Elastic Response Spectrum - EN 1998-1
The EN 1998-1 standard considers the elastic response spectrum as the basic representation of the seismic load. The spectrum is defined with the help of several basic parameters ag, TB, TC, TD, S and ξ. The design acceleration ag can be acquired from the maps of seismic regions. The proportional damping ratio ξ determines the damping of seismic waves in the soil/rock layers. Its value is typically assumed to be equal to 5%. The values of the remaining four parameters are specified according to the type of subsoil (types A - F) and the type of the required spectrum (1 and 2).
The values of parameters describing the horizontal elastic response spectrum of type 1 according to EN 1998-1
Ground type: | S | TB [s] | TC [s] | TD [s] |
A | 1.00 | 0.15 | 0.40 | 2.00 |
B | 1.20 | 0.15 | 0.50 | 2.00 |
C | 1.15 | 0.20 | 0.60 | 2.00 |
D | 1.35 | 0.20 | 0.80 | 2.00 |
E | 1.40 | 0.15 | 0.50 | 2.00 |
The values of parameters describing the horizontal elastic response spectrum of type 2 according to EN 1998-1
Ground type: | S | TB [s] | TC [s] | TD [s] |
A | 1.00 | 0.05 | 0.25 | 1.20 |
B | 1.35 | 0.05 | 0.25 | 1.20 |
C | 1.50 | 0.10 | 0.25 | 1.20 |
D | 1.80 | 0.10 | 0.30 | 1.20 |
E | 1.60 | 0.05 | 0.25 | 1.20 |
The values of parameters describing the vertical elastic response spectrum to EN 1998-1
Spectrum | avg/ag | TB [s] | TC [s] | TD [s] |
Type 1 | 0.90 | 0.05 | 0.15 | 1.00 |
Type 2 | 0.45 | 0.05 | 0.15 | 1.00 |
Literature:
EN 1998-1: Design of structures for earthquake resistance - Part 1: General rules, seismic actions and rules for buildings, (2006).