Research

20 pages, 6027 KiB

Open AccessArticle

3D Numerical Analysis Method for Simulating Collapse Behavior of RC Structures by Hybrid FEM/DEM

by Gyeongjo Min, Daisuke Fukuda and Sangho Cho

Appl. Sci. 2022, 12(6), 3073; https://doi.org/10.3390/app12063073 - 17 Mar 2022

Cited by 6 | Viewed by 1825

Recent years have seen an increase in demand for the demolition of obsolete and potentially hazardous structures, including reinforced concrete (RC) structures, using blasting techniques. However, because the risk of failure is significantly higher when applying blasting to demolish RC structures than mechanical [...] Read more.

Recent years have seen an increase in demand for the demolition of obsolete and potentially hazardous structures, including reinforced concrete (RC) structures, using blasting techniques. However, because the risk of failure is significantly higher when applying blasting to demolish RC structures than mechanical dismantling, it is critical to achieve the optimal demolition design and conditions using blasting by taking into account the major factors affecting a structure’s demolition. To this end, numerical analysis techniques have frequently been used to simulate the progressive failure resulting in the collapse of structures. In this study, the three-dimensional (3D) combined finite discrete element method (FDEM), which is accelerated by a parallel computation technique incorporating a general-purpose graphics processing unit (GPGPU), was coupled with the one-dimensional (1D) reinforcing bar (rebar) model as a numerical simulation tool for simulating the process of RC structure demolition by blasting. Three-point bending tests on the RC beams were simulated to validate the developed 3D FDEM code, including the calibration of 3D FDEM input parameters to simulate the concrete fracture in the RC beam accurately. The effect of the elements size for the concrete part on the RC beam’s fracture process was also discussed. Then, the developed 3D FDEM code was used to model the blasting demolition of a small-scale RC structure. The numerical simulation results for the progressive collapse of the RC structure were compared to the actual experimental results and found to be highly consistent. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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18 pages, 5042 KiB

Open AccessArticle

A Dynamic Procedure for Time and Space Domain Based on Differential Cubature Principle

by Qiang Xu, Hongjing Li and Yuchen Mei

Appl. Sci. 2022, 12(6), 2832; https://doi.org/10.3390/app12062832 - 10 Mar 2022

Viewed by 1406

Abstract

Based on the differential cubature (DC) principle, a dynamic procedure for simultaneous discretization of time and space is developed. A spatial–temporal differential cubature analysis method for dynamic problems is established with the Timoshenko shear beam; the reliability of analysis results obtained by which [...] Read more.

Based on the differential cubature (DC) principle, a dynamic procedure for simultaneous discretization of time and space is developed. A spatial–temporal differential cubature analysis method for dynamic problems is established with the Timoshenko shear beam; the reliability of analysis results obtained by which is verified, and the stability of the numerical scheme is studied. This method is extended to the two-dimensional structure, and the forced vibration analysis is carried out with the thin plate as an example. The research shows that the method can acquire highly accurate numerical results, and the calculated time-history numerical solution of beam displacement is extremely consistent with the analytical solution, which can adopt to the changes in beam properties and load parameters. With fewer nodes and longer time step than the finite element method (FEM), the method in this paper can still obtain stable and accurate results when solving displacement responses of plate under forced vibration. The numerical stability of this method is closely related to the grid form and the size of time step, and the increase in the number of nodes in the time domain is conducive to increasing the stability range. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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11 pages, 2800 KiB

Open AccessArticle

Non-Linear Analysis of Structures Utilizing Load-Discretization of Stiffness Matrix Method with Coordinate Update

by Najmadeen Saeed, Ahmed Manguri, Marcin Szczepanski and Robert Jankowski

Appl. Sci. 2022, 12(5), 2394; https://doi.org/10.3390/app12052394 - 25 Feb 2022

Cited by 2 | Viewed by 1720

Abstract

This paper proposes a stiffness method based structural analysis algorithm for geometrically non-linear structures. In this study, the applied load on the joints has been discretized to a sequence of a few loadings applied. Each loading step produces incremental external nodal displacements, which [...] Read more.

