Converting a lateral load column to a gravity load column

[33mmrrdd]

Hello, we are considering adding an additional floor level to an existing building. We are planning to design the new retrofitted structure as a bearing wall system and add shear walls to carry the lateral forces. My question is, how will we consider the existing columns in the model and carry only gravity loads? Am I correct if we will put hinges in the top and bottom of the existing columns on every floor in the model? So that the inertia forces at every floor will only be distributed now to the new shear wall via rigid diaphragms.

 

[KootK]

I would leave the column to beam joints as rigid and then let the lateral moments that they attract be your litmus test for whether or not your new walks are stiff enough to discourage the frames from meaningful lateral participation as you intend.

 

[SWComposites]

yes, you can't magically tell the columns to not pick up load; they won't listen to you. the model needs to consider the relative actual stiffness of the structural elements and apportion load appropriately.