Uncheck Draw local dimensions option under the Dimensions tab.
Start the Stirrup command ; confirm 10 millimeters for the bar diameter and 30 millimeters for the concrete cover.
Click the top-left corner and the bottom-right corner of the rectangle to insert the stirrup in the concrete section.
Copy the stirrup outside the concrete section and double click it. Uncheck the Display local dimensions option and change the thickness modality to Thin .