Studies on recent earthquakes highlighted that buildings with minimal structural damage still suffer from extensive damage and failure of nonstructural components. The dropping and damage of suspended ceiling systems, which typically consist of acceleration-sensitive nonstructural elements, resulted in lengthy functional disruptions and extended recovery time. This article experimentally and analytically examined the vibration properties of an integrated ceiling system considering the interactions with surrounding electrical equipment. The theoretical stiffness and corresponding frequency of electrical equipment were initially derived and then verified by subsequent vibration tests and numerical analyses. The seismic performance of the air conditioner (AC) was evaluated with different installment configurations based on design spectra and floor response spectra. Vibration tests of the suspended integrated ceiling system considering the interactions with surrounding equipment showed that the inclusion of peripheral constraints increased the first horizontal vibration frequency of the ceiling system by a factor of approximately 6. The natural frequencies of all components in the integrated ceiling system were almost identical, which was attributed to the coupled behavior between the ceiling panels and surrounding equipment, emphasizing the effect of interactions between adjacent components during dynamic analysis. Based on the above experimental investigation, an associated numerical model of the integrated ceiling system was created. Finally, corresponding parametric studies that included the interactions with surrounding equipment, reinforcing braces of ACs and strengthening members at the rise-up location between two elevations were performed. 相似文献
The transfer and evolution of stress among rock blocks directly change the void ratios of crushed rock masses and affect the flow of methane in coal mine gobs. In this study, a Lagrange framework and a discrete element method, along with the soft-sphere model and EDEM numerical software, were used. The compaction processes of rock blocks with diameters of 0.6, 0.8, and 1.0 m were simulated with the degrees of compression set at 0%, 5%, 10%, 15%, 20%, and 25%. This study examines the influence of stress on void ratios of compacted crushed rock masses in coal mine gobs. The results showed that stress was mainly transmitted downward through strong force chains. As the degree of compression increased, the strong force chains extended downward, which resulted in the stress at the upper rock mass to become significantly higher than that at the lower rock mass. It was determined that under different degrees of compression, the rock mass of coal mine gobs could be divided, from the bottom to the top, into a lower insufficient compression zone (ICZ) and an upper sufficient compression zone (SCZ). From bottom to top, the void ratios in the ICZ sharply decreased and those in the SCZ slowly decreased. Void ratios in the ICZ were 1.2–1.7 times higher than those in the SCZ.
Over the past 30 years, reclamation projects and related changes have impacted the hydrodynamics and sediment transport in the Bohai Sea. Three-dimensional tidal current models of the Bohai Sea and the Yellow Sea were constructed using the MIKE 3 model. We used a refined grid to simulate and analyze the effects of changes in coastline, depth, topography, reclamation, the Yellow River estuary, and coastal erosion on tidal systems, tide levels, tidal currents, residual currents, and tidal fluxes. The simulation results show that the relative change in the amplitude of the half-day tide is greater than that of the full-day tide. The changes in the tidal amplitudes of M2, S2, K1, and O1 caused by coastline changes accounted for 27.76–99.07% of the overall change in amplitude from 1987 to 2016, and water depth changes accounted for 0.93–72.24% of the overall change. The dominant factor driving coastline changes is reclamation, accounting for 99.55–99.91% of the amplitude changes in tidal waves, followed by coastal erosion, accounting for 0.05–0.40% of the tidal wave amplitude changes. The contribution of changes in the Yellow River estuary to tidal wave amplitude changes is small, accounting for 0.01–0.12% of the amplitude change factor. The change in the highest tide level (HTL) is mainly related to the amplitude change, and the correlation with the phase change is small. The dominant factor responsible for the change in the HTL is the tide amplitude change in M2, followed by S2, whereas the influence of the K1 and O1 tides on the change in the HTL is small. Reclamation resulted in a decrease in the vertical average maximum flow velocity (VVAM) in the Bohai Sea. Shallower water depths have led to an increase in the VVAM; deeper water depths have led to a decrease in the maximum flow velocity. The absolute value of the maximum flow velocity gradually decreases from the surface to the bottom, but the relative change value is basically constant. The changes in the tidal dynamics of the Bohai Sea are proportional to the degree of change in the coastline. The maximum and minimum changes in the tidal flux appear in Laizhou Bay (P-LZB) and Liaodong Bay (P-LDB), respectively. The changes in the tidal flux are related to the change in the area of the bay. Due to the reduced tidal flux, the water exchange capacity of the Bohai Sea has decreased, impacting the ecological environment of the Bohai Sea. Strictly controlling the scale of reclamation are important measures for reducing the decline in the water exchange capacity of the Bohai Sea and the deterioration of its ecological environment. 相似文献
正Dear Members of the Editorial Board,Contributors and Friends,2018 is the tenth anniversary of the Wenchuan earthquake disaster.To commemorate the Wenchuan earthquake disaster,the journal of Earthquake Engineering and Engineering Vibration(EEEV)will publish special sections with invited papers in the issues of 2018(January,April and July).We sincerely appreciate the contributions from the following experts:Professor Xilin Lu,Professor Michel Bruneau,Professor Baitao Sun,and Professor Gian Paolo Cimellaro. 相似文献