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Despite the complexity of real earthquake motions, the incident wavefield excitation for soil-structure interaction (SSI) analysis is conventionally derived from one-dimensional site response analysis (1D SRA), resulting in idealized, decoupled vertically incident shear and compressional waves for the horizontal and vertical components of the wavefield, respectively. Recent studies have revealed potentially significant deviation of the 1D free-field predictions from the actual three-dimensional (3D) site response and obtained physical insights into the mechanistic deficiencies of this simplified approach. Particularly, when applied to vertical motion estimation, 1D SRA can lead to consistent overprediction due to the refraction of inclined S waves in the actual wavefield that is not correctly accounted for in the idealized vertical P wave propagation model. However, in addition to the free-field site response, seismic demands on structures and non-structural components are also influenced by the dynamic characteristics of the structure and SSI effects. The extent to which the utilization of vertically propagating waves influences the structural system response is currently not well understood. With the recent realization of high-performance broadband physics-based 3D ground motion simulations, this study evaluates the impact of incident wavefield modeling on SSI analysis of representative building structures based on two essential ingredients: (1) realistic spatially dense simulated ground motions in shallow sedimentary basins as the reference incident motions for the local SSI model and (2) high-fidelity direct modeling of the soil-structure system that fully honors the complexity of the incident seismic waves. Numerical models for a suite of archetypal two-dimensional (2D) multi-story building frames were developed to study their seismic response under the following incident wavefield modeling conditions: (1) SSI models with reference incident waves from the 3D earthquake simulation, (2) SSI models with idealized vertically incident waves based on 1D SRA, and (3) conventional fixed-base models with base translational motions from 1D SRA. The impact of these modeling choices on various structural and non-structural demands is investigated and contrasted. The results show that, for the horizontal direction, the free-field linear and nonlinear site amplification and subsequent dynamic filtering of the base motions within the structure can be reasonably captured by the assumed vertically propagating shear waves. This leads to generally fair agreements for structural demands controlled by horizontal motions, including peak inter-story drifts and yielding of structural components. In contrast, vertical seismic demands on structures are overpredicted in most cases when using the 1D wavefields and can result in exacerbated structural damage. Special attention should be given to the potentially severe vertical floor accelerations predicted by the 1D approach due to the combined effects of fictitious free-field site amplification and significant vertical dynamic amplification along the building height. This can pose unrealistic challenges to seismic certification of acceleration-sensitive secondary equipment necessary for structural and operational functionality and containment barrier design of critical infrastructures. It is also demonstrated that vertical SSI effects can be more significant than those in the horizontal direction due to the large vertical structural stiffness and should be considered in vertical floor acceleration assessments, especially for massive high-rise buildings.

期刊论文 2025-07-01 DOI: 10.1002/eqe.4350 ISSN: 0098-8847

Smart weeding machine is an important tool for control of farmland weeds. To solve the high power consumption, low weeding rate, and high seedling damage rate of existing smart weeding machine in wheat fields, a power consumption model was established for the weed-soil- machine interactions process and a hob-type smart weeding machine of wheat fields was designed. The cutting-edge angle, roller radius, number of hob blades, and hob blade thickness were separately 20 degrees, 85 mm, 8, and 2 mm. A three-dimensional (3-d) structural model of the hob-type smart weeding machine was established on ProE and the operation process of the smart weeding machine's actuator was dynamically simulated in the discrete element method environment. On this basis, changes in performance indices including the operating width, operating depth, soil-throwing width, accumulation thickness, and average power consumption during the operation were investigated. Field tests of the hobtype smart weeding machine show that the operation width is 202.8 mm, which covers the inter-row area in wheat fields; the operation depth is 36 mm, at which roots of most weeds in wheat fields can be cut or pulled out; the soil-throwing width is 304.2 mm and the accumulation thickness is not higher than 20 mm, which is much lower than the height of wheat plants in the tillering stage. The average power during operation is 197.70 W, the weeding rate is 98.93 % and the seedling damage rate is 4.35 %. Compared to existing weeding machines reported, when the weed removal rates are similar, the power consumption of the weeding actuator developed in this study for wheat fields is reduced by approximately 54 %. On the premise of a comparable seedling damage rate, the weeding rate is increased by approximately 10 %, demonstrating notable characteristics of low power consumption and high efficiency.

期刊论文 2024-12-01 DOI: 10.1016/j.compag.2024.109519 ISSN: 0168-1699

This study addresses the critical need to understand the seismic behavior of cable-stayed bridges under Multi-Support Excitation (MSE) in order to mitigate earthquake-induced damage to these structures. The primary focus is on the investigation of response amplification phenomena and their seismic implications for cable-stayed bridges. Through a detailed comparative analysis of MSE and Synchronous Excitation (SE) across various structural locations, the study evaluates the impact of site-specific recorded ground motions of different earthquake categories. A pragmatic framework is developed to simulate realistic MSE ground motions for diverse earthquake scenarios, emphasizing the necessity of considering MSE in bridge design. The findings reveal a significant amplification of the design requirements due to antisymmetric mode excitation and increased tower and pier motions. The study also identified the need for in-depth analysis of cable-stayed bridges to address the increased vulnerability of tower-adjacent areas and to devise targeted reinforcement strategies of vulnerable components. These insights are critical for advancing seismic design practices and improving the resilience of cable-stayed bridges, contributing to safer urban infrastructure.

期刊论文 2024-12-01 DOI: 10.1177/13694332241281523 ISSN: 1369-4332

The effects of evolutionary Arias intensity are thoroughly investigated based on ground motion simulation and nonlinear dynamic response. A new methodology is developed to generate a series of spectral-equivalent synthetic motions with different energy accumulation paths using wavelet packets. Systematic studies are performed on dynamic responses of hysteretic systems and liquefiable grounds using the simulated motions and actual recordings. An attempt is made to develop the relationship between liquefaction-induced deformation and shaking intensity rate which is used to quantify the rate of Arias intensity accumulation. The results indicate the need of considering evolutionary Arias intensity in nonlinear dynamic analysis.

期刊论文 2024-06-10 DOI: 10.1080/13632469.2023.2296633 ISSN: 1363-2469
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