Identification of Cracks
Ans 1 : (a) The image given in the Q1(a) Soft Storey Mechanism When the ground floor or basement floor is kept opened because of parking or because of retail shops or so without considering the stiffness distribution along the height of the building lateral stiffness is reduced in the upper floors as compared to the end of the column which leads to the formation of the plastic hinge formation at the upper end of the ground floor leading to the deformation at the some location rather than in the overall structure. Strong column and weak beam design will prevents it from happening.
The damage caused because of this is not repairable.
(b)The image given in the Q1(b), showed that The portion of the column is left infill .Masonry wall does not cover the entire height of the column because of this the effective height of the column will get reduced and it behaves like shorter column ,Shorter column will attracts more shear forces often with disastrous effects. In RC and Masonry structures the inelastic shear deformation is accompanied with deterioration in both strength and stiffness which leads to the failure.
Shorter columns attracts larger shear forces and undergoes inelastic shear deformation. And here flexural behaviour will be no longer governing this column response and is now governed only by shear response.
The damage caused because of this is not repairable.
(c) The mode of the Failure as shown in the Q 1(c) is identified to be BEAM COLUMN CONNECTION FAILURE. The joint link between the beams and columns should not become the weak link. These kind of failure is caused because of plastic hinge formation at the undesirable locations. The beams and columns will be subjected to very high shear forces during the seismic activities and if it is not adequately reinforced it will result in the loss of strength and stiffness and may even leads to collapse.
The X shape Crack is the identification of shear failure. The plastic hinges must be formed at the end of the beams but not at the Beam Column Connection.
The damage caused because of this is not repairable.