Six equivalent linearization methods are summarized and calculation process of applying equivalent linearization method for displacement-based design of bridge engineering is studied. With the evaluation of volume stirrup ratio and safety performance of design structure, six different equivalent linearization methods are used in displacement-based design of bridge columns. The influence of equivalent linearization model and the damping adjust coefficient to seismic design results is studied. Study shows that there are big differences among the seismic design results based on different equivalent linearization methods. Equivalent damping ratio model and the damping adjust coefficient have great influence on seismic design results. Calculation errors of Kowalsky method and Iwan method and Ou method are very small. Calculation error of Kowalsky method is decreasing when displacement ductility factor increases. The calculated result based on the damping adjust coefficient provided by Eurocode8 specification is more close to the real one. Kowalsky method and the damping adjust coefficient of Eurocode8 specification is recommended to be used in displacement-based design of bridge engineering.

In this paper, the propagation of sound wave and the nonclassical nonlinear acoustic properties in concrete were studied theoretically and experimentally. The results show that the resonance frequency shifts with the increase of the amplitude of accelerometer and the amplitude of the third harmonics is proportional to the square of the amplitude of accelerometer at fundamental frequency, which are the properties of nonclassical nonlinear acoustics. The values of the nonlinearity parameters were determined from the dependences of the resonance frequency shift and higher harmonic amplitude on accelerometer amplitude at fundamental frequency. The experimental results show that the values of the nonlinearity parameter change with the quantity of the water content in concrete, which are qualitatively explained in this paper.

A comprehensive study of displacement-based design for reinforced concrete bridge columns is conducted. Section analysis software UC-Fyber is used to analyze the bending moment and curvature performance of columns’ sections, based on this, a new calculation method of target displacement of RC bridge columns is educed. Elastic displacement response spectrum, inelastic displacement response spectrum and inelastic demand spectrum are educed from acceleration spectra of Chinese Code JTG/T B02-01-2008; three simplified methods for displacement demand determination are developed. Example of the displacement-based design of bridge column was studied and checked by dynamic inelastic time-history analysis to clarify the reasonableness of the developed methods. Research shows that target displacement of RC bridge columns is relevant with concrete strength grade, longitudinal reinforcement ratio, height and the section form, etc; equivalent linearization method and inelastic displacement response spectrum method are based on the design response spectrum, could reach the target displacement and consider structure safety requirement; demand spectrum method is a simple and direct way to show design with graphics mode, with deficiency of structure capacity spectrum curve from pushover analysis differing from the reality.