Applied Mechanics and Materials Vols. 405-408

Abstract: Pure adhesive bond of FRP to concrete is not only weak but also unreliable in a long term. This problem can be effectively overcome by a newly developed bond enhancement system the hybrid bonded FRP system (HB-FRP) in which small mechanical fasteners are used to augment the bond. In this paper, theoretical modeling is reported for characterization of the interfacial bond of the HB-FRP system. Local bond-slip model involving adhesive and mechanical mechanisms is proposed. Based on the basic bond-slip model, load-slip response, ultimate bond strength, and effective bond length of the HB-FRP bond interface are obtained by analytical or numerical solution. Good agreement between the analytical and experimental results indicates that the proposed bond-slip model can well predict bond behaviors of HB-FRP joints.

Abstract: The expansion of cement mortar mixing expansive agent under standard curing and membrane curing conditions and compressive strength in constrained conditions are studied in this paper. Results show that the early expansion effect of calcium sulphoaluminate hydrate-calcium hydroxide expansive agent is obvious, mid-to late effect of magnesia expansive agent increase clearly. Compare with standard curing, the shrinkage of the basic cement mortar increase and expansion effect of expansive agent reduce under membrane curing. The expansion effect of expansive agent B is good and persistent under membrane curing, its applicable to used in the closed environment, such as concrete filled steel tubes. The compressive strength of mortar with expansion agent is a little more than the basic mortar under the condition of limit.

Abstract: This study examines the shear behaviors of concrete structure with recycled concrete and artificial sand (AS). Thirty-six beams were prepared with two strength grades (C35, C45) and different artificial sand replacement rates (0%, 30%, 50%, 70%, and 100%). They were submitted to four-point static stress test in order to distinguish the shear behaviors of ASCRC (AS-containing recycled concrete) and of natural concrete that is fabricated using original coarse aggregate and natural sand. Experimental results found the shear strengths values of the ASCRC were lower than the nature ones, with decreasing extents less than 20%. When AS-containing level ranged from 30% to 70%, the cube compressive and shear strengths were more lower than other replacement ratios. Shear force-shear strain curve of the ASCRC was found similar to that of the nature concrete. The peak strain of the ASCRC rose with the increase of the shear strength, but the slope of the curves was lower.

Abstract: The flexibility of connection between the steel plate and concrete slab gives rise to interface slip and additional deflection. A method of analysis for steel-concrete composite plate with slip effect resulting from studs is presented. The basic idea is to place a hypothetical thin shear-layer between steel and concrete slab, where all the shear deformation is concentrated in the thin layer. Analytical solutions for elastic critical buckling load of composite plate considering slip effect under axial compressive and pure shear are derived. The theory model and the solutions are then validated by means of three-dimensional finite element analysis.

Abstract: Since RCC dams huge volume and poor heat dissipation, thermal analysis plays an important role in the design and construction of RCC dams. This paper focuses on the application and verification of a two-dimensional finite element code developed for the thermal analysis of RCC dams. The effects of solar radiation and casting temperature were also evaluated in the analysis. The result has shown that, solar radiation has an evident influence on temperature history of both central and surface nodes in late ages, but contributes less to the temperature difference of them on the contrary. On the other hand, casting temperatures effect on temperature difference is obvious.

Abstract: This paper describes how to use the simulation calculation of finite element programs. Identification the internal force calculation formula of whole precast reinforced concrete composite insulation external wall with openings.In engineering on wall panels provide a basis for safe use.

Abstract: List The active of MgO was produced from magnesite tailings under certain conditions. The effect of calcinations temperature on the crystal structure of MgO was analyzed by XRD and SEM. Crystal particle of MgO was calculated according to Scherrer formula. The microstructural differences between the MgO agglomerates were examined by SEM at different temperatures. The activity of MgO was evaluated though conductivity which was measured by the conductivity meter. The activity of MgO effected by calcinations temperature was studied. The result showed that magnesite tailings was fully decomposed when that was calcined for 60min with the calcinations temperature of 1050°C, and the activity of MgO was very high. Established a hydration and expansion model of MgO is proposed to explain the activity of MgO.

Abstract: This paper presents a laboratory study on active belite cement clinker using boron oxide as dopant to stabilize high temperature phases of Dicalcium silicate (C₂S), and mineral waste as siliceous materials in complete replacement of clay. The clinker samples were soaked in Muffle Furnace at different burning temperatures and for various time durations, and then, cooled down to room temperature using air blower. Quantitative X-ray Diffraction analysis (QXRD) by Rietveld method indicates that major mineral components are Dicalcium Silicate (C₂S), Ferrite (C₂ (A_0.48F_1.52) O₅) and trace amount of Tricalcium Silicate (C₃S) in the cement clinkers. Among them, Dicalcium silicate is over 85 percent, Ferrite around 10 percent and Tricalcium silicate less than 10 percent. Thermogravimetric and Differential Scanning Calorimetric (TGA-DSC) spectrum shows that there is no significant phase change while cement clinker was cooling down, which means significant amount of high temperature polymorphic C₂S was stabilized during cooling process. It is agreeable with the results from QXRD analysis. Specifically, among polymorphic belite phases, α_H-C₂S accounts for around 66% of cement clinker, and α_L-C₂S for about 22% of cement clinker. In addition, massive belite phase was identified by Scanning Electronic Microscope (SEM) analysis and Light Microscopy analysis. At last, the mechanical tests on active belite cement show that active belite cement clinker has a slow strength development at early ages, but rapid strength gain at 28 days in comparison with belite clinker without adding boron oxide. Thus, this active belite cement clinker demonstrates very promising prospect in sustainable cement industry development. Keywords: Active Belite Cement Clinker; Doped; Boron Oxide; α_H-C₂S; α_L-C₂S; Strength Development

Abstract: The mechanical behaviors of super-elastic shape memory alloy are formulated based on Auricchios constitutive model. The finite element simulation method for the mechanical behaviors of super-elastic shape memory alloy using the software of ANSYS is introduced. The mechanical behaviors near crack-tip in a shape memory alloy plate with one inclining crack are numerically simulated by finite element method. Results show that the software of ANSYS can simulate the mechanical behaviors of shape memory alloy with crack effectively.

Abstract: Abstract.Under external loads, the continuously prefabricated slab of double-block ballastless track may crack easily. The cracks will reduce the durability and carrying capacity of the roadbed slab. Moreover, the cracks may also affect the use and safety of the double-block ballastless track during its service. When the roadbed slab crack, we should take some maintenance measures to maintain the normal use and durability of the double-block ballastless track. This paper based on the finite element method, established a beam-brick model for double-block ballastless track which has a through crack on the roadbed slab to analysis what kind of patching material is the most suitable when the most unfavorable loads act on the track. For this reason, we can provide theoretical basis for maintenance of double-block ballastless track .