Software Calibration And Sensitivity Analysis Of Ordinary Standard Bridge Response

Reliable seismic response models and software are necessary to support the assessment and design of California highway bridges. While nonlinear time history analysis using general purpose finite element tools typically give more accurate results compared to response spectrum and nonlinear static methods, the computed response is extremely sensitive to modeling parameters and analysis details. In addition, the computed time history response can vary significantly due to the finite element formulations implemented in different software packages. To address such differences, three-dimensional models of four ordinary standard bridges (OSBs) provided by Caltrans are analyzed using CSiBridge and OpenSees. With extensive calibration, these two software packages are able to give nominally similar results for modal and nonlinear static analyses, as well as for nonlinear dynamic analyses with multiple ground motions. Discrepancies between CSiBridge and OpenSees were found to lie primarily in the nonlinear abutment models and the cyclic concrete constitutive response of the columns. Additional sensitivity analyses carried out using the direct differentiation method (DDM) on only the OpenSees models confirm that the strength and stiffness of the abutments have a significant influence on the response of each OSB. From the software calibrations and sensitivity analyses, modeling guidelines and recommendations are made based on the choice of element formulation and constitutive model, and also the variability in response due to the choice of input parameter values