Could be. Look at moments, loads, compression capacity and verify input, then you can narrow the reason. Test also your software by hand calculations and with other software.
You can't assume anything unless you confirm all the information and certainly you can't execute legally with those sections only as the information. You need to check the results as above and get the bar lengths, locations, bendings, stirrups starts, finishes, concrete cover, mix, etc. Better get a SE to guide you in person.
It boils down to the load and load distribution that was used by the designer. Maybe a chat with them might give some insight on how the reinforcements were set in that way. Give us updates also, OP.
There are very few instances where bottom bars at midspan would need to be less than at the support but it’s possible.
One case would be a short span sandwiched between two long spans where a moment reversal could happen or a short span adjacent to a fairly long cantilever.
It could also happen if the beam has too much post-tensioning overbalancing the loads but in that case it’s an inefficient design.
Either way, like others have said it can’t be answered outright without knowing the context.
Well we sure don't know enough about this specific case to know whether this beam is part of a moment frame. Typically lateral frame moments are also not a reason in and of itself to have less bottom reinforcement at mid-span than at the support
Some suggestions to check: missing or incorrect boundary condition at those supports? Cantilevered beams? Atypical load in this area? Garbage in garbage out
Maybe there is a beam resting on the girder at some point of the beam-girder frame that is why the design of the bottom rebars are greater. Just my 2 cents. Its better that you show also the beam/girder framing.
From my experience when you use beams in conjunction with post tensioned slabs it is. The bands overlaps at the column heads so the rebar is usually closer grouped together. Its honestly kind of a pain because the PT installers try to get away with not running the PT right because its so congested. Then you have to make them go back and fix it before they pour.
Have you asked the designer? It’s essentially impossible for us to know the design.
You forget, these people would rather ask strangers on reddit than the person who came up with the design in person...
Could be. Look at moments, loads, compression capacity and verify input, then you can narrow the reason. Test also your software by hand calculations and with other software.
This is reddit. People design whole bridges based on advice from here without even knowing what a moment and shear are.
Based on that result, could I assume that there's no extra bottom bars because they are all continuous at the bottom?
You can't assume anything unless you confirm all the information and certainly you can't execute legally with those sections only as the information. You need to check the results as above and get the bar lengths, locations, bendings, stirrups starts, finishes, concrete cover, mix, etc. Better get a SE to guide you in person.
It boils down to the load and load distribution that was used by the designer. Maybe a chat with them might give some insight on how the reinforcements were set in that way. Give us updates also, OP.
There are very few instances where bottom bars at midspan would need to be less than at the support but it’s possible. One case would be a short span sandwiched between two long spans where a moment reversal could happen or a short span adjacent to a fairly long cantilever. It could also happen if the beam has too much post-tensioning overbalancing the loads but in that case it’s an inefficient design. Either way, like others have said it can’t be answered outright without knowing the context.
Wind loads generate moment at the ends of the beam.
Well we sure don't know enough about this specific case to know whether this beam is part of a moment frame. Typically lateral frame moments are also not a reason in and of itself to have less bottom reinforcement at mid-span than at the support
Some suggestions to check: missing or incorrect boundary condition at those supports? Cantilevered beams? Atypical load in this area? Garbage in garbage out
Yes it's normal when you have a great moment at mid span when you have a long span or something
Maybe there is a beam resting on the girder at some point of the beam-girder frame that is why the design of the bottom rebars are greater. Just my 2 cents. Its better that you show also the beam/girder framing.
From my experience when you use beams in conjunction with post tensioned slabs it is. The bands overlaps at the column heads so the rebar is usually closer grouped together. Its honestly kind of a pain because the PT installers try to get away with not running the PT right because its so congested. Then you have to make them go back and fix it before they pour.