Working Stress And Limit State Method Practice Questions

Consider the following statements : 1. Modulus of elasticity of concrete increases with increase in compressive strength of concrete. 2. Brittleness of concrete increases with decrease in compressive strength of concrete. 3. Shear strength of concrete increase with increase in compressive strength of concrete. The TRUE statements are

If the characteristic strength of concrete $f_{ck}$ is defined as the strength below which not more than 50% of the test results are expected to fall, the expression for $f_{ck}$ in terms of mean strength $f_{m}$ and standard deviation S would be

Assuming concrete below the neutral axis to be cracked, the shear stress across the depth of a singly-reinforced rectangular beam section

Consider the following statements : I. The width-to-thickness ratio limitations on the plate elements under compression in steel members are imposed by IS:800-1984 in order to avoid fabrication difficulties. II. In a doubly reinforced concrete beam, the strain in compressive reinforcement is higher than the strain in the adjoining concrete. III. If a cantilever I-section supports slab construction all along its length with sufficient friction between them, the permissible bending stress in compression will be the same as that in tension. The TRUE statements are

As per IS:456-2000, consider the following statements I. The modular ratio considered in the working stress method depends on the type of steel used. II. There is an upper limit on the nominal shear stress in beams (even with shear reinforcement) due to the possibility of crushing of concrete in diagonal compression. II. A rectangular slab whose length is equal to its width may not be a two-way slab for some support conditions. The TRUE statements are

In a random sampling procedure for cube strength of concrete, one sample consists of X number of specimens. These specimens are tested at 28 days and average strength of these X specimen is considered as test result of the sample, provided the individual variation in the strength of specimens is not more than $\pm$ Y percent of the average strength. The values of X and Y as per IS:456-2000 are

The partial factor of safety for concrete as per IS:456-2000 is

The flexural strength of M30 concrete as per IS:456-2000 is

Assume straight line instead of parabola for stress-strain curve of concrete as follows and partial factor of safety as 1.0. A rectangular under-reinforced concrete section of 300mm width and 500mm effective depth is reinforced with 3 bars of grade Fe 415, each of 16mm diameter. Concrete mix is M20. The depth of the neutral axis obtained as per IS:456-2000 differs from the depth of neutral axis obtained in above question by

For avoiding the limit state of collapse, the safety of RC structures is checked for appropriate combinations of Dead Load (DL), Imposed Load or Live Load (IL), Wind Load (WL) and Earthquake Load (EL). Which of the following load combinations is NOT considered ?

In the limit state design method of concrete structures, the recommended partial material safety factor ( $\gamma _m$ ) for steel according to IS:456-2000 is

The working stress method of design specifies the value of modular ratio, m=280/( 3 $\sigma _{cbc}$ ), where $\sigma _{cbc}$ is the allowable stress in bending compression in concrete. To what extent does the above value of 'm' make any allowance for the creep of concrete ?

Maximum strains in an extreme fibre in concrete and in the tension reinforcement (Fe-415 grade and Es= 200 $kN/mm^{2}$ ) in a balanced section at limit state of flexure are respectively

Group-I contain some properties of concrete/cement and Group-II contain list of some tests on concrete/cement. Match the property with the corresponding test.

Read the following two statements I. Maximum strain in concrete at the outermost compression fibre is taken to be 0.0035 in bending II. The maximum compressive strain in concrete in axial compression is taken as 0.002. Keeping the provisions of IS 456-2000 on limit state design in mind, which of the following is true?

As per the provisions of IS 456-2000, the (short term) modulus of elesticity of M25 grade concrete (in $N/mm^2$ ) can be assumed to be