UC San Diego

The use of high-strength steel reinforcement in seismic design of bridges is currently under investigation. Several benefits will come from its use, which includes a reduction in the construction time, a reduction in congestion and cost savings, among others.

Lotfizadeh (2019) performed an experimental work at the University of California San Diego to study the use of large-diameter high-strength steel reinforcement in earthquake resisting bridge elements. Part of the study considered a quasi-static test of a full-scale bridge column extending into a Type II shaft (enlarged diameter shaft) all reinforced with high-strength ASTM A706 Grade 80 reinforcement.

Data obtained from the study was used through this research to calibrate a detailed nonlinear finite element model. For this purpose, continuum 3D elements with fracture-plastic constitutive material law were used to represent the concrete and line elements with uniaxial constitutive materials to characterize the axial stress-strain response of high-strength steel reinforcement.

Calibration of the constitutive laws with the experimental data gave a good prediction of the overall and local behavior. The analysis was able to capture the opening and closure of flexural cracks by providing a lower limit to the tensile concrete stress, with smear tension stiffening.

The numerical simulation’s state of the art can fit the overall response of analytical models with a pretest, but to our knowledge, the distribution of the spread plasticity is usually not addressed or shown. In this research, a comprehensive study of both responses is addressed. Even when the model captured the overall structural behavior, the spread plasticity did not match with the experimental data as well as it did with the overall response.