrete abutment at each end of the bridge. One abutment has hinged (fixed) bearings for the I-beams while the other abutment has roller bearings (free to translate longitudinally. Thus each span has fixed-expansion type joint arrangement. I can't seem to dind any design textbooks or examples on this topic, but if the expansion joint at each span is say 1-1/2" wide, can the superstructure be assumed to brace the tops of the bents in the bridge's longitudinal direction when determining the unbraced length of the piles (for bucking analysis)? The resulting k-factor could make a big difference in the buckling analysis of the piles. Are there any good textbooks or design examples that speak to this topic?
Thank you.
The following scenario and question is for structural engineers who design bridges:
Designing a multi span bridge over a creek, say 12 spans each 40-ft for total 480-ft. Each span substructure is comprised of concrete cap supported on pipe piles. The cap and top of piles is approximately 10-feet above the water and the creek bed (mudline) is 10-feet below the waterline, with pile fixity located approximately 10-feet below the mudline. The superstructure is a concrete deck supported on I-beams that are simply supported on each bent. Each I-beam has a hinge bearing (fixed) at one end and a roller bearing (free to translate longitudinally at one end. There is a concrete abutment at each end of the bridge. One abutment has hinged (fixed) bearings for the I-beams while the other abutment has roller bearings (free to translate longitudinally. Thus each span has fixed-expansion type joint arrangement. I can't seem to dind any design textbooks or examples on this topic, but if the expansion joint at each span is say 1-1/2" wide, can the superstructure be assumed to brace the tops of the bents in the bridge's longitudinal direction when determining the unbraced length of the piles (for bucking analysis)? The resulting k-factor could make a big difference in the buckling analysis of the piles. Are there any good textbooks or design examples that speak to this topic?
Thank you.
