Spatial Finite Element Model Research Articles

Study on the Application of Determinant-MTMD(TMDD) Vibration Reduction in Cable-Supported Pedestrian Suspension Bridge

In this study, multiple tuned mass dampers (MTMDs) were studied to understand their impact on the human-induced vibration response and comfort level of a pedestrian cable-supported suspension bridge. A spatial finite element model based on a specific engineering case was established. The dynamic characteristics of the bridge under human-induced loads were investigated, and its comfort level under human-induced vibrations was analyzed using the time-history method. Then, this study adjusted the design parameters of the dampers based on various optimal damper parameter expressions. Furthermore, the damping effectiveness of MTMD under different mass ratios (μ) was evaluated, and it was found that increasing the mass ratio significantly impacts damping performance. Finally, determinant-TMD (TMDD) was introduced, and a comparison between the damping effect, robustness, and performance of TMDD and MTMD was conducted. The results indicate that while increasing the mass ratio does not linearly affect maximum vibration acceleration, the damping effect increases initially and then stabilizes, with a damping rate converging at approximately 55%. However, with the TMDD approach, the maximum damping rate can reach approximately 70%, enhancing comfort levels from the “minimum CL3” achieved with MTMD to the “medium CL2” level. Additionally, while TMDD’s robustness is slightly inferior to MTMD at lower mass ratios, it demonstrates superior robustness at higher mass ratios.

Research on topology optimization strut-and-tie model and prestress construction for cable-pylon anchorage zone of Fengshuba Bridge

To address the challenges associated with accurate load-bearing capacity calculation and prestress design for the cable-pylon anchorage zone of cable-stayed bridges, a case study focusing on the Fengshuba Bridge is conducted. Utilizing the Solid Isotropic Material with Penalization (SIMP) variable density topology optimization method, a strut-and-tie model (STM) is constructed for the cable-pylon anchorage zone. This model is subsequently employed to verify load-bearing capacity of the struts and nodes within the cable-pylon anchorage zone, as well as to calculate the required quantity of circumferential prestressing tendons. Additionally, a spatial segmental finite element model is established for the cable-pylon anchorage zone to perform a detailed analysis of prestressed structural optimization. This analysis determines various structural details, including the arrangement of prestressing tendons along the height, the design for prestressing blind zones, and the quantity of prestressing tendons. Subsequently, the optimized model is subjected to stress verification. The research results indicate that the adoption of dispersed tendon arrangement results in reduced principal tensile stress within the cable-pylon anchorage zone, in contrast to the concentrated tendon arrangement. The introduction of short prestressing steel bundles within the conduit of prestressing blind zones uniformly enhances the pre-compressive stress on the cable-pylon side wall. Due to the Poisson effect of materials, it is necessary to arrange prestressing tendons appropriately within the cable-pylon anchorage zone. Arranging prestressing steel bundles according to the proposed STM and structural optimization method adequately fulfills the structural force requirements of the cable-pylon anchorage zone.

The use of planar and three-dimensional calculation models for the numerical modeling of retaining walls in conditions of dense urban construction

In modern realities, the construction of multi-story buildings increasingly has to be carried out in the conditions of dense urban development. Since high-rise buildings are characterized by the presence of deep pits, there is a need to select the parameters of the enclosing structures (retaining walls) and take into account the influence of the pit arrangement and enclosing structures on the existing building. Numerical simulation of the stress-strain state (SSS) of the elements "soil base - existing structures - pit enclosure" was performed to assess the impact of choosing the dimensions of the calculation scheme when designing a deep pit and assessing its impact on existing buildings and selecting effective parameters of enclosing structures. with different dimension options (flat two-dimensional and spatial three-dimensional) calculation scheme. Modeling was performed using the finite element method using a nonlinear model of soil deformation in the Plaxis software package. Since the soil conditions within the construction site are complex (the presence of a significant layer of plastic and flowing clay soils and powerful aquifers), the level of groundwater within the construction site was taken into account in the modeling and the effect of water lowering during the development of the pit was modeled accordingly for a more correct assessment of the stress-strained state of pit enclosure elements and the impact on existing structures. Numerical calculations of retaining walls provide for taking into account the technological sequence of the construction of retaining walls and modeling of the step-by-step development of the pit. Studies have shown that the use of a spatial finite-element model of the system "soil base - existing structures - pit enclosure" provides an opportunity to more correctly and effectively assess the stress-deformed state of system elements due to taking into account the spatial rigidity of the elements of the pit enclosure and the foundations of existing structures. The values of the displacements of the retaining walls obtained by the calculation of the spatial finite element model (FEM) are 20% smaller than the values obtained using the plane FEM. The values of the bending moments obtained by the calculation of the spatial FEM are 10% smaller than the values obtained using the plane FEM.

