Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.78.3.255
Preeti Agarwal, P. Pal, P. Mehta
The analysis of simply supported single-cell skew-curved reinforced concrete (RC) box-girder bridges is carried out using a finite element based CsiBridge software. The behaviour of skew-curved box-girder bridges can not be anticipated simply by superimposing the individual effects of skewness and curvature, so it becomes important to examine the behaviour of such bridges considering the combined effects of skewness and curvature. A comprehensive parametric study is performed wherein the combined influence of the skew and curve angles is considered to determine the maximum bending moment, maximum shear force, maximum torsional moment and maximum vertical deflection of the bridge girders. The skew angle is varied from 0o to 60o at an interval of 10o, and the curve angle is varied from 0o to 60o at an interval of 12o. The scantly available literature on such bridges focuses mainly on the analysis of skew-curved bridges under dead and point loads. But, the effects of actual loadings may be different, thus, it is considered in the present study. It is found that the performance of these bridges having more curvature can be improved by introducing the skewness. Finally, several equations are deduced in the non-dimensional form for estimating the forces and deflection in the girders of simply supported skew-curved RC box-girder bridges, based upon the results of the straight one. The developed equations may be helpful to the designers in proportioning, analysing, and designing such bridges, as the correlation coefficient is about 0.99.
{"title":"Computation of design forces and deflection in skew-curved box-girder bridges","authors":"Preeti Agarwal, P. Pal, P. Mehta","doi":"10.12989/SEM.2021.78.3.255","DOIUrl":"https://doi.org/10.12989/SEM.2021.78.3.255","url":null,"abstract":"The analysis of simply supported single-cell skew-curved reinforced concrete (RC) box-girder bridges is carried out using a finite element based CsiBridge software. The behaviour of skew-curved box-girder bridges can not be anticipated simply by superimposing the individual effects of skewness and curvature, so it becomes important to examine the behaviour of such bridges considering the combined effects of skewness and curvature. A comprehensive parametric study is performed wherein the combined influence of the skew and curve angles is considered to determine the maximum bending moment, maximum shear force, maximum torsional moment and maximum vertical deflection of the bridge girders. The skew angle is varied from 0o to 60o at an interval of 10o, and the curve angle is varied from 0o to 60o at an interval of 12o. The scantly available literature on such bridges focuses mainly on the analysis of skew-curved bridges under dead and point loads. But, the effects of actual loadings may be different, thus, it is considered in the present study. It is found that the performance of these bridges having more curvature can be improved by introducing the skewness. Finally, several equations are deduced in the non-dimensional form for estimating the forces and deflection in the girders of simply supported skew-curved RC box-girder bridges, based upon the results of the straight one. The developed equations may be helpful to the designers in proportioning, analysing, and designing such bridges, as the correlation coefficient is about 0.99.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"78 1","pages":"255"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66125392","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.1.009
Emre Alpaslan, Z. Karaca
Response surface (RS) methods, a combination of mathematical and statistical techniques, have been widely used in design optimization, response prediction, and model validation in structural engineering systems. However, its usage in structural damage identification, especially for historic structures has not been quite common. For this purpose, this study attempts to investigate damage detection in a masonry arch bridge. Within the scope of this, a reduced-scale model of a one span historical masonry arch bridge was built in a laboratory environment. To determine the modal parameters of the reduced-scaled bridge model, operational modal analysis (OMA) was performed under ambient vibrations. Signals originated by sensitive accelerometers were collected to quantify the vibratory response of the reduced-scaled model bridge. The experimental natural frequencies, mode shapes, and damping ratios resulting from these measurements were figured out by using the Enhanced Frequency Domain Decomposition (EFDD) technique. The three-dimensional model of the reduced-scale bridge was created in the ANSYS finite element (FE) software program to expose the analytical dynamic characteristics of the bridge model. The results obtained in the experimental application were compared with those of the finite-element analysis of the bridge model. The calibration of the numeric model was utilized depending on the experimental modal analysis results of the reduced-scale bridge by using the RS method. Design of experiments was constructed by using central composite design, and the RS models were generated by performing the genetic aggregation approach. The optimum results between the experimental and numerical analyses were found by using the RS optimization. Then, regional damages created on the scaled model and the changes of dynamic properties of the damaged case were evaluated. The damage location was approximately identified by using the RS method in the calibrated finite-element model. The results demonstrated that the RS-based FE updating approach is an effective way for damage detection and localization in masonry type structures.
