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This work investigated the local buckling failure of high-strength and large-diameter pipelines containing a dent under bending moment. An improved three-dimensional numerical model was developed by considering the multiple nonlinearities of pipe geometry, material and the boundary conditions. The effect of yield strength and strain hardening parameters of pipeline steel on the critical buckling load at the dent was analyzed in detail. The results show that, the critical buckling moment of the pipeline decreases with the increase of n. However, when the internal pressure is low, the influence of internal pressure on the critical buckling moment is limited, and the hardening exponent affects the critical buckling moment only when n

This study presents the total energy response of the hemi-cylindrical shell with a steel material under the external blast loading by employing both theoretical approach and numerical simulation. Analytical approach demonstrate that the total energy contributed from blast is inverse proportional to the thickness of shell. It is proportional to the inverse tangent function applied by the ratio of denotation coordinate over the radius of shell. Moreover, to verify the theoretical inference, several numerical simulations were carried out. Those result agree well.

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.

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.