A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase w...A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase with the increase in the prestressing force at the tensioning stage, and the natural frequencies decrease after the cracks occur in the beams. Following the calculation formula of natural frequency of externally prestressed beam, which was reported in a literature, the natural frequencies of the experimental beams are calculated, and big errors are found between the test results and the calculated ones of natural frequency values. As a result, this paper has tried to adopt two methods to correct the rigidity parameter of the concrete beam in the formula for natural frequency calculation, and to use the corrected formula to calculate the frequencies of the experimental beams. The calculation results indicate a good consistency with the experimental ones, which verifies the feasibility of the corrected formula.展开更多
Analyses and computations of the natural frequencies of external prestressed concrete structures are the bases for studying the dynamic properties of such structures. We carded out dynamic tests on three types of exte...Analyses and computations of the natural frequencies of external prestressed concrete structures are the bases for studying the dynamic properties of such structures. We carded out dynamic tests on three types of external simply supported beams, pulling the beams gradually. Then vertical loads were applied to the beams while the frequencies and related coefficients were measured at every step. We calculated natural frequencies and the results indicate that natural frequencies increase as the prestressing force rises in the pre-crack stage, and decrease significantly during the post-crack stage. Substantial incoincidences exist between the calculated and experimental results for the frequency and its tendency to changel Based on the experimental results, we modified the stiffness and other parameters in the equations. The results calculated using the modified equations agree with experimental results well, so the modified eauations can be used nractically.展开更多
基金supported by the National Natural Science Foundation of China (No.50808090)
文摘A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase with the increase in the prestressing force at the tensioning stage, and the natural frequencies decrease after the cracks occur in the beams. Following the calculation formula of natural frequency of externally prestressed beam, which was reported in a literature, the natural frequencies of the experimental beams are calculated, and big errors are found between the test results and the calculated ones of natural frequency values. As a result, this paper has tried to adopt two methods to correct the rigidity parameter of the concrete beam in the formula for natural frequency calculation, and to use the corrected formula to calculate the frequencies of the experimental beams. The calculation results indicate a good consistency with the experimental ones, which verifies the feasibility of the corrected formula.
基金Funded by the National Science Foundation of China (No. 50808090)
文摘Analyses and computations of the natural frequencies of external prestressed concrete structures are the bases for studying the dynamic properties of such structures. We carded out dynamic tests on three types of external simply supported beams, pulling the beams gradually. Then vertical loads were applied to the beams while the frequencies and related coefficients were measured at every step. We calculated natural frequencies and the results indicate that natural frequencies increase as the prestressing force rises in the pre-crack stage, and decrease significantly during the post-crack stage. Substantial incoincidences exist between the calculated and experimental results for the frequency and its tendency to changel Based on the experimental results, we modified the stiffness and other parameters in the equations. The results calculated using the modified equations agree with experimental results well, so the modified eauations can be used nractically.
