12.1 Vibration of floor alone

At best this manual can only present estimates of spans where vibration is likely to become a factor for the floor only. In this case, the surrounding supports are assumed to be either walls, properly tied into the floor, or beams of sufficient stiffness to ensure that vibration is not a factor.  As this includes only a fraction of cases which are likely to present themselves, designers must carry out a vibration assessment to assure themselves that serviceability requirements are complied with.

For the case where a slab has rigid span supports,  span tables included within this manual have a vibration limit included. Spans above the red limit line are likely to perform adequately, while those below the red line must have comprehensive vibration calculations prepared to ensure compliance.

The basis of compliance occurs as follows:

(i) For floors where the natural frequency is  below 9 mHz, the peak acceleration must not exceed critical values.

(ii) For floors where the natural frequency is  above 9 mHz, (where walking excitation is the critical consideration) a minimum stiffness of the floor to a concentration load of1 kN per mm is required.

(iii) Design for rhythmic excitation is not included and where applicable, must be carried out to specific design.