Dynamic model of high-speed maglev train-guideway bridge system with a nonlinear suspension controller

To improve the anti-interference ability of maglev trains, a dynamic model of the high-speed maglev train with a nonlinear suspension controller for the guideway system is proposed in this paper. Based on the nonlinear characteristics of the magnetic suspension system, a nonlinear decoupling controller is designed using the feedback linearization theory. Then, a high-speed maglev train model is refined with a guideway coupling system, consisting of a maglev train simulated as a multi-body dynamics model with 537 degrees of freedom and a spatial finite element model of the guideway. Taking the Shanghai high-speed maglev train as an example, the correctness of the computational model is verified by comparing the modeling results with field measurement data, and the control effectiveness of the nonlinear controllers and the traditional PD controllers is compared considering different train speeds and disturbance forces. The results show that the suspension gap under the decoupling control is smaller than that under the PD control during the train operations. Under the same disturbance force, the decoupling control exhibits better control performance than the PD control. The variation amplitudes of the magnetic pole gaps are generally linearly related to the disturbance force.

Stress-strain states of reinforced concrete spans of a railroad overpass using a spatial finite element model

The paper presents the results of computational analysis of the stress-strain state of reinforced concrete spans of the railway (single-track railway line) overpass over the highway, under specified loads using spatial finite element models. The static load consists of a cohesion of three TEM-18 diesel locomotives and two loaded gondola cars (up to 25 tons per axle). The purpose of this study was to ensure reliable and safe operation of artificial structures on the railroads, as there is a constant increase in transit freight trains from China through the territory of Kazakhstan to near and far abroad, and often the load on the axle reaches 25 tons, and sometimes larger values – up to 27 tons per axle. The results of the study are recommended to be used for inspections and tests of typical girder bridge spans, as well as in the case of monitoring their technical condition with increasing operational loads.

Design and Treatment Case Analysis of Continuous T-beam External Prestressed Composite Reinforcement Based on Finite Element Model Calculation

The second section of a highway bridge is a 3×30m prestressed concrete continuous T-beam, of which the 5th span 4# T-beam was found to have multiple structural cracks, such as U-shaped cracks and vertical cracks, during regular inspections after one year of operation. Analysis has shown that this was attributed to the fact that the insufficient prestressing during construction caused inadequate prestressing in the beam body. In this sudy, Midas/Civil software is utilized to establish a spatial finite element model to estimate the loss of prestress in damaged T-beams, yielding results consistent with the inspected conditions. On this basis, an external prestressing reinforcement design plan is proposed. The innovative plan considers the impact of reinforcement on the hogging moment of continuous T-beams and optimizes the layout of prestressed steel strands. The layout and fixing methods of steel turning blocks and anchoring blocks are also optimized in accordance with the stress characteristics of continuous T-beams, with the bearing capacity and safety reserve improved. After checking and analyzing the crack width of the reinforced T-beam, it was found that the plan fully meets the requirements for prestressed concrete Class A components. According to plan, the damaged T-beam was repaired and reinforced, and continuous observation of the reinforced T-beam was conducted for two years. No new development of bridge defects was observed in the later stages, indicating a satisfactory reinforcement effect. This provides technical reference for similar projects.

