Identification of Cracks
1.
QUESTION: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)
a) The cracks are formed due to the flexural failure of the beam.This failure mode occurs when the loads on the beam exceed its flexural capacity. The shear strength of the beam should be greater than its flexural strength otherwise the shear failure would occur before flexural failure.This sometimes occurs due to the less clear cover provided to the beam .This failure is also called modulus of rupture which is caused as stress in material just before it yields.
To overcome this type of failure,main reinforcement is to be provided at the bottom and the top of the beam.The damage is repairable.First get the the reinforcement back in the alignment and fill surface using shotcrete emethod with better concrete grade.
b) 
b) This failure is occured due to honeycombing caused due to high slump concrete.Using of low slump concrete can help in avoiding these cracks in concrete.Honeycombing occurs due to the improper filling of concrete whithout using vibrator properly,making proper ratio of fine aggreagte to coarse aggregate.Poor concrete consolidation is the main cause of the honeycombing
c) 
c) These cracks are formed due to the column beam joint failure.If the beam is weak then the beam forms the plastic hinges at their end and develop flexural overstrength beoyond desired strength.The high internal forces developed cause critical bind conditionsand impose high shear demand in the joint core.This can be avoided by providing proper joint with bolts connections
2.
QUESTION: 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) 
a)The failure shown in the above image is column buckling.These typ of failure occurs when the column is ling and is not provided with the proper reinfrcement ,which causes the excess load from the above structure to get loaded in column and causes the buckling .generally buckling occurs at the mid of the columns where bending moment is maximum.To avoid this type of failure use proper stirrups placing with gaping distances and numbers.
b) 
b)The failure in the above picture is shear failure.a shear load is a type of force which tends to produrea sliding failure. the shear force can be wind load ,earthquake ,retaining walls etc. The size of the columns is increased in the direction of the shear to increase the shear capacity.
c) 
c)The failure shown in the above picis due to the short columns.In short columns ,failure takes place due to the yeilding and we define this phenomena as crushing.Short column is considered from the slenderness ratio which is the ratio of effective lenght to the least cross sectional area of the column.short columns will only fail because of compressive stress developed in the column..