Calibration of the stiffness of atomic force microscope (AFM) cantilevers is critical for industry and academic research. The multi-position calibration method for AFM cantilevers based on vibration is investigated. The position providing minimum uncertainty is deduced. The validity of the multi-position approach is shown via theoretical and experimental means. We applied it to the recently developed vibration method using an AFM cantilever with a normal stiffness of 0.1 N m−1. The standard deviation of the measured stiffness is 0.002 N m−1 with a mean value of 0.189 N m−1 and the relative combined uncertainty is approximately 7%, which is better than the approach using the single position at the tip of the cantilever.
Compared with other template construction technology, jacking formwork system has the advantages of self-climbing, less operating personnel, good safety and good construction quality, with relatively innovative construction techniques and technology and has been widely used in the construction of tall buildings in recent years. The lifting principles and characteristics of jacking formwork were introduced in the paper. Based on the application in a tall building project, construction technologies of the formwork were introduced.
Jacking formwork system has been widely used in the construction of tall buildings and modularized low-position jacking steel platform formwork system is made up of several assembled and turnover subsystems, including steel truss platform system, steel columns supporting system, formwork and rack system, two-way-acting hydraulic jack and its control system.The paper described the application of the system in Fuzhou Yu Yang Central Golden Plaza Project and construction site monitoring were conducted. According to the site monitoring result, the performance of the jacking formwork system is further illustrated. In the end some suggestions were put forward to ensure construction safet .
Four formwork support units were experimental studied by heaping load,including three glass fiber mat reinforced thermo plastics (GMT) formwork support units and one 18mm plywood formwork support unit. Compared with 18mm plywood formwork support unit, the vertical poles force distribution in GMT formwork support units were analyzed. The experimental parameter also included vertical poles height difference and their values were follows: 0mm, 2mm and 4mm. The results showed that the vertical poles force distribution are uneven in GMT formwork support unit and vertical pole height differences have influence on their force distribution.
Design theory of high or large-span form strut system cann’t meet the engineering requirement and deficiencies were pointed out. In this paper, variation rule of axial force of the strut with the whole course of concrete pouring had been studied by measuring on three sites. The result discovered that pouring method and floor modes have significant effect on axial force of high or large-span form strut system. Compared to manual pouring, pumping lead to not only horizontal impact force but also vertical impact force. Compared to flat roof, axial force of avertical strut in sloping roof form strut system were more uneven and the maximal difference reached to 2 times. Axial force between bottom part and top part at avertical strut are different due to the influence of horizontal strut and crossing strut. Due to analysis result, some corresponding advices were put out in the end.
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