Identification of Cracks

1.

a)

• It is form of flexural failure due to reversal of stress during earthquake.
• During stress reversal, support top experiences comp and bottom experiences tension.
• top comp 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)

• it is beam pull out failure due to insufficient development length of reinforcement in joints.
• 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)

• Its a plastic hinge failure.
• the damage occurred only in the joint zone first of all.
• cyclic lateral loading & stress reversal at the joints led to the damage.
• even the slab participated to its best to handle the tension (slab is severely cracked means it has undergone tension with its flange condition), but unable to control the damage.
• The joint can be strengthened.

2.

a)

• Its a soft storey failure, technically plastic hinge formation.
• due to absence of infill walls at the ground floor , the plastic hinge forms at the top of ground storey columns during lateral movement.
• based on the development of crush of concrete,
• it can be either repairable and non repairable.

b)

• its a pure shear failure.
• inadequate shear reinforcement compels concrete takes all the shear stresses.

c)

• Its a short column failure.
• an additional slab or a 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 given in the picture is not at all repairable