响应面方法是一种数学与统计相结合的方法，已广泛应用于结构工程系统的设计优化、响应预测和模型验证等方面。然而，它在结构损伤识别，特别是历史建筑损伤识别中的应用并不普遍。为此，本研究试图对砖石拱桥的损伤检测进行研究。在此范围内，在实验室环境下建立了一座单跨历史砌体拱桥的缩小模型。为了确定桥梁模型的模态参数，进行了环境振动下的运行模态分析(OMA)。通过采集敏感加速度计产生的信号，量化了模型桥梁的振动响应。利用增强频域分解(Enhanced Frequency Domain Decomposition, EFDD)技术计算得到实验固有频率、模态振型和阻尼比。在ANSYS有限元软件中建立缩比桥梁的三维模型，揭示桥梁模型的解析动力特性。将试验应用结果与桥梁模型有限元分析结果进行了比较。利用RS法对该桥梁进行了减尺试验模态分析，对数值模型进行了标定。采用中心组合设计构建试验设计，采用遗传聚集法生成RS模型。利用RS优化方法，在实验和数值分析中找到了最优的结果。在此基础上，对模型所产生的区域损伤和损伤体动力特性的变化进行了评价。在标定后的有限元模型中，采用RS法对损伤位置进行了近似识别。结果表明，基于rs的有限元更新方法是砌体结构损伤检测与定位的有效方法。
{"title":"Response surface-based model updating to detect damage on reduced-scale masonry arch bridge","authors":"Emre Alpaslan, Z. Karaca","doi":"10.12989/SEM.2021.79.1.009","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.1.009","url":null,"abstract":"Response surface (RS) methods, a combination of mathematical and statistical techniques, have been widely used in design optimization, response prediction, and model validation in structural engineering systems. However, its usage in structural damage identification, especially for historic structures has not been quite common. For this purpose, this study attempts to investigate damage detection in a masonry arch bridge. Within the scope of this, a reduced-scale model of a one span historical masonry arch bridge was built in a laboratory environment. To determine the modal parameters of the reduced-scaled bridge model, operational modal analysis (OMA) was performed under ambient vibrations. Signals originated by sensitive accelerometers were collected to quantify the vibratory response of the reduced-scaled model bridge. The experimental natural frequencies, mode shapes, and damping ratios resulting from these measurements were figured out by using the Enhanced Frequency Domain Decomposition (EFDD) technique. The three-dimensional model of the reduced-scale bridge was created in the ANSYS finite element (FE) software program to expose the analytical dynamic characteristics of the bridge model. The results obtained in the experimental application were compared with those of the finite-element analysis of the bridge model. The calibration of the numeric model was utilized depending on the experimental modal analysis results of the reduced-scale bridge by using the RS method. Design of experiments was constructed by using central composite design, and the RS models were generated by performing the genetic aggregation approach. The optimum results between the experimental and numerical analyses were found by using the RS optimization. Then, regional damages created on the scaled model and the changes of dynamic properties of the damaged case were evaluated. The damage location was approximately identified by using the RS method in the calibrated finite-element model. The results demonstrated that the RS-based FE updating approach is an effective way for damage detection and localization in masonry type structures.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"009"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66126838","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.6.665
Xinli Xu, Chunwei Zhang, F. Musharavati, T. Sebaey, Afrasyab Khan
In the present paper, wave propagation behavior of porous temperature-dependent functionally graded curved beams within the thermal environment is analyzed for the first time. A recently-developed method is utilized which considers the reciprocal effect of mass density and Young's modulus in order to explore the influence of porosity. Three different types of temperature variation (uniform temperature change (UTC), linear temperature change (LTC), sinusoidal temperature change (STC)) are employed to study the effect of various thermal loads. Euler-Bernoulli beam theory, also known as classic beam theory is implemented in order to derive kinetic and kinematic relations, and then Hamilton's principle is used to obtain governing equations of porous functionally graded curved beams. The obtained governing equations are analytically solved. Eventually, the influences of various parameters such as wave number, porosity coefficient, various types of temperature change and power index are covered and indicated in a set of illustrations.
