Designing for lateral loads in structures is often the more difficult problem for the structural engineers vs. designing the mechanism for supporting vertical loads.

Because of this, it is the lateral load problem that often determines the type of load-resisting system used in a building. In general, there are only a few mechanisms commonly used, alone or in combination, for assuring lateral stability. These methods are: diagonal braces, shear walls, and joint rigidity (frames).

Sometimes, one type of lateral load mechanism is used in one direction while another is used in the perpendicular direction. This does not often happen with wood and/or wood-masonry buildings, but it is very common with simple steel buildings as shown in the following figure. The steel frames resist lateral loads applied in the short direction while diagonal bracing stabilizes the building longitudinally.

The most commonly used lateral force resisting system (LFRS) for rectangular all-wood or low-rise masonry and wood buildings is the shear wall mechanism combined with horizontal diaphragms. This system – often referred to as a "box system" – falls within the UBC structural system category known as a "bearing wall system". In this case, the bearing walls support all or most of the gravity loads as well as functioning as shear walls to resist lateral loads.

System of walls (vertical) and roof and floor diaphragms (horizontal) that are generally simply supported and work together to support both vertical and horizontal loads.

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