Current Issue : October-December Volume : 2023 Issue Number : 4 Articles : 5 Articles
A stochastic earthquake ground motion database comprising twelve groups of simulated ground motions was introduced. Ground motions were generated using the stochastic semi-physical model of earthquake ground motions, based on a cluster analysis of 7778 recorded earthquake ground motion. All twelve groups of simulated earthquake ground motions were validated through the probability density evolution method (PDEM) by comparing their time histories and response spectra. As an application of the proposed database, an 18-story reinforced concrete (RC) frame-shear wall structure was analyzed using one group of simulated earthquake ground motions. The probability densities of the top displacement of the structure were estimated using PDEM, highlighting the significant stochasticity of the structural response. The seismic reliability of the structure was assessed by evaluating the extreme value distribution of the story drift angle. The investigations indicate that the proposed stochastic earthquake ground motion database effectively captures the inherent stochasticity of ground motions. Moreover, it contributes to enhancing the efficiency of reliability assessments for structures....
A D bolt, an energy-absorbing rock bolt, is a smooth steel bar with a number of anchors along its length.Theanchors, which can be spaced evenly or unevenly along its length, are firmly fixed within a borehole using either cement grout or resin, while the smooth sections of the bolt between the anchors may freely deform in response to rock dilation. A series of numerical simulations have been conducted using the finite difference method to investigate the effects of D bolt on the displacement increase of rock mass around a roadway in comparison with normal fully encapsulated rebar. As a result, the displacement of 49mm at the top of roadway roof in the D bolts supported model is much larger than 30.08mm in the fully encapsulated rebar bolts supported model so that the former is capable of absorbing potential deformation energy of rock mass around a roadway to tolerate the large deformation of rock. Plans of spacing arrangement of D bolt’s anchor have a significant effect on stress redistribution of the bolt. The numerical simulation result shows that for the D bolt with its whole length of 2.4 m, the length of its exposed section of 0.1 m, and the 4 anchors with the length of 0.1 m, the maximum tensile stress of 3.25 GPa generated in the D bolt with the ratio of the spacing between anchors (RSA) of 30 : 40 : 50 : 70 is lower about 1.13–1.31 times than the other D bolts with different ratio of spacing, and the changing range of stress is also the smallest, where the ratio of 30 : 40 : 50 : 70 indicates a ratio of lengths of deformable sections which is determined by turns from the innermost section of rock mass around roadway to the outermost section of roadway space. This study demonstrates that it is reasonable to employ the RSA of D bolt which makes it bring out its energy-absorbing capability to the full....
Undoubtedly, heritage buildings serve as essential embodiments of the cultural richness and diversity of the world’s states, and their conservation is of the utmost importance. Specifically, the protection of the structural integrity of these buildings is highly relevant not only because of the buildings themselves but also because they often contain precious artworks, such as sculptures, paintings, and frescoes. When a disaster causes damage to heritage buildings, these artworks will likely be damaged, resulting in the loss of historical and artistic materials and an intangible loss of memory and identity for people. To preserve heritage buildings, state-of-the-art recommendations inspired by the Venice Charter of 1964 suggest real-time monitoring of the progressive damage of existing structures, avoiding massive interventions, and providing immediate action in the case of a disaster. The most up-to-date digital information and analysis technologies, such as digital twins, can be employed to fulfil this approach. The implementation of the digital twin paradigm can be crucial in developing a preventive approach for built cultural heritage conservation, considering its key features of continuous data exchange with the physical system and predictive analysis. This paper presents a comprehensive overview of the digital twin concept in the architecture, engineering, construction, and operation (AECO) domain. It also critically discusses some applications within the context of preserving the structural integrity of architectural heritage, with a particular emphasis on masonry structures. Finally, a prototype of the digital twin paradigm for the preservation of heritage buildings’ structural integrity is proposed....
This paper presents a numerical study on the thermal effect of the insulation of lightweight concrete in hybrid GFRP-concrete structures. In these hybrid structures, the GFRP profiles are totally covered by normal and lightweight concrete and subjected to thermal loads. The problem with GFRP structures is their weak thermal resistance, even at moderately high temperatures. To promote some thermal insulation, it is recommended to cover the GFRP profile with concrete, but this increases its weight. Therefore, lightweight concrete may be a good solution due to its insulation capabilities. For this study, the thermal loads used in the numerical campaign are based on a nominal fire-curved ISO-834, and the temperature is measured at several points. Using these temperatures, it is possible to conclude that the effect of lightweight concrete may provide structural benefits when compared with classical standard structural concrete for covering GFRP profiles using different cover values (from 5.0 cm to 2.5 cm). For this work, commercial finite element software was used for the thermal nonlinear analysis. It was possible to conclude that with lightweight concrete, it is likely to have half of the cover and still maintain the same level of insulation as regular concrete....
Driven by the aesthetic pursuit of the urban landscape, pedestrian bridges become longer, lighter, and slender, which may be susceptible to unacceptable vibrations induced by human activities. This paper presented on-site vibration tests of a pedestrian bridge with a very low height-to-span ratio (1/60). The vibration characteristics and dynamic responses were analyzed using environmental, heel-drop, and walking tests. Then, a verified finite model was established to investigate the effect of the heightto- span ratio and the concrete filling ranges of tree-like steel piers on the vibration characteristics and acceleration responses of this kind of pedestrian bridges. Moreover, the relationship between different peak accelerations under heel-drop and walking at various frequencies by the same person was detailed and studied experimentally and by computer simulation, after which the ratios of the peak acceleration during walking and the one under heel-drop were recommended. Finally, a method that demonstrates the feasibility of predicting the peak acceleration of pedestrian bridges of a small height-to-span ratio across a range of walking frequencies was proposed based on a simplified heel-drop load model developed according to 60 time-history records....
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