{"title":"Wave propagation analysis of porous functionally graded curved beams in the thermal environment","authors":"Xinli Xu, Chunwei Zhang, F. Musharavati, T. Sebaey, Afrasyab Khan","doi":"10.12989/SEM.2021.79.6.665","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.6.665","url":null,"abstract":"In the present paper, wave propagation behavior of porous temperature-dependent functionally graded curved beams within the thermal environment is analyzed for the first time. A recently-developed method is utilized which considers the reciprocal effect of mass density and Young's modulus in order to explore the influence of porosity. Three different types of temperature variation (uniform temperature change (UTC), linear temperature change (LTC), sinusoidal temperature change (STC)) are employed to study the effect of various thermal loads. Euler-Bernoulli beam theory, also known as classic beam theory is implemented in order to derive kinetic and kinematic relations, and then Hamilton's principle is used to obtain governing equations of porous functionally graded curved beams. The obtained governing equations are analytically solved. Eventually, the influences of various parameters such as wave number, porosity coefficient, various types of temperature change and power index are covered and indicated in a set of illustrations.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"35 1","pages":"665"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66130157","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.6.723
B. E. Yapanmış, Necla Togun, S. Bağdatlı, Sevki Akkoca
The history of modern humanity is developing towards making the technological equipment used as small as possible to facilitate human life. From this perspective, it is expected that electromechanical systems should be reduced to a size suitable for the requirements of the era. Therefore, dimensionless motion analysis of beams on the devices such as electronics, optics, etc., is of great significance. In this study, the linear and nonlinear vibration of nanobeams, which are frequently used in nanostructures, are focused on. Scenarios have been created about the vibration of nanobeams on the magnetic field and elastic foundation. In addition to these, the boundary conditions (BC) of nanobeams having clamped-clamped and simple-simple support situations are investigated. Nonlinear and linear natural frequencies of nanobeams are found, and the results are presented in tables and graphs. When the results are examined, decreases the vibration amplitudes with the increase of magnetic field and the elastic foundation coefficient. Higher frequency values and correction terms were obtained in clamped-clamped support conditions due to the structure's stiffening.
{"title":"Magnetic field effect on nonlinear vibration of nonlocal nanobeam embedded in nonlinear elastic foundation","authors":"B. E. Yapanmış, Necla Togun, S. Bağdatlı, Sevki Akkoca","doi":"10.12989/SEM.2021.79.6.723","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.6.723","url":null,"abstract":"The history of modern humanity is developing towards making the technological equipment used as small as possible to facilitate human life. From this perspective, it is expected that electromechanical systems should be reduced to a size suitable for the requirements of the era. Therefore, dimensionless motion analysis of beams on the devices such as electronics, optics, etc., is of great significance. In this study, the linear and nonlinear vibration of nanobeams, which are frequently used in nanostructures, are focused on. Scenarios have been created about the vibration of nanobeams on the magnetic field and elastic foundation. In addition to these, the boundary conditions (BC) of nanobeams having clamped-clamped and simple-simple support situations are investigated. Nonlinear and linear natural frequencies of nanobeams are found, and the results are presented in tables and graphs. When the results are examined, decreases the vibration amplitudes with the increase of magnetic field and the elastic foundation coefficient. Higher frequency values and correction terms were obtained in clamped-clamped support conditions due to the structure's stiffening.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"723"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66130974","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.77.1.103
B. Karthick, M. Muthuraj
Ultra high strength concrete (UHSC) originally proposed by Richards and Cheyrezy (1995) composed of cement, silica fume, quartz sand, quartz powder, steel fibers, superplasticizer etc. Later, other ingredients such as fly ash, GGBS, metakaoline, copper slag, fine aggregate of different sizes have been added to original UHSC. In the present investigation, the combined effect of coarse aggregate (6mm – 10mm) and steel fibers (0.50%, 1.0% and 1.5%) has been studied on UHSC mixes to evaluate mechanical and fracture properties. Compressive strength, split tensile strength and modulus of elasticity were determined for the three UHSC mixes. Size dependent fracture energy was evaluated by using RILEM work of fracture and size independent fracture energy was evaluated by using (i) RILEM work of fracture with tail correction to load – deflection plot (ii) boundary effect method. The constitutive relationship between the residual stress carrying capacity (σ) and the corresponding crack opening (w) has been constructed in an inverse manner based on the concept of a non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams. It was found that (i) the size independent fracture energy obtained by using above two approaches yielded similar value and (ii) tensile stress increases with the increase of % of fibers. These two fracture properties will be very much useful for the analysis of cracked concrete structural components.
