huangyhg

bridge link to building
hi,
i have to design a very small reinforced concrete bridge link between a concrete cantilevered concrete footpath and a building.
typically i try to design these types of structures independent from the structure but in this case the bridge link is only 6-8 feet long. it might look funny to have too many columns.
because of the length i am planning to keep the bridge link independent at the cantilever supported with one column and attached directly to the building on the other end.
any thoughts against this?
thanks
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i assume you are having a deep slab section or a concrete slab supported on beam and anchored into the column. this will be my option.
having a space to locate a column for you to have one end rigid and the other end free is wise, and isolating the free end to move in the direction of crossing is also a good option to reduce any rotation on the existing building.
lexim
hinge it at both ends and construct out of steel.
if it is architecturally feasible, i would balance the bridge on one central column and provide only nominal braces at the ends to control lateral movement and vertical differentials.
thank for the repsonses.
steel is not an option so i am having a 6" slab supported on a beam/column.
the beam will be cast right up to the cantilever edge. since there a likely possibility of an undesirable crack, i plan to notch the edge of the cantilever and cast a small portion of the bridge link over the cantilevered slab. my thoughts are that the crack that will develop will be easier to maintain. i am thinking of placing some flexcell on the underside and along the edge of this overlap to help with any deflections/movements.
any additional thoughts?
thanks
your thoughts are good on the proposed solution especially the flexcell is very important to check any vertical movement. this movement could generate fatigue shearing stresses at the notched ends as the slab transfers some reaction to the existing building.(right??).
so i would check the stress at the notched end at the cross section change and i'll make sure i reinforce this area well against shearing stresses.
good luck.
lexim

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