This paper proposes a stiffness method based structural analysis algorithm for geometrically non-linear structures. In this study, the applied load on the joints has been discretized to a sequence of a few loadings applied. Each loading step produces incremental external nodal displacements, which are added to the corresponding coordinates to get a new geometrical shape of the structure. This process is iteratively repeated until the sum of the loading of all iterations matches the total initial applied loading. The size of the increments affects the technique’s accuracy, subsequently affecting the number of iterations. The configuration of non-linear geometrical structures is vital in the work; a slight change of the coordinates makes a considerable variation of nodal displacements. In this paper, three pin-jointed assemblies and a cantilever beam have been examined using the proposed technique; significantly reasonable outcomes emerged, compared to the non-linear approaches, such as Dynamic Relaxation Method (DRM) and Non-linear approach by Kwan. In a numerical sense, the dissimilarity between the results of the conventional Stiffness Matrix (SM) method and the non-linear method is about 228%, while the maximum discrepancy between the proposed approach and the non-linear methods is just above 15%. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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15 pages, 18780 KiB

Open AccessArticle

A Finite Element Study on Compressive Resistance Degradation of Square and Circular Steel Braces under Axial Cyclic Loading

by Hubdar Hussain, Xiangyu Gao and Anqi Shi

Appl. Sci. 2021, 11(13), 6094; https://doi.org/10.3390/app11136094 - 30 Jun 2021

Cited by 1 | Viewed by 1572

Abstract

In this study, detailed finite element analysis was conducted to examine the seismic performance of square and circular hollow steel braces under axial cyclic loading. Finite element models of braces were constructed using ABAQUS finite element analysis (FEA) software and validated with experimental [...] Read more.

In this study, detailed finite element analysis was conducted to examine the seismic performance of square and circular hollow steel braces under axial cyclic loading. Finite element models of braces were constructed using ABAQUS finite element analysis (FEA) software and validated with experimental results from previous papers to expand the specimen’s matrix. The influences of cross-section shape, slenderness ratio, and width/diameter-to-thickness ratio on hysteretic behavior and compressive-tensile strength degradation were studied. Simulation results of parametric studies show that both square and circular hollow braces have a better cyclic performance with smaller slenderness and width/diameter-to-thickness ratios, and their compressive-tensile resistances ratio significantly decreases from cycle to cycle after the occurrence of the global buckling of braces. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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21 pages, 1615 KiB

Open AccessArticle

Estimation of the Mechanical Parameters for a Reduced Coupled Flexural–Torsional Beam Model of a Tall Building by a Sub-Structure Approach

by Federico Cluni, Stefano Fiorucci, Vittorio Gusella and Massimiliano Gioffrè

Appl. Sci. 2021, 11(10), 4655; https://doi.org/10.3390/app11104655 - 19 May 2021

Cited by 2 | Viewed by 1567

Abstract

The use of equivalent beam models to estimate the dynamical characteristics of complex tall buildings has been investigated by several authors. The main reason is the structural response estimation to stochastic loads, such as wind and earthquake, using a reduced number of degrees [...] Read more.

The use of equivalent beam models to estimate the dynamical characteristics of complex tall buildings has been investigated by several authors. The main reason is the structural response estimation to stochastic loads, such as wind and earthquake, using a reduced number of degrees of freedom, which reduces the computational costs and therefore gives the designer an effective tool to explore a number of possible structural solutions. In this paper, a novel approach to calibrate the mechanical and dynamical features of a complete 3D Timoshenko beam, i.e., describing bending, shear and torsional behavior, is proposed. This approach is based on explicitly considering the sub-structures of the tall building. In particular, the frames, shear walls and lattice sub-systems are modeled as equivalent beams, constrained by means of rigid diaphragms at different floors. The overall dynamic features of the tall building are obtained by equating the deformation energy of an equivalent sandwich beam with that of the selected sub-structures. Finally, the 3D Timoshenko equivalent beam parameters are calibrated by minimizing a suitable function of modal natural frequencies and static displacements. The closed form modal solution of the equivalent beam model is used to obtain the response to stochastic loads. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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18 pages, 4580 KiB

Open AccessArticle

Simplified Numerical Analysis of Soil–Structure Systems Subjected to Monotonically Increasing Lateral Load

by Adriana Brandis, Ivan Kraus and Simon Petrovčič

Appl. Sci. 2021, 11(9), 4219; https://doi.org/10.3390/app11094219 - 06 May 2021

Cited by 5 | Viewed by 2270

Abstract

Numerical modelling of the soil in seismic design of structures is always a daunting task. The goal of this article is to develop a simplistic numerical modelling technique for shallow founded buildings on compliant soils. An existing large-scale experimental research (TRISEE) was used [...] Read more.

