Identification of Cracks
IDENTIFICATION OF CRACKS
What is the mode of failure or damage of the beams in the figure above? Are the damages repairable? Elaborate
Question 1:
a)
THE ABOVE FIGURE SHOWS FLEXURAL FAILURE BY THE CRACKS DEVELOPED AT BOTTOM OF THE FLANGE.
IN THE ABOVE IMAGE WE CAN SEE THAT CONCRETE IS CRUSHED AND REINFOCEMENT IS EXPOSED. IT IS THE SIGN OF RUPTURE AS CONCRETE IS SPALLED BEYOD THE REINFORCEMET. THE CRACK IS DEVELOPED AT THE BOTTOM OF THE BEAM AND THE TOP OF THE BEAM IS SAFE DUR TO SLAB FLANGE. THE REBAR YEIDING IS OCCURED IN THE SUPPORT.
BY OBSERVING THE IMAGE WE CAME TO CONCLUSTION THQAT THE FORM OF FALIURE IS FLEXURAL FAILURE DUE TO REVERSAL OF STRESS DURING EARTHQAUKE.
DURING STRESS REVERSAL SUPPORT TOP EXPERIENCES COMPRESSION AND BOTTOM EXPERIENCES TENSION.
TOP COMPRESSION IS MANAGED BY SLAB FLANAGE THE BOTTOM FAILED AS BOTTOM TENSION WAS NOT SATISFIED BY THE POEOVIDED REINFORCEMENT.
THE ABOVE STRUTURE CANNOT BE REPAIRED.
b) 
THE ABOVE FALURE IS BEAM PULL OUT FALIURE SUE TO INSUFFICEINT DEVELOPMENT LENGTH IN REINFORCEMENT JOINTS
THE CRACKS CAN BE SEEN ON BEAM COLUMN EDGE AND THE CRACKS SEEMS TO HAVE DEVELOPED THROUGH THE STRUCTURE AS IT LOOKS MUCH WIDER. CONCRETE IS SEVERELY CRUSHED AND BEAM LOOKS SEPARATED FROM COLUMN AT JOINTS.
DURING EARTH QAUKE THE HORIZONTAL MOVEMENT OF STRUCTURE MAKES THIS CONDITION WORSE AND DETACHED THE BEAM MEMBER FROM COLUMN
THE ABOVE CONDITION IS NOT REPAIRABLE AS IT IS DIFFICULT TO PROVIDE THE ANCHORAGE LENGTH BETWWEN TEO EXISTING STRUCTURE.
c) 
THE FIGURE REPRESENTS BEAM-COLUMN CONNECTION FAILURE CAUSED BY THE PLASTIC HINGE.
CRACKS ARE AT JOINT OF THE COLUMN.CRAKS IN BEAM DEVELOPED THROUGH ITS ENTIRE WIDTH.SLAB ALSO DEVELOPED MORE CRACKS ALONG THE BEAM WIDTH DIRECTION.
IT IS PALSTIC HINGE FALURE. THE DAMGE IS OCCURED AT JOINT ZONE FIRST.CYCLIC LATERAL LOADING AND STRESS REVERSAL AT THE JOINTS LED TO THE DAMAGE.
IT IS REAPIRABLE AS THE JOINTS ACAN BE STRENGTHENED.
Question 2:
a) 
IN THE ABOVE FIGURE THERE IS SOFT STOREY FAILURE HAS BE OCCURED. THE CONCRETE IS DAMAGED AT THE TOP OF COLUMN.
THE COLUMN LOKS LIKE IT IS PLACED AT BOTTOM FLOOR AND IN CORNER MOST LIKLEY TOP BE PARKING GROUND FLOOR.
ALSO THERE IS ABSENCE OF INFILL WALSS SO THE PLASTIC HINGE FORMS AT THE TOP OF GROUND OF GROUNG FLOOR.
THE FALURE IS REPAIRABLE IF IT IS NOT TOO SEVERE OTHERWISE IT IS NON-REPAIRABLE
b) 
THE ABOVE IMAGE SHOWS THE PURE SHEAR FAILURE
THE FAILURE IS OCUURED DUE TO LESS SHEAR REINFORCEMENT AND IT CAUSED INSUFFICENT REINFOCEMENT IN PLASTIC HIONGE LOCATION
THUS TH ECOLUMNS OF BUILDING MUST HAVE SUFFIENT TRANSVERSE REINFORCEMENT IN PLACSTIC HINGE REGION
THE FAILURE IS NON-REPAIRABLE
.
c) 
THE ABOVE FIGURE SHOWS THE SHORT COLUMN FAILURE.
THIS FALURE HAS OCCURED DUE TO ADDITONAL SALB PROVIDED AS MID HEIGHT AS WE CAN SEE IN THE FIGURE.
WHEN THE LENGTH OF COLUMN DECRESES THE COLUMN BECOMES STIFFER AND BRITTLE AND IT ATTRACTS MORE SHEAR FORCE
THE FAILURE IS NON-REPAIRABLE