Identification of Cracks

QUESTION no.1. ANS:

A).

1. This cracks will be formed due to the flexueral failure of a beam. The flexural strength known as modulus of ruputure, bend strength, or fracture strength, is a materila property., defined as the stress in a material just before it yields in a flexure test.

2. The flexural strength represents the highest stress experienced within the material and its moment of ruputure.it is measured in terms of stress.

3. To overcome this type of failure, main steel is provided at the bottom/top of the beam, The damages of are repairable, to repair damaged beams locate a local welder or metal shop and request angle iron, cut and drilled to the length of the beam being repaired.

4. Remove any pipes, wires, etc., before doing so. pry the joist hanger away from the beam, mount the angle iron on the jack and the temporary post.

5. Get the angle iron in place and slowly raise the jack until the angle is welded up against the damaged beam.

6. Screw the angle iron into the beam and remove the temporary post, slide any pipes or wires previously removed back through the beam turn the water and power back on.

B.

1. This cracks are formed due to the mistakes done in the construction and honey combing in concrete.

2. To avoid cracks in concrete, avoid using high slump concrete,conrete of moderate slump(less than 5 inches) result in less cracking.

3. High slump concrete can only be used if it is controlled by concrete admixtures by concrerte admixtures or designed such that segreation and bleeding of concrete is controlled.

4. Concrete admixtures such as water reducers or super plasticizers can be used to increase slump while reducing addition of water content.

5. Air entrained concrete can also be produced to increrase slump especially when concrete is to be subjected to freeze and thaw cycles.

6. The honey combing occurs when the fine gaps created by the coarse aggregates, As mentioned previously, poor concrete consolidation is usuallay the top cause of honey combing, along with poor vibration, improper ratio of fine to coarse aggregate, dry concrete and construction conditions that are not up to standard.

C.

1. This cracks are formed due to the beam - column joint failure, in the strong column - weak beam design, beams are expected to form plastic hinges at their ends and develop flexural over strength beyond the design strength.

2. The high internal forces developed at plastic hinges cause critical bond conditions in the longitudinal reingforcing bars passing through the joint and also impose high shear demand in the joint care.

3. The bond performance of the bars anchored in a joints affects the shear resisting mechanism to a significant extent.

QUESTION no. 2.:

A.

1. This cracks will be formed due to the flexural failure of a column, columns have the important role in all structural members of a building.

2. According to the base civil engineering concept, colimns failure wants to be occuring after beams and the other components damages, Performance of existing buildings in earthquakes indicates that the beams are less vulnerable to damage.

3. During earthquakes and their damage appears to be less critical to performance as compared with that of columns and column beam joints.

B.

1. This crack will be formed due to the shear failure of a column, lateral loads in a structure are carrying by vertical elements such as columns and shear walls.

2. When there are no shear walls, columns carry these lateral loads, Lateral loads are generated by winds, earthquake loads, from retaining structures etc.,

3. Shear links are provided to columns based on the shear forces excreted on them, further the size of the columns is increased in the direction of shear to increase the shear capacity.

C.

1. This cracks are formed due to the short column failure.

2. In short columns, failure takes place due to yielding and we define this phenomenon as,

CRUSHING. short columns are classified based up on slenderness ratio which is the ratio of the effective length ( length between point of zero moments) and least lateral dimension of the column.

3. Failure of column usually occurs due to anyone of the following stress developed in the column,.

4. Short column will fail only because of direct compressive stress developed in the column or we can also say that short column will usually fail due to direct compressive or crushing.

THESE ARE THE IDENTIFICATION OF CRACKS OF MODE OF FAILURE OR DAMAGE OF THE BEAMS EXPLAIN NEATLY STEP BY STEP.