Numerical modelling of the soil in seismic design of structures is always a daunting task. The goal of this article is to develop a simplistic numerical modelling technique for shallow founded buildings on compliant soils. An existing large-scale experimental research (TRISEE) was used for calibration. The physical model comprised of a rigid square foundation placed on a sand bed connected to a rigid column and was subjected to a dynamic sine loading. The results from the TRISEE experiment are well known and commonly used by researchers in this field, yet none of the numerical studies were conducted considering the loose sand case. Nonlinear link elements and linear springs were used for representing the soil. It was determined that the soil behavior is highly influenced by the stiffness, selected hysteresis model, and the p-y curve. Considering the software limitations, numerical models represent the experimental behavior in a good manner. Based on the results obtained from the experiment, a case study on a steel frame building with SSI effects included was conducted. Considering the results from this research, the authors recommend implementation of SSI effects into the building’s design phase since they exhibit unfavorable impacts on the seismic behavior and can lead to underdesigned structural elements. However, it has to be emphasized that certain limitations exist due to simplified modelling approaches that were used for this research. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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12 pages, 6850 KiB

Open AccessArticle

On the Influence of the Vertical Earthquake Component on Structural Responses of High-Rise Buildings Isolated with Double Friction Pendulum Bearings

by Phuong Hoa Hoang, Hoang Nam Phan and Van Nam Nguyen

Appl. Sci. 2021, 11(9), 3809; https://doi.org/10.3390/app11093809 - 23 Apr 2021

Cited by 5 | Viewed by 2439

Abstract

The double friction pendulum (DFP) bearing is adapted from the well-known single friction pendulum (SFP) bearing. This type of bearings has been widely used for structural vibration controls. The main advantage of the DFP is its capacity to accommodate larger displacements as compared [...] Read more.

The double friction pendulum (DFP) bearing is adapted from the well-known single friction pendulum (SFP) bearing. This type of bearings has been widely used for structural vibration controls. The main advantage of the DFP is its capacity to accommodate larger displacements as compared with the SFP one. This paper aims to assess the effect of the vertical earthquake component on the seismic behaviour of a base-isolated high-rise building. In this respect, the mathematical model of the building subjected to earthquake excitations with an implementation of a DFP bearing system is established. The model presented herein considers earthquake excitations in horizontal (X and Y) and vertical (Z) directions. A series model of two friction elements is presented for the bearing, where the friction load of the bearing surface is governed by a modified Bouc-Wen model, which is dependent on the sliding velocity and the contact pressure. The numerical results of an example of a base-isolated 9-story steel building subjected to near-source and far-field earthquakes show the high effectiveness of the bearing system in reduction of the seismic response of the building, especially in the near-source region, as well as exhibit considerable effectiveness of the vertical earthquake component on the bearing and structural behaviour. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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13 pages, 1521 KiB

Open AccessFeature PaperArticle

Nonlinear Dynamic Analysis of Seismically Base-Isolated Structures by a Novel OpenSees Hysteretic Material Model

by Nicoló Vaiana, Raffaele Capuano, Salvatore Sessa, Francesco Marmo and Luciano Rosati

Appl. Sci. 2021, 11(3), 900; https://doi.org/10.3390/app11030900 - 20 Jan 2021

Cited by 34 | Viewed by 4184

Abstract

The complex response characterizing elastomeric isolation bearings is reproduced by employing a novel uniaxial hysteretic model that has been recently formulated and successfully implemented in OpenSees. Such a novel OpenSees material model offers several advantages with respect to differential models typically available in [...] Read more.

