Design of floors for vibration quiz

Please answer the following 10 multiple choice questions, then click 'submit' to check the result. The pass mark for a CPD certificate is 8 out of 10, and you may retake the quiz as many times as you wish, but the questions will vary! Please note that one, two, three or all of the possible answers presented for each question may be right, and to gain a mark for that question all correct answers must be identified.

Good luck

Design of floors for vibration

Human perception to vibration depends on the direction of incidence of the acceleration relative to the human body. In the basicentric coordinate system, the z-axis corresponds to the direction of the human spine. In which of the situations below is the human body more sensitive to vibration?

Walking (z-axis perpendicular to the floor)
Lying down (z-axis parallel to the floor)
Sitting
Standing

The response factor of a floor is:

The peak acceleration of the floor
The peak acceleration of the floor divided by the base value
The root mean square (rms) acceleration of the floor
The rms acceleration of the floor divided by the base value (0.005 for z-axis vibrations)

What is a reasonable frequency range caused by walking?

2 Hz to 3 Hz
1 Hz to 2 Hz
2.8 Hz to 3.2 Hz
1.8 Hz to 2.2 Hz

Which of the following statements is incorrect? Human perception to vibration:

Depends on the frequency of the vibration
Depends on the direction of vibration relative to the spine
Is higher for intermittent vibrations
Is higher with vibrations having a frequency between of 4 and 8 Hz

The frequency of an element or system is inversely proportional to the square root of the deflection. On what loading is the deflection based in the UK?

Dead load + 30% of the imposed load
Dead load + 10% of the imposed load
Dead load only
Dead load + imposed load

When assessing vibrations in a floor, appropriate acceptance criteria can be referenced from where (more than one may apply)?

BS 5950: Structural use of steelwork in building
BS 6472: Guide to evaluation of human exposure to vibration in buildings
SCI publication P354 “Design of Floors for Vibration: a New Approach”
BS 6399: Loadings for buildings

Why do we calculate the natural frequency of a floor system? (tick all that apply)

To avoid resonant behaviour of the floor plate
To ensure that any dynamic effects do not induce loads greater than the static loads for which the floor plate has been designed
To ensure that the system frequency is sufficiently greater than the forcing or walking pace frequency
To obtain a qualitative prediction of the serviceability performance of the floor plate

Which of the following descriptions accurately describes primary beam mode?

The primary beams form nodal lines about which the secondary beams vibrate as simply supported members. The slab is assumed to be continuous over the secondary beams and so a fixed-ended boundary condition is used.
The primary beams vibrate about the columns as simply supported members, and the secondary beams and slab are taken to be simply supported
The primary beams vibrate about the columns as simply supported members, and the secondary beams and slab are taken to be fixed-ended
The primary beams vibrate about the columns as fixed-ended members, and the secondary beams and slab are taken to be simply supported

Where is the magnitude of damping of most importance?

Floors with low frequency
Floors with low frequency
Resonant floors
Floors subject to group activities

Which of the statements below are true with respect to the Variable Dose Value (VDV) method?

VDV’s can be used for hospital operating theatres
They relate the response factor or multiplying factor to the intermittency of vibration
VDV’s are independent of walking path length
Give the number of times that an activity can take place in a given exposure period