Clinker storage silos: Validation of dynamic performance through measurements and finite element simulation

The paper describes the design and application of a structural health monitoring system aimed at analysing the dynamic response of reinforced concrete silos for the storage of clinker. The in-situ dynamic measurements, supported by finite element simulations to assess the structural safety, were prompted by reports from people working in facilities near the silos in question, who complained of strong vibrations. The proposed approach combines the advantages of theoretical and operational modal analysis based on monitoring during normal use of the silos, including their emptying. The measurements were performed automatically and continuously over time, and only significant events, like shocks caused by clinker masses falling off the side walls of the silos, were saved into the remote server as the acceleration-time waveforms. They were registered with 4000 Hz frequency by piezoelectric accelerometers mounted on the bottom of the silos within the support structure. The data management system with predefined post-processing algorithms allow to extract dynamic parameters of the structure, which were then used to validate the spatial finite element model (FEM). What is worth underlying, the analysis took into account different degrees of filling of the silos, as these directly affect the dynamics of the structure. The results described hereafter were the basis for providing expertise on structural safety. The presented case study is an example of how automatic monitoring over a specified period of time can assist engineers in making rational decisions.

Анализ результатов натурных и расчетных исследований прочности и устойчивости каменно-набросной плотины Богучанской ГЭС с прогнозированием ее состояния

The results of complex field and computational studies of the strength and stability of the stone-fill dam of the Boguchanskaya HPP are presented. The purpose of the work is a comprehensive assessment of the state of the stone-fill dam of the Boguchanskaya HPP, including forecasting its condition. An analysis of the data of field observations was carried out, which showed a number of differences from the design prerequisites. Analysis of the data on precipitation and horizontal displacements of the marks installed on the berms of the lower thrust prism of the SFD of the Boguchanskaya HPP showed that they are not extinguished. On the basis of the developed and calibrated spatial permanent finite element model, comprehensive computational studies of the stress-strain state of the stone-fill dam of the Boguchanskaya HPP were carried out (including the sections in which the highest precipitation and horizontal displacements of the marks installed on the berms of the lower thrust prism of the stone-fill dam were recorded), taking into account the data of field observations, including deviations from the project. Calculations showed that with the actual of the stability factor of the lower slope was 1.32‑1.33, which exceeds the standard value of 1.25. At the stage of forecasting the state of the stone-fill dam of the Boguchanskaya HPP for the period up to 2040, the estimated value of the stability factor of the lower slope may be 1.25, which is equal to standard value (i.e. the margin is minimal). At present, the stability of the lower slope of the stone-fill dam is ensured, despite the deviations of the actual dimensions of the profile of the stone-fill dam from the design values. With further growth of sediment, as well as horizontal displacements of marks installed on the berms of the lower thrust prism, the stability of the lower slope of the stone-fill dam may change.

Расчеты напряженно-деформированного состояния сопряжения бетонной и каменно-набросной плотин Богучанской ГЭС

The conjugation interface of the concrete dam with the rock-fill dam is the most critical section of the pressure front of the Boguchanskaya HPP. The most important feature of the Boguchanskaya HPP is the presence of an impervious element – an asphalt concrete diaphragm, which is made using a special technology from a cast hydraulic asphalt concrete mixture laid in a heated state. The safety of the pressure front of the hydroelectric complex depends on the condition of the junction of the asphalt concrete diaphragm with section No. 34 of the concrete dam (including the condition of the contact joint between them). After the beginning of filling the reservoir in 2012, the opening of the contact joint between the ABD and section No. 34 of the concrete dam was recorded, and the settlement of the ABD relative to section No. 34 of the concrete dam was also noted. At present, the opening of the contact seam and the settlement cannot be called stabilized. The aim of the research is to determine the computational stress-strain state of the conjugation between the concrete and rock-fill dams of the Boguchanskaya HPP. On the basis of a spatial finite element model of the conjunction of a concrete dam with a rock-fill dam, taking into account the data of field observations and deviations from the design prerequisites, calculations of the stress-strain state were performed. The results of the calculations showed that the controlled values do not exceed the criterion values.

