Structural Engineering and Mechanics最新文献_第8页

Modal parameter estimation of civil structures based onimproved variational mode decomposition 基于改进变分模态分解的土木结构模态参数估计

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.79.6.683

L. Zhi, Feng Hu, Chunfeng Zhao, Jingfeng Wang

{"title":"Modal parameter estimation of civil structures based onimproved variational mode decomposition","authors":"L. Zhi, Feng Hu, Chunfeng Zhao, Jingfeng Wang","doi":"10.12989/SEM.2021.79.6.683","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.6.683","url":null,"abstract":"This paper proposes an improved variational mode decomposition (IVMD) algorithm for structural modal parameter estimation based on non-stationary responses. In this improved VMD, the mean envelope entropy (MEE) and particle swarm optimization (PSO) are first employed to determine the optimal decomposition parameters for the subsequent VMD analysis. Then the VMD algorithm is used to decompose the non-stationary data into a number of intrinsic mode functions (IMFs). After obtaining the IMFs based on the IVMD, structural modal parameters such as natural frequencies and damping ratios of civil structures can be determined by using Natural Excitation Technique (NExT) and Direct Interpolating approach (DI). The feasibility and accuracy of the proposed procedure are evaluated by both numerical and full-scale examples. The natural frequencies and damping ratios are successfully identified from the vibration responses with high noise and nonstationary characteristics. The results of this study illustrate that the proposed procedure provides a powerful approach to identify the modal parameters of civil structures using non-stationary responses.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"683"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66130484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Thermal frequency analysis of FG sandwich structure under variable temperature loading 变温载荷下FG夹层结构的热频率分析

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.77.1.057

Brundaban Sahoo, K. Mehar, Bamadev Sahoo, N. Sharma, S. Panda

{"title":"Thermal frequency analysis of FG sandwich structure under variable temperature loading","authors":"Brundaban Sahoo, K. Mehar, Bamadev Sahoo, N. Sharma, S. Panda","doi":"10.12989/SEM.2021.77.1.057","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.1.057","url":null,"abstract":"The thermal eigenvalue responses of the graded sandwich shell structure are evaluated numerically under the variable thermal loadings considering the temperature-dependent properties. The polynomial type rule-based sandwich panel model is derived using higher-order type kinematics considering the shear deformation in the framework of the equivalent single-layer theory. The frequency values are computed through an own home-made computer code (MATLAB environment) prepared using the finite element type higher-order formulation. The sandwich face-sheets and the metal core are discretized via isoparametric quadrilateral Lagrangian element. The model convergence is checked by solving the similar type published numerical examples in the open domain and extended for the comparison of natural frequencies to have the final confirmation of the model accuracy. Also, the influence of each variable structural parameter, i.e. the curvature ratios, core-face thickness ratios, end-support conditions, the power-law indices and sandwich types (symmetrical and unsymmetrical) on the thermal frequencies of FG sandwich curved shell panel model. The solutions are helping to bring out the necessary influence of one or more parameters on the frequencies. The effects of individual and the combined parameters as well as the temperature profiles (uniform, linear and nonlinear) are examined through several numerical examples, which affect the structural strength/stiffness values. The present study may help in designing the future graded structures which are under the influence of the variable temperature loading.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"57-74"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66119969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

Unified calculation model for the longitudinal fundamental frequency of continuous rigid frame bridge 连续刚构桥纵向基频统一计算模型

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.77.3.343

Yongjun Zhou, Yu Zhao, Jiangyuan Liu, Yuan Jing

{"title":"Unified calculation model for the longitudinal fundamental frequency of continuous rigid frame bridge","authors":"Yongjun Zhou, Yu Zhao, Jiangyuan Liu, Yuan Jing","doi":"10.12989/SEM.2021.77.3.343","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.3.343","url":null,"abstract":"The frequencies formulas of the bridge are of great importance in the design process since these formulas provide insight dynamic characteristics of the structure, which guides the designers to parametric analyses and the layout of the bridge in conceptual or preliminary design. Continuous rigid frame bridge is popular in the mountainous area. Mostly, this type of bridge was simplified either as a girder or cantilever when calculating the frequency, however, studies showed that the different configuration of the bridge made the problem more complex, and there is no unified fundamental calculation pattern for this kind of bridge. In this study, an empirical frequency equation is proposed as a function of pier's height, stiffness of pier and the weight of the structure. A unified fundamental frequency formula is presented based on the energy principle, then the typical continuous rigid frame bridge is investigated by finite element method (FEM) to study the dynamic characteristics of the structure, and then several key parameters are investigated on the effect of structural frequency. These parameters include the number, position and stiffness of the tie beam. Nonlinear regression analyses are conducted with a comprehensive statistical study from plenty of engineering structures. Finally, the proposed frequency equation is validated by field test results. The results show that the fundamental frequency of the continuous rigid frame bridge increases more than 15% when the tie beams are set, and it increases with the stiffness ratio of tie beam to pier. The results also show that the presented unified fundamental frequency has an error of 4.6% compared with the measured results. The investigation can predicate the approximate longitudinal fundamental frequency of continuous ridged frame bridge, which can provide reference for the seismic response and dynamic impact factor design of the pier.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"343-354"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66120827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimum stiffness values for impact element models to determine pounding forces between adjacent buildings 用于确定相邻建筑物之间冲击力的冲击单元模型的最佳刚度值

