Identification of Cracks

Question 1:

A)

Observation:

• Concrete crushed and the reinforcement is exposed.
• Concrete spalled beyond reinforcement which may be sign of rupture.
• Beam top portion looks safe beacuse of the flange advantage from slab.
• the crack develops from bottom to top means rebar yielding occurs in support bottom only.

Solution:

• Its from of flexural failure due to reversal of stress during earthqake.
• 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
• since the reinforcement got yielding it can not be repaired.

b)

Observation:

• Crakes along beams and column edge
• crakes seems to be have devoloped through the stracture as it looks much better
• Beams looks seperated from the column at the joints
• Concrete is not sevearly crushed.

Solution:

• Its beam pullout failure due to insafficient development length of reinforcement in joints
• During eartquake the horizontal moment of stracture makes this condition worse and detached the beam memeber from column.
• Provideing anchorage length between two existing concrete is very difficult . so not repeirable.

c)

Observation:

• Cracks are exactly at the join of column beam
• Cracks in beam developed through its entire width
• Sab also developed more cracks a long the beam width direction

SOlution:

• Its plastic hinge failure
• The damage occured only in the joint zone first of all.
• Cycalic lateral loading, stress reversal at the joints led to the damage
• EVen the slab partisipated to its best to handle the tension ( slab is sevearly craked means it has undergone tension with its flange condition) but unable to control the damage.
• the joint cen be strengthened.

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

Question 2:

a)

OBservation:

• Concrete damaged at the top of the column
• Concrete damaged all around the column face.
• Beams are safe.
• The location of the column looks at edge of the building.
• No walls are built along the column means it is propably at ground floor for parking car movement acess.

Solution:

• Its a soft story failure, tehnically plastic hinge formation.
• Due to absence of infill walls at the ground story columns duroing lateral moment
• based on the development crush of the concrete IT can iether be reperable or nor repirable.

b)

Observation:

• Concrete developed complete breakage diagonally
• Longitudnal reinforcement are intact.
• Shear rainforcement spaceing looks wider (which means propably lesser shear rebar provided)

Solution:

• Its is a pure shear failure.
• Inadequate shear rainforcement compels concrete takes all te shar stresses.

c)

Observation:

• Column failed completely
• Failure at top of the column
• there are two slabs connected to the column propably one midheight of the column
• The wooden piles might be a post failure support after colum failed. provideing temporary prop t avoid collapse of the entire stracture.

Solution:

• its a short column failure
• an additional slab or a beam connected to a column mid-height leads to this effect.
• this leads to failure especially if the connection is unintentinal and not accounted in design
• the failure in the picture is not at all repirable.