## Design using iteration of x

For moment where

(NEd - acc¥cbdc / Yc) / (0sc - 0st) [MEd - accnfckbdc(h / 2 - dc / 2) /Yc]

= depth of compression zone = Ax

= 0.8x < h where x = depth to neutral axis = 35 + 8 + 25 / 2 = 55 mm assuming H25 = 1.5

(°*st) = stress in reinforcement in compression (tension)

Figure 5.4

Section in axial compression and bending <Fig. 6.1>

Figure 5.4

Section in axial compression and bending <Fig. 6.1>

= 0.0035(h - x - d2) / x = 0.0035(300 - 200 - 55) / 200

= 1129.6 x 103 - 0.85 x 1.0 x 30 x 300 x 200 x 0.8 / (1.5 x 103) = 434.8 - 160

= 1141 mm2

985 x 106-085 x 10 x 30 x 300 x 200 x 0.8 (300/2-200 x 0.8/2) / (15 x 103) (300 /2-55) (434.8 +160)

95 x 554.8

Similarly for x = 212 mm

434.8

0.00054; .'. <rst = 109.MPa (1129.6 - 865.0) x 103

812 mm2

.'. as AsM/2 ~ AsM/2,, x = 212 mm is approximately correct and Asm ~ AsM, ~ 1628 mm2

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