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.77.2.293

Yazan M. Jaradat, H. Far

{"title":"Optimum stiffness values for impact element models to determine pounding forces between adjacent buildings","authors":"Yazan M. Jaradat, H. Far","doi":"10.12989/SEM.2021.77.2.293","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.2.293","url":null,"abstract":"Structural failure due to seismic pounding between two adjacent buildings is one of the major concerns in the context of structural damage. Pounding between adjacent structures is a commonly observed phenomenon during major earthquakes. When modelling the structural response, stiffness of impact spring elements is considered to be one of the most important parameters when the impact force during collision of adjacent buildings is calculated. Determining valid and realistic stiffness values is essential in numerical simulations of pounding forces between adjacent buildings in order to achieve reasonable results. Several impact model stiffness values have been presented by various researchers to simulate pounding forces between adjacent structures. These values were mathematically calculated or estimated. In this study, a linear spring impact element model is used to simulate the pounding forces between two adjacent structures. An experimental model reported in literature was adopted to investigate the effect of different impact element stiffness k on the force intensity and number of impacts simulated by Finite Element (FE) analysis. Several numerical analyses have been conducted using SAP2000 and the collected results were used for further mathematical evaluations. The results of this study concluded the major factors that may actualise the stiffness value for impact element models. The number of impacts and the maximum impact force were found to be the core concept for finding the optimal range of stiffness values. For the experimental model investigated, the range of optimal stiffness values has also been presented and discussed.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"63 1","pages":"293-304"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66121076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Seismic response of torsional structures considering the possibility of diaphragm flexibility 考虑膜片挠性可能性的扭转结构地震反应

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.77.4.463

Hamed Eivani, A. S. Moghadam

{"title":"Seismic response of torsional structures considering the possibility of diaphragm flexibility","authors":"Hamed Eivani, A. S. Moghadam","doi":"10.12989/SEM.2021.77.4.463","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.4.463","url":null,"abstract":"Fully rigid floor diaphragm is one of the main assumptions that are widely used in common practices due to its simple application. However, determining the exact degree of diaphragms flexibility cannot be easily accomplished without finite element modeling, which is an expensive and time-consuming procedure. Therefore, it is always possible that apparently rigid diaphragms, based on prescriptive limitations of seismic codes, experience some degrees of flexibility during the earthquakes. Since diaphragm flexibility has more uncertainties in asymmetric-plan structures, this study focuses on errors resulting from probable floor diaphragm flexibility of torsionally restrained structures. The analytical models used in this study were single-story buildings with asymmetric plan and RC shear walls. Although floor system is not considered explicitly, a wide range of considered diaphragm flexibility, from fully rigid to quite flexible, allows the results to be generalizable to a lot of lateral load resisting systems as well as floor systems. It has been shown that in addition to previously known effects of diaphragm flexibility, presence of orthogonal side elements during design procedure with rigid diaphragm assumption and rapid reduction in their absorbed forces can also be an important source to increase errors due to flexibility. Accordingly, from the obtained results the authors suggest designers to consider the possibility of diaphragm flexibility and its adverse effects, especially in torsionally restrained systems in their common designs.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"463-472"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66121443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nonlocal effects on propagation of waves in a generalized thermoelastic solid half space 广义热弹性固体半空间中波传播的非局部效应

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.77.4.473

Baljeet Singh, R. Bijarnia

{"title":"Nonlocal effects on propagation of waves in a generalized thermoelastic solid half space","authors":"Baljeet Singh, R. Bijarnia","doi":"10.12989/SEM.2021.77.4.473","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.4.473","url":null,"abstract":"The propagation of plane waves in a linear, homogeneous and isotropic nonlocal generalized thermoelastic solid medium is considered in the framework of Lord and Shulman generalization. The governing field equations are formulated and specialized in a plane. Plane wave solutions of governing equations show that there exists three plane waves, namely, P, thermal and SV waves which propagate with distinct speeds. Reflection of P and SV waves from thermally insulated or isothermal boundary of a half-space is considered. The relevant boundary conditions are applied at stress free boundary and a nonhomogeneous system of three equations in reflection coefficients is obtained. For incidence of both P and SV waves, the expressions for energy ratios of reflected P, thermal and SV waves are also obtained. The speeds and energy ratios of reflected waves are computed for relevant physical constants of a thermoelastic material. The speeds of plane waves are plotted against nonlocal parameter and frequency. The energy ratios of reflected waves are also plotted against the angle of incidence of P wave at a thermally insulated stress-free surface. The effect of nonlocal parameter is shown graphically on the speeds and energy ratios of reflected waves.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"473-479"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66121497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Non-destructive evaluation of steel and GFRP reinforced beams using AE and DIC techniques 用声发射和DIC技术对钢和玻璃钢加固梁进行无损评价

