Design Technology of Continuous Beam-Arch Combination Bridges

In this paper,a research was conducted on the design technology of continuous beam-arch composite bridges.A brief introduction is given on the of continuous beam-arch composite bridges,its basic mechanical characteristics is analyzed,and three aspects of design technology is studied,which are rise-span ratio,stiffness ratio,and bridge deck cracking.This article acts as a reference for relevant design units in China to improve the design of continuous beam-arch combination bridges.

A numerical investigation into the solids phase chromatography using a combined continuous and discrete approach

Solids phase chromatography for particle classification is based on different retention times of particles with different properties when they are elutriated through a confined geometry. This work aims at a fundamental understanding of such a technology by using the combined continuous and discrete method. A packed bed is employed as the model confined geometry. The numerical method is compared first with experimental observations, followed by a parametric analysis of the effects on the flow hydrodynamics and solids behaviour of various parameters including the number of injected particles, the superficial gas velocity, the contact stiffness and the diameter ratio of the packed column to the packed particles. The results show that the modelling captures some important features of the flow of an injected pulse of fine particles in a packed bed. An increase in the number of injected particles or the superficial gas velocity reduces the retention time, whereas the contact stiffness does not show much effect over the range of 5 × 10^2 to 5× 10^4 N/m. It is also found that the effect on the retention time of the diameter ratio of the packed column to the packed particles seems complex showing a non-monotonous dependence.

Numerical simulation of sedimentation of microparticles usingthe discrete particle method

A mathematical model has been formulated based on the combined continuous and discrete particle method for investigating the sedimentation behaviour of microparticles in aqueous suspensions, by treating the fluid phase as continuous and the particles phase as discrete, thus allowing the behaviour of individual particles to be followed and the evolution of the structure of the particle phase to be investigated as a function of time. The model takes into account most of the prevailing forces acting on individual particles including van der Waals attractive, electrostatic repulsive, gravitational, Brownian, depletion, steric, contact and drag forces. A code has also been developed based on the model. This paper reports some preliminary modelling results of mono-dispersed microparticles settling in aqueous suspensions under various conditions. The results show the short time dynamics of the fluid phase, which has a similar order of magnitude to the particle phase. Such short time dynamics could bear significance to processes such as particle aggregation when their size becomes very small. Preliminary analyses of the results have also been carried out on the evolution of particle settling based on a newly proposed parameter, local normalised volume fraction （LNVF）.