Identification of Cracks

1) What is the mode of failure or damage of the beams in the figure above? Would you characterize the case as damage or as a failure? Are the damages repairable? Elaborate.

A)

1. This crack will be formed due to the flexural failure of a beam.
2. The flexural strength, known as modulus of rupture, bend strength, or fracture strength, is a material property, defined as the stress in a material just before it yields in a flexure test.
3. It represents the highest stress experienced within the material at its moment of rupture. It is measured in terms of stress.
4. To overcome this type of failure, main steel is provided at the bottom/top of the beam. Damage is caused due to insufficient of reinforcement or concrete.
5. No, the damage cannot be repaired as the reinforcement has yeilded.

B).

1. This cracks are formed due to the mistakes done in concreting and honeycombing in concreting.
2. Its a Beam pull out failure due to insufficient developmen length of reinforcement in joints
3. During earthquake, the horizontal movement of structure makes this condition worse and detached the beam member from column.
4. Providing anchorage length between two existing concrete is very difficult.
5. To avoid cracks in concrete, avoid using high slump concrete.
6. So this failure is not repairable.

C).

1. This cracks are formed due to the beam-column joint failure.
2. In the Strong Column-Weak Beam design, beams are expected to form plastic hinges at their end and develop flexural overstrength beyond design strength.
3. Cracks in the beam developed through its entire width.
4. The damage occurd only in joint zone first.
5. The bond performances of the bars anchored in a joint effect the shear resisting mechanism to a significant extent
6. The joint can be strengthed therefore repairable.

Question 2:

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

A).

1. This cracks are formed due to flexural failure of a beam.
2. Colmuns have the most important role in the structure.
3. In this failure, Concrete damaged all around the column face.
4. Beams are looking safe.
5. Its a soft story failure, Technically plastic hinge formation.
6. Based on the development of crush of concrete it can be either repairable or non repairable.

B).

1. This crack will be formed due to the shear failure of a column.
2. Lateral loads in a structure are carrying by verticl elements such as columns and shear walls.
3. When there are no shear walls, columns carry these lateral loads.
4. Lateral loads are generated by winds, earthquake loads, from reataining structures, etc.
5. Inadequate shear reinforcement compels concrete takes all shear stresses.

C).

• This cracks are formed due to short column failure.
• Short column is classified base upon slenderness Ratio.
• Failure of Column usually occurs due to anyone of the following stresses developed in the column.
• 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.