Pedestrian bridge shear crack

[charliealphabravo]

I am looking at options for the repair of a shear crack in a cast-in-place pedestrian bridge (early 70s). The condition was discovered during renovations and runs the full width of the bridge although the crack widths at the opposite end are acceptable.

The bridge is about 30 feet wide and spans about the same distance. I only have an architectural plan at this point so I haven't confirmed the longitudinal reinforcement, but seeing as it is basically a 12" thick flat plate I don't expect to find much effective shear reinforcement. The railings are integral cast-in-place, but as you can see they were discontinued near the support.

Thanks in advance.

 

[charliealphabravo]

I appreciate the thoughts on the direct retrofit. I was wondering about the feasibility of that. Again at this point the structural sheets of the plan have not turned up.

With all that in mind, grasshopper would like to pose a few feasibility questions:

What would shear reinforcement look like in a 12"D by 30'W slab? Would you model it as (30) parallel 12"Wx12"D beams? Would the shear reinforcement be effective after cover requirements? In structural slabs, shear deficiency is normally made up with concrete drop panels or capitals I think.

 

[hokie66]

Yes, you are right to ignore those who want to retrofit shear reinforcement. A 12" thick solid slab like this doesn't normally need shear reinforcement, and stirrups would not have prevented what has happened. Just support it at the end of the side walls, then make good the cracked part and release the longitudinal restraint.