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 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.

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

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

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 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.

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 approach, service loads are used in the whole design and the strength of material is not utilized in the full extent. In this method of design, stresses acting on structural members are calculated based on elastic method and they are designed not to exceed certain allowable values. In fact, the whole structure during the lifespan may only experience loading stresses far below the ultimate state and that is the reason why this method is called working stress approach. Under such scenario, the most economical design can hardly be obtained by using working stress approach which is now commonly used in the design of temporary works.
In limit state approach, for each material and load, a partial safety factor is assigned individually depending on the material properties and load properties. Therefore, each element of load and material properties is accurately assessed resulting in a more refined and accurate analysis of the structure. In this connection, the material strength can be utilized to its maximum value during its lifespan and loads can be assessed with reasonable probability of occurrence. Limit state approach is commonly used for the majority of reinforced concrete design because it ensures the utilization of material strength with the lowest construction cost input.

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paper on civil engineering in my email address
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How we can calculate the quantity of sand, & cement, & also
aggregate for a slab.
Length 25'/3.28 = 7.62 Mtr
width 20'/3.28 = 6.09 Mtr
depth 6" /3.28 = 0.152 Mtr