1.What are Seismic joints?
Seismic joints are frequently required between adjacent buildings and are often introduced to separate two or more parts of the same building.
Seismic joints occur naturally when one building is built adjacent to another, whether or not the buildings are linked functionally. Seismic joints are also frequently introduced to separate wings, or other parts of a single building. A seismic joint typically creates a separation between the adjacent buildings or parts of buildings that includes separation of walls, floors, roof and, in the case of joints within the same building, may also include separation, or accommodation for movement of piping, HVAC ducts, and other elements that have a functional need to cross the joint. The design of seismic joints is complex and includes efforts by all members of the design team to assure that the joint is properly sized, adequately sealed from weather and safe to walk on, as well as providing for adequate movement of other systems crossing the joint and means to maintain the fire ratings of the floor, roof and wall systems. Joints are costly and architecturally undesirable, so they should be incorporated with discretion.
2.What is the difference between Expansion Joints
Seismic joints are similar to expansion joints, but at the same time very different. Expansion joints are introduced to accommodate building movements caused by shrinkage, creep, or temperature changes. They are often one-way joints, that is, they are primarily intended to accommodate movements in the direction perpendicular to the joint. Expansion joints are also commonly placed at some regular interval of length based on the expected rate of shrinkage or temperature movement expected to occur over the building length. Seismic joints, on the other hand, must accommodate movement in both orthogonal directions simultaneously and their spacing is not typically affected by building length or size.