What are the disadvantages of working stress method?

Working stress method does not give reasonable measure of strength, which is more fundamental measure of resistance than is allowable stress. Another drawback in working stress method is that safety is applied only to stress level. Loads are considered to be deterministic (without variation).

What is the significance of modular ratio in design?

Modular ratio is the ratio of Modulus of Elasticity of Steel to Modulus of Elasticity of Concrete, Modular ration significance is to finding losses in prestress. because of the influence of creep. Reinforced concrete is made up of two material,ie,concrete and steel.

Why working stress method is uneconomical?

(iii) It does not use any factor of safety with respect to loads. It means, there is no provision for the uncertainties associated with the estimation of loads. (iv) It does not account for shrinkage and creep which are time dependent and plastic in nature. (v) This method gives uneconomical sections.

What are the limitations of WSM?

Dis-advantages of WSM:

• It gives larger section of structural members, thus it is uneconomical.
• It assumes that, stress and strain relationship is constant for concrete, which is not true.
• WSM does not consider the mode of failure of the structure (brittle or ductile).

What are three limitations and shortcomings of the working stress method of designing?

Limitations of working stress method : The assumptions of linear elastic behaviour and control of stresses within specially defined permissible stresses are unrealistic due to several reasons viz., creep, shrinkage and other long term effects, stress concentration and other secondary effects.

What is modular ratio in design of RCC?

In the case of reinforced concrete structure modular ratio is the ratio of elasticity modulus of steel and concrete. The value of of stresses in concrete and steel is related using modular ratio. m is the modular ratio used to relate stress in reinforcement and concrete.

What is meant by over-reinforced section?

Reinforced concrete beam sections in which the failure strain in concrete is reached earlier than the yield strain of steel is reached, are called over-reinforced beam sections.

What is the difference between WSM and modular ratio?

The WSM doesn’t show the actual strength nor gives the true factor of safety of this structure under failure. The modular ratio design results in a larger percentage of compression steel than that given by the limit state design, thus leading to un-economic design.

What is working stress method of RCC design?

Working Stress method is the old way of designing, in present era structures are generally designed using Limit State Method. In WSM concrete is considered as elastic whereas in LSM concrete is generally assumed as plastic. As discussed above there are two different methods of RCC Design which can be distinguish as follows :

What are the two methods of structural design in RCC?

RCC Structural Elements are designed by two methods or two Design Philosophies, Working Stress Method (WSM) Limit State Method (LSM) Working Stress method is the old way of designing, in present era structures are generally designed using Limit State Method.

What are the disadvantages of WSM?

Here material strength is underestimated and loads are generally working loads with extra safety i.e. overestimated. 6. WSM satisfies serviceability criteria but highly uneconomical. Major concern is Safety and Serviceability before failure. 7. The plane section before bending remains plane after bending means stress-strain diagram linear.