Identification of Cracks

1) Objectives of the challenge are:

Awarenes on structural failures

Distinguishing structural and non-structural failures

To know how to observe a structural issue

Understanding seismic failures

a) Observations:

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 develops from bottom to top means rebar yielding occurs in support bottom only

Its form of flexural failure due to reversal of stress during earthquake

During stress reversal, suport 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

b) Observations:

Cracks along Beam-column edge

Cracks seem to have developed through the structure as it looks much wider

Beam looks separated from the column at joints

Concrete is not severly crushed

Its beam pull out failure due to insuffiecient 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) Observations:

Crackes are exactly at the joint of column-beam

Cracks in beam developed through its entire width

Slab also developed more crackes along the beam width direction

Its a plastic hinge failure

The damage occurred only in the joint zone first of all

Cyclic lateral loading and 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) Concrete damaged at top of the column

Concrete damaged all around the column face

Beams are safe

The loaction of a columns looks at the edge of the building

No walls are built along the column means it is probably at ground floor, for parking car movement access

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 either be repairable or Non repairable.

b) Observations:

Concrete developed complete breakage diagonally

Longitudinal reinforcement are intact

Shear reinforcement spacing looks wider (Which means probably lesser shear rebar provided)

Its a pure shear failure

Inadequate shear reinforcement compels concrete takes all the shear stresses

c) Observations

Column failes completely

Failure at top of the column

There are two slabs connected to the column, probably one at mid height 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

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