limt state method concept- in limt state concept, the
structure are designe to with stand safety of all loads
liable to act on it through out its life.so the acceptable
limit for safteym and serviceability recquirements before
fauilure occutrs is called limit state.
in working stress method the structure are desigined by
considering stress acting on the structure. the stress are
tensile stress,wind, earthquick etc.

working stress method did not consider the factor of safety
and involved very high use of steel,thus making the
structure otherwise safe.
however, limit state design considers the factor of safety
and provides 4 limit states for safe design

limt state method concept- in limt state concept, the
structure are designe to with stand safety of all loads
liable to act on it through out its life.so the acceptable
limit for safteym and serviceability recquirements before
fauilure occutrs is called limit state.
in working stress method the structure are desigined by
considering stress acting on the structure. the stress are
tensile stress,wind, earthquick etc.

in limit stress desing strss are calculated bye consdering
factor loads,
working desing metho actual load are consider. and most inn
practices in fields.

In WSM the factor of safety of concrete is assumed to be 3 and factor of safety of steel is 1.8,so that it requires more percentage of steel and also in WSM the concrete and steel have a linear variation in elastic property.It is one of the main reason for failure of this method.
In LSM the factor of safety of concrete is assumed to be 1.5 and factor of safety of steel is 1.15.so that the percentage of steel rods used is very less when compared to the WSM.

wsm is uneconomical as true behavior of material is not
taken into consideration.it consider upto only elastic
limit,so 100% strength of material is not achieved.

in lsm behaviour of material upto failure is taken into
account hence whole strength is utilised.

• In working stress,Stresses in an element is
obtained from the working loads and compared with
permissible stresses.The method follows linear stress-
strain behavior of both the materials.Material capabilities
are under estimated to large extent.moreover Ultimate load
carrying capacity cannot be predicted accurately.
• Whereas in limit state method, stresses are
obtained from design loads and compared with design
strength.In this method, it follows linear strain
relationship but not linear stress relationship (one of the
major difference between the two methods of design).The
ultimate stresses of materials itself are used as allowable
stresses.The material capabilities are not under estimated
as much as they are in working stress method. Partial
safety factors are used in limit state method.

Structures Which can release Load's are designed by WSM,Eg DAMS, CANALS: But Structures In which V cannot release load But only can transfer it,r designed by LSM.

in working stress method the design is done by using factor
of safety but in the limit state design factor of safety is
not considered. most of the present designs are based on
limit state method for attaining more life of structure

why loss of strength in concrete in 7 days cube test i am
not geting mim 7 days strength that is 67 percent for M-35
and my mix design is perfect there is no doughty,and my
results are near to 7days percentage but not 67 percent.