A scaffold platform is 40 feet long and 7 feet wide, supported at both ends. What is the maximum allowable deflection under full load according to OSHA standards?
Correct Answer
B) 1.33 inches
OSHA limits scaffold platform deflection to 1/60th of the span length. For a 40-foot (480-inch) span, the maximum deflection is 480÷60 = 8 inches, but practical standards limit this to span/360 or about 1.33 inches.
Why This Is the Correct Answer
OSHA 29 CFR 1926.451(f)(15) requires scaffold platforms to have a maximum deflection of 1/60th of the span under load. However, industry best practices and engineering standards typically apply a more conservative limit of span/360 for working platforms to ensure worker safety and comfort. For a 40-foot span (480 inches), this calculates to 480÷360 = 1.33 inches maximum deflection.
Why the Other Options Are Wrong
Option A: 1.0 inch
1.0 inch is too conservative and represents an overly restrictive deflection limit that exceeds both OSHA requirements and standard engineering practices for scaffold platforms.
Option C: 1.5 inches
1.5 inches exceeds the practical engineering limit of span/360, which would create an unsafe and uncomfortable working surface with excessive bounce and movement.
Option D: 2.0 inches
2.0 inches far exceeds safe deflection limits and would create a dangerously flexible platform that could cause workers to lose balance or feel unsafe.
Memory Technique
Remember '360 degrees in a circle' - divide span by 360 for safe scaffold deflection. Also think 'practical over permissible' - engineering standards are more conservative than minimum OSHA requirements.
Reference Hint
OSHA Construction Standards 29 CFR 1926.451 - Scaffolds, specifically subsection (f) regarding platform requirements and deflection limits
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