A full line represents a positive yield line caused by a sagging (yield moment,so that the concrete cracks in tension in the bottom face of the slab A broken line represents a negative yield line caused by a hogging (yield moment so that tensile cracking occurs in the top face. Negative yield line Simple support 77777777772 Simple support
• A full line represents a positive yield line caused by a sagging（下沉） yield moment, so that the concrete cracks in tension in the bottom face of the slab • A broken line represents a negative yield line caused by a hogging（翘曲） yield moment so that tensile cracking occurs in the top face
·The convention(惯例)for support conditions is as follows:. Single hatching represents a simply supported edge; Double hatching represents a built-in edge; A line by itself represents a free edge. Negative yield line Simple support 777777777777 Simple support
• The convention （惯例）for support conditions is as follows: Single hatching represents a simply supported edge; Double hatching represents a built-in edge; A line by itself represents a free edge
The following comments should be noted: 0 The yield lines divide the slab into several regions,called rigid regions,which are assumed to remain plane,so that all rotations take place in the yield lines. Yield lines are straight and they end at a slab boundary. A yield line between two rigid regions must pass through the intersection of the axes of rotation of the two regions (the supports form the axis of rotation). An axis of rotation usually lies along a line of support and passes over columns
The following comments should be noted: • The yield lines divide the slab into several regions, called rigid regions, which are assumed to remain plane, so that all rotations take place in the yield lines. • Yield lines are straight and they end at a slab boundary. • A yield line between two rigid regions must pass through the intersection of the axes of rotation of the two regions (the supports form the axis of rotation). • An axis of rotation usually lies along a line of support and passes over columns
A yield-line pattern indicates how a slab collapses,just as a plastic-hinge mechanism indicates how a framework collapses KW M 1) (2) M M - T7 L=6.1 Plastic-hinge mechanisms of a framework
A yield-line pattern indicates how a slab collapses, just as a plastic-hinge mechanism indicates how a framework collapses Plastic-hinge mechanisms of a framework