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As a general 3D structural analysis software, SCIA Engineer is able to provide a detailed analysis of most civil engineering structures. However, the particular field of seismic design of buildings requires specific tools in order to improve the efficiency of that process. The tools presented in this document are primarily intended for an effective modelization and analysis buildings under seismic action.
The overall seismic behaviour of a building can very often be analyzed accurately by considering each floor as a mass linked to neighbouring floors by walls and columns. Therefore the concept of storeys is widely used in this context. Several aspects of data input, as well as analysis model, result output and design functionality will be directly linked to the storeys of a building.
The IRS (Improved Reduced System) analysis will be used for the computation of eigenmodes of the structure. That technique allows reducing drastically the number of degrees of freedom of a large finite element mesh. The computation time is reduced accordingly. Moreover, most of the local vibration modes, which are irrelevant for the overall seismic response of the structure, will not appear in the results – unlike in standard FE analysis.
SCIA Engineer also supports seismic analysis of buildings using the simplified method of Equivalent Lateral Forces (ELF). Although it is a purely static analysis of the structure, some input of data related to dynamic analysis is required, such as masses and combinations of mass groups, which is used when generating the ELF loading of the structure.
Storey results give a synthetic view of results in each storey. Displacements, accelerations, internal forces and resultant forces may be displayed per storey, either as bulk values for each storey, or as detailed results for each wall and column. That feature may also be used for fast and comprehensive load descending output.
Most seismic design standards require that torsional effects due to accidental mass eccentricity are taken into account. Based on storey data, the effects of accidental eccentricity may be included in the model according to various methods.
This chapter gives specific information about the seismic analysis of buildings. Read also the chapter dedicated to general seismic analysis in SCIA Engineer.
Important information and help about troubleshooting of dynamic and seismic analysis is provided in Dynamic analysis troubleshooting.