Bispec 2.20

Bispec is a nonlinear spectral analysis program that is capable of performing unidirectional and bidirectional dynamic time-history analysis of a dynamic oscillator pendulum system under an earthquake ground motion acceleration record. It can perform a single dynamic analysis of one system, or a series of dynamic analyses resulting in an “Spectrum”, or a series of such spectra for multiple ground motion records.

Bispec offers great flexibility for modifying and varying the dynamic properties of the dynamic system (mass, stiffness, damping etc.), and the liner and nonlinear properties of the nonlinear element (yield strength, etc.). The program currently supports 10 different hysteretic element models: a linear model, 8 nonlinear hysteretic models, and a plasticity-based bilinear model with bidirectional interaction.

These various provided models can be used to represent the structural response of a large variety of structures (building, bridges, tower, tanks, etc.), as well as the seismic response of many different seismic systems (steel moment frame and braced systems, reinforced concrete moment frames and shear walls, precast, prestressed and post-tensioned concrete systems, base isolation devices, energy dissipation devices, etc.).

Bispec can compute linear spectra for specified ranges of frequencies and damping ratios. It can also compute nonlinear “Constant Strength”, “Constant Ductility” and “Constant Damage” spectra. The user specifies the range of required frequencies as well as the applicable range of strength, ductility or damage index, and the program can compute the spectra for one or multiple ground motion records.

Several ground motion formats can be easily imported and analyzed. Currently supported formats are the SAC, PEER, NGA, USC, SMC (USGS), and CSMIP (CDMG) ground motion formats. The program also supports a User-Defined option that can be used to fit a wide variety of other simple formats.

Bispec can be used as an educational tool to teach students about dynamic behavior, as well as an engineering tool that allows engineers to compute response spectra of design ground motions and investigate the sensitivity of structural response to various structural properties such as strength, stiffness, and shape of the hysteretic force-displacement curve.

It is also a very effective research tool that can be used to perform parametric analyses of large numbers of ground motion records. With 10 different hysteretic models, and about 61 different spectral quantities that can be reported ranging from spectral displacement and acceleration, to system forces and ductilities, and including various energy and power spectral values, it provides unlimited options for research and investigation of the dynamic response under ground motion records.