IDARC-BRIDGE is a computer program for nonlinear analysis of bridges that allows many aspects of bridge behavior to be explicitly modeled. Many of the primary developments and enhancements to this program have linked research with analytical developments.

The current version includes the following element types:

Column Elements
Beam Elements
Shear Wall Elements
Edge Column Elements
Transverse Beam Elements
Column elements were modeled considering macromodels with inelastic flexural deformations, and elastic shear and axial deformations. Beam elements are modeled using a nonlinear flexural stiffness model with linear elastic shear deformations considered. Shear wall include inelastic shear and bending deformations, with an uncoupled elastic axial component. Edge column elements were introduced considering only inelastic axial deformations. Transverse beam elements, that have an effect on the rotational deformation of the shear walls or beams to which they are connected, are modeled using elastic linear and rotational springs.

One of the significant features incorporated in the program, to implement inelastic behavior in the macromodels, is the distributed flexibility model that replaced the commonly used hinge model developed for steel frames. The hinge model is not suitable for reinforced concrete elements since the inelastic deformation is distributed along the member rather than being concentrated at critical sections (Park et al., 1987). To trace the hysteretic response of a section a three parameter model was developed. Through the combination of three basic parameters and a trilinear skeleton curve stiffness degradation, strength deterioration and pinching response can be modeled.