Flexure

The design procedure for flexural design is given in Figure 2; this includes derived formulae based on the simplified rectangular stress block from Eurocode 2. Table 3 may be used to determine bending moments and shear forces for beams, provided the notes to the table are observed.

Table 3

Bending moment and shear coefficients for beams

Table 3

Bending moment and shear coefficients for beams

Moment

Shear

Outer support

25% of span moment

G.45 (G + Q)

Near middle of end span

0.090 Cl + 0.100 Ql

At first interior support

-0.094 (C + Q) l

G.63 (G + Q)a

At middle of interior spans

0.066 Cl + 0.086 Ql

At interior supports

-0.075 (C + Q) l

G.5G (G + Q)

Key a 0.55 (G + Q) may be used adjacent to the interior span.

1 Redistribution of support moments by 15% has been included.

2 Applicable to 3 or more spans only and where Qk < Ck.

3 Minimum span > 0.85 longest span.

4 l is the span, C is the total of the ULS permanent actions, Q is the total of the ULS variable actions.

Table 4

Values for K'

Table 4

Values for K'

% redistribution

D (redistribution ratio)

K '

0

1.00

0.208a

10

0.90

0.182a

15

0.85

0.168

20

0.80

0.153

25

0.75

0.137

30

0.70

0.120

Key a It ¬°soften recomended in the UK that ^'should be limited to 0.168 to ensure ductile failure.

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