SummaryIn this paper, the governing equations of the outrigger‐braced structure are formulated by considering the influence of core‐wall width. The axial forces in the columns are considered as unknowns and the compatibility of the column's axial deformation is considered in formulating the governing equations. Then, the governing equations for the optimum locations of outriggers are formulated by minimizing the top drift of central core wall. After that, the influence of core‐wall width on the optimum outrigger locations, the drift‐reduction efficiency and moment‐reduction efficiency is investigated numerically. Some results are presented for the reference in the preliminary design of the outrigger‐braced structures.
{"title":"Influence of core width on the optimization analysis of the outrigger‐braced structure","authors":"Xin Chen, Guo‐Kang Er, Vai Pan Iu","doi":"10.1002/tal.2075","DOIUrl":"https://doi.org/10.1002/tal.2075","url":null,"abstract":"SummaryIn this paper, the governing equations of the outrigger‐braced structure are formulated by considering the influence of core‐wall width. The axial forces in the columns are considered as unknowns and the compatibility of the column's axial deformation is considered in formulating the governing equations. Then, the governing equations for the optimum locations of outriggers are formulated by minimizing the top drift of central core wall. After that, the influence of core‐wall width on the optimum outrigger locations, the drift‐reduction efficiency and moment‐reduction efficiency is investigated numerically. Some results are presented for the reference in the preliminary design of the outrigger‐braced structures.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
SummaryThis paper presents a new performance‐based seismic design method for the design of repairable linked column frame (LCF) and linked column system (LCS). Currently, the biggest problem of these systems is the lack of a simple and practical design method that leads to the design of optimal models with sufficient seismic capacity. The interaction of the primary and secondary systems, changing the lateral load pattern during an earthquake, and the implementation of the target performance objectives have complicated the design of these systems. The evaluations carried out in this research show that the rotation of link beams must be controlled in the design. Therefore, the ultimate plastic rotation of links is determined to be 0.01 rad for the seismic intensity of design base earthquake and 0.015 rad for maximum considered earthquake. The results show that the models designed using the presented method are optimal, have sufficient seismic capacity, and achieve the target performance objectives. In addition, although previous researches have shown that these systems have a suitable seismic behavior, their seismic behavior have not been compared with other structural systems. Comparing can show the behavioral characteristics of a new structural system; hence, the elastic and plastic behavior of the LCF and LCS models have been compared with other common steel structural systems using all analysis methods. Moreover, in the presented method for the design of LCF and LCS systems, nonlinear time history analysis using the endurance time method (ETM) is used, and due to the newness of the endurance time method, its results are compared with the median results of nonlinear time history analysis at different seismic hazard levels and incremental dynamic analysis (IDA), in 45 samples. The results show that the endurance time analysis is a reasonable and efficient method, and in this comparison, the difference between the results of ETM and IDA methods is 6% on average.
