Identification of Cracks

Question 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

Answer:

a)

 Crack is formed due to flexural failure in beams. As we can see that damage is caused more to the beam then column. Damage is caused due to insufficient of reinforcement or concrete. To overcome this failures steel must be provided at top/bottom of beam. These damages are repairable, while repairing this we need to remove pipes, wires and turn off the water and power connection. It can be repaired by adding cement to the damaged part

• Its form of Flexural failure due to reversal of stress during earthquake
• During stress reversal, Support top experiences Compression and Bottom experiences tension
• Top compression is managed by Slab advantage Bottom tension was not satisfied by the provided reinforcement
• Since the reinforcement got yielded, it cannot be repaired 

b)

  These cracks are formed due to high slump concrete. Beams and columns carry heavy load. So, first step is to relieve part of its load. This is done by providing supports at beam column joints. Remove the damage concrete until cored steel reinforcement is visible.

• Cracks along Beam-Column edge.
• Cracks seem to have developed through the structure as it looks much wider.
• Beam looks separated from the column at joints.
• Concrete is not severely crushed.
• Its Beam pull out failure due to insufficient development length of reinforcement in Joints
• During earthquake, The horizontal movement of structure makes this condition worse and detached the beam member
• from column Providing anchorage length between two
• existing concrete is very difficult So not repairable

C)

 

Cracks are formed due to beam column connection failure. It occurred due to high shear forces during seismic activity. If it is not properly repaired excessive loss in strength, then structure will collapse.

Question 2:

a)

 

It is formed due to the failure in column due to buckling. Buckling is the sudden change in shape of a structural component under load. If a structure is subjected to gradually increase in load, member may suddenly change the shape.

 b)

  

Due to Shear failure in column. Lateral loads carried in vertical elements of structure. Size of columns is increased in direction of shear to increase shear capacity. High shear forces are attracted by shorter columns. These failures occur during earthquake at open ground floor level.

c)

It is formed due to short column failure. Short columns fail by crushing at very high stress levels that are above the elastic limit of column materials. It is a critical type of concrete column damage occurs at these columns.