Question
The self-weight of the steel box is too large.
I'm trying to calculate the self-weight of a steel box girder.
It's a 2-box girder, and the self-weight of each box should be around 2000kN, but the current reaction forces are showing 2~2.5 times more.
It seems like the defined section properties are being incorrectly applied in self-weight.
Could the concrete slab's weight be included in the calculation?
Should I define the section as a simple rectangular section and then calculate the reaction forces?
Answer
This issue arises when the self-weight of the concrete slab is considered and the slab's self-weight is separately entered, resulting in a duplication of the self-weight.
In the section properties input dialog, Ds/Dc represents the weight ratio of concrete to steel. In the case of steel composite sections, the elastic modulus and weight ratio of concrete are converted and calculated based on the steel girder.
The equivalent weight of the slab is calculated based on the Ds/Dc values entered here. If you enter the concrete slab self-weight as a separate load, you must enter 0 in that field.