Identification of Cracks
1.What is the mode of failure or damage of the beams in the figure above? Are the damages repairable? Elaborate
AIM:- To identify the mode of failure of the beams in the figure and identify the damage whether it is repairable or not
INTRODUCTION:- The most common causes of failure during earthquake are:-
1) Formation of plastic hinge at undesirable location
2) Confinement failure of column building. This is due to inappropriate detailing of plastic hinge location.
3) Influence of partial height infill increasing column shear force (short column effect) which causes undesirable mode of vibration
4) Beam column connection failure
5) Bearing capacity failure due to liquefaction
SOLUTION:-
a) From figure it shows that the failure occurs due to flexural tension. This failure initiates by yielding of steel reinforcement followed by compression of concrete at compression side of the beam. The signs of this type of failure are the development of cracks at the tension side of the beam which further extend to the compression side. These cracks are mostly vertical and located at the middle third of the beam.
From the figure it can be observed that:-
- Concrete crushed and the reinforcement exposed
- Concrete spalled beyond the reinforcement
- Cracks are not propagated towards the upper face of the beam
From the above figure it can be observed that reinforcements cannot be repairable as it already looses its strength. This may haapen due to improper vibration or not providing cover to the bottom of the tension reinforcement. It can be repairable only with the use of providing additional concrete with required compressive strength
b) From figure it shows that the failure occurs due to improper mixing of concrete or not providing compaction to the concrete with tamping rod. It cannot be repairable. The best solution is to conduct slump cone test at site with proper admixtures. Also grouting process can be adopted in such cases.
c) From the above figure it shows that the failure occures due to beam column connection failure. Sizeable cracks can also be occured at the slab portion.Undesirable plastic hinges are developed at both beam and column ends. Beam-Column junction can be strengthened by adopting retrofitting techniques to limit the cause of failure but is not economical
RESULTS:- All the modes of failures or damage of the beam has been illustrated.
2. What is the mode of failure or damage of the columns in the figure above? Are the damages repairable? Elaborate
AIM:- To identify the mode of failure of the columns in the figure and identify the damage whether it is repairable or not
INTRODUCTION:-
The most common causes of failure during earthquake are:-
1) Formation of plastic hinge at undesirable location
2) Confinement failure of column building. This is due to inappropriate detailing of plastic hinge location.
3) Influence of partial height infill increasing column shear force (short column effect) which causes undesirable mode of vibration
4) Beam column connection failure
5) Bearing capacity failure due to liquefaction
SOLUTION:-
a) From the above figure it shows that the failure occurs due to soft storey one. Infill walls are not been constructed probably at the ground level. Grouting process can be adopted in such cases. Yielding of steel can also observed in this figure which cannot be repairable.
b) From the above figure it shows that the failure occurs due to shear failure. Shear reinforcements are not closely widely spaced whereas longitudinal reinforcements are properly intact. It cannot be repairable because the damage is severe
c) From the above figure it shows that the failure occurs due to short column failure. As a reuslt of it the column has been crushed. It can be repairable by providing suitable retrofitting technique such as steel jacketing .
RESULTS:- All the modes of failures or damage of the column has been illustrated.