Identification of Cracks
Answer 1. A
OBSERVATION:
As we can see that:
Concrete crushed and the reinforcement is exposed
Concrete spalled beyond the reinforcement which may be a sign of rupture
Beam top portion looks safe because of the flange advantage from slab
The crack developes from bottom to top means rebar yeilding occurs in support bottom only
RESULT:
Its form of flexural failure due to reverse of stress during earthquake
During stress reversal 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
Since the reinforcement got yielded, it can not be repaired
Answer 1. B
OBSERVATION:
Cracks along Beam- Column edge
Cracks seem to have developed thrugh the structure as it looks much wider
Beam looks separated from the column at joints
Concrete is not severely crushed
RESULT:
Its a Beam pull out failure due to insufficient developmen 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 its not repairable
Answer 1. C
OBSERVATION:
Cracks 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
RESULT:
Its a plastic hinge failure
The damage occured only in the joint zone first of all
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
The joint can be strengthed therefore repairable.
Answer 2. A
OBSERVATION:
Concrete damaged at top of the column
Concrete damaged all round the column face
Beams are safe
The location of column looks at edge of the building
No walls are built along the column means it is probably at ground floor, for parking car movement access
RESULT:
Its a soft story failure, Technically plastic hinge formation
Due to absence of infill walls at the ground floor,The plastic hinge forms at the top of ground story column durin lateral movement
Based on the development of crush of concrete it can be either repairable or non repairable
Answer 2. B
OBSERVATION:
Concrete developed complete breakage diagnolly
Longitudnal reinforcements are intact
Shear reinforcement spacing looks wider which means probably lesser shear rebar provided
RESULT:
Its a pure shear failure
Inadequate shear reiforcement compels concrete takes all the shear stresses
Answer 2. C
OBSERVATIONS:
Column failed completely
Failure at top of column
There are two slabs connected to columns , probably one at mid of the column
The wooden piles might be a post failure support after column failed, providing temporary prop to avoid collapse of the entire structure
RESULT:
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 designs
The failure shown in the picture is not at all repairable