Prestressed Anchor Frame Beam Internal Force Calculation And Take Into Account The Friction Influence

Frame beam with prestressed cable is a new active fense technic about slope reinforce and fense, it pass the enormous force of the prestressed cables by the reinforced concrete frame to change the stress state, transfer the self-stabilization of the slope body. It safe and steady, light and beautiful, and the economic benefit is superior to the traditional heavy-duty supporting structures obviously. But at present, it has no relative criterion about the design and count of the prestressed cable frame beam, the theory is far behind the practice, and the departments of design usually use experience comparison to estimate the internal force of the beam, or use the general building foundation method to calculate, such as "inverted girder" and Winkler foundation method. Because of the inherent limitation of the methods and models, they can not reflect the mutual effects of the frame and foundation under some conditions, such as the usually meted close-grained thick terrene or rock slope, which have good elastic property. Further more, there is no discussion about the change of the internal force of the beam caused by the huge friction between the frame and the slope,In the thesis, semi-infinite solid model is introduced to calculate the internal force about the frame beam, and on the basis of it, estimate the afresh distributing of the beam stress caused by the friction. Semi-infinite model looks the foundation as a homogenous, continuous and elastic semi-infinite body, it can reflect the continuous deformation, especially suit to the close-grained thick terrene or rock slope which have good elastic property. Use the known conclusion about the semi-infinite elastic body of the elasticity as the base of the calculation. First, split the frame as transverse beam and upright beam, then use chain-bar method to transform the infinite statically indeterminate system to the finite indeterminate system, finally, get the calculation formula of the beam stress. When calculating the effect of the friction, after a series of tentative and simplifications. For the transverse beam, ignoring the torque produced by the friction of the beam foot, and looking the friction as a uniform force loaded on the medial axis of it. So the mechanical model can looked as a uniform stressedcantilever and fixed beam; for the upright beam, the friction of the beam foot parallel loaded on it, the mechanical model can looked as a uniform friction cantilever and fixed beam. At last, using the elasticity's technology to deduce a formula about the effect of the friction.Expecting the deduced formula can serve the project design, reduce the reinforcement ratio, sectional size or reduce concrete, steel bar properly, optimize the design, economize the investment, and serve the foundation construction in the mountainous area.