Identification of Cracks
1. AIM:
⦁ To determine the mode of failure or damage of the beams in the picture and the determination of the damages and the repairement.
TYPES OF FAILURES IN THE BEAMS AND COLUMNS:
⦁ Flexural tension failiure
⦁ Flexural compression failure
⦁ Shear failure
⦁ Diagonal tension failure
⦁ Shear compression failure
⦁ Splitting shear failure
⦁ Anchorage failure
⦁ Failure due to pure compression
⦁ Failure due to inelastic inability.
1(a):
OBSERVATION FROM THE IMAGE:
⦁ As we can see that, concrete crushed and the reinforcement is fully visible.
⦁ concrete fall upto the rebars which may be the sign of rupture.
⦁ Beam top portion looks safe because of the flange advantage from slab.
⦁ The crack develops from the bottom to top means rebar yielding occurs in support bottom only.
MODE OF FAILURE:
⦁ It forms a flexural failure due to reverse of stress during earthquake.
⦁ During stress reversal, support top experiences compression and bottom experiences tension.
⦁ Top compression is managed by slab advantage. bottom tension was not satisfied by the provided reinforcement.
REPAIREMENT:
⦁ As the reinforcement got exposed and got upto yielding, it can not be repaired.
1(b):
OBSERVATION FROM THE IMAGE:
⦁ As we observed cracks along beam column edge.
⦁ Cracks seems to have developed through the structure as it looks much wider.
⦁ Beam looks seperated from the column at joints.
⦁ concrete is not fully crushed.
MODE OF FAILURE:
⦁ Its a beam pull out failure due to the insufficient developement length of reinforcement in joints.
⦁ During earthquake, the horizontal movement of structure makes this condition worse and detached the beam member from the column.
REPAIREMENT:
⦁ Providing anchorage length between two existing concrete is very difficuilt. so it is not repairable.
1(c):
OBSERVATION FROM THE IMAGE:
⦁ As we observed, cracks are exactly at the joint of column and beam.
⦁ Cracks in beam developed through its entire width.
⦁ We can see the cracks in the slabs in the direction of beam width.
MODE OF FAILURE:
⦁ Its a plastic hinge failure. the plastic hinge failure occurs only at the joints.
⦁ The damage occured only in the joint zone.
⦁ cyclic lateral loading and stress reversal at the joints led to damage.
⦁ even the slab participated to its best to handle the tension.
⦁ slab is severly cracked means it has undergone tension with its flange condition.
⦁ but unable to control the damage.
REPAIREMENT:
⦁ The joint can be strengthened therefore it is repairable.
2. AIM:
⦁ To determine the mode of failure or damage of the beams in the picture and the determination of the damages and the repairement.
2(a):
OBSERVATION FROM THE IMAGE:
⦁ Concrete damaged at the top of column.
⦁ concrete damaged all around the column face.
⦁ beams are safe as there seems no damage to them.
⦁ As the image shown the brighter environment at left it definietley a outer column or to be specific column lies edge of the building.
⦁ No wall are built along the column means it is probably at ground floor, to be specific it is may be parking lot area.
MODE OF FAILURE:
⦁ Its a soft storey failure, technically plastic hinge formation.
⦁ Due to absence of walls at the ground floor, the plastic hinge forms at the top of ground storey column during lateral movement.
REPAIREMENT:
⦁ Based on the developement of crush of concrete it can be either repairable or non-repairable (it fully depend on the severity of plastic hinge failure, if it in severe it cannot be repaired or vice versa).
2(b:
OBSERVATION FROM THE IMAGE:
⦁ As we observed, the concrete is fully crushed.
⦁ the rebars are fully visible, it affect on the whole structure.
⦁ concrete developed complete breakage diagonally.
⦁ the reinforcement is intact but by the time it may be buckeled as the rebars doesn't have a binding material.
⦁ shear reinforcement spacing looks wider which means probably lesser shear rebar provided.
MODE OF FAILURE:
⦁ Its a pure shear failure.
⦁ Inadequate shear reinforcement compels concrete takes all the shear stresses.
REPAIREMENT:
⦁ As the shear occurs (transfered) only from concrete it somehow repairable.
2(c):
OBSERVATION FROM THE IMAGE:
⦁ Column failed completely.
⦁ Failure at the top of column is completely visible.
⦁ There are two slabs connected to columns probably one at mid of the column.
⦁ There is not a single bonding of any member to the column is visible.
⦁ The wooden rods may be added as a failure support after column failed, providing temporary prop to avoid collapse of the entire structure.
MODE OF FAILUIRE:
⦁ Its a short column failure.
⦁ An additional slab or a beam connected to a column in mid height leads to its effects.
⦁ This leads to failure especially if the connection is unintentional and not accounted in design.
REPAIREMENT:
⦁ It cannot be repairable as of it is completely shear failure.