| Standard | Title | Reference Tools | Reference Table |
|---|---|---|---|
| EN 1998-1 | General rules, seismic actions and rules for buildings | - | - |
| EN 1998-2 | Bridges | - | - |
| EN 1998-3 | Assessment and retrofitting of buildings | - | - |
| EN 1998-4 | Silos, tanks and pipelines | - | - |
| EN 1998-5 | Foundations, retaining structures and geotechnical aspects | - | - |
| EN 1998-6 | Towers, masts and chimneys | - | - |
What this standard covers
EN 1998 (Eurocode 8 - Design of structures for earthquake resistance) covers the seismic design of buildings, bridges, towers, tanks, silos and foundations, and the assessment and retrofitting of existing structures.
EN 1998-1 gives the general rules for buildings: seismic zoning and ground types, the design response spectrum, the methods of analysis, behaviour factors, and the capacity-design and detailing rules that make a structure ductile. EN 1998-2 covers bridges, EN 1998-3 assessment and retrofitting of existing buildings, EN 1998-4 silos and tanks, EN 1998-5 foundations and geotechnical aspects, and EN 1998-6 towers and chimneys.
The governing idea is that a structure is not designed to remain elastic in a strong earthquake but to deform in a controlled, ductile way. The elastic force is reduced by a behaviour factor that reflects how much ductility the system can deliver, and capacity design rules then ensure that yielding happens in chosen locations while brittle modes stay stronger than the members framing into them.
What you will find in it
- Ground types and zoning
- Site classification and the reference ground acceleration, which together set the seismic demand at a site.
- Design spectrum
- The elastic and design response spectra, from which seismic force is derived once the structure's period is known.
- Behaviour factor
- The reduction applied to elastic force to reflect ductility, and the ductility class and structural system that justify a given value.
- Methods of analysis
- Lateral force, modal response spectrum, and nonlinear methods, and the regularity conditions that decide which is permitted.
- Regularity
- Regularity in plan and elevation, and its consequences for the analysis model and the behaviour factor.
- Capacity design
- The rules that direct yielding into intended plastic zones - strong column, weak beam - and protect brittle modes such as shear.
- Detailing for ductility
- Confinement, transverse reinforcement and connection detailing that let a member sustain cyclic deformation without losing strength.
- Existing structures
- Assessment of existing buildings against defined performance levels and the design of retrofitting measures, in EN 1998-3.
When to use this standard
Use EN 1998 wherever seismic action must be considered. It supplements rather than replaces the material Eurocodes: gravity design still follows EN 1992, EN 1993, EN 1994, EN 1995 or EN 1996, and EN 1998 adds the seismic action, the analysis requirements and the ductile detailing. The Vietnamese equivalent is TCVN 9386.
How it fits with the other standards
Seismic action from EN 1998 is combined with other actions using EN 1990, with gravity loads from EN 1991. Members are designed to the material Eurocodes with the additional seismic detailing of EN 1998; foundations and geotechnical aspects follow EN 1998-5 alongside EN 1997.
What each part covers
- EN 1998-1
- The general part for buildings: ground types and the design spectrum, methods of analysis, behaviour factors, regularity, and the capacity-design and ductile detailing rules by material.
- EN 1998-2
- Bridges. Seismic design of bridge structures, including the design of bearings and the treatment of the substructure and its foundations.
- EN 1998-3
- Assessment and retrofitting of buildings. How an existing structure is assessed against defined performance levels, and how strengthening measures are designed - a different problem from new design.
- EN 1998-4
- Silos, tanks and pipelines. Seismic design where the stored contents themselves respond to the shaking, including the sloshing of liquids.
- EN 1998-5
- Foundations, retaining structures and geotechnical aspects. Seismic bearing capacity, earth pressures during an earthquake, and the assessment of liquefaction.
- EN 1998-6
- Towers, masts and chimneys. Slender structures whose higher modes of vibration matter, unlike the fundamental-mode behaviour that dominates most buildings.