Identification of Cracks
1)a.Observation concrete cruushed and the 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 advanced from the slab
The crack develops from bottom to top means rebar yielding occurs in support bottom only.
Answer
Its form of flexural failure due to reversal of stress during eathquake
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 providded reinforcement.
Since the reinforcement got yielded, it can not be replaced.
2)b.Observations
Cracks along the beam column edge.
Cracks seem to be have developed through the structure as it looks much wider.
Beam looks seperated from the column at the joints.
concreet is not severely crushed.
Answer:
Its beam pull out failure due to insufficient development length of reinforcement in joints
During earthquake, The horizontal movements 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
1(c) Observations
cracks are exactly at the joints of column and beam
cracks in beam developed through its entire width
slab also developed more cracks along the beam width direction
Answer
Its aplastic hinge failure
The damage occured in 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 strentheed
2(1)Observations
Concrete damage at the top of the column
Concrete damaged all around the column face
Beams are safe
The location of column looks at edge of the building
The walls are built along the column means it is probably at ground floor , for parking car movements access
Answer
It's 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 deevelopment of crush of concrete, It can either be repairable or non-repairable
2(b) Observation
Concrete developed complete breakage diagonally
Longitudinal reinforcements are intact
shear reinforcement spacing looks wider (which means Probably lesser shear rebarprovided)
Answer
It's a pure shear failure
Inadequate shear reeinforcement compells concrete takes all the shear stresses
2(c) Observations
Column failure completely
Failure at top of column.
There are two slabs connnected to the column , probably one at mid height of the column.
The wooden piles might be a post failure support after column failed, providing temperary prop to avoid collapse of the entire structure.
Answer:
Its a short column faire
An additional slab or a beam connected to a column in mid height leads to the effect
This leads to failure especally if the connection is unintentional and not accounted in design
The failure given in the picture is not at all repairable.