Advanced Materials Research Vols. 838-841

Abstract: Based on extended finite element method (XFEM) of the finite element software platform-ABAQUS, three-point bending numerical simulation of CFRP reinforced concrete beam with initial crack has been made to predict the 3D crack propagation path. The numerical tests present the crack propagation path under ultimate load and crack damage modes of non-CFRP and some different CFRP plies. The results show that the strength of CFRP reinforced concrete beam is obviously improved and the crack which previous penetrate through doesnt penetrate through concrete beam under CFRP reinforce based on multiple optometric numerical simulation results. The results of this paper can also provide some foundations for damage mode, the ultimate load and CFRP overlay design of reinforced concrete beams.

Abstract: The impact of blast load is always taken into consideration in significant pillar bearing component and protective construction. The LS-DYNA software was employed to simulate three typical concrete filled steel tubular (CFST) columns under blast load. The JHC model was used for concrete material and the MAT_PLASTIC_KINEMATIC model which accounted for the strain rate used for steel. Three section concrete-filled steel tube columns are analyzed in different proportion of distance and get the damage form of pillars and displacement of key points. The results show: In proportion to the same distance, the antiknock ability of circular cross section is better than the other two sections. Although in filled concrete damage is serious, but the steel tube columns improve the ductility of the columns. With the increase of proportion of distance, pillar deformation gradually decrease.

Abstract: Using the finite element analysis software ABAQUS, the section temperature field of reinforced concrete columns under fire was analyzed. On this basis, the influence of the section size, the number of heated surface and the time of fire on the surface temperature were analyzed. Calculations indicate that the impact of the section size on temperature field cannot be considered when one surface was heated, three or surrounded by fire-sectional dimensions the influence was time-related. When the cross-sectional size reaches a certain value, the number of exposed surface on the temperature field can be neglected. Sectional temperature increased by time and the temperature rise rate is high at start then slow down close by fire surface, however, the rate is more stable all the time at internal surface.

Abstract: In this paper, an analytical example was given to show the time-varying regularity of stress and deformation of composite box girder. The distribution of deflection along the span at initial time and ultimate time was calculated. It was found that the mid-span deflection increased rapidly during the initial 50 days, and became stable after 300 days. The stress of steel increased while the stress of concrete decreased and both of the variation rates gradually slowed down with time. The regularity of stress of steel and concrete with time are similar to that of the mid-span deflection.

Abstract: GFRP bars and PC strand combination pile that is configuration GFRP bars in the compression zone of the general pile, in the tension zone configuration PC strand. Pile construction is completed and before the excavation, applied partially prestressed for the tension zone of PC strand, so that GFRP bars in tension, with the excavation pit, GFRP bars tendons pulling force gradually reduced; When the excavation to a certain depth, the second prestressed steel strand so until the excavation is completed. In summary, the technology features is GFRP bars, concrete piles, PC strand all in tension. This makes full use of the concrete compression performance, GFRP bars and PC strand tensile good performance characteristics.

Abstract: It is very crucial to analyze the flexural bearing capacity of the steel-high strength concrete composite beams, but the combination on the flange of steel beam and their bearing capacity is limited with certain inevitability,in addition, in the negative bending regions of continuous composite beams, with the constant increase of load, the process of the whole structure will cause damages in the negative moment region. In order to avoid this kind of damages, we must use general finite element program ANSYS to analyze thebearing capacity of the steel and high strength concrete composite beams. Besides further studying the influence factors of bearing capacity, and ensuring the safety of our engineering performance can be in favor of the engineering structure.

Abstract: Non-mining fracturing of shaft lining is a special mine geological disaster in Huadong thick alluvium Mining Districts, which is mainly induced by the additional stress result from compressive deformation of the bottom aquifer water loss. On the basis of summarizing the geological conditions and failure characteristics of non-mining fracturing of shaft lining, this paper analyses the size and variation with different influencing factors of additional stress in outer wall through establishing 3-D numerical modeling. The relationship between stress condition of non-mining fracturing of shaft lining and head loss of bottom water-bearing stratum is determined using the classic elastic solution to thick-walled cylinder according to the proceeding modeling results; and the head loss of bottom water-bearing stratum corresponding to the failure limit state of pitshaft damage is obtained.

Abstract: Under the shear rheological conditions, debris filled with mud weak interlayer shows viscoelastic rheological laws. On the basis of non-linear regression analysis of rheological parameters, the relationship between shear stress and rheological parameters was researched. The study reveals that, with the increase of shear stress, weak interlayers instantaneous deformation, constant strain rate and the final elastic strain increase, while the delay time has not been found certain regularity. Under the shear rheological conditions, when the stress level is low, the constitutive model of weak interlayer can be described by Burgers model; when the stress level is high, Cvisc model should be used.

Abstract: Cynodon dactylon has become a dominant riparian species in the reservoir region after the Three Gorges project was finished. In order to determine the effect of the species in soil conservation and slope reinforcement and the variation over time, the soil erosion resistance and shear strength of plants soil-root systems were tested during different seasons in a year through control experiment. Results showed that C. dactylon roots enhanced significantly soil conservation and slope reinforcement. The tensile strength of C. dactylon roots reached from 65.34 to 91.22Kpa/mm2 after three to twelve month growth, so did the soil erosion resistance coefficient from 0.34 to 0.86, shear strength from 20.82 to 25.98Kpa increasing by 39.62%, 154.90% and 24.74% respectively. We conclude that the temporal dynamics of C. dactylon roots influenced the performance of soil-root system in soil conservation and slope reinforcement.

Abstract: To discuss the relationship between matric suction and strength under different drying-wetting cycle paths of residual clay, soil water characteristic curve was determined by the filter paper method. The shear strength, unconfined compressive strength and matric suction were obtained during desorption and adsorption at the drying and wetting cycle. The experimental results show that the matric suction of soil specimens subjected to different drying and wetting cycle paths are different although at the same water content. Contributions of internal friction angle and cohesion to shear strength are different at different matric suction. In the low matric suction stage, matric suction mainly contribute to shear strength by affecting the cohesion, yet in the high matric suction stage by increasing both the internal friction angle and cohesion; in the transition matric suction stage, the contribution of cohesion decreases while the contribution of internal friction angle increases. Furthermore, the unconfined compressive strength of specimens subjected to the drying and wetting cycle path of desorption first and then adsorption is reduced and increase with the opposite path.