Sensitive use analysis DG11

Tekla Structural Designer
2021
Tekla Structural Designer

Sensitive use analysis DG11

The vibration check calculations can be performed for sensitive equipment & occupancy if required.

These calculations make use of Chapter 6 of DG11 2nd Edition (2016) with revisions and errata of 27 July 2018. They only cover ⅓ octave spectral velocity and acceleration.

For these calculations the mode shape factors ɸE and ɸW are taken as 1.0. i.e. it is conservatively assumed that the walker and sensitive equipment or sensitive occupant are both at mid-bay.

Use Case - Sensitive Equipment

If walking speed = Very Slow ,

fstep
 = 
1.25 Hz
  
[Table 6-1]
V1/3
 = 
(250 * 106) / (β * W) * (fstep2.43 / fn1.8) * (1 - e-2*π*β*fn / fstep)
  
[Eqn 6-3a]
A1/3/g
 = 
(100 * 4.2) / (β * W) * (fstep2.43 / fn0.8) * (1 - e-2*π*β*fn / fstep)
  
[Eqn 6-8a]

Else if walking speed = Slow , or Moderate or Fast

fstep , fL , fU and γ as appropriate to selected walking speed
  
[Table 6-1]

If fn ≤ fL

V1/3
 = 
(175 * 106) / (β * W * fn0.5) * (e-γ*fn)
  
[Eqn 6-3b]1
A1/3/g
 = 
(100 * 6.4) / (β * W) * (e-γ*fn)
  
[Eqn 6-8b]1

If fn ≥ fU

V1/3
 = 
(250 * 106) / (β * W) * (fstep2.43 / fn1.8) * (1 - e-2*π*β*fn / fstep)
  
[Eqn 6-3b]2
A1/3/g
 = 
(100 * 4.2) / (β * W) * (fstep2.43 / fn0.8) * (1 - e-2*π*β*fn / fstep)
  
[Eqn 6-8b]2

Else if fL < fn < fU

For V1/3

  1. evaluate [Eqn 6-3b]1 with fn = fL , then
  2. evaluate [Eqn 6-3b]2 with fn = fU , then
  3. linear interpolate for actual fn

For A1/3/ g

  1. evaluate [Eqn 6-8b]1 with fn = fL , then
  2. evaluate [Eqn 6-8b]2 with fn = fU , then
  3. linear interpolate for actual fn

Use Case - Sensitive Occupancy

Note: DG11 2nd Edn does not provide explicit ⅓ octave spectral Acceleration equations for Sensitive Occupancy, so in Tekla Structural Designer these equations have been derived from the ⅓ octave spectral Acceleration equations for Sensitive Equipment by ‘modifying’ them by factors 200/250 (for very slow walking) and 120/175 (for other walking speeds).

These modification factors are derived from consideration of the differences between ⅓ octave spectral Velocity equations for Sensitive Equipment and Sensitive Occupancy, which are given explicitly in DG11 2nd Edn.

If walking speed = Very Slow ,

fstep
 = 
1.25 Hz
  
[Table 6-1]
V1/3
 = 
(200 * 106) / (β * W) * (fstep2.43 / fn1.8) * (1 - e-2*π*β*fn / fstep) [Eqn 6-9a]
A1/3/g
 = 
(200/250)*(100 * 4.2) / (β * W) * (fstep2.43 / fn0.8) * (1 - e-2*π*β*fn / fstep) [Eqn 6-8a] modified

Else if walking speed = Slow , or Moderate or Fast

fstep , fL , fU and γ as appropriate to selected walking speed
  
[Table 6-1]

If fn ≤ fL

V1/3
 = 
(120 * 106) / (β * W * fn0.5) * (e-γ*fn)
  
[Eqn 6-9b]1
A1/3/g
 = 
(120/175)*(100 * 6.4) / (β * W) * (e-γ*fn) [Eqn 6-8b]1 modified

If fn ≥ fU

V1/3
 = 
(200 * 106) / (β * W) * (fstep2.43 / fn1.8) * (1 - e-2*π*β*fn / fstep)
  
[Eqn 6-9b]2
A1/3/g
 = 
(200/250)*(100 * 4.2) / (β * W) * (fstep2.43 / fn0.8) * (1 - e-2*π*β*fn / fstep) [Eqn 6-8b]2 modified

Else if fL < fn < fU

For V1/3

  1. evaluate [Eqn 6-9b]1 with fn = fL, then
  2. evaluate [Eqn 6-9b]2 with fn = fU , then
  3. linear interpolate for actual fn

For A1/3/ g

  1. evaluate [Eqn 6-8b]1 modified with fn = fL , then
  2. evaluate [Eqn 6-8b]2 modified with n = fU , then
  3. linear interpolate for actual fn
Czy to było pomocne?
Wstecz
Dalej