The lateral force method of analysis

Introduction the lateral force method versus modal response spectrum analysis In the lateral force method a linear static analysis of the structure is performed under a set of lateral forces applied separately in two orthogonal horizontal directions, X and Y. The intent is to simulate through these forces the peak inertia loads induced by the horizontal component of the seismic action in the two directions, X or Y. Owing to the familiarity and experience of structural engineers with...

Modal response spectrum analysis

Modal analysis and its results Clause 4.3.3.3 Unlike linear static analysis, designers may not be so familiar with linear dynamic analysis of the modal response spectrum type. Moreover, some commercial computer programs with modal response spectrum analysis capability may not perform such an analysis in accordance with the relevant requirements of Eurocode 8. For instance, along the line of other seismic design codes e.g. some US codes , a program may use the modal response spectrum...

Nonlinear methods of analysis

Introduction field of application The primary use of non-linear methods of analysis within the framework of Eurocode 8 is to evaluate the seismic performance of new designs, or to assess existing or retrofitted buildings. In fact, in EN 1998-3 on the assessment and retrofitting of buildings the reference analysis methods are the non-linear ones. In the context of EN 1998-1, non-linear methods are limited to the detailed evaluation of the seismic performance of a new building design...

Definition and role of primary and secondary seismic elements

Clauses 4.2.2 1 , EN 1998-1 recognizes that a certain number of structural elements which are not essential 4.2.2 3 parts of the seismic-resisting structural system of the building may be considered as'secondary seismic', as far as their role and contribution to earthquake resistance of the building is concerned. The main objective of this distinction is to allow for some simplification of the seismic design by not considering such elements in the structural model used for the seismic analysis...

Behaviour factor q of concrete buildings designed for energy dissipation

In building structures designed for energy dissipation and ductility, the value of the behaviour Clause 5.2.2.2 factor q, by which the elastic spectrum used in linear analysis is reduced, depends on the type of lateral-force-resisting system and on the ductility class selected for the design. As we will see in Section 5.6.3.2 the value of the q factor is linked, directly or indirectly, to the local ductility demands in members and hence to the corresponding detailing requirements. As in DCL...

Compliance criteria for the nolocalcollapse requirement

Norway Seismic Spectrum

The no-(local-)collapse performance level is considered as the ultimate limit state against Clauses 2.2.1(1), which the structure should be designed according to the EN 1990 on the basis of structural 2.2.2(I), design.3 Unlike the damage limitation limit state, which is verified on the basis of deformation- 2.2.2(2) based criteria, design for the no-(local-)collapse ultimate limit state is force-based. This is against the physical reality showing that it is the deformation that causes a...

Large lightly reinforced walls

Walls with a large horizontal dimension compared with their height cannot be designed effectively for energy dissipation through plastic hinging at the base, as they cannot be easily fixed there against rotation relative to the rest of the structural system. Design of such a wall for plastic hinging at the base is even more difficult if the wall is monolithically connected with one or more transverse walls also large enough not to be considered merely as flange s or rib s of the first wall....