## Continuous beam on pin supports

This calculation is intended to show a typical hand calculation for a continuous simply supported beam using coefficients to determine moments and shears.

A 450 mm deep x 300 mm wide rectangular beam is required to support office loads of §k = 30.2 kN / m and qk = 11.5 kN / m over 2 no. 6 m spans. /ck = 30 MPa, /yk = 500 MPa. Assume 300 mm wide supports, a 50-year design life and a requirement for a 2-hour resistance to fire in an external but sheltered environment.

<BS EN 1990 & NA Tables

9.2.1.5(1), 9.2.1.5(2)> <8.7.3>

Figure 4.1

Continuous rectangular beam

Figure 4.1

Continuous rectangular beam

Figure 4.2

Section through beam

Figure 4.2

Section through beam

4.2.1 Actions

Permanent kN / m

Variable

where cmin max[cm ri where cm

= minimum cover due to bond = diameter of bar.

Assume 25 mm main bars cmindur = minimum cover due to environmental conditions.

Assuming XC3 (moderate humidity or cyclic wet and dry) and secondarily XF1 (moderate water saturation without de-icing salt) using C30/37 concrete , cmin.dur = 25 mm Acdev= allowance in design for deviation. Assuming no measurement of cover Acdev= 10 mm cnom = 25 + 10 = 35 mm

Fire:

Check adequacy of section for 2 hours fire resistance (i.e. R = 120) For bmin = 300 mm, minimum axis distance, a = 35 mm a OK

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