Numerical Modeling of Cutting Characteristics during Short Hole Drilling: Modeling of Kinetic Characteristics

Analyzing the cutting process characteristics opens up significant opportunities to improve various material machining processes. Numerical modeling is a well-established, powerful technique for determining various characteristics of cutting processes. The developed spatial finite element model of short hole drilling is used to determine the kinetic characteristics of the machining process, in particular, the components of cutting force and cutting power. To determine the component model parameters for the numerical model of drilling, the constitutive equation parameters, and the parameters of the contact interaction between the drill and the machined material on the example of AISI 1045 steel machining, the orthogonal cutting process was used. These parameters are determined using the inverse method. The DOE (Design of Experiment) sensitivity analysis was applied as a procedure for determining the component models parameters, which is realized by multiple simulations using the developed spatial FEM model of orthogonal cutting and the subsequent determination of generalized values of the required parameters by finding the intersection of the individual value sets of these parameters. The target values for the DOE analysis were experimentally determined kinetic characteristics of the orthogonal cutting process. The constitutive equation and contact interaction parameters were used to simulate the short hole drilling process. The comparison of experimentally determined and simulated values of the kinetic characteristics of the drilling process for a significant range of cutting speed and drill feed changes has established their satisfactory coincidence. The simulated value deviation from the corresponding measured characteristics in the whole range of cutting speed and drill feed variation did not exceed 23%.

Compaction of the snow base of Vostok station wintering complex

The compaction of the snow base of the wintering complex under construction of the Russian Antarctic station “Vostok” is considered, which was required due to the unsuitability of the natural snow base for the perception of loads from the supports of the foundation of the wintering complex. Technical solutions were developed for snow base compaction on the basis of heating by solar radiation with the use of thermal mat and on the basis of snow vacuuming. The computational justification of the developed technical solutions was performed, which was carried out based on spatial finite element models using the computational software complex ANSYS. In this case, to substantiate the method of snow base compaction by solar radiation heating with the use of thermal mat, the calculated volume was analyzed, including the snow base zone, thermal mat and the space filled with air. When substantiating the method of snow base compaction by snow vacuuming, there was explored the calculation area for modeling the method of vacuuming for the hermetic volume of the excavation pit with immersed columns under the wintering complex foundation supports. The results of the of the calculated research have fully confirmed the assumptions laid down in the technical solutions for compaction of the wintering complex snow base by using of thermal mat and snow vacuuming.

Research on Dynamic Response of a Single-Tower Cable-Stayed Bridge with Successive Cable Breaks Based on a 3D Index

Aiming at the problem of cable breakage of an asymmetric single-tower cable-stayed bridge by taking a single-tower cable-stayed bridge that has been in operation for more than 20 years as an engineering example, a spatial finite element model that reflected the actual stress state of the structure was established and a method for solving the time point of cable breakage was proposed. The results show that the strength of the main girder, pylon and cable could meet the stress requirements of the vibration caused by successive cable breaks, and the maximum dynamic displacement of the main girder did not exceed the stiffness limit. Although the breakage of the stay cable caused the stress in the adjacent position and the corresponding position on the opposite side of the tower to increase sharply, the stress fluctuation in other positions was small. The fluctuation of the dynamic stress of the cable tower was relatively small, but the displacement of the tower top changed greatly. The dynamic response of the cables breaking in succession was less than that of simultaneous breaking, and the structural vibration caused by cable breaking was not as severe as that caused by simultaneous breaking.

A finite element approach to the numerical solutions of Leland’s model

In this paper, finite element method is applied to Leland’s model for numerical simulation of option pricing with transaction costs. Spatial finite element models based on P1 and/or P2 elements are formulated in combination with a Crank–Nicolson-type temporal scheme. The temporal scheme is implemented using the Rannacher approach. Examples with several sets of parameter values are presented and compared with finite difference results in the literature. Spatial–temporal mesh-size ratios are observed for controlling the stability of our method. Our results compare favourably with the finite difference results in the literature for the model.