{"title":"Effect of medium coarse aggregate on fracture properties of ultra high strength concrete","authors":"B. Karthick, M. Muthuraj","doi":"10.12989/SEM.2021.77.1.103","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.1.103","url":null,"abstract":"Ultra high strength concrete (UHSC) originally proposed by Richards and Cheyrezy (1995) composed of cement, silica fume, quartz sand, quartz powder, steel fibers, superplasticizer etc. Later, other ingredients such as fly ash, GGBS, metakaoline, copper slag, fine aggregate of different sizes have been added to original UHSC. In the present investigation, the combined effect of coarse aggregate (6mm – 10mm) and steel fibers (0.50%, 1.0% and 1.5%) has been studied on UHSC mixes to evaluate mechanical and fracture properties. Compressive strength, split tensile strength and modulus of elasticity were determined for the three UHSC mixes. Size dependent fracture energy was evaluated by using RILEM work of fracture and size independent fracture energy was evaluated by using (i) RILEM work of fracture with tail correction to load – deflection plot (ii) boundary effect method. The constitutive relationship between the residual stress carrying capacity (σ) and the corresponding crack opening (w) has been constructed in an inverse manner based on the concept of a non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams. It was found that (i) the size independent fracture energy obtained by using above two approaches yielded similar value and (ii) tensile stress increases with the increase of % of fibers. These two fracture properties will be very much useful for the analysis of cracked concrete structural components.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"103-114"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66120077","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}
The effect of distribution shape of porosity using a quasi-3D theory for free vibration analysis of FG microbeams is studied analytically in the present paper. The microbeams are simply-supported and nonhomogeneous, with power function variation of Young's modulus along their thickness. The modified coupled stress theory is utilized to consolidate size dependency of microbeam. Both even and uneven distribution shape of porosity are considered and the effective properties of porous FG microbeams are defined by theoretical formula with an additional term of porosity. The equation of motion is obtained through Hamilton's principle, however, Navier type solution method is used to obtain frequencies. The influences played by many parameters are also investigated.
