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362 Barry’s Advanced Construction of Buildings
Reinforcement cage
for external column
Links to form
reinforcement
cage
Cranked U bars fit inside
the main beam and column
reinforcement cages
Reinforcement cage for
external wall beam
Lacing bars
to provide
structural
continuity
Main
reinforcement
Reinforcement
cage for main
beam
Figure 6.9 Reinforcement cages for reinforced concrete beam and column.
Figure 6.9 is an illustration of the junction of the reinforcement for a main beam with
an external beam and an external column. The longitudinal bars for the beams finish just
short of the column reinforcement for ease of positioning the beam cages. Continuity bars
are fixed through the column and wired to beam reinforcement. U bars fixed inside the
column reinforcement and wired to the main beam serve to anchor the beam to the column
against lateral forces.
Figure 6.10a is an illustration of the reinforcement for the junction of four beams with
a column. It can be seen that the reinforcement for intersecting beams is arranged to cross
over at the intersection inside the columns. Figure 6.10b shows the next stage where the
column, floor and beam have been cast and encased in concrete; starter bars are left protruding
so that the lower column reinforcement cage can be tied to the next column cage.
The correct term for linking the column starter bars to the next column cage is a ‘column
splice’. Figure 6.10b is an illustration of a column splice made in vertical cages for convenience
in erecting formwork floor by floor and handling cages. In the reinforcement illustrated
in Figure 6.9 and Figure 6.10, the reinforcing bars are deformed to improve anchorage
and to obviate the necessity for hooked or bent ends of bars that considerably increase the
labour of assembling reinforcing cages.
Spacers for reinforcement
To ensure that there is the correct cover of concrete around reinforcement to protect the
steel from corrosion and to provide adequate fire protection, it is necessary to fix spacers
to reinforcing bars between the bars and the formwork. The spacers hold the reinforcement