Building Expansion Joint for High-Rise Buildings: Wind and Seismic Considerations

High-rise buildings experience significant lateral movements from wind loading and seismic response that must be accommodated by the expansion joints. The joint design must consider not only thermal movements but also the dynamic movements from these lateral loads. Wind-induced movements in high-rise buildings can be significant. A 50-story building with a natural frequency of 0.2 Hz may have a peak wind-induced displacement at the top of 50-100 mm under the design wind load. The expansion joint at the mid-height of the building must accommodate the differential movement between the two halves of the building caused by this wind-induced sway. Seismic movements in high-rise buildings are even larger than wind movements in high seismic zones. The seismic displacement at the top of a 50-story building can be 300-500 mm under the design earthquake. The expansion joint must accommodate the differential seismic displacement between adjacent building sections. Interstory drift is the relative horizontal displacement between adjacent floors, expressed as a fraction of the story height. Building codes typically limit the interstory drift to 1/400 to 1/200 of the story height under wind loading and 1/50 to 1/25 under seismic loading. The expansion joint must accommodate the cumulative drift over the height of the building. Facade joints in high-rise buildings must accommodate both the thermal movement and the wind-induced movement of the building. The facade panels must be connected to the building structure with sliding connections that allow movement in the horizontal direction while maintaining vertical support. The joint between adjacent facade panels must be wide enough to accommodate the full movement range. Fire resistance of expansion joints in high-rise buildings is critical for life safety. The joint must maintain its fire resistance rating for the required period to prevent fire spread between building sections. Intumescent fire stops and fire-rated joint covers are required for joints in fire-rated assemblies.