Design of Steel Structures Questions and Answers - Characteristic Loads

1. Which IS code is used for calculating different loads on different structures?
a) IS 800
b) IS 200
c) IS 300
d) IS 875

  Discussion

Answer: d
Explanation: IS 875 (all 5 parts) is recommended by Bureau of Indian Standards for calculating various types of loads on the structure. Part 1 is for dead loads, part 2 for imposed loads, part 3 for wind load, part 4 for snow loads and part 5 for special loads and combinations.

2. Which of the following load is to be considered on liquid retaining structure?
a) hydrostatic load
b) wave and current load
c) earth pressure
d) dynamic load

  Discussion

Answer: a
Explanation: Hydrostatic load is considered on liquid retaining structures or hydraulic structures. Wave and current load is considered in marine and offshore structure. Earth pressure is considered in basements, retaining walls, column footings, etc. Dynamic load is due to earthquake and wind.

3. The probability that a specific load will be exceeded during life of structure depends on _______
a) wind
b) factor of safety
c) partial factor of safety
d) period of exposure

  Discussion

Answer: d
Explanation: The probability that a specific load will be exceeded during life of structure depends on period of exposure. It also depends on magnitude of design load.

4. What is characteristic load?
a) seismic load
b) load which will be exceeded by certain probability during life of structure
c) load which will not be exceeded by certain probability during life of structure
d) pressure load

  Discussion

Answer: c
Explanation: Characteristic load is the load which will not be exceeded by certain assumed or pre-assumed probability during life of structure. These loads are anticipated loads due to self weight, imposed load, snow, wind load, etc.

5. Which of the following is not included in imposed load classification?
a) Residential load
b) Earthquake load
c) Industrial load
d) Educational load

  Discussion

Answer: b
Explanation: Imposed loads are gravity loads other than dead load and cover factors such as occupancy by people, stored material etc. It is classified into following groups : (i)residential, (ii)educational, (iii)institutional, (iv)assembly halls, (v)office and business buildings, (vi)mercantile buildings, (vii)industrial, (viii)storage buildings.

6. What is the minimum imposed load on roof trusses as per IS code?
a) 0.5 kN/m2
b) 0.4 kN/m2
c) 0.9 kN/m2
d) 0.75 kN/m2

  Discussion

Answer: b
Explanation: As per IS 875, the minimum imposed load on roof truss should be 0.4 kN/m2. For sloping roof upto 10˚, the imposed load is taken as 0.5 kN/m2 if access is not provided and 0.75 kN/m2 if access is provided.

7. For roofs of slope greater than 10˚, the imposed load is reduced by ____ for every degree rise in slope.
a) 0.02 kN/m2
b) 0.05 kN/m2
c) 0.75 kN/m2
d) 0.5 kN/m2

  Discussion

Answer: a
Explanation: As per IS 875, for roofs of slope greater than 10o, the imposed load is taken as 0.75 kN/m2 and reduced by 0.02 kN/m2 for every degree rise in slope.

8. Calculate imposed load on roof truss of span 20m with slope of 20o.
a) 0.75 kN/m2
b) 0.95 kN/m2
c) 0.45 kN/m2
d) 0.55 kN/m2

  Discussion

Answer: d
Explanation: As per IS 875, for roofs of slope greater than 10o, the imposed load is reduced by 0.02 kN/m2 for every degree rise in slope.
Therefore, Imposed load = 0.75 – 0.02*(20o-10o) = 0.55 kN/m2.

9. Which IS Code is used for designing a structure considering earthquake loads?
a) IS 800
b) IS 875
c) IS 1893
d) IS 456

  Discussion

Answer: c
Explanation: IS 1893(Part 1) is used for designing a structure considering earthquake loads. For all other loads like dead load, wind load, IS 875 is used for design.

10. What is the load factor considered for steel structures when combination of dead load and earthquake load is considered?
a) 1.5
b) 1.3
c) 1.2
d) 1.7

  Discussion

Answer: d
Explanation: In plastic design of steel structures, load factor is 1.7 when combination of dead load and earthquake load is considered i.e. 1.7(DL + EL) or 1.7(DL – EL).