Identification of Cracks

1)What is the mode of failure or damage of the beams in the figure above? Are the damages repairable? Elaborate

a)

• By observation its seen like the concrete is crushed and reinforcement is exposed
• Concrete is broken beyond the reinforcement it is sign of rupture
• In the image its seen the beam top portion is safe because of the flange of the slab
• The crack occurs from bottom to top
• It is form of Flexural Failure due to reversal of stress during earthquake
• During stress reversal, support top experiences tension
• Top compression is managed by slab advantage. Bottom tension was not satisfied by the provided reinforcement
• Since the reinforcement got yielded it can not be repaired

b)

• The cracks is along Beam-Column edge
• Cracks seem to have developed through the structural as it looks much wider
• Beam look sepa1rated from the column at joint
• Concrete is not severely crushed
• Its beam pull out failure due to insufficient development length of reinforcement in joint
• During earthquake the horizontal movement of structure makes this condition worse and detached the beam member from column
• Providing anchorage length between two existing concrete is very difficult. So not repairable

c)

• Crakes are exactly at the joint of column-beam
• Cracks in beam developed through its entire width
• Slab also developed more cracks along the beam width direction
• It’s a plastic hinge failure
• The damage occurred only in the joint zone first of all
• Cycle lateral loading & stress reversal at the joint led to the damage
• Even the slab participated to its best to handle the tension but unable to control the damage
• The joint can be strengthened

2)

a)

• Concrete damage at top of a column
• Concrete damaged all around the column face
• Beam are safe
• The location of column looks at edge of the building
• No wall are built along the column means it is probable at ground floor for parking car movement access
• It is soft story failure technically plastic hinge formation
• Due to absence of infill wall at the ground floor the plastic hinge forms at the top of ground story column during lateral movement
• Based on the development of crush of concrete it can either be repairable or non-repairable

b)

• Concrete developed completely breakage diagonally
• Longitudinal reinforcement are intact
• Shear reinforcement spacing looks wider
• It is pure shear failure
• Inadequate shear reinforcement compels concrete takes all the shear stresses
• It is not repairable

c)

• It is short column failure
• Failure at top of the column
• Column failed completely
• An additional slab or beam connected to a column in mid-height leads to this effect
• This leads to failure especially if the connection is unintentional and not accounted in design
• The failure give in the picture in not at all repairable