Advanced Materials Research Vols. 446-449

Abstract: The question of the pretensioning force of the wrapping wires for a suspension bridge is one of the important subjects. It could prevent the main cable from eroding by air or chemicals. And it must have some loss under the influence of dead loading, each mobile load and environment[1]. Now, the research of wrapping wire of the main cable is not much at home and abroad. And wrapping wire tension is mainly obtained depending on engineering experience. This paper has an experiment about the wrapping wire of Yangmingtan Bridge in Harbin to draw conclusions that wrapping wires tension which is 2m far from the cable clips is reduced extensively, more than 80%. But the residual tension, 8m from the cable clips, is about 35% of the initial tension. In addition, the wrapping wires tension which is about 93cm far from pre-wrapped wire-loops remains stable. Finally, starting from calculation theory, the paper puts forward that the wrapping wire tension should be 2.0kN.

Abstract: This article is undertaken with the results of the detection of structural highway bridge in the west of Ezhou subsidiary line after completion and its analysis of completing and analyzing bridge dynamic Load Tests, in order to introduce three means of tests: the pulse tests, vehicle tests and bump tests. Finally we discuss the advantages and disadvantages, as well as the prospects.

Abstract: For normal consolidated or low over consolidated saturated structured clays, a constitutive model of the clay was proposed by introducing a structural parameter d in order to quantitatively describe the change of its deformation and strength based on unified hardening model. Stress-strain and body strain of the clay were predicted by the new model and were measured by K0 consolidated compression and shearing tests. The rationality and feasibility of the new model were proved by comparing the predictive and experimental value. The results show that the model can well describe structural characteristics, deformation and mechanical properties of the saturated structured clays; predictive value of stresses and strains are basically in agreement with experimental ones, and this further proves the rationality and feasibility of the new model.

Abstract: The temperature of the steel tube of a CFT column rises rapidly upon a fire causing the deterioration of its strength, while the concrete inside of the tube having large heat capacity provides fire-resistance performance. In order to employ CFT columns as fire-resistant structure, it is necessary to conduct studies on the factors exerting influence on structural capacities and the influence associated with each condition. Concrete’s compressive strength, cross-sectional size, axial load ratio and boundary condition are the major factors which are influential in fire-resistance performance. In particular, boundary condition between columns and beams is one of the major factors which decide fire-resistance performance because it exerts influence on load carrying capacity. The result of the test conducted in this study showed that fire-resistance time of 106 minutes was secured in the specimens with clamped ends and that of 89 minutes in those with pinned ends when cross-sectional size was 360 by 360. In the specimens with cross-sectional size of 280 x 280, fire-resistance time of 113 minutes was secured under the condition of clamped ends and that of 78 minutes was secured under the condition of pinned ends.

Abstract: Indirect test method of installing vibrating wire strain gauges as sensors in outer surface of steel tube rib is adopted to carry out the research of concrete-filled steel tube (CFST) self pre-stress test for a half-through CFST arch bridge with a main span of 240m. The results show that indirect test method is a practical approach for self pre-stress test, and the measured value of self pre-stress from this method is much smaller than that of being theoretically calculated by concrete free expansion ratio.

Abstract: Nondestructive testing technology on prestressed pipe grouting is an important issue in recent years. Some research methods including Radar Method, Ray Method, and Impact Echo Method were contrasted and verified in this paper. The applicable scope and the defect detectable effect of these methods mentioned above was studied exploringly. The achievements obtained this paper were certain to be significant for the detection on pipeling grouting quality and defect inside concrete.

Abstract: This paper put circular hollow bridge pier under cold wave as an example. Based on solid heat conduction principle, we selected its border and initialized condition according with actual circumstance. Combining solid heat conduction differential equation and generalized hooke’s law which takes temperature stress into account, we have calculated the temperature and stress of concrete piers with different reinforcement ratio by ANSYS finite element software. These results indicate that the longitudinal bars and horizontal ring stirrups in concrete circular hollow pier under cold wave will increase its outer surface temperature tensile stress. Namely the reinforcements in concrete circular hollow pier not only do not prevent its outer surface cracks under the action of cold wave, but will also promote the surface cracks to produce faster. Therein, the contribution of horizontal ring stirrups to the surface cracks is greater than the longitudinal bars.

Abstract: According to the definition of the sound radiation, a theoretical model is developed for acoustic radiation from a plate into air space. Then, the calculation for acoustic radiation coefficient at different frequencies and critical frequency of building members are carried out, also the radiation coefficient curves varied with frequency are gained. Comparison with the results of the radiation coefficient with different thicknesses and materials, the results show that: the sound radiation coefficient is so low to be neglected below the critical frequency; while it tends to a constant value of 1 above the critical frequency, and the maximum value occurs at critical frequency. Due to influence of radiation on the sound transmission in a structure, sound radiation coefficient plays a significant role on the option of sound insulation materials during the practical engineer.

Abstract: Non-linear numerical simulation is done on A-type super high pier by using finite element analysis software ANSYS, obtaining the node stress distribution under load in the node area taken in the sequential layer analysis of overall mode. The conclusion is mainly as follows: the change of width and thickness of cross beam exerts slight impact on the maximum stress of the node while the change of cross beam depth impacts the node stress much. From the computation, it can be concluded that proper reduction of cross beam depth is beneficial to the node stress.

Abstract: Combined with the practical design of a prestressed concrete continuous box-girder bridge with changed sections, the effect of side-web slope on the loading properties of this bridge was analyzed. The numerical modes of this bridge were built using the specialist FEM software, 5 side-web slopes were considered by changing the width of box floor. The results show that the changes of side-web slope influence the mid-span deflection of box-girder in a small range under vehicle load, but affect obviously on the transversal loading properties such as crack width and flexural resistance of the box roof. Based on this, the suitable side-web slope is selected. It may be referenced by the similar design of this kind of bridges.