Human-Induced Vibration Analysis and Reduction Design for Super Long Span Pedestrian Arch Bridges with Tuned Mass Dampers

With the increasing demands on span length, aesthetics, and urban landscapes of pedestrian bridges, the fundamental frequency of pedestrian bridges is continuing to decrease, and their vibration and walking comfort issues are becoming increasingly prominent. The pedestrian load model of the pedestrian bridge was introduced here referencing current design specifications, and a spatial finite element model was established to study the dynamic characteristics of the case of a long-span pedestrian arch bridge. The comfort of the bridge under human-induced vibration was analyzed using the time history analysis method. According to the optimal damper parameter expression, the design parameters of the damper were obtained. In addition, the vibration reduction effects of different generalized mass ratios were analyzed, and the damping effects of setting the tuned mass damper (TMD) at different positions were compared. The results indicated that setting the TMD on the bridge can enhance the damping effect, and the transverse vibration can be suppressed by setting TMDs on both the arch ribs and the bridge deck. The research content could provide recommended parameters for the vibration reduction design of long-span pedestrian arch bridges.

Research on Optimal Arch Rib Inclination of Large Span Highway CFST through Arch Bridge

To investigate the reasonable range of the inclination angle of arch ribs, a spatial finite element method was employed based on a concrete-filled steel tube (CFST) basket-handle through an arch bridge with a span of 360 m. A spatial finite element model was established using Midas/Civil software, which was verified with actual bridge data. The effects of different arch rib inclination angles were investigated under static loads. The structural natural frequencies, linear elastic stability coefficients, internal forces, and displacements were comprehensively considered to determine the reasonable range of the inclination angle. The results show that when the inclination angle ranges between 8° and 10°, the first, third, and sixth natural frequencies of the structure are increased. It effectively improves the lateral and torsional stiffness of the arch ribs while ensuring optimal out-of-plane stability of the arch ribs. Compared with the parallel arch, the stability is improved by 20.2%. The effects of angle variation on displacement and internal force of the arch ribs were not significant. Considering all indicators, the optimal range of the inclination angle for the arch ribs of 300-m-level highway CFST arch bridges is suggested to be 8~10°.

Dynamic Response Analysis of Orthotropic Saturated Subgrade-Pavement Slab

Based on the Kirchhoff thin plate theory, a three-dimensional spatial mechanical model of the subgrade pavement with an infinite elastic plate on the orthotropic saturated foundation in the rectangular coordinate system is established, and the differential equations under a moving harmonic load are derived. The partial differential equations are solved by using coordinate transform and Fourier transform, and the analytical solutions of the dynamic responses of the plate and foundation are obtained. A three-dimensional spatial finite element model of subgrade-pavement is established by ABAQUS finite element software. The correctness of the method is verified by comparing the theoretical solution with the finite element solution. The influence of foundation parameters on plate displacement and vertical normal stress of soil is further studied. The results show that considering the orthogonal anisotropy of saturated soil, the dynamic response of subgrade-pavement slab interaction can be described more accurately.

Information Modeling of the Administrative Multi-Storey Building Frame Reconstruction

Introduction. The present study is targeting the problem of choosing construction solutions for strengthening the frame of a reconstructed multi-storey administrative building. The object of the study is the former Council of Ministers building in the town of Sukhum, Republic of Abkhazia.Materials and methods. During the examination of the building under study, instrumental and visual inspection methods were implemented, which revealed the significant deflection of the roof slab and of two supporting steel beams, as well as emergence of cracks in the load bearing structures and the destruction of partitions. According to the results of examination the dimensional-planning drawings and a structures’ defects list were elaborated. A spatial finite element model of the building was developed in the LIRA-SAPR software package, taking into account the developed dimensionalplanning solutions for the reconstruction of the facility under study. Loads and impacts were set taking into account the requirements of relevant design standards. The detected defects of the structures’ elements were considered.Results. The dynamic calculation of the building frame by finite element method is carried out. The calculation results analysis has shown that all three forms of oscillations are torsional, which proves the structural solutions of the building frame to be complex and requires additional calculations to ensure reliability of construction solutions. The building frame dynamic loads are set taking into account the requirements for buildings with a complex structure frame. The results of the general static calculation has shown that the load-bearing structures of a building are in operating state except for the roof slab.Discussion and Conclusions. Based on the results of a numerical experiment on modeling the operation of the roof slab, the rational solutions for its reconstruction have been developed, recommendations on considering the seismic impacts on the reconstructed building frame of the Council of Ministers have been given.

