Challenge

Identification of Cracks

QUESTION 1

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

ANSWER 1

This crack will be formed due to the flexural of a beam
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
The flexure strength represents the highest stress experienced within the material at its moment of rupture
It is measured in terms of stress
To overcome this type of failure, main steel is provided at the bottom/top of the beam
The damages are repairable
To repair damaged beams, located a local welder or metal shop and request angle iron, cut and drilled to the length of the beam being repaired
Remove any pipes, wires, etc. currently going through the beam
Be sure to turn off the water, power, etc. before doing so
Try to joist hanger away from the beam
Mount the angle iron on the jack and the temporary post
Get the angle iron in place and slowly raise the jack until the angle iron is wedged up against the damaged beam
Screw the angle iron into the beam and remove the temporary post
Slide any pipes or wires previously removed back through the beam and turn the water and power back on

This crack is formed due to the mistake done in the construction and honeycombing in the concrete
To avoid cracks in concrete, avoid using high slump concrete
Concrete of moderate slump results in less cracking
High slump concrete can only be used if it is controlled.
Concrete admixtures such as water reducers or superplasticizers can be used to increase slump while reducing the addition of water content
Air entertained concrete can also be produced to increase slump especially when concrete is to be subjected to freeze and thaw cycles
The honeycombing occurs when the fine mortar fails to thoroughly fall and fill the gaps created by the coarse aggregate
As mentioned previously, poor vibration, the improper ratio of fine to coarse aggregate, dry concrete, and construction conditions that are not up to standards

This crack is formed due to beam-column joint failure
In the strong column-weak beam design, beams are expected to form plastics hinges at their ends and develop flexural overstrength beyond the design strength
The high internal forces developed at plastic hinges cause critical bond conditions in the longitudinal reinforcing bars passing through the joint and also impose high shear demand in the joint core
The bond performances of the bars anchored in a joint effect the shear resisting mechanism to a significant extent

ANSWER 2

This crack is formed due to flexural failure of column
Columns have the most important role in all structural members of a building
According to the basic Civil Engineers concepts, columns failure wants to be occurring after beams and the other components damages
Performance of existing buildings in earthquakes indicates that the beams are less vulnerable to damage during earthquakes and their damages appear to be less critical to performance as compared with that of columns and column-beam joints

This crack is formed due to shear failure of column
Lateral loads in a structure are carried by vertical elements such as columns and shear walls
When there are no shear walls, columns carry these lateral loads
Lateral loads are generated by winds, earthquake loads, retaining structures, etc.
Shear links are provided to columns based on the shear forces excreted on them
Further, the size of columns is increased in direction of shear to increase the shear capacity

This crack is formed due to the short column failure
In the short column, failure takes place due to yielding and we define this phenomenon as CRUSHING
Short columns are classified based upon slenderness Ratio which is the ratio of the effective length and least lateral dimensions of the column
Failure of column usually occur due to any of the following stresses developed in the column
The short column will fail only because of direct compressive stress developed in the column or we can also say that the short column will usually fail due to direct compression or crushing

Ship work like this
in your own course.