Response spectrum generator according to NPR 9998:2015 (Netherlands standard)

Procedure to input a new NPR 9998 seismic spectrum

  1. Expand branch Libraries of the main tree menu.
  2. Expand sub-branch Loads.
  3. Start function Seismic spectrum to open the Seismic Spectrum Manager.
  4. Click button New.
  5. In combo box Input type select option NPR 9998 - Netherlands standard.
  6. Review and, if required, adjust the spectrum parameters.
  7. Click button Code parameter to review or modify the code-defined parameters of the spectrum.
  8. Confirm the code parameters with OK.
  9. Click OK to confirm the spectrum.
  10. Close the Seismic Spectrum Manager.

Spectrum definition and code parameters

A response spectrum can be defined according to NPR 9998:2015 clause 3.2.2.2 by selecting NPR 9998 - Netherlands standard as Input type.

Max frequency & Step

The values of the spectrum are generated between a maximum period of 4 seconds (=0.25 Hz) and the input maximum frequency, using the input Step value.

Code parameters

This button opens the dialogue defining the code-dependent parameters.

Coeff. accel. ag,ref

Reference value of the peak ground acceleration from seismic map, expressed as a multiple of g

Definition of the spectrum

Type of spectrum definition, elastic or design

q - behaviour factor

Behaviour factor (only for design spectrum)

Direction

Direction of the seismic action, horizontal or vertical

ξ [%]

Relative damping

Consequence class

CC1 - CC3 for elastic spectrum

CC1A, CC1B, CC2, CC3 for design spectrum

Subsoil type

Types of soil: A, B, C

Limit state

Near collapse (NC), Significant damage (SD), Damage limitation(DL)

kag, γm, TLS,ref, Tref, β manually?

No: kag, γm, TLS,ref, Tref, β are defined according to the selected consequence class and subsoil type

Yes: kag, γm, TLS,ref, Tref, β are defined by the user

kag

Coefficient depending on the consequence class and the subsoil type

γm

Defined from spectrum definition type, consequence class, subsoil type, and limit state or user defined

TLS,ref

Reference return time of the reference seismic load, depending on the considered limit state

Tref

Reference period

β

Reliability index

γm, TLS,ref, Tref and β are displayed only for information. They are not used in the calculation of the spectrum.

Theoretical background

Horizontal elastic spectrum acc. NPR 9998:2015 3.2.2.2.1

Vertical elastic spectrum acc. NPR 9998:2015 3.2.2.2.2

Horizontal design spectrum acc. NPR 9998:2015 3.2.2.2.3

TB, TC, SMS, SM1 are the same as for the horizontal elastic spectrum.

Vertical design spectrum acc. NPR 9998:2015 3.2.2.2.3

TB,vert, TC,vert, ag,d,vert are the same as for the vertical elastic spectrum.

Tabulated values from NPR 9998:2015 tables 2.1 and 2.2

Definition of the spectrum Consequence class Subsoil type Limit state kag γm TLS,ref [yr] Tref [yr] β
Elastic CC3 A NC 1.9 1.3 3600 50 3.1
Elastic CC3 A SD 1.7 1 2500 50 3.1
Elastic CC3 A DL 1 1 500 50 3.1
Elastic CC3 B NC 1.9 1.3 3600 50 3.1
Elastic CC3 B SD 1.5 1 1500 50 3.1
Elastic CC3 B DL 0.7 1 200 50 3.1
Elastic CC2 A NC 1.6 1.2 1800 50 2.7
Elastic CC2 A SD 1.5 1 1500 50 2.7
Elastic CC2 A DL 0.7 1 200 50 2.7
Elastic CC2 B NC 1.6 1.2 1800 50 2.7
Elastic CC2 B SD 1.3 1.3 1000 50 2.7
Elastic CC2 B DL 0.5 1 100 50 2.7
Elastic CC2 C NC 1.6 1.2 1800 50 2.7
Elastic CC2 C SD 1 1 500 50 2.7
Elastic CC2 C DL 0.4 1 50 50 2.7
Elastic CC1 A NC 1.4 1.1 1200 50 2.4
Elastic CC1 A SD 1 1 500 50 2.4
Elastic CC1 A DL 0.4 1 50 50 2.4
Elastic CC1 B NC 1.4 1.1 1200 50 2.4
Elastic CC1 B SD 0.7 1 200 50 2.4
Elastic CC1 B DL 0.3 1 30 50 2.4
Elastic CC1 C NC 1.4 1.1 350 15 3
Elastic CC1 C SD 1.4 1.1 350 15 3
Elastic CC1 C DL 1.4 1.1 350 15 3
Design CC3 A NC 1.8 1.3 3000 15 3.3
Design CC3 A SD 1.8 1.3 3000 15 3.3
Design CC3 A DL 1.8 1.3 3000 15 3.3
Design CC3 B NC 1.8 1.3 3000 15 3.3
Design CC3 B SD 1.8 1.3 3000 15 3.3
Design CC3 B DL 1.8 1.3 3000 15 3.3
Design CC2 A NC 1.5 1.2 1500 15 3.1
Design CC2 A SD 1.5 1.2 1500 15 3.1
Design CC2 A DL 1.5 1.2 1500 15 3.1
Design CC2 B NC 1.5 1.2 1500 15 3.1
Design CC2 B SD 1.5 1.2 1500 15 3.1
Design CC2 B DL 1.5 1.2 1500 15 3.1
Design CC2 C NC 1.5 1.2 1500 15 3.1
Design CC2 C SD 1.5 1.2 1500 15 3.1
Design CC2 C DL 1.5 1.2 1500 15 3.1
Design CC1B A NC 1.2 1.1 800 15 2.8
Design CC1B A SD 1.2 1.1 800 15 2.8
Design CC1B A DL 1.2 1.1 800 15 2.8
Design CC1B B NC 1.2 1.1 800 15 2.8
Design CC1B B SD 1.2 1.1 800 15 2.8
Design CC1B B DL 1.2 1.1 800 15 2.8
Design CC1A A NC 1.2 1.1 200 1 2.8
Design CC1A A SD 1.2 1.1 200 1 2.8
Design CC1A A DL 1.2 1.1 200 1 2.8