{"title":"Study and analysis of the free vibration for FGM microbeam containing various distribution shape of porosity","authors":"Youcef Tlidji, Rabia Benferhat, Hassaine Daouadji Tahar","doi":"10.12989/SEM.2021.77.2.217","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.2.217","url":null,"abstract":"The effect of distribution shape of porosity using a quasi-3D theory for free vibration analysis of FG microbeams is studied analytically in the present paper. The microbeams are simply-supported and nonhomogeneous, with power function variation of Young's modulus along their thickness. The modified coupled stress theory is utilized to consolidate size dependency of microbeam. Both even and uneven distribution shape of porosity are considered and the effective properties of porous FG microbeams are defined by theoretical formula with an additional term of porosity. The equation of motion is obtained through Hamilton's principle, however, Navier type solution method is used to obtain frequencies. The influences played by many parameters are also investigated.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"217-229"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66120596","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.77.3.369
Junwen Zhou, Mingxin Zhao
The seismic responses of elevated tanks considering liquid-structure interaction are presented under horizontal earthquake. The scaled model tank is fabricated to study the dynamic responses of anchored tank and newly designed uplift tank with replaced dampers. The natural frequencies for structural mode are obtained by modal analysis. The dynamic responses of tanks are completed by finite element method, which are compared with the results from experiment. The displacement parallel and perpendicular to the excitation direction are both gained as well as structural acceleration. The strain of tank walls and the axial strain of columns are also obtained afterwards. The seismic responses of liquid storage tank can be calculated by the finite element model effectively and the results match well with the one measured by experiment. The aim is to provide a new type of tank system with vertical constraint relaxed which leads to lower stress level. With the liquid volume increasing, the structural fundamental frequency has a great reduction and the one of uplift tank are even smaller. Compared with anchored tank, the displacement of uplift tank is magnified, the strain for tank walls and columns parallel to excitation direction reduces obviously, while the one perpendicular to earthquake direction increases a lot, but the values are still small. The stress level of new tank seems to be more even due to uplift effect. The new type of tank can realize recoverable function by replacing dampers after earthquake.
{"title":"Shaking table test of liquid storage tank with finite element analysis considering uplift effect","authors":"Junwen Zhou, Mingxin Zhao","doi":"10.12989/SEM.2021.77.3.369","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.3.369","url":null,"abstract":"The seismic responses of elevated tanks considering liquid-structure interaction are presented under horizontal earthquake. The scaled model tank is fabricated to study the dynamic responses of anchored tank and newly designed uplift tank with replaced dampers. The natural frequencies for structural mode are obtained by modal analysis. The dynamic responses of tanks are completed by finite element method, which are compared with the results from experiment. The displacement parallel and perpendicular to the excitation direction are both gained as well as structural acceleration. The strain of tank walls and the axial strain of columns are also obtained afterwards. The seismic responses of liquid storage tank can be calculated by the finite element model effectively and the results match well with the one measured by experiment. The aim is to provide a new type of tank system with vertical constraint relaxed which leads to lower stress level. With the liquid volume increasing, the structural fundamental frequency has a great reduction and the one of uplift tank are even smaller. Compared with anchored tank, the displacement of uplift tank is magnified, the strain for tank walls and columns parallel to excitation direction reduces obviously, while the one perpendicular to earthquake direction increases a lot, but the values are still small. The stress level of new tank seems to be more even due to uplift effect. The new type of tank can realize recoverable function by replacing dampers after earthquake.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"369-381"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66120871","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.77.3.407
Gholamali Mirali-Katouli, G. Abdollahzadeh
Seismic isolation is one of the best-advanced methods for controlling seismic vibrations in buildings, bridges and nuclear facilities. A new Friction Multi-Layer Elastomeric Seismic Isolator (FMESI) has been modeled, analyzed and investigated by ABAQUS finite element analysis software and then, compared to real models. A number of friction cores have been used instead of the lead core therefore, some of the previous isolator problems have been almost resolved. Moreover, Studies show that the proposed isolator provides suitable initial stiffness and acceptable hysteresis behavior under different vertical and horizontal loading conditions and also internal stresses in different layers are acceptable. Also, as a result, the initial stiffness and overall area of the curves increase, as friction coefficients of the cores increase, although the frictional coefficients must be within a certain range.
