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
a)
Crack is formed due to not provide suffisent cover to the beams. As we can see that damage is caused more to the beam then column. Damage is caused due to water reach to the steel and steel start rusting and it affect bonding between steel and concrete . To overcome this failures sufficent cover blocks are must be provided at top/bottom of beam. This 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.
b) 
This cracks are formed due to high slump concrete and also not provide suffisunt steel bars to the column spacing between bars are also decreasuse . 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 corred steel reinforcement is visible.and provide some more steel bar.
c) 
Cracks are formed due to beam column connection failure. It occured 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 changes 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 shear column failure. shear columns fail at very high stress levels that are above the elastic limit of column materal It is a critical type of concrete column damage occurs at these columns. spacing between longitudnel steel bar are more in this case .we can prevent this type of failure by decreasing the spacing between longitudenl as wel as stirups spacing on the starting and end point on the columns and beam ..generally we take 100mm on the joints and 150mm between the columns