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.77.5.637

G. Sharma, Shruti Sharma, Sandeep Sharma

{"title":"Non-destructive evaluation of steel and GFRP reinforced beams using AE and DIC techniques","authors":"G. Sharma, Shruti Sharma, Sandeep Sharma","doi":"10.12989/SEM.2021.77.5.637","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.5.637","url":null,"abstract":"The paper presents an investigation of the widely varying mechanical performance and behaviour of steel and Glass Fibre Reinforced Polymer (GFRP) reinforced concrete beams using non-destructive techniques of Acoustic Emission (AE) and Digital Image Correlation (DIC) under four-point bending. Laboratory experiments are performed on both differently reinforced concrete beams with 0.33%, 0.52% and 1.11% of tension reinforcement against balanced section. The results show that the ultimate load-carrying capacity increases with an increase in tensile reinforcement in both cases. In addition to that, AE waveform parameters of amplitude and number of AE hits successfully correlates and picks up the divergent mechanism of cracking initiation and progression of failure in steel reinforced and GFRP reinforced concrete beams. AE activity is about 20- 30% more in GFRP-RC beams as compared to steel-RC beams. It was primarily due to the lower modulus of elasticity of GFRP bars leading to much larger ductility and deflections as compared to steel-RC beams. Furthermore, AE XY event plots and longitudinal strain profiles using DIC gives an online and real-time visual display of progressive AE activity and strains respectively to efficaciously depict the crack evolution and their advancement in steel-RC and GFRP-RC beams which show a close matching with the micro-and macro-cracks visually observed in the actual beams at various stages of loading.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"637-650"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66122935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A unified approach to shear and torsion in reinforced concrete 钢筋混凝土抗剪和抗扭的统一方法

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.77.5.691

K. Rahal

{"title":"A unified approach to shear and torsion in reinforced concrete","authors":"K. Rahal","doi":"10.12989/SEM.2021.77.5.691","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.5.691","url":null,"abstract":"Reinforced concrete (RC) beams can be subjected to a complex combination of shear forces (V), torsional moments (T), flexural moments (M) and axial loads (N). This paper proposes a unified approach for the analysis of these elements. An existing model for the analysis of orthogonally reinforced concrete membrane elements subjected to in-plane shear and normal stresses is generalized to apply to the case of beams subjected to the complex loading. The combination of V and T can be critical. Torsion is modelled using the hollow-tube analogy. A direct equation for the calculation of the thickness of the equivalent hollow tube is proposed, and the shear stresses caused by V and T are combined using a simple approach. The development and the evaluation of the model are described. The calculations of the model are compared to experimental data from 350 beams subjected to various combinations of stress-resultants and to the calculations of the ACI and the CSA codes. The proposed model provides the most favorable results. It is also shown that it can accurately model the interaction between V and T. The proposed model provides a unified treatment of shear in beams subjected to complex stress-resultants and in thin membrane elements subjected to in-plane stresses.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"691-703"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66123374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

High-velocity powder compaction: An experimental investigation, modelling, and optimization 高速粉末压实:实验调查，建模和优化

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.78.2.145

T. M. Mostofi, M. Sayah-Badkhor, M. Rezasefat, H. Babaei, T. Ozbakkaloglu

{"title":"High-velocity powder compaction: An experimental investigation, modelling, and optimization","authors":"T. M. Mostofi, M. Sayah-Badkhor, M. Rezasefat, H. Babaei, T. Ozbakkaloglu","doi":"10.12989/SEM.2021.78.2.145","DOIUrl":"https://doi.org/10.12989/SEM.2021.78.2.145","url":null,"abstract":"Dynamic compaction of Aluminum powder using gas detonation forming technique was investigated. The experiments were carried out on four different conditions of total pre-detonation pressure. The effects of the initial powder mass and grain particle size on the green density and strength of compacted specimens were investigated. The relationships between the mentioned powder design parameters and the final features of specimens were characterized using Response Surface Methodology (RSM). Artificial Neural Network (ANN) models using the Group Method of Data Handling (GMDH) algorithm were also developed to predict the green density and green strength of compacted specimens. Furthermore, the desirability function was employed for multi-objective optimization purposes. The obtained optimal solutions were verified with three new experiments and ANN models. The obtained experimental results corresponding to the best optimal setting with the desirability of 1 are 2714 kg m3 and 21.5 MPa for the green density and green strength, respectively, which are very close to the predicted values.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"78 1","pages":"145"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66124902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Microstructural and mechanical characteristics of self-compacting concrete with waste rubber 废橡胶自密实混凝土的微观结构和力学特性

IF 2.2 4区工程技术

Structural Engineering and Mechanics Pub Date : 2021-01-01 DOI: 10.12989/SEM.2021.78.2.175

M. Hadzima-Nyarko, K. E. Nyarko, D. Djikanović, G. Branković

引用次数: 3