If a,/ho is relative high,the diagonal crack (a-b-c)spreads to e,splitting the beam into two pieces along an inclined crack (a- b-c-e).This is typical diagonal tension failure. If a /ho is relative low,the diagonal crack (a-b-c)spreads but stops atj;the crack widens and propagates along the level of tension reinforcement(g-h),destroying the bond between the reinforcement and the surrounding concrete.This is the shear-bond failure. The shear-bond failure also occurs in the Category I members: 45°
If is relative high, the diagonal crack (a-b-c) spreads to e, splitting the beam into two pieces along an inclined crack (a- b-c-e). This is typical diagonal tension failure. If is relative low, the diagonal crack (a-b-c) spreads but stops at j ; the crack widens and propagates along the level of tension reinforcement (g-h), destroying the bond between the reinforcement and the surrounding concrete. This is the shear-bond failure. a / h0 v The shear-bond failure also occurs in the Category II members: a / h0 v
4.Category Iv a,/ho>6 )Flexural failure F 2 分 我 Beams with such a high value of a /ho usually fail in bending
4. Category IV ( a / h0 6 ): Flexural failure v Beams with such a high value of usually fail in bending. a / h0 v
0.5 V.-aconst f.oho 0.4 b×ho=120mmX182mm 纵筋2中12 0.3 feu =27.26N/mm2 f.bh 0.2 0.1 0 斜压【 2 3 4 1弯曲 5 破坏{剪压破坏 斜拉破坏 破坏 1
0 f bh V c cr
7.1.3 Mechanisms of shear transfer of RC Beams without Shear Reinforcement · Consider a typical beam in bending and shear shown below,which is reinforced with longitudinal steel against bending. Fig.7.1-5 A typical beam in bending and shear
7.1.3 Mechanisms of shear transfer of RC Beams without Shear Reinforcement • Consider a typical beam in bending and shear shown below, which is reinforced with longitudinal steel against bending. Fig. 7.1-5 A typical beam in bending and shear
The shear force is transmitted through the cracked beam by a combination of three mechanisms (Fig.7.1-6) local crushing local crushing (a) (b) uncracked concrete neutral axis (c) Fig.7.1-6 Shear transfer mechanisms.(a)Dowel action;(b)aggregate interlock;(c)shear stresses in uncracked concrete
The shear force is transmitted through the cracked beam by a combination of three mechanisms (Fig. 7.1-6) Fig. 7.1-6 Shear transfer mechanisms. (a) Dowel action; (b) aggregate interlock; (c) shear stresses in uncracked concrete