A structural steel component weighing 30,000 kg is being lifted by two cranes. Crane Alpha is handling 60% of the load, and Crane Beta is handling 40%. The rigging for Crane Alpha consists of a two-leg bridle sling with an included angle of 90 degrees between the sling legs. What is the approximate tension in each leg of Crane Alpha's sling?

Question: A structural steel component weighing 30,000 kg is being lifted by two cranes. Crane Alpha is handling 60% of the load, and Crane Beta is handling 40%. The rigging for Crane Alpha consists of a two-leg bridle sling with an included angle of 90 degrees between the sling legs. What is the approximate tension in each leg of Crane Alpha's sling?

Answer options: ✅ 10,600 kg

• 12,750 kg
• 9,000 kg
• 18,000 kg

Correct answer: 10,600 kg

Explanation: Crane Alpha's share of the load is 60% of 30,000 kg = 18,000 kg. For a two-leg bridle sling, the tension (T) in each leg is T = (Load / 2) / cos (angle from vertical). An included angle of 90 degrees means each leg makes a 45-degree angle with the vertical. So, T = (18,000 kg / 2) / cos(45°) = 9,000 kg / 0.707 ≈ 12,727 kg. Re-evaluating the options, 10,600 kg is for 60 degrees included angle, (18000/2)/(cos30) = 9000/0.866 which is 10392kg. Let's re-calculate for the 90 degree included angle. If the included angle is 90 degrees, the angle from vertical is 45 degrees. T = (18000 / 2) / cos(45 degrees) = 9000 / 0.7071 = 12727 kg. Option B (12,750 kg) is a very close approximation.