Question

# 1. (a) Explain the difference between columns which are short and slender and those which are...

1. (a) Explain the difference between
columns which are short and slender
and those which are braced and
unbraced.
(b) Calculate the ultimate axial load
capacity of a short-braced column
supporting an approximately
symmetrical arrangement of beams
assuming that it is 500 mm square
and is reinforced with eight
20 mm diameter bars. Assume that
fcu = 40 N/mm2, fy = 500 N/mm2 and
the concrete cover is 25 mm. Design
the shear reinforcement for the
column.

2. (a) A braced column which is 300 mm
square is restrained such that it has an
effective height of 4.5 m. Classify the
column as short or slender.

(b) The column supports:
(1) an ultimate axial load of 500 kN
and a bending moment of
200 kNm, or
(2) an ultimate axial load of 800 kN
and bending moments of 75 kNm
about the x-axis and 50 kNm
Design the longitudinal steel for both
design charts assuming fcu = 40 N/mm2,
fy = 500 N/mm2 and the covers to all
reinforcement is 35 mm.

3. An internal column in a multi-storey
building supporting an approximately
symmetrical arrangement of beams carries
an ultimate load of 2,000 kN. The storey
height is 5.2 m and the effective height
factor is 0.85, fcu = 35 N/mm2 and
fy = 500 N/mm2.
Assuming that the column is square,
short and braced, calculate:
1. a suitable cross-section for the column;
2. the area of the longitudinal
reinforcement;
3. the size and spacing of the links.
Sketch the reinforcement detail in cross-section.