Study On Several Key Problems About Structure Analysis Of Large Rectangular Beam Aqueduct

Aqueduct (Water Bridge) is the overhead crossing water-carriage building that connecting the canal system and crossing the mountains, valleys, the road, so it is very important construction of water conservancy projects. With the materials and construction technology development, aqueduct scale is growing. South-to-North water diversion project was a state key project, large-scale long-distance inter-basin water need build a number of large and medium-sized aqueducts; the water flow, water depth and water loads are great, living in the world in terms of scale. In contrast to the large rectangular beam aqueduct, its study is far lagging behind, particularly the study about box body temperature field of sunlight and thermal stress, and more longitudinal beam aqueduct of the force and structure form of choice, Aqueduct dynamic properties of the beam aqueduct is very little.The second chapter of this paper taking the Shenzhen Reservoir aqueduct project as an example, analyzes the reason why the box aqueduct temperature can cause sunlight temperature difference, calculate the aqueduct initial conditions and boundary conditions under sunlight temperature field. Use finite element analysis theory, constitute the plane model, use the finite element software to put up effective simulation on Aqueduct sunlight temperature effect, one can see box girder temperature's sunlight temperature distribution is more complicated, from the box-slot body's temperature distribution, The roof temperature change most intense, followed by sternum, the soleplate minimum. The outer surface of the roof occur maximum temperature at about 2:00 p.m.; the outer surface of the east sternum occurs maximum temperature at about 11:00; the outer surface of the west sternum at about 3:30 p.m. occurs a maximum temperature; the outer surface of the soleplate at about15:00 occurs maximum temperature. Then using the results fits temperature conic curve of the box aqueduct's vertical and horizontal cross-section and thickness of the board; and it is pointed out that the fitting conic accord with actual temperature distribution trend more than exponential distribution curve of relevant norms so can be used as the basis for the calculation of temperature stress.The third chapter of this paper analyzes the concrete box aqueduct structure produces thermal stress under the influence of temperature change in the sunshine. The finite element method analysis shows that:the largest tensile stress in cross-section width way presents to the lower edge of the roof plate, the largest tensile stress in cross-section height way presents to the sternum wall, the largest tensile stress in cross-section length way presents to the corner of sternum's inner wall; longitudinal tensile stress in the corner of sternum's top(inner edge)is relatively larger, tensile stress gradually decreases along sternum top-down vertically; longitudinal compression stress on the roof plate's outer margin is the largest. It can be seen: concrete box aqueduct body surface under sunshine temperature will have a substantial thermal stress, and its value has exceeded the design of concrete tensile strength. Therefore, the thermal stress under the sunshine's temperature difference in the box aqueduct body structural design must be seriously considered, in the design we should appropriately configure temperature reinforcing steel bar.Chapter IV of this paper aims at the stress trait of large multi-Longitudinal Beam strong-link structure, contrasts a variety of structural analysis methods, points out the Practicality Space Analysis Method recommended by this paper. In aqueduct complex structure space design, we may adopt the Practicality Space Analysis Method to calculate internal force and put up reinforced design, use 3D finite element method to checking the main cross section of the stress state. The side wall of multi-Longitudinal Beam rectangular Aqueduct with large boundary beam can be used as Longitudinal Beam, taking full advantage of the characteristics of side wall's large stiffness, retaining the horizontal and vertical load-bearing combination, can greatly enhance the stiffness and carrying capacity of the edge of longitudinal beam, coupled with cross-section beams with larger stiffness on the distribution of load between longitudinal beam, make the force of middle longitudinal beam decreases, this can give full play to the edge of longitudinal beam bending ability, can effectively reduce the effect of the water load in the longitudinal beam and their cross-moment and stress, thereby increase aqueduct's capacity to leap, we should give priority to the use in large aqueduct in the design.In the fifth chapter of this paper, through the study of Fluid-Structure Interaction theory, we use the equivalent of spring mass system (simplified by Housner water model) to simulate dynamic interaction of the fluid and the structure, and use ANSYS to put up the seismic analysis of large aqueduct with beam. Through consideration of water sloshing, the result of large rectangle aqueduct with beam shows that, the existence of the water substance has a greater impact on the dynamic characteristics of the aqueduct; the sloshing of water can effectively reduce the water body's own seismic response. If seeing water body as a rigid body, adding all quality to the aqueduct, it will seriously exaggerate the earthquake inertia force of the water. When tank water quality remains unchanged, and aqueduct body changes from single-slot into a two-hand, the natural frequency of water in aqueduct and the natural frequency of structure changes, then the largest displacement of frusta at the bottom and the greatest moment and shear of frusta on the top reduce under the earthquake wave. Analyzing that depth-width ratio of aqueduct's cross section effect aqueduct's earthquake resistant structure, the largest displacement of frusta at the bottom and the greatest moment and shear of frusta on the top change along with the tank body changes under different depth-width ratio. Therefore, when cutting aqueduct body section and choosing depth-width ratio we should consider its influence to reduce the seismic response of aqueduct pier.