Advanced Materials Research Vols. 446-449

Abstract: The characteristics of crack load, failure load, crack and deflection of steel fiber reinforced concrete wall-beams simply supported have been studied though the tests of 12 steel fiber reinforced concrete wall-beams simply supported specimens. The upper steel of joists changing from tensile reinforcement to compressive reinforcement, neutral axis moving from joists to walls and phenomenon of stress redistribution in wall-beams with the increase of external load have been found; the optimum mixing amount of steel fiber has been determine and the increase rate of crack load and failure load comparing steel fiber reinforced concrete wall-beams simply supported with ordinary ones has been raised. It is good for the practical constructions application that steel fiber increases the ductility of simply supported wall-beams.

Abstract: Based on the theory of thin-walled curved bar and considered the impact of initial curvature and prestress on the vertical flexure, the shear lag warp displacement function is replenished on the basic deformation of the curved box girder flange plate, for which the longitudinal dispersive function is utilized. According to the energy functional differential methods, the coupled bending tosion and shear lag of elasticity governing differential equations of curved prestressed box girder are deduced with different boundary conditions in considering prestress and initial curvature. The numerical solution is gained by Galerlein method. The calculated value of this article coincides well with the value of the experiment and finite-element method. It builds the theory analysing basic of shear lag effect of curved box girder bridge considering prestress and initial curvature.

Abstract: To gain an insight into the protective mechanism of surface biodeposition, a theoretical study of carbon dioxide diffusion through surface-biodeposited concrete is required. The present paper proposes a physical model for surface biodeposition and the concept of water-percolated porosity, and develops a theoretical model to predict carbonation of surface-biodeposited concrete structures. The model describes movement and retention of heat, moisture and carbon dioxide by means of balance equations and diffusion laws. The influences of biodeposition and substrate properties on carbon dioxide diffusion are studied by a finite difference model. Results indicate that carbon dioxide diffusion is controlled by both the biodeposition and the substrate. Biodeposition can significantly reduce carbon dioxide concentration at the concrete surface, but this interfacial concentration increases with time.

Abstract: The concrete which take coral fragments as aggregate can solve the shortage of building materials in the ocean reef island effectively, The coral concrete shall be classified as light weight aggregate concrete from the angle of the apparent density of building materials, its basic mechanical properties are similar to ordinary light weight aggregate, but there are also significantly different. The different between coral concrete and pumecrete、haydite concrete and the basic mechanics characteristics of coral concrete were study in this paper. The intensity、development of intensity with age、stress-strain relations、failure mode under load were discussed.

Abstract: Bio-deposition has led to the exploration of remediation and improvement technique in the field of cementitious materials. The aim of this study was to investigate the effects of bio-deposited carbonate on parameters affecting concrete properties and the effects of bio-deposition on the durability of concrete specimens. The remediation efficacy of cracks in concrete was studied through compressive strength test and flexural failure test. Water absorption and the resistance towards carbonation of concrete were analyzed by water absorptivity test and concrete accelerated carbonation test, respectively. Experimental results show that bio-deposition is able to make the improvement in concrete compressive strength and the remediation of cracks. Bacterial deposition of calcite on the surface of the concrete specimens results in a decrease of capillary water uptake and carbonation rate constant, and an increase in resistance towards degradation processes.

Abstract: The experimental research on the strength of the steel bar embedded in the masonry wall is presented in this paper. Six existing masonry buildings of different construction age are concerned in site test. Only the steel bar with diameter of 6mm and embedded depth of 100mm is selected as the specimen for test. Few cases of damage by the rapture of glue are found. The two failure modes as cone rapture of brick and yield of steel bar illustrate the effectiveness of the embedded steel bar. By the pull-off test and side push test, the strength of the embedded steel bar in the masonry wall is got.

Abstract: As a new approach of the sustainable design, parametric design, which is also known as computational design, has become the new focus in architecture digital design. Parametric design which mostly applied in architectural design of landmark building is a special architectural type. Instead of ignoring social attribute and environmental characteristics of building, more architects are attracted to the amazing form of building from the result of parametric design. We should pay more attention to context, environmental factors and social influence in parametric design process, and give landmark building more social significance.

Abstract: Experimental studies on size effect of flexural behavior of reinforced concrete beams are not carried out fully. Standard values are based on test results of small-size components, which are different from large-size components in practical engineering. For size effect on quasi-brittle materials such as concrete, related researches have been carried out for many years, but related test study combined with concrete structures or components are not sufficient. This article is based on experimental study of 13 reinforced concrete free beams, obtaining test data during different loading stage, such as carrying capacity, deflection, steel and concrete strain etc. Test results show that size effect of flexural behavior of RC free beams is mainly reflected in reinforcement yielding stage and concrete crushing stage. The negative size effect due to concrete material is not significant. Yet internal force arm and longitudinal reinforcement have a positive size effect on flexural behavior, strength and ductility reserves show a growing trend with specimen size increasing. The safety of calculation theory of bearing capacity in code is verified indirectly.

Abstract: Two types of beam Strengthening-Bolt spliced connection were analyzed by using ABAQUS. The results showed that Beam Strengthen- Bolt Spliced Connection can effectively make the relocation of the plastic hinge. The plastic rotation and energy dissipation capacity of beam Strengthen-Bolt spliced connection exhibited excellent.

Abstract: The common quality questiones in mass concrete construction are temperature crack. Tensile stress producted in concrete when the temperature deformations were constrainted by internal and external impacted. Temperature stress is the main reason leading to cracks in concrete. Union Nanyang Cement Branch in the second phase 6000 t / day cement clinker production line. Through the foundation mass concrete temperature and strain monitoring and thermal stress calculations. Crack control measures were made for mass concrete construction.