
 Bispec Spectral Quantities Bispec computes a large number of spectral quantities that can be plotted and examined in the Spectral Analysis dialog. They can also be exported to text files for further analysis. In the spectral analysis window, different spectral values can be selected for plotting along the horizontal or vertical axis. This allows any two spectral quantities to be plotted against each other providing a high degree of freedom for the user to explore alternative data plotting and interpretation forms. In addition to computed spectral quantities, some of the basic input properties can also be plotted such as period, mass and stiffness. This allows for example plotting any quantity vs. period (T) or stiffness (K). In general, the available quantities are divided into 5 separate groups of related quantities: Basic Properties: Period (T), frequency (f), Stiffness (K), Damping Ratio (z ), Mass (M), Hardening Stiffness (Kh), Hardening Stiffness Ratio (Kh/K), Postyield period (Tsec), PDelta ratio (P/KL), Damping Coefficient (C), Nonlinear Damping Coefficient (Csup), and nonlinear damping exponent (alpha). Effective Properties: Effective Period (Teff), Effective Frequency (feff), Effective Stiffness (Keff), Effective Linear Viscous Damping (bIeff), Effective Nonlinear Viscous Damping (bVeff), Total Effective Viscous Damping (bV+Ieff), Effective Hysteretic Damping (bHeff), and Total Effective Damping (bTot_eff). Kinematics (D, V, A): Sd, Sv, Sar, Sat, PSv, PSa, Dres, Dres/dy, Dres/Sd. Yielding related quantities: Dyp, Dyn, Gamma (Dinel/Del), Ductility, Pos Ductility, Neg Ductility, YE (Yield Events), Pos YE, Neg YE, Collapse. Forces: Sfs, Sfd, Sfa, Fyp, Fyn, Cy (Fyp/W), R (Fel/Fyp), Cs (Sfs/W), Eta (Fyp/(M*PGA)) Energy and Power: EI, EK, EE, EH, EHnr, ED, PI, PK, PE, PH, PHnr, PD, and DI_BB (damage index).
The following table lists the 61 spectral quantities and sdof properties that are available for plotting in the spectral results dialog. Each quantity is listed with its symbol, description, dimensional form and physical units. Highlighted text indicates recent changes and additions to Bispec. See the Bispec Help Manual (installed with software) for more details.
Symbol  Description  Physical Units  Unit  Basic Properties  T  Period  T  s  f  Frequency  F  Hz  K  Stiffness  F/L  Kip/in  Damping %  Damping    %  M  Mass  M  Kip*s2/in  Kh  Hardening Stiffness  F/L  Kip/in  Kh/K  Hardening Stiffness Ratio      Tsec  Postyield period, corresponding to Kh  T  s  PDelta ratio  PDelta Ratio = P/KL, (where L is the effective height)      C  Damping Coefficient for Linear Viscous Damping (LVD)  F.t/L  Kip.s/in  Csup  Damping Coefficient for Nonlinear Viscous Damping (NLVD)  F.(t/L)α  Kip.(s/in)α  Alpha (α)  Exponent coefficient for Nonlinear Viscoud Damping (NLVD)      Effective Properties  Teff  Effective Period  T  s  feff  Effective Frequency  F  Hz  Keff  Effective Stiffness  F/L  Kip/in  βIeff %  Effective Inherent (Linear) Viscous Damping (LVD)    %  βVeff %  Effective Supplemental (Nonlinear) Viscous Damping (LVD)    %  βV+Ieff %  Total Effective Viscous Damping (LVD+NLVD)    %  βHeff %  Effective Hysteretic Damping    %  βTot_eff %  Total Effective Damping (Hysteretic + Viscous)    %  Kinematics (D, V, A)  Sd  Spectral Displacement  L  in  Sv  Spectral Velocity  L/t  in/s  Sar  Spectral Acceleration (Relative)  L/t2  in/s2  Sat  Spectral Acceleration (Absolute)  L/t2  in/s2  PSv  PseudoSpectral Velocity = Sd*(2π/T)  L/t  in/s  PSa  PseudoSpectral Acceleration = Sd*(2π/T)2  L/t2  in/s2  Dres  Residual Displacement at end of record (Absolute)  L  in  Dres/Dyp  Residual ductility      Dres/Sd  Dres/Sd ratio      Yielding  Dyp  Positive yield displacement  L  in  Dyn  Negative yield displacement (Signed)  L  in  Gamma (γ)  Dinel/Del: Ratio of inelastic Sd to elastic Sd      Ductility  Peak Ratio inelastic displacement to yield displacement, computed as the larger of "Pos Ductility" and "Neg Ductility"      Pos Ductility  Positive Ductility (Dmax/Dyp)      Neg Ductility  Negative Ductility (Dmin/Dyn)      YE  Number of yielding events      Pos YE  Number of positive yield events      Neg YE  Number of negative yield events      Collapse  Collapse indicator (1: Collapse, 0: No Collapse)      Forces  Sfs  Hysteretic Force = max(fs)  F  Kip  Sfd  Damping Force = max(fd)  F  Kip  Sfa  Inertia Force = M*Sat, also equal to max(fs+fd)  F  Kip  Fyp  Positive yield force  F  Kip  Fyn  Negative yield force, (Signed)  F  Kip  Cy (Fyp/W)  Normalized Yield Capacity      R  Fel/Fyp: Ratio of elastic Sfs to Fyp      Cs (Sfs/W)  Normalized Peak Force      Eta (η)  Normalized yield strength = Fyp/(M*PGA)      Energy & Power  EI  Input Energy  F.L  Kip.in  EK  Kinetic Energy  F.L  Kip.in  EE  Elastic Energy  F.L  Kip.in  EH  Hysteretic Energy  F.L  Kip.in  EHnr  Hysteretic NonRecoverable Energy  F.L  Kip.in  ED  Damping Energy  F.L  Kip.in  PI  Input Power  F.L/t  Kip.in/s  PK  Kinetic Power  F.L/t  Kip.in/s  PE  Elastic Power  F.L/t  Kip.in/s  PH  Hysteretic Power  F.L/t  Kip.in/s  PHnr  Hysteretic NonRecoverable Power  F.L/t  Kip.in/s  PD  Damping Power  F.L/t  Kip.in/s  DI_BB  Damage index (Bozorgnia and Bertero)     
 
