As per IS 456, Basic values of span to effective depth ratios for spans up to 10m for continuous beams is
26
IS 456 Span to Effective Depth Ratio Basics
Understanding the span to effective depth ratio is crucial in the design of reinforced concrete beams. This ratio helps limit the deflection of the beam, ensuring it meets the serviceability requirements as specified by the Indian Standard code, IS 456:2000.
IS 456 Code Provisions
Clause 23.2.1 of IS 456:2000 deals with the limit state of serviceability: deflection. It provides basic values for the span to effective depth ratios for different types of beams and slabs to control deflection. These basic values are applicable for members not exceeding 10 meters in span. For spans longer than 10 meters, these values need to be modified using specific factors.
Ratio for Continuous Beams
According to Table 5 of IS 456:2000, the basic span to effective depth ratio ($L_a/d$) for continuous beams is specified.
- For simply supported beams, the basic ratio is 20.
- For cantilevers, the basic ratio is 7.
- For continuous beams, the basic ratio is 26.
The question specifically asks for the value for continuous beams for spans up to 10m. Therefore, the correct basic value according to IS 456 is 26.
Answer Explanation
Comparing the options with the IS 456 code provisions:
- Option 1 (7): This is the basic value for cantilevers.
- Option 2 (20): This is the basic value for simply supported beams.
- Option 3 (26): This is the basic value for continuous beams as per IS 456 for spans up to 10m.
- Option 4 (None of the above): Incorrect, as 26 is a valid basic value.
Thus, the correct basic value for the span to effective depth ratio for continuous beams as per IS 456 for spans up to 10m is 26.
Important Questions from Miscellaneous
A stone is thrown horizontally from the top of a 20 m high building with a speed of 12 m/s. It hits the ground at a distance R from the building. Taking g = 10 m/s2 and neglecting air resistance will give :
A sphere of volume V is made of a material with lower density than water. While on Earth, it floats on water with its volume f1V (f1 < 1) submerged. On the other hand, on a spaceship accelerating with acceleration a < g (g is the acceleration due to gravity on Earth) in outer space, its submerged volume in water is f2V. Then:
A railway wagon (open at the top) of mass M1 is moving with speed v1 along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes M2 and speed becomes v2. Taking the rain to be falling vertically and the water stationery inside the wagon, the relation between the two speeds v1 and v2 is :
Consider the following statements:
1. Distance between the longitudes becomes zero on North Pole and South Pole.
2. Distance between the longitudes is maximum on the Equator.
3. Number of longitudes is more than number of latitudes.
Which of the statements given above is/are correct?
One block of 2⋅0 kg mass is placed on top of another block of 3⋅0 kg mass. The coefficient of static friction between the two blocks is 0⋅2. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as 10 m/s2, the maximum value of the frictional force is :
