Current Issue : October-December Volume : 2022 Issue Number : 4 Articles : 5 Articles
The vibration induced by blasting excavation of the subway tunnel in complex urban environments may cause harmful effects on adjacent buildings. Investigating the dynamic response of adjacent buildings is a key issue to predict and control blasting hazards. In this paper, the blasting excavation of the subway tunnel right below a building was selected as a case study, and the blast vibrations in the field were monitored. The Hilbert–Huang Transform (HHT) model was used to extract and analyze the timefrequency characteristic parameters of blasting dynamic response signals. By substituting intrinsic mode functions (IMF) component frequency and instantaneous energy for main frequency and blasting total input energy, respectively, the characteristics of time-instantaneous frequency-instantaneous energy of buildings under blasting seismic load were analyzed, and the concept of effective duration of vibration was proposed....
Building structure health monitoring is essential for modern buildings, sensors related to building structure health monitoring are often made with microelectrostatic cantilever beam (MECB), and the performance of this kind of devices is often affected by instability, which affects the measurement results and accuracy. Therefore, it is necessary to study the nonlinear dynamic characteristics of the MECB in the process of bending and pull-in. In this paper, based on the energy principle and fluid pressure film damping effect, the dynamic equation mathematical model of MECB is established and then the dynamic characteristics of the pull-in and lift-off voltage of the MECB and the harmonic motion characteristics under the bias voltage are obtained, which provides guidance for the design of the electrostatic driving sensor....
This paper analyses the characteristics of the mechanical behavior of a trussed steel and concrete box beam under bending conditions based on the structural stressing state theory and the numerical shape function method. Firstly, the parametric generalized strain energy density was introduced to characterize the structural stressing state of trussed steel stud concrete box girders, and the strain energy density sum was plotted. Then the Mann-Kendall criterion was used to discriminate the leap point of the curve change and to redefine the structural failure load. By analyzing the strain and displacement, the existence of a sudden change in the structural response during the load-bearing process was again demonstrated. Afterwards, the numerical shape function method was used to extend the strain data, and further in-depth analyses of strain/stress fields and internal forces were carried out to show in detail the working characteristics of each under load. Through an in-depth analysis from different angles, the rationality of updating the failure load was verified. Finally, the effects of different structure parameters on the evolution of the structural stresses of the members were analyzed in a transversal comparison. The analysis results of the stress state of a steel-concrete truss structure reveal the working behavior characteristics of a steel-concrete truss structure from a new angle, which provides a reference for the design of a steel-concrete truss structure in the future....
In this paper, the losses caused by earthquake and the damage brought to engineering structures are firstly introduced. Then, the types of seismic damage of such structures are introduced with reinforced concrete frame structure as an example. Next, the seismic design methods of structures in domestic and foreign codes are summarized, mainly including seismic measures and seismic structural measures, and the types and applications of seismic shock absorption technology are further introduced. Finally, the effectiveness of the seismic shock absorption technology is verified by using the passive control method as an example....
In Italy, the interest in the industrial areas dates back to 1970, when industry began to be considered as identity and memory of the population, until 1990, when industrial constructions became cultural and historical goods. This interest was also justified by the necessity to recover these often‐abandoned sites through structural and seismic interventions. For this purpose, the cataloguing of the different industrial buildings in Italy was made by the Italian Consortium ReLUIS “Network of Seismic Engineering University Laboratories”, through the “Cartis Long Spans” form, to obtain indications on the seismic vulnerability of this built heritage. In the current paper, the seismic analysis and the combined seismic–energy retrofit of a former reinforced concrete tobacco factory in Cervinara, within the district of Avellino (Italy), were carried out. This work proposes a seismic retrofit intervention of the examined structure, erected at the end of the 1960s, based on the use of steel exoskeletons. The proposed intervention can be seen as a novel strategy for requalification of industrial buildings, as well as for regeneration and restoration of the value of industrial areas. It was shown that these devices allow a considerable increase of the seismic safety indices, which attain values significantly greater than 1, to reach the building retrofitting. Subsequently, a photovoltaic plant using high‐efficiency panels is proposed to provide the entire hub’s energy requirement. It was found that the annual production/square meterage of the building is between 20% and 60% lower than that of school and office buildings. As a whole, the analysis results demonstrated that exoskeletons are an effective intervention to improve the seismic features of the studied industrial building without neglecting architectural quality, sustainability, and environmental issues....
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