The complex response characterizing elastomeric isolation bearings is reproduced by employing a novel uniaxial hysteretic model that has been recently formulated and successfully implemented in OpenSees. Such a novel OpenSees material model offers several advantages with respect to differential models typically available in commercial software products for structural analysis, such as 3D-BASIS and CSi programs. Firstly, it is based on a set of only five model parameters that have a clear mechanical significance; such a property not only allows one to drastically simplify the parameters identification process, but it also allows the model to be used in practice. In addition, the model does not require numerical methods for the evaluation of the restoring force since the latter is computed by solving an algebraic equation. To encourage researchers and designers to adopt the proposed model for research and practical purposes, we demonstrate its accuracy by performing some numerical tests in OpenSees. In particular, we first employ the recently implemented model to compute the nonlinear dynamic response of a seismically base-isolated structure with elastomeric bearings and, subsequently, we compare the results with those obtained by modeling the seismic isolators with the OpenSees BoucWen uniaxial material model, that is one of the most popular and accurate hysteretic models currently available in OpenSees. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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18 pages, 3729 KiB

Open AccessArticle

Damping Estimation of an Eight-Story Steel Building Equipped with Oil Dampers

by Pengchao Yang, Songtao Xue, Liyu Xie and Miao Cao

Appl. Sci. 2020, 10(24), 8989; https://doi.org/10.3390/app10248989 - 16 Dec 2020

Cited by 2 | Viewed by 2042

Abstract

The damping estimation of an eight-story steel building equipped with oil dampers is examined, carried out by adopting a proposed framework, which consists of an enhanced strain-energy method and an improved direct method for model updating. The building is located at Tohoku Institute [...] Read more.

The damping estimation of an eight-story steel building equipped with oil dampers is examined, carried out by adopting a proposed framework, which consists of an enhanced strain-energy method and an improved direct method for model updating. The building is located at Tohoku Institute of Technology and is equipped with a structural monitoring system that measures its seismic response, including floor acceleration and displacement and force of oil dampers. The enhanced strain-energy method is first developed and employed to assess the supplemental damping and stiffness provided by oil dampers, herein quantified in the form of equivalent damping ratios and natural frequencies. Then, modal characteristics extracted from the earthquake measurements are modified accordingly and utilized for the building model updating, in which mass and stiffness matrices are corrected by the improved direct method. The updated model accurately reproduces the target modal data, especially measured mode participation factors, and is further used for the building response predictions. Through prediction validations, the precision of the modified modal parameters is verified. Finally, a large earthquake event is chosen to demonstrate the effectiveness of the proposed framework for the damping estimation of the investigated building. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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21 pages, 9726 KiB

Open AccessArticle

Lining Fatigue Test and Influence Zoning of Tridimensional Cross-Tunnel under High-Speed Train Loads

by Weichao Yang, E Deng, Chenghua Shi, Ning Liu, Ruizhen Fei and Huan Yue

Appl. Sci. 2020, 10(16), 5694; https://doi.org/10.3390/app10165694 - 17 Aug 2020

Cited by 5 | Viewed by 1819

Abstract

Tridimensional cross tunnels usually manifest the vulnerable components of a high-speed railway caused by the sophistication of the structural pattern and the continuous shock from the train. The frequent defect of tunnel lining at the intersection would affect the safe operation of the [...] Read more.

Tridimensional cross tunnels usually manifest the vulnerable components of a high-speed railway caused by the sophistication of the structural pattern and the continuous shock from the train. The frequent defect of tunnel lining at the intersection would affect the safe operation of the two rails. As a result, attention has been paid to fatigue damage caused by the long-term dynamic load from a running train, in order to ensure the safety and serviceability of the cross tunnel lining. However, an influence zoning method with respect to tunnel crossing for the direct estimation of whether the lining structure is damaged due to the train load, and to what extent, is unavailable. In this paper, a systematic study that consists of numerical simulation and fatigue damage experiment is conducted to develop an approximate method to enable practicing engineers to evaluate reasonable design parameters. The initial static stress, which corresponds to the static tensile stress of secondary lining under the stratum load, and the maximum dynamic stress, which refers to the maximum dynamic tensile stress under the train load, are estimated according to the numerical simulation. A simplified damage evolution model and its parameters are identified on the basis of a systematic fatigue damage experiment. Finally, the influence zoning method is conducted on the basis of two criteria, namely (1) that initial stress level should not exceed 0.6, and (2) that load cycles should not exceed N = 2 × 10⁶ times. Thus, the practicing parameters during the cross tunnel design, such as surrounding rock mass, cross angle, rock pillar thickness between two tunnels, and train speed can be utilized conveniently by using the proposed calculation charts, according to the identification of initial stress level and the magnitude of dynamic stresses caused by the train load. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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19 pages, 6734 KiB

