Identification of Cracks
ANS:1
A)
OBSERVATION:
CONCRETE CRUSHED AND REINFORCEMET IS EXPOSED
CONCRETE SPALLED BEYOND THE REINFORCEMENT WHICH MAY BE SIGN OF REPTURE
THE TOP PORTION OF THE BEAM LOOKS LIKE SAFE BECAUSE OF THE FLANGE ADVANTAGE FROM THE SLAB
THE CRACK DEVELOPS FROM THE BOTTOM TO TOP MEANS THE REBAR HAS REACHED ITS PLASTIC STATE AT DOTTOM PORTION.
RESULT:
IT'S A FORM OF FLEXURAL FAILURE DUE TO REVERSAL OF THE STREE DURING EARTHQUAKE.
DURING STRESS REVERSAL STRUCTURE TOP EXPERIENCES THE COMPRESSION AND BOTTOM EXPERIENCES THE COMPRESSION AND BOTTOM EXPERIENCES THE TENSION.
TOP COMPRESSION IS SATISIFIED WITH SLAB ADVANTAGE AND BOTTOM TENSION WAS NOT SATISIFIED BY THE PROVIDE REINFORCEMENT.
SINCE THE REINFORCEMENT GOT YIELDED IT CAN'T BE REPAIRED.
B)
OBSERVATION:
THE CRACKS ARE PRESENT ALONG THE BEAM COLUMN-EDGE
CRACK SEEMS TO HAVE DEVELOPED THROUGH STRUCTURE AS IT LOOKS MUCH WIDER.
BEAMS LOOKS SPERATED FROM THE COLUMN AT JOINTS
CONCRETE IS NOT SEVERELY CRUSHED.
RESULT:
IT'S A BEAM PULLOUT FAILURE DUE TO INSUFFICIENT DEVELOPMENT LENGTH OF REINFORCEMENT IN JOINT
DURING EARTHQUAKE THE HORIZONTAL MOVEMENT OF THE STRUCTURE MAKES THIS CONDITION WORSE AND DETACHED THE BEAM MEMBER FROM THE COLUMN.
PROVIDING ANCHORAGE LENGTH BETWEEN TWO EXISTING CONCRETE IN VERY DIFFICULT. SO NOT REPAIRABLE.
C)
OBSERVATION:
CRACKS ARE EXCCTLY AT THE POINT OF THE COLUMN BEAMS
CRACKS IN WIDTH DEVELOPED THROUGH ITS ENTIRE WITH.
SLABS ALSO DEVELOPED MORE CRACKS ALONG THE BAAM WIDTH DIRECTION.
RESULT:
IT'S PLASTIC HINGE FAILURE.
THE DAMAGE OCCURE ONLY AT THE JOINT
CYCLIC LATERAL LOADING AND STRESS REVERSAL LED TO THIS JOINT.
EVEN THE SLAB PARTICIPATED TO HANDLE THE TENSION BUT UNABLE TO CONTROAL THE DAMAGE.
THE JOINT CAN BE STRENGTENED.
ANS:2
A)
OBSERVATION:
CONCRETE DAMAGED AT TOP OF THE COLUMN
CONCRETE DAMAGED AT ALL AROUND THE COLUMN FACE
HERE BEAMS ARE SAFE.
THE LOACATION OF THE COLUMN LOOKS LIKE IT IS PRESENT OUTSIDE THE BUILDING.
NO WALLS ARE BUILT ALONG THE COLUMN MENAS IT'S PROBABLY AT THE GROUND FLOOR WHICH IS USED FOR PARKING.
RESULT:
IT A SOFTSTORY FAILURE AND IT'S A PLASTIC HINGE FORMATION.
DUE TO ABSENCE OF INFILL WALLS AT THE GROUND FLOOR THE PLASTIC HINGE FORM AT THE TOP OF GROUND FLOOR STORY COLUMN DURING LATERAL MOVEMENT
BASED ON THE DEVELOPMENT OF CRUSH OF CONCRETE IT CAN EITHER REPAIRABLE ON NON REPAIRABLE.
B)
OBSERVATION:
CONCRETE DEVELOPPED COMPLETE BREAKAGE DIAGONALLY.
LONGITUDINAL REINFORCEMENT ARE INTACT
SHEAR REINFORCEMENT LOOKS WIDER.
RESULT:
IT IS PURE SHEAR FAILURE.
INADEQUATE SHEAR REINFORCEMENT COMPELS CONCRETE TAKES ALL THE SHEAR STRESSES.
C)
OBSERVATION:
COLUMN FAILED COMPLETELY
FAILURE AT TOP OF COLUMN PROBABLY ONE AT MID HEIGHT OF THE COLUMN.
WOODEN PILE MIGHT BE OST FAILURE SUPPORTED AFTER COLUMN FAILED PROVIDING TEMPORARY PROP TO AVOID COLLAPSE OF THE ENTIRE STRUCTURE.
RESULT:
IT'S A SHORT COLUMN FAILURE.
AN ADDITIONAL SLAB OR BEAM ARE CONNECTED TO THE COLUN IN MID HEIGHT LEADS TO THIS EFFECT.
THIS LEADS TO FAILURE ESPECIALLY IF THE CONNECTION IS UNINTENTIONAL AND NOT ACCOUNTED IN DESIGN.
THE FAILURE GIVEN IN PICTURE IS NOT AT ALL REPAIRABLE.