Design And Field Measurement Analysis For Formwork And Falsework Of Oval Structural

The construction technique of the existing oval structure in pouring concrete is formwork worked with scaffolding. The formwork can not withstand the central force, which are difficult to construction and brings in security hidden trouble. The paper takes formwork system of oval structural as the main object, the main content is presented as follows:Based on lack of the existing formwork system, relate with architectural features of oval structure, to design the hyperbolic ring shaped large steel formwork which can withstand a certain force. And make clear with the auxiliary support of hyperbolic oval shaped large steel formwork, for design formwork system of top of oval structure. Those auxiliary supports are used by fastener-style tubular steel falsework.Initial value of right-angle fastener's torsional stiffness was got from the right-angle fastener torsional stiffness test, under tightened torque by different bolts. And then the relationship between stiffness and initial blot tightening torque was established by two parameters logarithm nonlinear modal. A FEM was established to simulate the fastener-style tubular steel falsework. The FEM result was compared with the test result to ensure numerical analysis method of fastener-style tubular steel falsework. Based on the above methods, the impact of stability capacity that the built parameter acts on the oval structure's formwork bracket was found out.Hold the actual project for example, introduced the construction scheme of oval structure's formwork system in details. Using conventional non-destructive stress measurement method for formwork system of this project in field test, to compare and analyze each testing points of stress-time curve under the formwork system, and find out the distribution and variation rule under formwork and its supporting system in processing of construction. The results show that, in the process of pouring the concrete into formwork, face-plate of hyperbolic oval shaped large steel formwork makes greater deformation than vertical fin, and vertical fin made greater deformation than transverse rib, to prove transverse rib own better carrying capacity, and proved it is rational design of the formwork. Vertical fin of formwork transfers load to diagonal bracing,and then diagonal bracing transfers load to circumference horizontal bars directly , after horizontal bars transfer the load to upright, then, most of the load be moved to the upright that connect with circumference horizontal bars, the upright will transfer the load by steps from bottom to top, and a small part of the load and spread around the bars,radial horizontal bar forced weakly, the mainly force is taken by circumference horizontal bars and upright. In processing of construction, part of bars get into uninstalling situation and short duration. in the process of pouring the concrete into formwork, the pouring concrete can be a variable load with some impact force,load's acting effect can be decline soon in the bars. The changing of interior force between formwork and bars during vibration of concrete pouring, however the changing is not palpable, so that it can be ignored in calculating. Support calculation of the relevant existing specification are uniform rectangular frame determined by the vertical load test, the stress values from field test and simulation are greater than the design.