{"title":"A new performance‐based seismic design method using endurance time analysis for linked column frame system and a comparison of structural systems and seismic analysis methods","authors":"Vahid Jaberi, Masume Jaberi, Abazar Asghari","doi":"10.1002/tal.2100","DOIUrl":"https://doi.org/10.1002/tal.2100","url":null,"abstract":"SummaryThis paper presents a new performance‐based seismic design method for the design of repairable linked column frame (LCF) and linked column system (LCS). Currently, the biggest problem of these systems is the lack of a simple and practical design method that leads to the design of optimal models with sufficient seismic capacity. The interaction of the primary and secondary systems, changing the lateral load pattern during an earthquake, and the implementation of the target performance objectives have complicated the design of these systems. The evaluations carried out in this research show that the rotation of link beams must be controlled in the design. Therefore, the ultimate plastic rotation of links is determined to be 0.01 rad for the seismic intensity of design base earthquake and 0.015 rad for maximum considered earthquake. The results show that the models designed using the presented method are optimal, have sufficient seismic capacity, and achieve the target performance objectives. In addition, although previous researches have shown that these systems have a suitable seismic behavior, their seismic behavior have not been compared with other structural systems. Comparing can show the behavioral characteristics of a new structural system; hence, the elastic and plastic behavior of the LCF and LCS models have been compared with other common steel structural systems using all analysis methods. Moreover, in the presented method for the design of LCF and LCS systems, nonlinear time history analysis using the endurance time method (ETM) is used, and due to the newness of the endurance time method, its results are compared with the median results of nonlinear time history analysis at different seismic hazard levels and incremental dynamic analysis (IDA), in 45 samples. The results show that the endurance time analysis is a reasonable and efficient method, and in this comparison, the difference between the results of ETM and IDA methods is 6% on average.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
SummaryThe use of curved forms in tall buildings has increased recently due to their structural and esthetic advantages. Diagrid structures are typically used for these buildings because of their ability to express curved forms. There are, however, few studies about the curvature of tall buildings. This paper examines the effect of curvature on the wind force on tall curved buildings with diagrid system. So, to achieve this, the form of tall curved buildings is investigated, and the commonly used equations that constitute their form are determined. Then, applying computational fluid dynamics simulation, wind force was calculated on the developed alternatives which were created by the equations. Besides, the structural mass of each model is calculated by optimizing the cross‐section of the members. It is concluded that considering the conditions of the applied model, by increasing the concavity of the form, the suction on the building's facade increases. Further, with the increase of the concavity in the plan and elevation, the along wind force on the structure and overturning moment increases. Also, it is observed that the structural efficiency of curvilinear buildings is only appropriate to a certain extent of curvature, and with its increase, the structural efficiency decreases. This article offers useful information for the preliminary design of tall buildings.
{"title":"Investigating the effect of form curvature on diagrid tall buildings considering wind loads","authors":"Aram Alizadegan, Amirreza Ardekani, Mahmood Golabchi","doi":"10.1002/tal.2093","DOIUrl":"https://doi.org/10.1002/tal.2093","url":null,"abstract":"SummaryThe use of curved forms in tall buildings has increased recently due to their structural and esthetic advantages. Diagrid structures are typically used for these buildings because of their ability to express curved forms. There are, however, few studies about the curvature of tall buildings. This paper examines the effect of curvature on the wind force on tall curved buildings with diagrid system. So, to achieve this, the form of tall curved buildings is investigated, and the commonly used equations that constitute their form are determined. Then, applying computational fluid dynamics simulation, wind force was calculated on the developed alternatives which were created by the equations. Besides, the structural mass of each model is calculated by optimizing the cross‐section of the members. It is concluded that considering the conditions of the applied model, by increasing the concavity of the form, the suction on the building's facade increases. Further, with the increase of the concavity in the plan and elevation, the along wind force on the structure and overturning moment increases. Also, it is observed that the structural efficiency of curvilinear buildings is only appropriate to a certain extent of curvature, and with its increase, the structural efficiency decreases. This article offers useful information for the preliminary design of tall buildings.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qiang Xu, Liping Xu, Linghui Meng, Yuyang Liu, Yinhui Bai
SummaryIn order to study the dynamic characteristics and human‐induced vibration response of light steel foamed concrete composite floor (LCSF), the vibration characteristics of 4.2 m × 5 m LCSF model were tested under the condition of opposite side support, and the natural vibration frequency of LCSF was obtained. The orthogonal anisotropic elastic plate and the simulated beam element were used, respectively, to compute the natural vibration frequency of the LCSF, and the estimated findings were compared with those obtained from measurements. The discrepancy between the calculated results and the measured results of the approximate beam element using the natural vibration frequency calculation technique is around 13%, but the error for the plate element using the calculated results and the tested results is about 23%. To examine the floor's vibration response under the factors of step frequency, walking path, pedestrian density, and load distribution, the LCSF underwent a human‐induced vibration test. The test results show that the fundamental frequency of the LCSF specimen is about 11 Hz, which can meet the requirements of the specification. However, the vibration response of the LCSF specimen under different conditions of pedestrian load is significantly different. With the acceleration of step frequency and the increase and concentration of load, the floor's vibration response becomes more visible. In the route test, it is established that LCSF has the attribute of a unidirectional plate. The natural vibration frequency of similar floor slab can be calculated by the method of simulating the natural vibration frequency of beam element. The findings can serve as a guide for LCSF research and implementation.
