huangyhg

curved concrete beam in elevation
i have to design a curved concrete beam in elevation for a retail building. the architect wants it to have a tunnel like feel when entering the building.
the length of the beam in plan is about 35' feet. the curved length of the beam is going to be about 55' long.
are there any books or code references that i could refer to for concrete curved beams? i am guessing the curved beam would result in a horizontal force at its ends along with the vertical down force. i am having second thoughts about designing the beam, because i think the spans are too big
would it be much easier,using hss tubes forming the curve in lieu of the concrete and then infilling w/ wood/steel studs to give the curved appearance.

so its a semi circular arch then?
steel beam with timber framed cladding is always cheaper but not as durable, best to check with architect if this is acceptable.
look up roarks or similar for a formula on this, it can be designed with no horizontal restraint at the base.
i have used curved hss tubes before for a design that i did for a walkway. it looks like a space ship landing dock. anyway, steel hot rolled sections are bent that way a lot of times and it is not unusual. i suggest you specify a curved steel beam. make sure your connections are designed appropriately. this is the easiest way to handle that problem in my opinion.
model the beam and supports for boundary conditions. first with roller supports and second with restrained supports. the answer will be somewhere between and if you can design for the worst case and get a reasonable result then you have it. will only be a question of how big it needs to be. unless it has very large loads it sounds like it should work in concrete.
one more thing, you need to be extra careful about lateral torsional buckling if you use a wide flange.
how will it be formed? forming it in place would be quite expensive. maybe you should form it flat on the ground and hoist it in place.
or you could design it as a three hinged arch and pour one half on top of the other, then raise both halves with a couple of cranes and connect all of the hinges.
a three hinged arch is statically determinate and easy to analyze. it requires horizontal reactions at the supports to support gravity load.
ba
i think just modeling the structure in an able 3d program will get you reasonable approximation to the behaviour. if it is curved only in plan, just caring for the forces and displacements should end with the problem, provided you have enough structural clearance for rc construction. if the beam is curved in plan and elevation, i woud try to brace it to some structural elements at the fa?ade, bridging with the canopy roof elements; stabilizing this way laterally the thing will diminish further troubles.
hi,
a good reference book is " reinforced concrete designer's manual" by reynolds & steedman. an excellent book.
lexim
check "structural concrete: theory and design 4th edition by m. nadim hassoun & akthem al manaseer" it is kind of decent rc reference. i believe it covers design of beams curved in plan but not sure about beams curved in elevation.
the benefits of hss lay in its torsional stiffness, and considerably lighter than concrete. but bend to tight curve and splicing by field welding may cause some headaches.
we don't seem to be getting a lot of feedback from the op on this thread.
ba

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