1. Category I(a./ho<1 )Deep beam failure 会 The structural behaviour approaches that of deep beams. The diagonal crack occurs approximately along a line joining the loading and support points.It forms as a result of the splitting action of the compression force transmitted directly from the loading point to the support
1. Category I (a / h0 1 ): Deep beam failure v • The diagonal crack occurs approximately along a line joining the loading and support points. It forms as a result of the splitting action of the compression force transmitted directly from the loading point to the support. • The structural behaviour approaches that of deep beams
The shear-web crack initiates frequently at about d/3 about the bottom face,then propagates simultaneously towards the loading and support points.When the crack has penetrated sufficiently deeply into the concrete zone at the loading/the support points,crashing failure of concrete occurs. The mode of failure may be an anchorage failure at the end of the reinforcement due to the large tensile force. 3 high compression here compression strut tension tie
• The shear-web crack initiates frequently at about d/3 about the bottom face, then propagates simultaneously towards the loading and support points. When the crack has penetrated sufficiently deeply into the concrete zone at the loading/the support points, crashing failure of concrete occurs. • The mode of failure may be an anchorage failure at the end of the reinforcement due to the large tensile force
2.Category II: 1<a,/ho<3 Shear-compression failure d crushing of concrete The diagonal crack often forms as a development of a flexural crack.Eventually,the diagonal crack penetrates into the concrete compression zone at the loading point Crashing failure of the concrete occurs
2. Category II: • Shear-compression failure 1 a / h0 3 v The diagonal crack often forms as a development of a flexural crack. Eventually, the diagonal crack penetrates into the concrete compression zone at the loading point. Crashing failure of the concrete occurs
。Dowel(销拴)failure dowel action The member can fail owing to dowel failure of the longitudinal reinforcement at the point of the inclined crack
• Dowel（销拴） failure The member can fail owing to dowel failure of the longitudinal reinforcement at the point of the inclined crack
3.Category III(3<a,/ho<6 )Diagonal tension failure 0- Flexural crack (a-b)is developed before the compressive force is great enough to develop shear-web cracks.Then the flexural crack (a-b)nearest the support would propagate towards loading point,becoming an inclined crack (a-b-c)known as a flexural-shear crack
3. Category III ( 3 a / h0 6 v ): Diagonal tension failure Flexural crack (a-b) is developed before the compressive force is great enough to develop shear-web cracks. Then the flexural crack (a-b) nearest the support would propagate towards loading point, becoming an inclined crack (a-b-c) known as a flexural-shear crack