Genetic algorithm is a non-numerical optimization method which based on natural selection and population genetics.Using genetic algorithm to optimize the mix proportion design of high performance concrete, it takes into account the economic profitability on the foundation of satisfying the requirements of durability, strength, workability and dimensional stability of concrete, it establishes a mathematic model applying the performance of material as constraint condition, and the economic cost as optimization target.Using binary coding to represent the chromosome bit serial of individual, through selection, crossover, mutation and other genetic operator to conduct global probability search, taking the principle of “survival of the fittest”, finally achieve the best population and individual. Compare the results of optimization with the mix proportion in practice engineering case, we can reach the conclusion that Genetic Algorithm could reduce the cost, save energy, provides better use value on engineering practice.
The main structure of passenger dedicated railway serves in complex physical environment, so its high durability is expected. In contrast to normal HPC applications, higher requirements are addressed for the application in passenger dedicated railway, which include control of raw material quality, selection of HPC design strength, and mix proportion design procedures. In this paper, the choice of HPC constituents, the principles of mix proportion design, and the design of HPC mix proportion for passenger dedicated railway based on overall calculation method are presented. Its application case in Quzhou Section of the Hangzhou-Changsha Passenger Dedicated Railway has shown that t the design of HPC mix proportion for passenger dedicated railway based on overall calculation method is effective and deserves popularization.
By processing waste into recycled aggregate concrete, and producing recycled concrete aggregate with 50 percent of it replacing natural gravel, we make a study of different curing conditions on the carbonation of recycled concrete as well as the resistance capacity of steel corrosion. The experiment results indicate that the depth of carbonation of recycled concrete increases sharply with the standard curing period lowering. The recycled concrete steel corrosion resistance rate decreases as standard maintenance ages. The recycled concrete steel corrosion rate is much lower than the general concrete steel. The steel corrosion weight loss rate of general concrete is less than 0.3%, with no rusting of the steel. The steel corrosion weight loss rate of recycled concrete is mostly more than 0.3%, with apparent rusting.
Early shrinkage of concrete includes plastic shrinkage before the final setting, drying shrinkage during hardening process and autogenous shrinkage. Concrete drying shrinkage which is caused by evaporation is a major factor for the concrete volume change. By ring constrained test and free shrinkage CONCEN test, this paper studies the impact of polypropylene fibers on the shrinkage properties of concrete at the early age. The test shows that the polypropylene fibers can significantly reduce the early shrinkage of concrete, the best content of C30 concrete should be 0.9kg/m3.
The technology of strengthening RC beam with CFRP sheets is now a hotspot of research in civil engineering. The FEM analysis was made for the whole deformation course of the flexural behavior of RC beam with CFRP sheets on lateral side, and the result was coincided with the experimental results.
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