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

Version 2.3 May 2008350 kNm atsupport250 kNm at 0.2 Ø intothe support face200 kNm atsupport facecentre line of beamcolumn elementsidealized as lineelements in analysis8000.2×800Bending MomentDiagramFigure 3.5 – Reduced moment to Support Face forsupport providing rotational restraintIn Figure 3.5, the bending moment at support face is 200 kNm which canbe the design moment of the beam if the support face is rectangular.However, as it is smaller than 0.65×350 = 227.5 kNm. 227.5 kNmshould be used for design.If the support is circular and the moment at 0.2Ø into the support and thebending moment at the section is 250 kNm, then 250 kNm will be thedesign moment as it is greater than 0.65×350 = 227.5 kNm.For beam (or slab) spanning continuously over a support considered notproviding rotational restraint (e.g. wall support), the Code allowsmoment reduction by support shear times one eighth of the support widthto the moment obtained by analysis. Figure 3.6 indicates a numericalWorked Example 3.3.Worked Example 3.3By Figure 3.6, the design support moment at the support under0.8consideration can be reduced to 250 − 200×= 230kNm.813