Influence of the soil base on the stress-strain state of a large-span building with a cylinder-and-slab roof

The authors consider finite element models of a large-span building with a cylinder-and-slab roof as a large spatial mechanical system with different boundary conditions. The first model represents the superstructure of the building with a fixed-end at the soil base level. In the second model, the superstructure is based on the substructure, which includes a pile foundation and a soil base with different physical and mechanical properties. The purpose of the study is a comparative numerical analysis of the stress-strain state of a large-span building with different boundary conditions. The numerical study revealed the influence of the structural features of the substructure of the building, as well as the physical and mechanical properties of the soil base on the stress-strain state of the long-span roof and the building as a whole. Numerical static analysis of spatial finite element models of a large-span building was carried out in the СAE class Femap NX Nastran software package. The results of the static analysis demonstrated a significant structural influence of the substructure of a large-span building on the characteristics of its stress-strain state. In the next article, it is proposed to conduct a modal analysis for these building models.

CRITICAL ANALYSIS OF APPROACHES TO DETERMINING THE STRESS-STRAIN STATE OF THE "HORIZONTAL WORKING – LAYERED MASSIF" SYSTEM

Purpose. To perform a critical analysis of approaches to determining the stress-strain state of the "horizontal working – layered massif" system. Obtain informed decisions for applying a specific approach to the case of a layered massif. To substantiate the metric of finite element models of the system "horizontal working – layered massif". Methodology. To achieve the purpose, the peculiarities of approaches to determining the stress-strain state of the system "horizontal working – rock massif" were analyzed. It has been proven that layering is the most important structural feature of the surrounding rock massif. A detailed analysis of mathematical methods for solving elastic-plastic problems for rock massifs was performed. Findings. During the analysis of solving the problem of determining the stress-strain state of the system "horizontal working – layered massif", two approaches were identified, each of which has its own set of methods. These approaches are analytical one and numerical, each of them has special features. It has been confirmed that recently the studies of the system "horizontal working - rock massif" are mostly based on the numerical approach, leaving only a small share of the total volume to the analytical one. It was determined that the introduction of numerical methods, in particular, the method of finite elements in specialized software complexes, allowed to change the concept of research in geomechanics and mechanics of underground structures, shifting the focus to mathematical and simulation modeling. Originality. Based on the results of the critical analysis of the approaches, the use of numerical analysis based on finite-element models is scientifically substantiated. It is this approach to determining the stress-strain state of the "horizontal working – layered massif" system that allows for layering to be taken into account without additional assumptions. Practical value. In the course of research, it has been proven that a spatial finite-element model from a flat prototype, but limited to a thickness of 0.1 or 1 m, is adequate for the given task, provided that plane deformation is considered.

Spatial variability and stochastic finite element model of unreinforced masonry veneer wall system under Out-of-plane loading

Inconsistency in the quality of workmanship, the weather during construction, and materials may result in the high unit-to-unit spatial variability of mechanical properties in the same masonry structure. This paper develops a numerical modelling strategy and focuses on the stochastic assessment of unreinforced masonry (URM) veneer walls with spatially variable wall constituent material properties subjected to out-of-plane loading. 3-D finite element modelling of experimentally tested veneer walls was conducted using a micro-modelling approach combined with the Monte Carlo Simulation technique. Spatial stochastic finite element analysis considered the spatial variability of the properties of the wall components (mortar flexural tensile strength) and compared them with non-spatial analysis. The non-spatial analysis overestimates the wall system failure compared to spatial analysis, and the spatial analysis is considered to more realistically represent the variabilities of the URM veneer wall system. Sensitivity analysis is conducted to check the sensitivity of the veneer system behaviour to variability in the various input parameters. The variability of experimental results obtained in a parallel study are quantified and compared with stochastic finite element analysis (SFEA) results. The SFEA model developed in this study can estimate the behaviour and system peak load reasonably and are considered to be from the similar population as test results. Model errors are also included to assess the efficiency of the SFEA model.