2012/11/22 6.4.2 Shear resistance of members 6.4.2 Shear resistance of members ion ratio:definc al she What's ditt ent from To dirtemin size of a member's section we should: bh≥fyE,',Bf) 6.4.2 Shear resistance of members 6.4.2 Shear resistance of members r六 M27s'10.20A.=5ym'/A. 5.46 6.4.3 strong shear-weak flexure Shear strength ofbeams ralfailureand prevent s n is I 7 2012/11/22 7 6.4.2 Shear resistance of members Members in a Frame: BEAM, COLUMN, and JOINT What's different from beam and column? A member subjected to an axial force of 0.1fc Ag or less can be treated as a beam (Ag = the gross area of the section, fc = design compression strength for concrete). To dirtermin size of a member's section we should: ( , , ) 0 RE c c bh  f  V  f • Shear compression ratio : defined as nominal shear stress divided by design compression strength of concrete (cylinder strength), or V/f cbh0 , to quantify a nominal shear stress across a beam section • To ensure that premature diagonal compression failure not occur before the onset of yielding of shear reinforcement, the diagonal compression principal stress should be limited. 6.4.2 Shear resistance of members For Beam：If ratio of span to depth (跨高比) is greater than 2.5, For Column and Wall：If shear span ratio (剪跨比) is greater than 2, the design shear force should satisfy the following equation: RE c c RE c c c c RE bh V f V f V f bh       / 0.20 5 / (0.20 ) 1 0 0     6.4.2 Shear resistance of members (0.15 ) 1 bh0 V f c c RE    For Beam：If ratio of span to depth (跨高比) is NOT greater than 2.5, For Column and Wall：If shear span ratio (剪跨比) is NOT greater than 2, the design shear force should satisfy the following equation: (0.30 ) 1 j c j j RE Vj  f b h  For Joint：  (5.46) 6.4.2 Shear resistance of members  To ensure ductile flexural failure and prevent brittle shear failure, a principle of “strong shear—weak flexure” should be followed in seismic design of reinforced concrete beams. Gb n r b l b vb V l M M V     6.4.3 strong shear—weak flexure For beams in grade 1 frames, is 1.3. For beams in grade 2 frames, is 1.2. For beams in grade 3 frames, is 1.1. vb vb vb Gb n r bua l bua V l M M V    1.1 For beams in grade 1 and earhtquake intensity 9,the beam and lintel may not be adjusted,but it should satisfy the following requirement. Shear strength of beams