What is the maximum interior angle from the load to the anchorage systems in a dual main system?

What is the maximum interior angle from the load to the anchorage systems in a dual main system?

• A. Less than 90 degrees
• B. Greater than 90 degrees
• C. Exactly 90 degrees
• D. No restriction

Answer: (A)

In a dual main system, two independent lifelines carry the load, so the forces in the lines meet at the load point and form a vector combination. Keeping the interior angle between the two lifelines under 90 degrees ensures the resulting force is directed more predictably down the ropes and distributes loads safely between the anchors. If the angle opens beyond 90 degrees, the horizontal components increase, raising peak loads on the anchors and increasing the risk of unequal loading or cross-loading. For safe and reliable loading, the maximum interior angle is less than 90 degrees.

In a dual main system, two independent lifelines carry the load, so the forces in the lines meet at the load point and form a vector combination. Keeping the interior angle between the two lifelines under 90 degrees ensures the resulting force is directed more predictably down the ropes and distributes loads safely between the anchors. If the angle opens beyond 90 degrees, the horizontal components increase, raising peak loads on the anchors and increasing the risk of unequal loading or cross-loading. For safe and reliable loading, the maximum interior angle is less than 90 degrees.