Earthquake Engineering Questions and Answers – Design Spectra

This set of Earthquake Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Design Spectra”.

1. Who proposed the graph of design spectra?
a) Esteva
b) Reid
c) Wegener
d) Seed

Explanation: Graph of design spectra was recommended by Seed for 5% damping at 84.1 percentile. Esteva derived the attenuation relationships for peak ground motions. Reid proposed the elastic rebound theory. The theory of plate tectonics was developed by Wegener.

2. Where does the transition from amplified ground acceleration to ground acceleration for 5% critical damping ratio ends?
a) 40
b) 30
c) 17
d) 9

Explanation: According to Newmark, the transition from amplified ground acceleration to ground acceleration starts at frequency of 6 Hz for all values of damping and ends at 17 Hz for 5% damping. The transition ends at 40 Hz for 0.5% damping, 30 Hz for 2% damping and 9 Hz for 10% damping.

3. For 84.1 percentile the larger horizontal component is approximately 2/3 of the vertical component.
a) True
b) False

Explanation: According to Mohraz the ratio of vertical component and larger horizontal component (RV) is 0.65. Therefore, the vertical component is nearly 2/3 of the larger horizontal component for 84.1 percentile. For mean value or 50 percentiles, the vertical component is approximately half of the larger horizontal component as RV is 0.48.

4. To plot the design spectrum, how many seismic records were analyzed by Seed?
a) 30
b) 31
c) 104
d) 150

Explanation: Seed analyzed total 104 seismic records to plot the design response spectra. Out of the 104 records, 15 records were of soft to medium clay and sand, 30 records of deep cohesionless soils, 31 records of stiff soil conditions and 28 records of rock. Based on these record he finally gave an average and smooth curve for AEC Regulatory Guide.

5. Which of the following is a smooth response spectrum that specifies the level of seismic resistance required for design?
a) The time history curve
b) The design spectrum
c) The analysis spectrum
d) The attenuation curve

Explanation: The design response spectrum is a smooth response spectrum that stipulates the level of seismic resistance required for design of any structure. The design spectrum can be considered as the specification of the required strength of a structure. Strength is dependent on the frequency.

6. What is the displacement corresponding to 1g ZPA for alluvial soil?
a) 91 cm
b) 30 cm
c) 40 cm
d) 75 cm

Explanation: According to the design response spectrum given by Newmark, the value of displacement corresponding to 1g ZPA for alluvial soil is 91 cm. The peak ground velocity for 1g ZPA for alluvial soil is 122 cm/s. For a rock, the peak ground velocity is 58 cm/s and the displacement is 30 cm.

7. The effects due to vertical earthquake shaking shall not be considered for which of the following condition?
a) Structure has vertical or plan irregularities
b) Structure located in seismic zone II
c) Structure is rested on soft soil
d) Bridges

Explanation: The effects due to vertical earthquake shaking shall not be considered for structures located in zone II. These effects are considered for structures located in zone IV or V. Other conditions when these effects are considered are bridges, structure rested on soft soil, structure having plan and vertical irregularities, structure having large horizontal overhangs of structural members, etc.

8. Which of the following is not a desirable attribute of an earthquake resistant building?
a) Good structural configuration
b) Adequate lateral stiffness
c) Lateral strength
d) Brittleness

Explanation: Brittleness of the structure is not a desirable attribute of an earthquake resistant building. A building should have adequate ductility so that it can undergo large deformations under severe earthquake shaking even after yielding. A brittle structure will not undergo large deformations but collapse completely without giving any warnings.

9. What is the value of the ratio of vertical component and larger horizontal component (RV) for 84.1 percentile?
a) 0.65
b) 0.98
c) 0.48
d) 0.83

Explanation: For 84.1 percentile, the value of the ratio of vertical component and larger horizontal component (RV) is 0.65 and the ratio of smaller and larger horizontal component (RS) is 0.98. For 50 percentile, the value of RV is 0.48 and RS is 0.83. These ratios were derived by Mohraz.

10. The transition from amplified ground acceleration to ground acceleration starts and ends at the same value for all critical damping ratio.
a) False
b) True

Explanation: Newmark proposed that the transition from amplified ground acceleration to ground acceleration starts at a constant value of 6 Hz for all critical damping ratios but it does not end at the same value. The transition ends at 40, 30, 17 and 9 Hz for critical damping ratios of 0.5%, 2%, 5% and 10% respectively.

Sanfoundry Global Education & Learning Series – Earthquake Engineering.

To practice all areas of Earthquake Engineering, here is complete set of Multiple Choice Questions and Answers.

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