Hi ,
Please help me to sort out this issue.
Actually, I am modeling an underground rectangular water tank of 13m x 10m with top slab on it .
Top slab is supported on side walls and intermediate beams in between the slab.
After assigning all the loads, analysis done. Top slab is behaving as a whole without considering the intermediate beams.(i.e. slab is spanning for whole length )
Hence the slab thickness arrived was very huge.
regards
Varunkumar P
Probably the slab and intermediate beams do not shear common nodes (slab and beams are not meshed). If you could attach your model, we could check it.
1-node to node beam.stdDear sir, PFA the staad of my model. After merging the beam node with slab mesh, still my deflection behaves as whole.
Your beams are modeled so that the centroid of the beam is coincident with the centroid of the slab. This will reduce the stiffness of the beams. You can offset the beams in the negative Y direction to achieve the proper stiffness. Ensure that the offset and beam depth don't double count the concrete that's shared between the beam and the slab. The relatively stiffer beams will attract more load and reduce the moment in the slab.
The 0.2m top slab thickness is actually on the thin side for such a slab. The US codes would recommend 50mm concrete cover over the reinforcing on a water tank.
yeah I have checked sir, There is a change in displacement results due to stiffness I think.Moment what I am getting for beam is not matching with my manual results as I considered the beam as simply supported. STAAD is showing with very less moments but what I am getting is double the times of STAAD results. Whether I can trust the behavior of STAAD or else consider the maximum moment from manual. Not able to visualize the behavior, Please guide me
Good observations.
It is difficult to separate out the behavior of the beam elements from the slab elements. In the model, the beam is acting compositely with the slab so that that slab takes the compression portion of the moment and the beam takes the tension portion of the moment. This results in an un-conservative moment reported for the beams.
Personally, for relatively simple beams like these, I would calculate the beams by hand which would provide a somewhat conservative result (using simple supports) and use the model to calculate the moments in the slab.
thank you sir