Protastructure Crack May 2026

Problem: A 250mm flat slab with 3000mm spans showed crack widths of 0.45 mm (limit 0.3 mm) in ProtaStructure.

Attempted fix 1: Increased rebar from T12@200 to T16@200. Result: Crack width reduced to 0.38 mm – still failing. protastructure crack

Solution: Changed rebar to T12@150 (smaller bars, closer spacing) and increased cover from 25mm to 30mm (to improve bond). New crack width: 0.24 mm – Pass. Problem: A 250mm flat slab with 3000mm spans

Lesson: ProtaStructure confirms that bar spacing matters more than total area for crack control. Solution: Changed rebar to T12@150 (smaller bars, closer

If you model a beam at an angle (e.g., 44.9 degrees instead of 45), Protastructure’s solver creates a massive number of small terms in the stiffness matrix. Always use the Rotate tool with exact angles. Avoid manual dragging.

Do not try to analyze the whole 20-story building again.

If your Protastructure model has just "cracked" (frozen/errored), follow this rescue protocol.