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Structural Steel Frames 297
Concrete core and steel hangers
support floor beams
Concrete access
core takes wind
loads and
supports braced
cantilevers that
support steel
hangers
supporting floor
beams
Figure 5.19 Reinforced concrete core supporting cantilever beams and steel hangers.
core, illustrated in Figure 5.19, it is necessary to transfer wind forces, acting on the walls,
to the core. The systems of bracing that are used combine bracing through solid concrete
floor plates and cross bracing to structural steel floors. The type of cross bracing illustrated
in Figure 5.19 takes the form of braced girders hung from the frame to the four corners of
the building and carried back, below floor level, and tied to the core to act as hung, cantilevered
cross wind bracing.
Connections and fasteners
Usual practice is to use long lengths of steel column between which shorter lengths of beam
are connected to minimise the number of column to column joints and for the convenience
of setting beam ends on shelf angles bolted to columns. In making the connections of four
beam ends to a column, it is usual to connect the ends of main beams to the thicker material
of column flanges and the secondary, more lightly loaded beam ends to the thinner
web material. The ready cut beams are placed on the shelf or seating angles, which have
been shop or site bolted to columns, as illustrated in Figure 5.20. The beam ends are bolted
to the projecting flanges of the shelf angles. Angle side cleats are bolted to the flange of
columns and webs to main beams, and angle top cleats to the web of columns and flanges
of secondary beams. The side and top cleats serve the purpose of maintaining beams in
their correct position. Where convenient, angle cleats are bolted to columns and beams in
the fabricator’s shop to reduce site connections to a minimum. These simple cleat connections
can be accurately and quickly made to provide support and connections between
beams and columns.