6.3.3 Structural Layout

To enhance the overall robustness of the structure, the measures listed below are recommended.

• In frame structures, column spacing should be limited. Large column spacing decreases likelihood that the structure will be able to redistribute load in event of column failure.
• The exterior bay is the most vulnerable to damage, particularly for buildings that are close to public streets. It is also less capable of redistributing loads in the event of member loss, since two-way load distribution is not possible. It is desirable to have a shallow bay adjacent to the building exterior to limit the extent of damage.
• Use of transfer girders is strongly discouraged. Loss of a transfer girder or one of its supports can destabilize a significant area of the building. Transfer girders are often found at the building exterior to accommodate loading docks or generous entries, increasing their vulnerability to air-blast effects. It is highly desirable to add redundant transfer systems where transfer girders are required.
• In bearing-wall systems that rely primarily on interior cross-walls, interior longitudinal walls should be periodically spaced to enhance stability and to control the lateral progression of damage.
• In bearing-wall systems that rely on exterior walls, perpendicular walls or substantial pilasters should be provided at a regular spacing to control the amount of wall that is likely to be affected.