Template > Response Spectrum IRC

Generation of the response spectrum according to IRC:6-2010

Setting

Description

Parameters

Setting	Description
Type	Type of the response spectrum in reference to the definitions in the IRC (Type I, Type II, Type III, User-defined) Selecting Type will automatically fill the default values of T_hor and Sa_par according to the definitions in the IRC. User-defined values can be given when selecting the option User-defined in Type.
T_hor (s)	Period value at end of the horizontal branch for the definition of the different resp. spectr. types
Sa_par (-)	Resp. spectr. value factor for describing the parabolic branch for the definition of the different resp. spectr. types
Damping (%)	Damping ratio in terms of percent
Factor (-)	Damping factor (dimensionless) Evaluated from Damping according to IRC definitions and informatively displayed. A user-defined factor can be given when selecting the option User-defined in Damping.

Output variable

Name of the variable that describes the response spectrum

The default name will be set up as IRC_Sa. A two-digit alpha-numeric postfix can be added to that name (e.g. in case that more than one response spectrum is generated to not overwrite the existing ones).

The variable (and the related variables, formulas and tables) is stored in Properties > Variables and can be used when defining the earthquake load (Schedule > Load Definition > Earthquake Load).

The variable describing the response spectrum will be given in terms of Sa/g (-) as a function of the period T (s).

Ground acceleration

The following input helps to evaluate the respective design ground acceleration ag that must be given when defining the vectors within the earthquake load definition:

Setting	Description
Seismic Zone	Seismic Zone as defined in IRC Table 6 for evaluating Zone factor Z. A user-defined Zone factor Z can be input when selecting the option User-defined.
Seismic class	Seismic Class as defined in IRC Table 7 for evaluating Importance Factor I. A user-defined Importance Factor I can be input when selecting the option User-defined.
Resp. reduct. factor R	Response reduction factor R as defined in IRC Table 8.
Ground acceleration ag	Ground acceleration ag considering horizontal seismic coefficient Ah evaluated from the parameters defined above: ag = Z/2 * I/R *g