{"title":"Experimental study on fundamental frequency and human‐induced vibration characteristics of light steel foam concrete composite floor","authors":"Qiang Xu, Liping Xu, Linghui Meng, Yuyang Liu, Yinhui Bai","doi":"10.1002/tal.2096","DOIUrl":"https://doi.org/10.1002/tal.2096","url":null,"abstract":"SummaryIn order to study the dynamic characteristics and human‐induced vibration response of light steel foamed concrete composite floor (LCSF), the vibration characteristics of 4.2 m × 5 m LCSF model were tested under the condition of opposite side support, and the natural vibration frequency of LCSF was obtained. The orthogonal anisotropic elastic plate and the simulated beam element were used, respectively, to compute the natural vibration frequency of the LCSF, and the estimated findings were compared with those obtained from measurements. The discrepancy between the calculated results and the measured results of the approximate beam element using the natural vibration frequency calculation technique is around 13%, but the error for the plate element using the calculated results and the tested results is about 23%. To examine the floor's vibration response under the factors of step frequency, walking path, pedestrian density, and load distribution, the LCSF underwent a human‐induced vibration test. The test results show that the fundamental frequency of the LCSF specimen is about 11 Hz, which can meet the requirements of the specification. However, the vibration response of the LCSF specimen under different conditions of pedestrian load is significantly different. With the acceleration of step frequency and the increase and concentration of load, the floor's vibration response becomes more visible. In the route test, it is established that LCSF has the attribute of a unidirectional plate. The natural vibration frequency of similar floor slab can be calculated by the method of simulating the natural vibration frequency of beam element. The findings can serve as a guide for LCSF research and implementation.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
SummaryIn operational modal analysis (OMA), only structural responses are typically available. In this context, bias and variance (uncertainty) errors may exist in modal estimates (especially damping estimates), resulting in inaccurate determination of the modal properties of large‐scale structures under harsh excitations. To this end, a hybrid OMA framework based on the modal decoupling, the natural excitation technique, the random decrement technique (RDT), and improved eigensystem realization algorithm (ERA) with the automated stabilization diagram is presented to perform high‐accuracy modal estimates with uncertainty quantification for large‐scale structures under normal and severe ambient excitations. The accuracy and effectiveness of the hybrid framework for identifying the modal parameters are validated by numerical simulation study of a framework structural model. Furthermore, the hybrid framework is applied to analyze recorded acceleration responses of a supertall building with 600‐m height under normal excitations and typhoon condition to verify its applicability in field measurements. The numerical simulation and field measurement studies demonstrate that the hybrid framework can not only perform precise modal estimations with uncertainty quantification through a single ambient vibration measurement but also effectively reveal the variations of modal properties of supertall structures under harsh excitations from multiple perspectives. This paper aims to enhance the reliability and accuracy of modal estimation for engineering structures and further provide insight into the variations of dynamic properties of large‐scale civil structures under severe excitations.
