A three-phase composite material specimen consisting of aggregates, mortar matrix and their bonding material is created through the Monte-Carlo method. The Mazars isotropic damage evolution model is used to describe the meso-mechanics damage deterioration of concrete. And the finite element method is adopted to simulate respectively the uniaxial compression numerical models of two, three and full graded specimens with sphere and polyhedron aggregates. Following are the conclusions from the test results: the ultimate load capacity of arbitrary polyhedron aggregate specimen is greater than that of the sphere one of the same grade; the size effect law exists in these numerical models of concrete specimens; the stiffness of the polyhedron aggregates’ specimen of the same grade is greater than that of the sphere ones’, and the softening curves of the sphere aggregate model are easier than those of the polyhedron by comparison in the softening phase of stress-strain curves.

The value of thermal parameter is very crucial in simulating analysis on temperature control for mass concrete. The inverse analysis on some practical project is done by genetic algorithm and finite element method on the basis of observational data of temperature on the site. The temperature control simulation calculation is performed based on parameters obtained from inverse analysis on this project, so that the temperature distribution is consistent basically with the practical one. With improvement of micro-genetic algorithm, the genetic algorithm becomes globally-optimal by changing the optimal reserving and re-starting strategies. The results show this method is very practical in high precision of calculation in mass concrete parametric inversion.

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.