{"title":"A new proposed Friction Multi-layered Elastomeric Seismic Isolator (FMESI)","authors":"Gholamali Mirali-Katouli, G. Abdollahzadeh","doi":"10.12989/SEM.2021.77.3.407","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.3.407","url":null,"abstract":"Seismic isolation is one of the best-advanced methods for controlling seismic vibrations in buildings, bridges and nuclear facilities. A new Friction Multi-Layer Elastomeric Seismic Isolator (FMESI) has been modeled, analyzed and investigated by ABAQUS finite element analysis software and then, compared to real models. A number of friction cores have been used instead of the lead core therefore, some of the previous isolator problems have been almost resolved. Moreover, Studies show that the proposed isolator provides suitable initial stiffness and acceptable hysteresis behavior under different vertical and horizontal loading conditions and also internal stresses in different layers are acceptable. Also, as a result, the initial stiffness and overall area of the curves increase, as friction coefficients of the cores increase, although the frictional coefficients must be within a certain range.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"407-416"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66121018","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.77.4.495
Hung V. Dang, M. Raza, H. Tran-Ngoc, T. Bui-Tien, H. Nguyen
This study devises a novel approach, namely quadruple 1D convolutional neural network, for detecting connection stiffness reduction in steel truss bridge structure using experimental and numerical modal data. The method is developed based on expertise in two domains: firstly, in Structural Health Monitoring, the mode shapes and its high-order derivatives, including second, third, and fourth derivatives, are accurate indicators in assessing damages. Secondly, in the Machine Learning literature, the deep convolutional neural networks are able to extract relevant features from input data, then perform classification tasks with high accuracy and reduced time complexity. The efficacy and effectiveness of the present method are supported through an extensive case study with the railway Nam O bridge. It delivers highly accurate results in assessing damage localization and damage severity for single as well as multiple damage scenarios. In addition, the robustness of this method is tested with the presence of white noise reflecting unavoidable uncertainties in signal processing and modeling in reality. The proposed approach is able to provide stable results with data corrupted by noise up to 10%.
{"title":"Connection stiffness reduction analysis in steel bridge via deep CNN and modal experimental data","authors":"Hung V. Dang, M. Raza, H. Tran-Ngoc, T. Bui-Tien, H. Nguyen","doi":"10.12989/SEM.2021.77.4.495","DOIUrl":"https://doi.org/10.12989/SEM.2021.77.4.495","url":null,"abstract":"This study devises a novel approach, namely quadruple 1D convolutional neural network, for detecting connection stiffness reduction in steel truss bridge structure using experimental and numerical modal data. The method is developed based on expertise in two domains: firstly, in Structural Health Monitoring, the mode shapes and its high-order derivatives, including second, third, and fourth derivatives, are accurate indicators in assessing damages. Secondly, in the Machine Learning literature, the deep convolutional neural networks are able to extract relevant features from input data, then perform classification tasks with high accuracy and reduced time complexity. The efficacy and effectiveness of the present method are supported through an extensive case study with the railway Nam O bridge. It delivers highly accurate results in assessing damage localization and damage severity for single as well as multiple damage scenarios. In addition, the robustness of this method is tested with the presence of white noise reflecting unavoidable uncertainties in signal processing and modeling in reality. The proposed approach is able to provide stable results with data corrupted by noise up to 10%.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"77 1","pages":"495-508"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66121272","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}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.78.1.053
T. Nahar, M. Rahman, Dookie Kim
The determination of the damage index to reveal the performance level of a structure can constitute the seismic risk generalization approach based on the parametric analysis. This study implemented this concept to one kind of civil engineering structure that is the concrete gravity dam. Different cases of the structure exhibit their individual responses, which constitute different considerations. Therefore, this approach allows the parametric study of concrete as well as soil for evaluating the seismic nature in the generalized case. To ensure that the target algorithm applicable to most of the concrete gravity dams, a very simple procedure has been considered. In order to develop a correlated algorithm (by response surface methodology; RSM) between the ground motion and the structural property, randomized sampling was adopted through a stochastic method called half-fractional central composite design. The responses in the case of fluid-foundation-dam interaction (FFDI) make it more reliable by introducing the foundation as being bounded by infinite elements. To evaluate the seismic generalization of FFDI models, incremental dynamic analysis (IDA) was carried out under the impacts of various earthquake records, which have been selected from the Pacific Earthquake Engineering Research Center data. Here, the displacement-based damage indexed fragility curves have been generated to show the variation in the seismic pattern of the dam. The responses to the sensitivity analysis of the various parameters presented here are the most effective controlling factors for the concrete gravity dam. Finally, to establish the accuracy of the proposed approach, reliable verification was adopted in this study.
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