Challenge

Identification of Cracks

1. What is the mode of failure or damage of the beams in the figure above? Are the damages repairable? Elaborate

FLEXURAL FAILURE OF BEAM.

This crack is formed due to flexural failure of a beam
the fluxural strength known as modulus of rupture, bending strength or fracture strength is a material property defined as the stress in the material just before it yields in a flexure test.
the flexure stress represent the highest stress experienced within the material at the moment of rupture.
It is measured in terms of stress, to overcome this type of failure main steel is provided @ the top/bottom of the beam.
The damages of repairable, To repair damaged beams , locate local welder or metal shop and request angle iron , cut and drilled to the length of the beam being repaired
Remove any pipes, wires etc., curremtly going to the beam ,
be sure to turn off water/power , etc.
mount the angle iron on the jack and the temporary post , Get the angle iron the place and slowly raise the jack until the angle iron is wedged up against the damaged beam .
Screw the angle iron into the beam and remove the temporary post / slide any pipes or wires previously removed back through the beam and turn the water and power back on.

FAILURE DUE TO ERROR IN CONSTRUCTION.

Mistakenly reduce the bar diameter
construct an incorrect column in location
changes in the grade of concrete
lack of strength in the concrete due to the failure of concrete supplier
improperly treated the honey comb in the column could lead to a failure , when loads are applied.
cavities inside the column that were not filled properly in construction ground reduce the compressive area of the column.
As a result its axial capacity will be reduced

BEAM COLUMN CONNECTION FAILURE .

Short column weak beam philosopy explain the type of failure in the column.
the weak beam strong column ensures that a plastic hinge is formed in the beam rather than column and column remains elastic as far as possible
this is achieved by making column stronger such that its strength becomes equal or greater than that of the beam.
strong beams on light column is not appropriate in earthquake prone region and thus weak beam strong column arrangement should be the choice as it postpones collapse of the structure,
In order to facialate the philosopy mild steel may be used as longitudinal reinforcement of beam and high strength steel for column .

Question 2:

COMPRESSION IN FAILURE.

When a column is subjected to high compressive load, the concrete and steel expreinces and stresses as a result the column fails without undergoing any lateral deformation.
the concrete is crushed and steel yields , hence column fails due to material failure.
It is a column failure for predestals, as pedestals have slenderness ratio value less than 3, due to which they do not undergo any lateral deformation (bending) due to concentric loads.

REMEDY / SOLUTION TO AVOID FAILURE.

To keep the generated stresses under permissible limits , the concrete column must be designed with sufficient cross- section area.

2. b.)

SHEAR FAILURE :

Shear failure occurs when the acting shear force exceeds the shear capacity of the corresponding section of the structural menber
shear force acts along a plane parallel to the direction of force and hence , producing a sliding failure on beam
shear failure is considered as brittle failure as it does not provide any warning before complete failure.

TYPES OF SHEAR FAILURE:

REMEDY / SOLUTION TO AVOID FAILURE:

Shear reinforcement must be provided as per codal provisions provided by IS 456:2000
Provide adequate shear links
high grade concrete deformed bars must be used for proper anchorage

2 c.)

SHORT COLUMN FAILURE .

Short columns are commanly subjected to axial loads, lateral loads and moments , short columns under the action of lateral load and moments undergo lateral moments and bending
under such circumstances when the stresses in steel and concrete reach their yield stress material failure happens and rcc column failures . this type of failures is also called as combined compression and bending failure.
short column effect generally occurs in the building resting on the slopping ground.
The performance of short column during an earthquake is poor , this is because a tail column and short column of some cross section move horizontally by amount , howeever a short coulmn is stiiff than tall column hence it attracts larger earthquake forces.

REMEDY -

Columns must be constructed keeping central line strength any abnormally might cause excessive lateral deflection, under infuence of lateral or axial loads
trhe column which are lightly sustain short column effect should be failed be detailed as per IS13920:1993 over a full height of column sustaining this effect.
the special confining reinforcement must extend beyond the short column into the coulmns vertically above and below some distance.

Ship work like this
in your own course.