The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fct is given by
The approximate relations are,
fcs = 0.66 fcr
fct = 0.50 fcr
As compared to working stress method of design, limit state method takes concrete to
The material factor of safety in limit state method is less as compared to that in working stress method.
If the depth of neutral axis for a singly reinforced balanced rectangular section is represented by kd in working stress design, then the value of k for a balanced section,
The value of k is given by,
k = mc/(t + mc)
For a balanced section,
Examine the following statements:
1. Factor of safety for steel should be based on its yield stress.
2. Factor of safety for steel should be based on its ultimate stress.
3. Factor of safety for concrete should be based on its yield stress.
4. Factor of safety for concrete should be based on its ultimate stress.
The correct statements are:
A beam collapses when stress is equal to its yield strength and stress in concrete reaches its ultimate strength.
What should be the minimum grade of reinforced concrete in and around sea coast construction?
Concrete in sea water or exposed directly along the sea coast shall be at least M20 grade in the case of plain concrete and M30 in case of reinforced concrete. The use of slag or pozzolana cement is advantageous under such conditions.
On which one of the following concepts is the basic principle of structural design based?
In tall, buildings, it is important to control lateral displacements within the serviceability limit state. A structural system may be classified as follows:
(i) Buildings frame system
(ii) Moment resisting frame system
(iii) Dual frame system
(iv) Tube system
In a moment resistant frame, the relative stiffness of beam and columns is very important. A frame may be designed using weak column-strong beam proportions or strong column - weak beam proportions. A frame with weak beam-strong column is more stable and therefore highly desirable.
When is a masonry wall known as a shear wall?
A wall which carries horizontal loads in its own plane is called shear wall.
A masonry wall has height ‘h' ,length L and thickness 't'. The allowable stress based or slenderness is calculated on the basis of
The slenderness ratio of a wall or column is defined as the ratio of effective height to its effective thickness. For a wall, the effective height is replaced by the effective length if effective height happens to be less.
As the span of a bridge increases, how does the impact factor vary?
Impact factor for RC bridges, I = 4.5/6 + L
where L is the length of span in meters.
At what stress does the first flexural crack appear in RCC beams made of M25 grade concrete?
Flexural strength of concrete is given by,
= 0.7 x 5 = 3.5 MPa