7.3 Commercial Retail Space Occupancy

Commercial retail space such as malls, movie theatres, hotels, night clubs, casinos, and other spaces that house large public populations gathering for shopping or entertainment have their own unique features that increase their vulnerability compared with that of office buildings. Often, these spaces are low-rise buildings that have large interior spaces with high, laterally unsupported walls, long-span roofs, and interior columns spaced relatively far apart. They are generally constructed using lightweight construction and may be prefabricated. This type of construction has little if any redundancy, which increases the structural vulnerability significantly.

The primary goal for this type of construction is to prevent progressive collapse of the building in response to a large-scale attack. Where possible, floor-to-floor height and bay spacing should be reduced, and lateral bracing of the columns and roof joists should be provided. Connections should be designed to be at least as strong as the members. Secondary structural framing systems further enhance protection. To limit laceration injuries, lamination of glass is recommended. Consider structural partition walls or shelving units placed within the space that will stop the roof system from falling directly on the occupants in the event of collapse. If this approach is used, take care that the partitions have sufficient lateral support so that they do not topple over.

In these large spaces, it is virtually impossible to isolate HVAC to protect against CBR-type threats. In this case, negative zone pressurization or smoke-evacuation methods become critically important. Also, mechanical areas should be protected with restricted access and a hardened shell (walls, ceiling and floor). It is also recommended to have centralized redundant control stations, easily accessible by appropriate personnel. Consideration should be given to providing additional, clearly marked, easily located egress routes to facilitate mass evacuation. If there are business offices serving these buildings with a sizable workforce, consider relocating these and other mixed-use functions to a separate, offsite location.