In order to study the variation of wind field characteristics under the influence of thermal effects at a bridge site in a deep-cutting gorge with high-altitude and temperature difference, the simulation of natural convection was realized by adding momentum source terms in FLUENT. And the correctness of the simulation results was verified. Then, choosing Dadu River Bridge located at a deepcutting gorge in western Sichuan as an engineering background, combined with the variation of temperature tested at the bridge site, the numerical simulation of the wind field characteristics at the bridge site was carried out under the influence of the thermal effects. The influences of different thermal factors on the surface wind characteristics of bridge site area were discussed. The wind characteristics at the bridge site under the combined action of different wind velocities and thermal effects were analyzed. As shown in the results, the maximum vertical wind velocity caused by the thermal effects at the height of main girder is 3.0 m/s, and the maximum horizontal wind velocity is 6.4 m/s. When the upcoming wind velocity is greater than 5.0 m/s, the thermal effects have been significantly reduced, and the wind field at the bridge site is mainly influenced by the upcoming wind velocity, wind direction, and local terrain. Under the influence of thermal, the surface temperature distribution at the bridge site is significantly uneven, which are obviously different from the case of not considering the thermal effects.
As long-span cross-sea bridges extend to deeper sea areas, the bridge pile tends to increase in its slenderness ratio and becomes more susceptible to waves. To improve the structural stability at the construction stage, this study analyses wave-induced response of foundations. The wave theory and the method used for computing wave forces on foundations are first introduced. Then, a pile group foundation is taken as the research object, and different pile lengths ranging from 16 m to 46 m are considered. The wave-induced response of the piles and the cap is calculated. After understanding the effect of the pile length, three optimized foundations are proposed with the aim of reducing the free length of the pile, and the corresponding finite element models are established to compare their wave-induced response. The results show that the displacement at the top of the foundation increases with the increase in the pile length until the cap partly emerges from water and so does the internal force at the bottom. Setting a constraint in the middle of the piles can reduce their free lengths and is favourable to the wave-induced response of the foundation except for the shearing force. A stronger constraint shows better effects on improvement of the stability of the foundation. The conclusions provide reference for optimization on pile foundations of deepwater bridges.
Quality management was the key to the survival and development of construction enterprises. This paper discussed the construction enterprises should carry on the quality management at two levels of the internal quality management of construction enterprises and their construction project quality management, that could make construction enterprises to embark on a high-quality and efficient development road.
One new type piezoeletric microactuator was designed in this paper, in order to improve the output characteristic of microactuator mechanism, piezoeletric analysis was performed and the optimization model was built with w b and α as design variables, the maximal output horizontal-plane displacement and the minimum vertical-plane displacement as objective. The final optimize result shows that the output horizontal-plane displacement of microactuator raises twice from 0.3µm to 0.6µm, meanwhile, the output vertical-displacement decreases from 0.093µm to 0.075µm by approximately 21 percent, the horizontal output characteristic has a remarkable improvement, so the optimal result can provide validity theoritical guidance for coming design strategy.
As a result of the path route and the width change and in order to connect south of K4 + 726.852 bridge with road in HengZhou avenue smoothly, we need to reverse the cross slope which takes up 2 percent of the bridge deck. We analyze three different reform plans, so as to ensure security of HengZhou bridge. Firstly, we compare the influences for the bridge structure bearing capacity from different projects. Secondly, we study the transformed force performance. Thirdly, we evaluate the bearing capacity. Result shows that transformation surfacing method is costless and easy to operate. The bearing capacity meet the requirements after the transformation. The research achievement has some reference value to other similar bridge for strengthening
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