摘要在运行模态分析（OMA）中，通常只能获得结构响应。在这种情况下，模态估计值（尤其是阻尼估计值）可能存在偏差和方差（不确定性）误差，导致无法准确确定大型结构在恶劣激励下的模态特性。为此，本文提出了一种基于模态解耦技术、自然激励技术、随机递减技术（RDT）和带有自动稳定图的改进型特征系统实现算法（ERA）的混合 OMA 框架，用于在正常和恶劣环境激励下对大型结构进行高精度模态估算和不确定性量化。通过对框架结构模型进行数值模拟研究，验证了混合框架在确定模态参数方面的准确性和有效性。此外，混合框架还被应用于分析一座 600 米高的超高层建筑在正常激励和台风条件下的加速度响应，以验证其在现场测量中的适用性。数值模拟和现场测量研究表明，混合框架不仅能通过单次环境振动测量进行精确的模态估算和不确定性量化，还能从多个角度有效揭示超高层结构在恶劣激励下的模态特性变化。本文旨在提高工程结构模态估算的可靠性和准确性，并进一步揭示大型民用结构在恶劣激励下的动态特性变化。
{"title":"Modal identification with uncertainty quantification of large‐scale civil structures via a hybrid operation modal analysis framework","authors":"Mengmeng Sun, Qiusheng Li","doi":"10.1002/tal.2102","DOIUrl":"https://doi.org/10.1002/tal.2102","url":null,"abstract":"SummaryIn operational modal analysis (OMA), only structural responses are typically available. In this context, bias and variance (uncertainty) errors may exist in modal estimates (especially damping estimates), resulting in inaccurate determination of the modal properties of large‐scale structures under harsh excitations. To this end, a hybrid OMA framework based on the modal decoupling, the natural excitation technique, the random decrement technique (RDT), and improved eigensystem realization algorithm (ERA) with the automated stabilization diagram is presented to perform high‐accuracy modal estimates with uncertainty quantification for large‐scale structures under normal and severe ambient excitations. The accuracy and effectiveness of the hybrid framework for identifying the modal parameters are validated by numerical simulation study of a framework structural model. Furthermore, the hybrid framework is applied to analyze recorded acceleration responses of a supertall building with 600‐m height under normal excitations and typhoon condition to verify its applicability in field measurements. The numerical simulation and field measurement studies demonstrate that the hybrid framework can not only perform precise modal estimations with uncertainty quantification through a single ambient vibration measurement but also effectively reveal the variations of modal properties of supertall structures under harsh excitations from multiple perspectives. This paper aims to enhance the reliability and accuracy of modal estimation for engineering structures and further provide insight into the variations of dynamic properties of large‐scale civil structures under severe excitations.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139950088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
SummaryThis research deals with a frame‐supported shear wall for urban over‐track building of vehicle depot in Chisha, Guangzhou, China, which is characterized by its remarkable height of 160.8 m. Technical issues are commonly encountered in these kinds of buildings due to discontinuous vertical structural rigidity, large podium, and structural transition. These challenges significantly impact the engineering process, especially when the rigidity difference between transfer story exceeding the threefold, as well as the building height exceeds limit as in code. In this paper, a shaking table test was developed based on a 1:10 scaled model of the structure. Using similarity theory, the dynamic similarity relationship was established for the design of the model. Subsequently, the experimental model was constructed with the configuration of critical parameters such as mass design, sensor placement, and seismic test conditions. This was followed by in‐depth analysis, recording component failures and investigating key aspects such as dynamic characteristics, that is, acceleration and displacement responses and shear force distribution under different earthquake intensities. A theoretical seismic response of the prototype structure was derived from the test results. The shaking table tests confirmed that the structure met the stringent seismic design requirements as prescribed in the Chinese standards, with no damage under minor earthquakes, repairability under moderate earthquakes, and collapse prevention under rare earthquakes. The results of the study provide valuable insights along with improvement measures for the design and development of similar urban over‐track buildings, potentially contributing to more efficient land use in urban China.
