Manual for Design and Detailings of Reinforced Concrete to Code of ...

Version 2.3 May 2008Beam carryingunbalancedtorsion inducedby slab needs becheckedFigure 3.30 – Illustration for necessity of checking against torsion3.9.2 Calculation of torsional rigidity of a rectangular section for analysis (ingrillage system) is by (Ceqn 6.64) of the Code1 3C = βhminhmaxwhere β is to be read from Table 6.16 of the Code2reproduced as Table 3.4 of this Manual.h max /h min 1 1.5 2 3 5 >5β 0.14 0.20 0.23 0.26 0.29 0.33Table 3.4 – Values of coefficient β3.9.3 Calculation of torsional shear stressUpon arrival of the torsion on the rectangular section, the torsional shear stressis calculated by (Ceqn 6.65) of the Code2Tv t=2 ⎛ hmin⎞hmin⎜hmax− ⎟⎝ 3 ⎠and in case of a section such as T or L sections made of rectangles, the section3should be broken up into two or more rectangles such that the ∑h minhmaxismaximized and the total Torsional moment T be apportioned to eachrectangle in accordance with (Ceqn 6.66) of the Code as⎛3⎞⎜ hminhmaxT × ⎟ .⎜3⎟⎝ ∑ hminh max ⎠43