Open AccessArticle

Response Characteristics of Cross Tunnel Lining under Dynamic Train Load

by Ang Wang, Chenghua Shi, Chenyang Zhao, E Deng, Weichao Yang and Hong He

Appl. Sci. 2020, 10(12), 4406; https://doi.org/10.3390/app10124406 - 26 Jun 2020

Cited by 10 | Viewed by 2654

Abstract

The crossing area is a vulnerable component of the interchange high-speed railway tunnel because of the high-static stress level and the long-term dynamic train load in the operation period. Although attention has been paid to this problem, the response characteristics of high-speed railway [...] Read more.

The crossing area is a vulnerable component of the interchange high-speed railway tunnel because of the high-static stress level and the long-term dynamic train load in the operation period. Although attention has been paid to this problem, the response characteristics of high-speed railway tunnel lining at the cross position under the dynamic train load may still need further research as very little investigation is available on this issue at present. In this paper, the initial stress state and dynamic response characteristics of tunnel lining were studied using the three-dimensional finite element method. Furthermore, the damage evolutionary characteristics of the tunnel inverted arch under dynamic and initial static loads were researched using a set of self-developed indoor fatigue test devices. The size of the test box is 400 × 300 × 250 mm (length × width × height). Numerical simulation results indicate that the displacement and stress levels of tunnel lining are very high at the cross position. The stress increment of tunnel lining due to the dynamic train load is more likely to induce a break in the tunnel lining at this position. The indoor fatigue tests reveal that the change of structural strain increment amplitude and strain ratio is obvious when the dynamic load stress level is higher. It is better for dynamic stress levels not to exceed 0.6 times of structural tensile strength to avoid the tunnel lining being damaged in the long-time service period. The initial static load has an influence on the tunnel inverted arch, and the static stress level should be lower than 0.65 times of structural tensile strength to ensure the tunnel has long-time serviceability. This paper provides a reference for the future design of new cross tunnels and the operation safety evaluation and disease regulation of existing high-speed railway tunnels. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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15 pages, 9397 KiB

Open AccessArticle

Identification and Model Update of the Dynamic Properties of the San Silvestro Belfry in L’Aquila and Estimation of Bell’s Dynamic Actions

by Angelo Aloisio, Ilaria Capanna, Riccardo Cirella, Rocco Alaggio, Franco Di Fabio and Massimo Fragiacomo

Appl. Sci. 2020, 10(12), 4289; https://doi.org/10.3390/app10124289 - 22 Jun 2020

Cited by 18 | Viewed by 1921

Abstract

The authors investigated the dynamic behaviour of the San Silvestro belfry in L’Aquila (Italy). The 2009 earthquake in L’Aquila caused severe damages to the entire masonry complex. Extensive rehabilitation works, ended in 2019, repaired the structure and enhanced its seismic safety. In this [...] Read more.

The authors investigated the dynamic behaviour of the San Silvestro belfry in L’Aquila (Italy). The 2009 earthquake in L’Aquila caused severe damages to the entire masonry complex. Extensive rehabilitation works, ended in 2019, repaired the structure and enhanced its seismic safety. In this paper, the authors discuss three aspects typical of masonry towers by interpreting the outcomes of Operational Modal Analysis carried out on December 2019: the interactions between the tower and the masonry complex, the dynamic effects of the bell, and the seismic reliability assessment of the tower. Specifically, the experimental mode shapes drive the estimation of an equivalent cross-section, whose principal axes of inertia match with the directions of oscillation of the mode shapes, and the parameters of an equivalent cantilevered beam roughly representative of the tower dynamics. In a second step, a two-degrees-of-freedom analytical model simulates the dynamic coupling between the tower and the more massive bell. The response of the system to a set of seven strong-motion earthquakes yields the assessment of the bell effects over the seismic performance of the masonry tower. Full article

(This article belongs to the Special Issue Dynamics of Building Structures)

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