Cs

S is the first moment of area of the reinforcement about the centroid of the section.

I is the second moment of area of the section. S and / should be calculated for both the uncracked and fully cracked conditions. Curvature of the uncracked section

Table a4

1 0.60 x 10"3 x 25.64 x 495.5 x 103 7 = -7535^0®- = 10 X 10 rad /mm csl

Curvature of the cracked section

Sa = As(d - x) - A's (x - d') = 581.5 x 103 mm3 1 0.60 x 10"3 x 25.64 x 581.5 x 103

— = --- = 1.64 x 10"6rad./mm r „ 5448 x 106

csll

Therefore

cs csll 'csl

= [(0.88 x 1.64) + (1 - 0.88) x 1.0] x 10"6 = 1.563 x 10"6 rad./mm

The total curvature at mid-span

- = - + - = (3.567 + 1.563) x 10"6 = 5.130 x 10~6rad./mm tot cs

The flexural, shrinkage and total curvatures at positions x/l along the span are given in Table 10.1.

Table 10.1 Curvatures x 106 (rad./mm)

xll

Moment (kNm)

1 r.

1 'i,

f

1 r

0 0

Post a comment