As we’ve discussed, barrier cable is used in parking garages to allow for improved visibility and airflow. However, the most common design hazard in parking garages is vehicle impact. In order to keep drivers and passengers safe, the American Society of Civil Engineer’s “Minimum Design Loads for Buildings and Other Structures” section 4.5.3 specifies that:
Vehicle barrier systems for passenger vehicles shall be designed to resist a single load of 6,000 lb applied horizontally in any direction to the barrier system, and shall have anchorages or attachments capable of transferring this load to the structure. For design of the system, the load shall be assumed to act at heights between 1 ft 6 in. and 2 ft 3 in. above the ﬂoor or ramp surface, selected to produce the maximum load effect. The load shall be applied on an area not to exceed 12 in. by 12 in. and located so as to produce the maximum load effects.
This provides the first limit state of the barrier cable system. Because of the applied load’s footprint, designers assume that the load will be applied to 3 adjacent cables, which can start as low as 12 inches off the ramp and stop as high as 33 inches above the ramp. In general, designers assume that this load will produce the maximum stress in the barrier cable.