In this study, the broadband ground motions of the 2021 M7.4 Maduo earthquake were simulated to overcome the scarcity of ground motion recordings and the low resolution of macroseismic intensity map in sparsely populated high-altitude regions. The simulation was conducted with a hybrid methodology, combining a stochastic high-frequency simulation with a low-frequency ground motion simulation, from the regional 1-D velocity structure model and the Wang WM et al. (2022) source rupture model, respectively. We found that the three-component waveforms simulated for specific stations matched the waveforms recorded at those stations, in terms of amplitude, duration, and frequency content. The validation results demonstrate the ability of the hybrid simulation method to reproduce the main characteristics of the observed ground motions for the 2021 Maduo earthquake over a broad frequency range. Our simulations suggest that the official map of macroseismic intensity tends to overestimate shaking by one intensity unit. Comparisons of simulations with empirical ground motion models indicate generally good consistency between the simulated and empirically predicted intensity measures. The high-frequency components of ground motions were found to be more prominent, while the low-frequency components were not, which is unexpected for large earthquakes. Our simulations provide valuable insight into the effects of source complexity on the level and variability of the resulting ground motions. The acceleration and velocity time histories and corresponding response spectra were provided for selected representative sites where no records were available. The simulated results have important implications for evaluating the performance of engineering structures in the epicentral regions of this earthquake and for estimating seismic hazards in the Tibetan regions where no strong ground motion records are available for large earthquakes.
To reduce the incidence of safety accidents during the construction of all-steel-type attached lifting scaffolds and address the research gaps in related fields, in this study a theoretical model of trajectory crossing accidents was coupled with an analysis of similar safety accidents to determine the causes of accidents in the construction of high-rise buildings using steel-type attached lifting scaffolds. To do so, a safety evaluation index system covering all steel-type attached lifting scaffolds that comprises five first-level indicators and 17 second-level indicators was established. The first-level indicators cover three risk dimensions: unsafe human behavior (personal operations), unsafe conditions (material performance, structural calculation, components and connections), and lack of management (safety management). A combined multi-agent-based modeling (MABM) method and structural entropy weight were used to calculate a comprehensive weight for better alignment of the weight calculation results with objective laws. A safety assessment model for an all-steel-type attached lifting scaffolding was constructed using grey relative Euclidean weighted correlation theory to enable the calculation of a grey-to-Euclidean weighted correlation degree that directly correlates with the degree of security. Using the established assessment model, four projects were subjected to a safety evaluation, with the results validating the model by revealing that its output was consistent with the actual security situation.
To determine the winning bidder of renovation projects scientifically and reasonably, this paper constructs a bid evaluation model for renovation projects based on unascertained measure theory and the entropy weight method. According to the classification criteria of each index, a single-index unascertained measure function is constructed, and the unascertained measure of each index is calculated. The index weight is determined by the entropy weight method, the bid evaluation grade is determined by credible degree recognition criteria, superiority ranking is carried out, and the optimal result is obtained. Finally, an actual case study is used to verify the validity and practicability of the model. This case study shows that the model is an organic combination of the entropy weight method and unascertained measure theory and can provide a new idea for bid evaluation of renovation projects.
Abstract The displacement response of structures is an important parameter in structural health monitoring (SHM). Displacement responses can be applied in both structural performance monitoring and structural dynamic characteristics monitoring. To overcome the shortcomings of traditional contact sensors, a vision-based multi-point structural displacement measurement system equipped with an inexpensive surveillance camera and a consumer camera was developed herein. In addition, to reduce the computing time of target tracking, an improved region-matching algorithm based on the prior knowledge of structural deformation was proposed. Numerical results revealed that the improved region-matching algorithm could save computing time without reducing location accuracy. Moreover, static and dynamic loading tests were conducted on a scale model of a suspension bridge to validate the effectiveness of the proposed vision-based measurement system. Displacement responses and modal parameters obtained from the vision-based measurement system were compared with those of traditional contact sensors, and a satisfactory consistency was obtained. Hence, the proposed vision-based measurement system could be a cost-effective alternative to conventional displacement sensors and accelerometers for SHM.
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