{"title":"Seismic performance of a frame‐supported shear wall over‐track building through shaking table test","authors":"Ying Zhou, Qidong Chen, Hao Wu, Hongchang Wen, Xingzhong Nong, Yongsheng Wu, Peng Xiao","doi":"10.1002/tal.2098","DOIUrl":"https://doi.org/10.1002/tal.2098","url":null,"abstract":"SummaryThis research deals with a frame‐supported shear wall for urban over‐track building of vehicle depot in Chisha, Guangzhou, China, which is characterized by its remarkable height of 160.8 m. Technical issues are commonly encountered in these kinds of buildings due to discontinuous vertical structural rigidity, large podium, and structural transition. These challenges significantly impact the engineering process, especially when the rigidity difference between transfer story exceeding the threefold, as well as the building height exceeds limit as in code. In this paper, a shaking table test was developed based on a 1:10 scaled model of the structure. Using similarity theory, the dynamic similarity relationship was established for the design of the model. Subsequently, the experimental model was constructed with the configuration of critical parameters such as mass design, sensor placement, and seismic test conditions. This was followed by in‐depth analysis, recording component failures and investigating key aspects such as dynamic characteristics, that is, acceleration and displacement responses and shear force distribution under different earthquake intensities. A theoretical seismic response of the prototype structure was derived from the test results. The shaking table tests confirmed that the structure met the stringent seismic design requirements as prescribed in the Chinese standards, with no damage under minor earthquakes, repairability under moderate earthquakes, and collapse prevention under rare earthquakes. The results of the study provide valuable insights along with improvement measures for the design and development of similar urban over‐track buildings, potentially contributing to more efficient land use in urban China.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139950020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
SummaryThis research investigates the influence of wind on four closely spaced parallel building models using computational fluid dynamics (CFD). The buildings are positioned either perpendicular to the wind direction or at various oblique angles. The aerodynamic results obtained for these buildings in an interfering condition are compared to those of an isolated tall building using the interference and obliquity effect (IOE) factor. Graphical comparisons are made among the different models and faces, considering various obliquity angles (OAs). The inner building models exhibit higher pressure and force coefficients at higher OAs. The variation of pressure coefficients along the horizontal peripheral direction is also analyzed, and the trade‐offs of higher and lower OAs are discussed for the different building models. Furthermore, an artificial neural network (ANN) is trained using surface pressure coefficients from approximately 6000 data points distributed over different facets of building models. Categorical encoding is employed using one‐hot encoding‐based dummy variables for different building models, while numerical variables such as OA and X, Y, and Z coordinates are included as input for the ANN. The ANN is trained using a total of 238,340 data points (considering different building models and different OA scenarios), and its parameters are monitored during training to minimize errors and achieve high predictability. Finally, a representative case is used to plot the pressure contour obtained from the trained ANN, which is shown to be highly comparable to the CFD‐based contour.
摘要本研究利用计算流体动力学（CFD）技术研究了风对四个间距较近的平行建筑模型的影响。这些建筑物的位置要么与风向垂直，要么呈不同的斜角。利用干扰和斜度效应 (IOE) 因子，将这些建筑物在干扰条件下获得的空气动力学结果与孤立高楼的空气动力学结果进行比较。考虑到不同的斜角 (OA)，对不同的模型和面进行了图形比较。内部建筑模型在较高的 OA 下表现出较高的压力和力系数。此外，还分析了压力系数沿水平周边方向的变化，并讨论了不同建筑模型在较高和较低 OA 值之间的权衡。此外，利用分布在不同建筑模型表面的约 6000 个数据点的表面压力系数，对人工神经网络（ANN）进行了训练。针对不同的建筑模型，采用了基于单次编码的虚拟变量进行分类编码，而 OA 和 X、Y、Z 坐标等数值变量则被作为人工神经网络的输入变量。使用总计 238 340 个数据点（考虑到不同的建筑模型和不同的 OA 情景）对方差分析网络进行了训练，并在训练过程中对其参数进行监控，以尽量减少误差并实现高预测性。最后，使用一个具有代表性的案例绘制了由训练有素的 ANN 得出的压力等值线，结果表明该压力等值线与基于 CFD 的等值线具有很高的可比性。
{"title":"Computational fluid dynamics and artificial neural network‐based analysis and forecasting of wind effects on obliquely parallel multiple building models using categorical variable encoding","authors":"Prasenjit Sanyal, Sujit Kumar Dalui","doi":"10.1002/tal.2105","DOIUrl":"https://doi.org/10.1002/tal.2105","url":null,"abstract":"SummaryThis research investigates the influence of wind on four closely spaced parallel building models using computational fluid dynamics (CFD). The buildings are positioned either perpendicular to the wind direction or at various oblique angles. The aerodynamic results obtained for these buildings in an interfering condition are compared to those of an isolated tall building using the interference and obliquity effect (IOE) factor. Graphical comparisons are made among the different models and faces, considering various obliquity angles (OAs). The inner building models exhibit higher pressure and force coefficients at higher OAs. The variation of pressure coefficients along the horizontal peripheral direction is also analyzed, and