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Ancient masonry pagodas hold significant scientific, historical, and cultural importance. However, due to the complexity of masonry materials, structures, and boundary conditions, establishing finite element static and dynamic models for ancient masonry pagodas is highly challenging. This study aimed to explore the dynamic characteristics and finite element numerical simulation methods of ancient masonry pagodas in Yongzhou, Hunan province. It focused on the Huilong Pagoda in Yongzhou, where in situ test experiments under natural excitation are conducted. The SSI and NExT-ERA methods were employed to determine the ancient pagoda's natural frequencies, vibration patterns, and damping ratios, and to validate the NExT-ERA method. The macroscopic numerical model of the Huilong Pagoda was calibrated using measured results. Subsequently, the NExT-ERA identification results were compared and analyzed with the numerical simulation results of the dynamic characteristics. The results indicate that the first three orders of natural frequencies for the ancient pagoda in the east–west direction are 1.937 Hz, 6.802 Hz, and 21.361 Hz, respectively. Similarly, the first three orders of natural frequencies in the north–south direction are 1.935 Hz, 7.439 Hz, and 21.398 Hz. The results obtained from both methods revealed that the overall structural damping ratio ranges from 0.21% to 2.89%. The numerical model was analyzed using ANSYS, and the first three orders of natural frequencies obtained were highly consistent with the measured values, exhibiting a maximum relative error of 8.54%. The numerical simulation method developed in this study can effectively simulate masonry pagodas. [ABSTRACT FROM AUTHOR]

This study investigates the vibration response and dynamic characteristics of the Shigudeng Pavilion under environmental excitation, employing a comprehensive approach that includes vibration response measurements, theoretical analysis, and finite element numerical simulation. An in-depth examination of the appearance and stress status of the Shigudeng Pavilion in Yao Ancient Village in southern Hunan was conducted, and the horizontal acceleration of different floors of the pavilion under environmental excitation was ascertained through field measurements. The NExT-ERA method was utilized to identify the modal parameters (frequency, damping ratio, and vibration pattern) of the measured timber construction. Subsequently, a finite element analysis model of the ancient timber building was developed and refined using ANSYS Workbench finite element software. This study proposes a specific repair plan addressing apparent defects and structural damage in the measured ancient timber building, offering theoretical and technical references for the conservation and repair of similar structures. [ABSTRACT FROM AUTHOR]

To investigate the differences in cadmium (Cd) and lead (Pb) uptake and translocation among rape cultivars and genotypes and select suitable rape cultivars for both safe production and soil remediation, a field experiment was carried out with 39 rape cultivars of three genotypes on a farmland polluted with Cd and Pb in eastern Hunan Province, China. The Cd and Pb contents in rape tissues were measured, and the amount of Cd and Pb removed was calculated. The results showed that Cd in rape plants accumulated mostly in stems, while Pb accumulated mostly in roots. The Cd accumulation in various rape tissues followed the sequence stem > root > husk > rapeseed, while the Pb accumulation followed the sequence root > stem > husk > rapeseed. The total Cd and Pb removed by planting rape were 4.50–23.6 g ha−1 and 5.85–13.7 g ha−1, respectively, and the Cd and Pb contents in rapeseeds were in the range 0.11–0.47 mg kg−1 and 0.03–0.84 mg kg−1, respectively. Only the Pb content in rapeseed of "Youyan 9" exceeded the limit of the maximum levels of contaminants in foods (GB2762-2017, Pb ≤ 0.2 mg kg−1). In this experiment, the roots of most rape cultivars showed a greater capacity for Cd transport, while the stems showed a greater capacity for Pb transport. Except for the TFstem-husk for Cd, there were no significant differences in the TFs and BAFs of 39 rape cultivars, and clear variations in Cd content were found in the stems of the three genotypes, while there was no significant difference in the Cd and Pb contents in the other tissues. In the farmland polluted with Cd and Pb, planting "Xiangzayou 695" and "Youyan 2013" not only reduced soil pollution but also allowed the production of safe rapeseed. [ABSTRACT FROM AUTHOR]