Carichi nozionali

A structural model with no initial geometric imperfections can appear stable because it is mathematically perfect. In realtà, it might sit in an unstable equilibrium: any small disturbance will cause it to fail. Notional loads are used in various structural engineering codes around the world to simulate geometric imperfections. While it is possible to model these imperfections directly, that approach usually leads to complex models that are difficult to validate. Simply adding horizontal loads is a simpler way of achieving the same goal: disturbing the model to test whether it lies in unstable equilibrium.

Creating notional load groups in S3D

You can add notional loads in S3D by heading over to Edit -> Loads -> Notional Loads.

This will open the following pop-up window:

Qui, you can create as many notional loads as required. Dietro le quinte, S3D will create horizontal loads associated with the selected gravity loads. Most standards ask for 2 notional loads per orthogonal direction, so there is an option to generate all four notional loads at once in the Horizontal Axis Direction (Global Axis) cadere in picchiata. Please note that by default, the load groups created will use the reserved name NLX, dove X is the ID of the notional load.

Attributing load groups to load combinations

For the notional load groups to be considered in the analysis, they must be included in the load combinations table. This can be done manually in the load combinations table, or the notional loads can be assigned to the notional load type in a design standard and generated automatically.