Vertical tie requirement

Maximum axial load per floor = 1.05×480.7 + 0.33×192.0 = 568.1 kN

Vertical tie reinforcement As= 568.1 x 103/460 = 1235 mm2

Total provision of bolt (root area) = 362 x 6

= 2172 mm2 > 1235 mm2 OK

Total provision of welded bars to base plate = 8T16

= 1609 mm2 > 1235 mm2 OK

Vertical column tie requirement is satisfactory at the column to column joint.

4. Design of corbel

a. Check shear stress

V = V/bd

= 430.8 x 103/(500 x 275)

= 3.13 N/mm2 < 0.8Vfcu = 5.66 N/mm2

adopt max. vc = 5.00 N/mm2 OK

і. Main steel

0.9(z/d)(ayd)(1 – z/d)
(a„/d)2 + (z/d)2

v/fcu = 3.13/50 = 0.063
a„/d = 125/275 = 0.454

Hence (z/d)2 – 0.866(z/d) + 0.0276 = 0 z/d = 0.833

200 (z/d – 0.55) / (1 – z/d)

200 (0.833 – 0.55) / (1 – 0.833) 339 N/mm2

Ft = V x ajz

= 430.8x 125/(0.833×275) = 235.1 kN > V/2

Figure 4.10 Reforcement Details Of Precast Column (12>Storey Office Block)

Beading Reinforcement

Assuming no effective restraint at support: Ultimate bending moment at mid-span

= 44.50 X 3.49/8

= 19.41 kN/m

153-25-5 123 mm

Say d =

120 mm

z

0.5+ 10.25-f M

d

У V0.9bd2fcu/

=

0.5+ / 0.25-/ 19.41 x 106

V .9 X 1000 x 1202 X 45/

0.965

use -5- =

0.95

z =

114 mm

A,

M

0.87fyz

=

19.41 x 106

0.87x460x 114

=

425 mm2/m

Use T10-150 c/c. provided A, = 523 mm2/m

Deflection

M

19.41 x 106

bd2

1000 x 1202

=

1.35

f„

5/8 fy X Ag req / As prov

=

5/8x460x425/523

=

234 N/mmz

Tension modification factor

(477-fv)

0 =

0.55 + о

120 (0.9 + M/bd )

477 – 234

0.55+ ———————-

120(0.9 + 1.35)

Cl.3.10.2.2, Parti, CP 65,

basic span/depth ratio of staircase flight =

£

0 x (span/depth ratio)

3490

1.45 x 23

=

105 mm< 120 mm

Leave a reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>