Identification of Cracks

Question 1: - What is the mode of failure or damage of the beams in the figure below? Are the damages repairable? Elaborate

AIM: - To determine the mode of failure or damage of the beams in the pictures and determination of the damages repairement

INTRODUCTION: - We all already know that the failures occur in the beam and columns or structural members which we will find out in this project with observation of the images provided

TYPES OF FAILURES IN THE BEAMS AND COLUMNS ARE AS BELOW: -

• Flexural Tension Failure
• Flexural Compression Failure
• Shear failure
• Diagonal Tension Failure
• Shear Compression Failure
• Splitting Shear Failure
• Anchorage Failure
• Failure Due to Pure Compression
• Failure Due to Combined Compression and Bending
• Failure due to Inelastic Inability

a)

OBSERVATION FROM THE IMAGE: -

1. As we can see that, Concrete crushed and the reinforcement is fully visible
2. Concrete fall up to the rebars which may be a sign of rupture
3. Beam top portion looks safe because of the flange advantage from slab
4. The crack develops from bottom to top means rebar yielding occurs in support bottom only

ANSWER: -

1. Its form of flexural failure due to reverse of stress during earthquake as we can see in the elaborate image above
2. During stress reversal reversal, support top experiences compression and bottom experiences tension
3. Top compression is managed by slab advantage. Bottom tension was not satisfied by the provided reinforcement

REPAIR PROBABILITY: -

• As the reinforcement got exposed, and get up to yielding , it cannot be repaired

b)

OBSERVATION FROM THE IMAGE: -

1. As we observed Cracks along Beam- Column edge
2. Cracks seem to have developed through the structure as it looks much wider
3. Beam looks separated from the column at joints
4. Concrete is not fully (severally) crushed

ANSWER: -

1. It’s a Beam pull out failure due to insufficient development length of reinforcement in joints
2. During earthquake, the horizontal movement of structure makes this condition worse and detached the beam member from column

REPAIR PROBABILITY: -

• Providing anchorage length between two existing concrete is very difficult. So it’s not repairable

c)

OBSERVATION FROM THE IMAGE: -

1. As we observed, Cracks are exactly at the joint of column and Beam
2. Cracks in Beam developed through its entire width
3. we can see the cracks in the slabs in the direction of the beam width

ANSWER: -

1. It’s a plastic hinge failure, as we know plastic hinge failure occurred only at the joints
2. The damage occurred only in the joint zone first of all
3. Cyclic lateral loading and stress reversal at the joints led to damage
4. 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

REPAIR PROBABILITY: - The joint can be strengthened therefore repairable.

Question 2: -

a)

OBSERVATION FROM THE IMAGE: -

1. As we observed, Concrete damaged at top of the column
2. Concrete damaged all-round the column face
3. Beams are safe as they we seem no damage to them
4. As the image shown the brighter environment at left it definitely an outer column or to be specific column lies edge of the building
5. No walls are built along the column means it is probably at ground floor, to be specific it is may be parking lots area

ANSWER: -

• It’s a soft story failure, technically plastic hinge formation
• Due to absence of walls at the ground floor, the plastic hinge forms at the top of ground story column during lateral movement

REPAIR PROBABILITY: - Based on the development of crush of concrete it can be either repairable or non-repairable (it fully depends on the severity of the plastic hinge failure, if it in severe it cannot be repair or vice versa)

b)

OBSERVATION FROM THE IMAGE: -

1. As we can observed, the concrete is fully crushed
2. The rebars are fully visible, in it effect on the whole structure
3. Concrete developed complete breakage diagonally
4. The reinforcement is intact but the by the time it may be buckled as the rebars doesn’t have a binding material
5. Shear reinforcement spacing looks wider which means probably lesser shear rebar provided

ANSWER: -

1. It’s a pure shear failure
2. Inadequate shear reinforcement compels concrete takes all the shear stresses

REPAIR PROBABILITY: - As the shear occurs (transferred) only in from concrete it somehow repairable

c)

OBSERVATION FROM THE IMAGE: -

1. As we can observed, Column failed completely
2. Failure at top of column is visible
3. There are two slabs connected to columns, probably one at mid of the column
4. There is not a single bonding of any member to the column is visible
5. The wooden rods may be added as a failure support after column failed, providing temporary prop to avoid collapse of the entire structure

ANSWER: -

• It’s 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

REPAIR PROBABILITY: - AS because it completely shears failure it cannot be repairable