the trade‐offs of higher and lower OAs are discussed for the different building models. Furthermore, an artificial neural network (ANN) is trained using surface pressure coefficients from approximately 6000 data points distributed over different facets of building models. Categorical encoding is employed using one‐hot encoding‐based dummy variables for different building models, while numerical variables such as OA and X, Y, and Z coordinates are included as input for the ANN. The ANN is trained using a total of 238,340 data points (considering different building models and different OA scenarios), and its parameters are monitored during training to minimize errors and achieve high predictability. Finally, a representative case is used to plot the pressure contour obtained from the trained ANN, which is shown to be highly comparable to the CFD‐based contour.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139950024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao‐Jun Yao, Ting‐Hua Yi, Chun‐Xu Qu, Hong‐Nan Li
SummaryModal identification method based on blind source separation (BSS) technique has gained extensive attentions for civil structures. Developing the complex modes estimation method is important in practical applications because the assumption of proportional damping is not always satisfied. Sparse component analysis (SCA) performs well in underdetermined BSS problems. However, SCA is confined to the situation of proportional damping. In this study, a generalized SCA method is proposed to extend the original SCA method to both real and complex modes identification. First, the general formulation of complex modes is extended by the analytic form to eliminate the complex conjugate part in the BSS model. A new single‐source‐point detection method that is available to handle real and complex modes is proposed. Local outlier factor method is adopted to remove the outliers in single source points. Subsequently, complex‐valued modal matrix is calculated by the clustering technique. Then, modal responses are recovered using the complex version of smoothed zero norm method, where modal frequencies and damping ratios can be extracted. Finally, the effectiveness of the proposed method is demonstrated for identification of real and complex modes, close modes, and underdetermined problem. The application to a benchmark structure demonstrates the effectiveness for practical applications.
{"title":"Modal identification of non‐classically damped structures using generalized sparse component analysis","authors":"Xiao‐Jun Yao, Ting‐Hua Yi, Chun‐Xu Qu, Hong‐Nan Li","doi":"10.1002/tal.2101","DOIUrl":"https://doi.org/10.1002/tal.2101","url":null,"abstract":"SummaryModal identification method based on blind source separation (BSS) technique has gained extensive attentions for civil structures. Developing the complex modes estimation method is important in practical applications because the assumption of proportional damping is not always satisfied. Sparse component analysis (SCA) performs well in underdetermined BSS problems. However, SCA is confined to the situation of proportional damping. In this study, a generalized SCA method is proposed to extend the original SCA method to both real and complex modes identification. First, the general formulation of complex modes is extended by the analytic form to eliminate the complex conjugate part in the BSS model. A new single‐source‐point detection method that is available to handle real and complex modes is proposed. Local outlier factor method is adopted to remove the outliers in single source points. Subsequently, complex‐valued modal matrix is calculated by the clustering technique. Then, modal responses are recovered using the complex version of smoothed zero norm method, where modal frequencies and damping ratios can be extracted. Finally, the effectiveness of the proposed method is demonstrated for identification of real and complex modes, close modes, and underdetermined problem. The application to a benchmark structure demonstrates the effectiveness for practical applications.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139950025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the seismic impact of concrete floors on reduced beam section beam-to-column joints through four quasi-static cyclic tests. We examine mechanical properties, failure modes, and processes against specific criteria. Additionally, we analyze hysteretic response, energy dissipation, stiffness, capacity, and stress–strain mechanisms. Moreover, the ABAQUS platform was used to reproduce the specimen nonlinear finite element model to compare and analyze the test results. The results showed that the specimens exhibit excellent energy dissipation capacity and ductility (with a coefficient of 5.00); the column-bar connection characteristics affect the maximum capacity and plastic hinge behavior in the reduced beam area. The reduced section of beam's upper flange could not improve the overall seismic performance of the joint. The observed failure sequence is as follows: concrete floor cracking, beam flange yielding, reinforcement fracture, lower flange yielding in the reduced beam area, and overall joint failure. This sequence confirms that the joint fulfills the design criteria of a “strong column-weak beam” by achieving the target of plastic hinge outward movement.
