Identification of Cracks

1.Aim:

The mode of failure or damage of the beams . Would you characterize the case as damage or as a failure. Are the damages repairable.

The mode of failure or damage of the beams:

• These are the various types of cracks from in the concrete structure.
• These mode not a failure its is damades of beam it can be rectified before it gets failure.
• Depending upon the crack the situtation can be assed and remedial measure taken accordingly.
• A simple method to found the crack is superfical or deep is to strike the concrete with the hammer.
• If the hammer makes the ringing sound then crack is superficial while if the noise is dull,then the means delamination the occured in concred and crack is deep.
• In the above picture have Structural crack.

• It means the member is overstressed.the location the crack will indicate what type of failure mode in structural member.
• In the above Beam its has a negative felxural cracks is founded.due the negative moment of the beam.
• In this beam top rod is low tensile strength of the beam is less for the design.

The remides for damage:

• If the hammer makes the ringing sound then crack is superficial while if the noise is dull,then the means delamination the occured in concred and crack is deep.

• We can do retrofiting method to slove this problem.
• If this case the concrete cover needs to removed and rust must be removed from all around the reinforcement,the member should be repaired by applying rust inhabitor and polymer or cement based repair material or epoxy coating is used .

2.Aim:

The mode of failure or damage of the beams . Would you characterize the case as damage or as a failure. Are the damages repairable.

The above picture in a&c is a pure compression failure:

• The above showed column are not damaged it cause a failure.
• The column is an element that transfers the weight of a structure as axial stress to the foundation or supporting element.
• Concrete is capable of carrying the compressive load is dominant in carrying loads whereas in other elements such as beams compressive stress is taken only by part of the section.
• Reinforcement is also provided to columns where it is not possible concrete to carry the whole load or as nominal reinforcements.
• The column can fail in compress due to the increase of the axial stress than its capacity. These types of failure could be due to the following reasons.
• Reinforcement and concrete have certain capacity based on there amount and area of the section. If axial stress is greater than that capacity column will fail in compression.
• Further, the reinforcement and concrete have their own stain that they can bear. the concrete is capable of carrying a strain up to 0.0035 and steel starts yielding at a strain of 0.002 and it can increase greater than the concrete.
• When the axial stress exceeds a certain amount resulting in concrete strain grater than 0.0035 concrete will fail suddenly. It will be a sudden crushing of concrete.
• If the section is sufficiently reinforced, it will provide warnings before these types of column failure.

The above picture in B is a Shear failure:

• Lateral loads in a structure are carrying 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, from retaining structures, etc.

• 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.

• In general, failure of columns due to shear can be identified as the failure of design. Designers should have provided adequate shear links or sections to carry the shear forces.

Repair of column:

• Before starting the repair of a concrete column, the axial dead load, axial live load, horizontal load and its associated moments must be known.
• Repairs to concrete columns it is structural repair restores or strengthens the affected columns.
• The column cross section supported with jackiting.
• For picture B shear failure first do remide of this methods.Cathodic protection to stop reinforcing steel corrosion.
• Re-alkalization of the reinforcing steel to stop corrosion.
• Chloride extraction to retard the reinforcing steel corrosion.
• For picture A&C can use this method.Confinement using steel plate, carbon, or glass fiber materials.
• Addition of shear collars to increase the shear capacity of intermediate floors.
• Addition of a steel plate assembly to increase moment capacity..
• The application of a protection system to prevent future corrosion.