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

∑A trVersion 2.3 May 2008no. of bars. So ≥ 0 .833×4 = 3. 333. Using T12 – 4 legs – 125 iss(ix)∑ A tradequate as provided is 3.619. It should be noted that case (b)sis generally not the controlling case.At laps in general, the sum of reinforcement sizes in a particular layershould not exceed 40% of the beam width as illustrated by a numericalexample in Figure 3.13 (Cl. 9.2.1.3 of the Code);bar diameterd = 40bar diameterd = 40Sum of reinforcementsizes = 40 × 8 = 320< 0.4 × 900 = 360.So O.K.beam width b = 900Figure 3.13 – Illustration of sum of reinforcement sizes at laps ≤ 0.4 ofbeam width(x)(xi)Minimum clear spacing of bars should be the greatest of bar diameter,20 mm and aggregate size + 5 mm (Cl. 8.2 of the Code);Maximum clear spacing between adjacent bars near tension face of abeam ≤ 70000β b /f y ≤ 300 mm where β b is the ratio of momentredistribution (ratio of moment after redistribution to moment beforeredistribution) or alternatively ≤ 47000/f s ≤ 300 mm wherefs2 fyAs,req 1= × . Based on the former with β b = 1 (no3Aβs,provb(xii)redistribution), the maximum clear spacing is 152 mm (Cl. 9.2.1.4 ofthe Code);Requirements for containment of compression steel bars is identical tothat of columns (Cl. 9.5.2.2 of the Code) : Every corner bar and eachalternate bar (and bundle) in an outer layer should be supported by alink passing around the bar and having an included angle ≤ 135 o . Linksshould be adequately anchored by means of hook through a bent angle≥ 135 o . No bar within a compression zone be more than 150 mm froma restrained bar (anchored by links of included angle ≥ 135 o ) asillustrated in Figure 3.14;31