| 摘要 |
An expansion joint or fire break for a main runner which has a web portion interconnecting a bead having a rectangular cross section with a pair of outwardly extending flanges characterized by an aperture in the web portion, a portion of the bead above the web portion being deformed to provide a modified bead having a flattened portion of reduced width connected to an upper sub-bead portion of a greater width, three notches extending transversely through the upper sub-bead and the aperture having an arrangement including shear lines and cuts to define bending lines or regions for the web that extend through the notches of the sub-bead and to define three bending lines or areas for the flanges, which are aligned with the bending lines in the web. When the runner is subjected to elevated temperatures, the compressive forces formed by thermal expansion will be relieved by the modified bead and web buckling laterally outward with bending in the three bend regions as the flanges buckle downward with bending in three bend areas.
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