Advanced Materials Research Vols. 989-994

Abstract: The accelerated wear test of metal materials is researched, and the boundary conditions which required by failure mechanism consistency receive a meaningful exploration. This work presents a physical model about the boundary of accelerated stress to support accelerated test design. According to the material properties, the accelerated stress is restricted by three boundaries which are the boundary of the normal load, the boundary of relative speed and the boundary of their product. This research shows that failure mechanism consistency in accelerated wear test manifests as consistency of parameters in statistics, yet in physics, it depends on the three boundaries.

Abstract: On the basis of Umansky box-girder torsion theory, the software of ANSYS is applied to simulate related engineering model. In considering a variety of live load conditions, the lateral stability of multi-span single-pier variable cross-section box-girder under torsion eccentric load is analyzed. Analysis results reveal that under different working conditions, the factors affecting the transverse stability of the bridge and the proportion of the value on each, such as gravity, the span ratio and the distance between support are different; When the overload ratio is 2 times larger, the bridge stability safety coefficient decreases along the curve and changes rapidly. In the future design of this kind of bridge, the overall lateral stability should be paid much more attention. Some methods and suggestions about how to prevent the emergence of security and stability problems are put forward in the end.

Abstract: The effect of convex platform shape on stress distribution in nickel-based superalloy thin plate produced by Vacuum Countergravity Casting (VCC) has been studied by numerical simulation. The result shows that convex platform significantly changes the stress distribution in its adjacent area. The stress-affected zone (SAZ) of both types of convex platform appears uneven. SAZ is significantly greater in the diagonal direction than that in the horizontal direction. The angle effect contribution rate (AECR) is defined. When S1=1mm and S=6, AECR has the larger values in both convex platform shapes, and AECR of square convex platform is even up to 7.589. When S1 is larger than 2mm, the relationship between angle effect and S1 or S is not obvious for square convex platform.

Abstract: Geometrical parameters of welded joint affect the stress concentration coefficient seriously. In order to increase the fatigue property of welded structure, it has great significance to reduce stress concentration coefficient of welded structures by researching and improving the geometry of welded joints. In this paper, the effects of weld tangent line angle θ on the stress concentration coefficient of welded cruciform joints of magnesium alloy were analyzed by using ABAQUS finite element program, and the change rule of stress concentration coefficient with the variation of the parameter was also researched. The calculation results indicate that reducing the weld tangent line angle θ can effectively decrease the stress concentration coefficient of welded cruciform joints, so as to improve the fatigue property of welded structures. In order to have high reliability and safety of welded structures of magnesium alloy, the true weld tangent line angle θ should be controlled less than 25°.

Abstract: Geometrical parameters of welded joint affect the stress concentration coefficient seriously. In order to increase the fatigue property of welded structure, it has great significance to reduce stress concentration coefficient of welded structures by researching and improving the geometry of welded joints. In this paper, the effects of weld toe inclination angle θ and weld edge transition arc radius r on the stress concentration coefficient of welded butt joints of magnesium alloy were analyzed by using ABAQUS finite element program, and the change rule of stress concentration coefficient with the variation of the two parameters was also researched. The calculation results indicate that reducing weld toe inclination angle or increasing transition arc radius can effectively decrease the stress concentration coefficient of welded butt joints, so as to improve the fatigue property of welded structures. For the safe use of welded structures, the true weld edge transition arc radius r should be greater than 3mm, and weld toe inclination angle θ should be smaller than 30°.

Abstract: This paper first analyzes the strength and deformation characteristics of gangue dispersion, Subsequent analysis of the effect of water on the strength, deformation characteristics. And discusses the permeability characteristics of gangue dispersion and dispersion of particle size, pore characteristics and the dumping years effect on its permeability.

Abstract: An experimental study of tensile failure behaviors of L-shaped adhesive-bonded and bolted hybrid composite joints, which are designed to connect composite cabins, is performed. A set of rigid jigs was designed to fix the specimens and ensure to apply an axial tensile load. The damage processes, failure loads and ultimate failure patterns of the joints are obtained from the tests. Some indentation around the fastener hole and remarkable discontinuity departure between the top and bottom L-shaped laminates which leads to the catastrophic failure can be observed on the specimens. It follows that the discontinuity is the weak spot and required to be strengthened.

Abstract: There are many links between temperature and toughness of the building. To quantify the association between them, a model of temperature and toughness is proposed to analyze toughness relationship at different temperatures of the building. Collapse warning is performed by difference of security risks in temperature grades of buildings to obtain model relationship of temperature and toughness, so as to achieve an accurate assessment of the risk of collapse for high-rise building under different fire rating. The experimental results show that, proposed method at different building fire levels on accession of efficiency, time and accuracy of building collapse risk are better than traditional methods, which is capable of efficiently assessing the risk of high-rise buildings collapse in exceptional temperature.

Abstract: In certain high temperatures conditions, tensile strength of steel concrete varies due to changes in ambient temperature environments, which greatly influences structural characteristics and material properties. For this reason, relational model between reinforced tensile strength of building and temperature is proposed. Information of reinforced concrete structure collecting by ultrasonic sensors is processed to be anti-inference and build relationships employing PSO algorithm. Experimental results show that this model can be a good measure of property relationships between temperature and tensile strength of reinforced concrete structure.

Abstract: This paper was based on the parallel and cross section on the east coast of Xiangjiang river crossing tunnel on Yingpan road in Changsha City, and studied on the affects of partition of it adjacent construction. The conclusions were drawn as followings: When the vertical spacing is larger than 4D, it didn’t need to consider the influence of vertical spacing on parallel interchange tunnels close construction, can be considered as two parallel tunnels. And when the level spacing is larger than 4D, it didn’t need to consider the influence of level spacing on parallel interchange tunnels close construction, can be considered as two intersecting tunnels.