{"title":"Seismic behavior of reduced beam section joints considering concrete floor effect","authors":"Shengcan Lu, Liang Luo, Xiangxi Han, Anqi Liu","doi":"10.1002/tal.2092","DOIUrl":"https://doi.org/10.1002/tal.2092","url":null,"abstract":"This study investigates the seismic impact of concrete floors on reduced beam section beam-to-column joints through four quasi-static cyclic tests. We examine mechanical properties, failure modes, and processes against specific criteria. Additionally, we analyze hysteretic response, energy dissipation, stiffness, capacity, and stress–strain mechanisms. Moreover, the ABAQUS platform was used to reproduce the specimen nonlinear finite element model to compare and analyze the test results. The results showed that the specimens exhibit excellent energy dissipation capacity and ductility (with a coefficient of 5.00); the column-bar connection characteristics affect the maximum capacity and plastic hinge behavior in the reduced beam area. The reduced section of beam's upper flange could not improve the overall seismic performance of the joint. The observed failure sequence is as follows: concrete floor cracking, beam flange yielding, reinforcement fracture, lower flange yielding in the reduced beam area, and overall joint failure. This sequence confirms that the joint fulfills the design criteria of a “strong column-weak beam” by achieving the target of plastic hinge outward movement.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139750864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent studies have investigated the impact of minimum longitudinal reinforcement limits on the ductility of the plastic hinge region of reinforced concrete (RC) walls, resulting in revised minimum reinforcement limits in design standards. The objective of this research was to investigate the influence of the longitudinal reinforcement distribution or termination rules for the additional reinforcement at the end regions of the wall up the wall height on the response of taller lightly RC walls. A model utilizing a displacement-based fiber element was developed and validated against tested walls with a range of longitudinal reinforcement contents. Pushover analyses were then conducted on a 20-story wall prototype to investigate the sensitivity of key design parameters, including axial load pattern, curtailment heights of the longitudinal reinforcement in the plastic hinge region, reinforcement content at wall base, reinforcement strain-hardening ratio, and the length over which the reinforcement curtailment occurred. The results indicate that the current minimum reinforcement provisions in ACI 318–19 are insufficient to prevent reinforcement yielding outside the plastic hinge region at the wall base.
{"title":"Investigation of reinforcement curtailment in tall lightly reinforced structural concrete walls","authors":"Tianhua Deng, Richard S. Henry","doi":"10.1002/tal.2074","DOIUrl":"https://doi.org/10.1002/tal.2074","url":null,"abstract":"Recent studies have investigated the impact of minimum longitudinal reinforcement limits on the ductility of the plastic hinge region of reinforced concrete (RC) walls, resulting in revised minimum reinforcement limits in design standards. The objective of this research was to investigate the influence of the longitudinal reinforcement distribution or termination rules for the additional reinforcement at the end regions of the wall up the wall height on the response of taller lightly RC walls. A model utilizing a displacement-based fiber element was developed and validated against tested walls with a range of longitudinal reinforcement contents. Pushover analyses were then conducted on a 20-story wall prototype to investigate the sensitivity of key design parameters, including axial load pattern, curtailment heights of the longitudinal reinforcement in the plastic hinge region, reinforcement content at wall base, reinforcement strain-hardening ratio, and the length over which the reinforcement curtailment occurred. The results indicate that the current minimum reinforcement provisions in ACI 318–19 are insufficient to prevent reinforcement yielding outside the plastic hinge region at the wall base.","PeriodicalId":501238,"journal":{"name":"The Structural Design of Tall and Special Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139561330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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