JavaScript must be enabled in order to use this site.Please enable JavaScript in your browser and refresh the page. To add an opening and trimmer bars to a slab together Have a slab placed in your model. Select (Add Trimmers to Openings). On the model, click to select the slab. Adjust the settings on the Opening Trimmers dialog. Select (Select Concrete). On your model, draw the opening by placing corner points on the slab. Be sure to draw a closed shape. Click OK . Parent topic: Slabs and Slab Reinforcement