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Seismic tests of post-tensioned self-centering building frames with column and slab restraints

Chung-Che CHOU, Jun-Hen CHEN

《结构与土木工程前沿（英文）》 2011年 第5卷 第3期   页码 323-334 doi: 10.1007/s11709-011-0119-5

摘要： Post-tensioned (PT) self-centering moment frames have been developed as an alternative to typical moment-resisting frames (MRFs) for earthquake resistance. When a PT frame deforms laterally, gaps between the beams and columns open. However, the gaps are constrained by the columns and the slab in a real PT self-centering building frame. This paper presents a methodology for evaluating the column restraint and beam compression force based on the column deformation and gap openings at all stories. The method is verified by cyclic tests of a full-scale, two-bay by one-story PT frame. Moreover, a sliding slab is proposed to minimize restraints on the expansion of the PT frame. Shaking table tests were conducted on a reduced-scale, two-by-two bay one-story specimen, which comprises one PT frame and two gravitational frames. The PT frame and gravitational frames are self-centering throughout the tests, responding in phase with only minor differences in peak drifts caused by expansion of the PT frame. When the specimen is excited by a simulation of the 1999 Chi-Chi earthquake with a peak ground acceleration of 1.87 g, the maximum interstory drift and the residual drift are 7.2% and 0.01%, respectively.

关键词： post-tensioned frame     frame expansion     column restraint     sliding slab     frame test     shake table test    

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Development of rocking constraint device with vertical damping capacity for three-dimensional base-isolated frame

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 350-367 doi: 10.1007/s11709-022-0923-0

摘要： A new rocking constraint device (RCD) is developed for three-dimensional (3D) base-isolated frame structures by connecting a custom-designed cylinder pair to provide vertical damping with replaceable damping components installed outside the cylinders when the superstructure undergoes translational motion, and rocking constraint capacity when the superstructure is susceptible to rocking. Theoretical formulas for calculating the damping and rocking constraint stiffness of the RCD are proposed. Two series of sinusoidal loading tests are conducted at different loading frequencies and amplitudes to verify the damping and rocking constraint performance of the RCD. The test results show that the cylinder without orifices on its piston can provide the desired damping with a replaceable damping component, and that the RCD can effectively suppress rocking. Although the vertical stiffness of an individual cylinder is affected by the location of the replaceable damping component and loading frequency, the average vertical stiffness of the two cylinders, which determines the rocking constraint stiffness of the RCD, is independent of the two factors. Comparisons of the test and theoretical results indicate that the errors of the proposed formulas for calculating the damping and rocking constraint stiffness of the RCD do not exceed 12.9% and 11.0%, respectively.

关键词： three-dimensional isolation     rocking behavior     rocking constraint device     replaceable damping component     sinusoidal test    

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Seismic performance of moment resisting steel frame subjected to earthquake excitations

Fadzli M. NAZRI, Pang Yew KEN

《结构与土木工程前沿（英文）》 2014年 第8卷 第1期   页码 19-25 doi: 10.1007/s11709-014-0240-3

摘要： This study presents static and dynamic assessments on the steel structures. Pushover analysis (POA) and incremental dynamic analysis (IDA) were run on moment resisting steel frames. The IDA study involves successive scaling and application of each accelerogram followed by assessment of the maximum response. Steel frames are subjected to nonlinear inelastic time history analysis for 14 different scaled ground motions, 7 near field and 7 far field. The results obtained from POA on the 3, 6 and 9 storey steel frames show consistent results for both uniform and triangular lateral loading. Uniform loading shows that the steel frames exhibits higher base shear than the triangular loading. The IDA results show that the far field ground motions has caused all steel frame design within the research to collapse while near field ground motion only caused some steel frames to collapse. The POA can be used to estimate the performance-based-seismic-design (PBSD) limit states of the steel frames with consistency while the IDA seems to be quite inconsistent. It is concluded that the POA can be consistently used to estimate the limit states of steel frames while limit state estimations from IDA requires carefully selected ground motions with considerations of important parameters.

关键词： incremental dynamic analysis (IDA)     pushover analysis     performance-based seismic design    

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Tests on impact effect of partial fracture at steel frame connections

CHEN Yiyi, BIAN Ruoning

《结构与土木工程前沿（英文）》 2008年 第2卷 第4期   页码 295-301 doi: 10.1007/s11709-008-0049-z

摘要： Impact effect of sudden fracture at steel frame connections under severe earthquake or other extreme loads is presented in this paper. The relation of impulse caused by structural fracture to the release of inner force at the cracked location, the magnitude of the response to impact on the basis of one degree of freedom model, and the ratio of the peak value of response to natural period of the system are investigated. Two types of fracture tests were designed and carried out both on uniaxial steel bar tensioned and moment resistant steel frame model. It is proven that the response during the fracture process can be measured quite well using high-frequency data processing system. It is also revealed that the instant fracture of structural connection is characterized by progressive and partial fracture. Numerical evaluation of the impact effect of connection fracture is carried out.

关键词： structural fracture     natural     fracture     progressive     high-frequency    

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Deep reinforcement learning-based critical element identification and demolition planning of frame structures

Shaojun ZHU; Makoto OHSAKI; Kazuki HAYASHI; Shaohan ZONG; Xiaonong GUO

《结构与土木工程前沿（英文）》 2022年 第16卷 第11期   页码 1397-1414 doi: 10.1007/s11709-022-0860-y

摘要： This paper proposes a framework for critical element identification and demolition planning of frame structures. Innovative quantitative indices considering the severity of the ultimate collapse scenario are proposed using reinforcement learning and graph embedding. The action is defined as removing an element, and the state is described by integrating the joint and element features into a comprehensive feature vector for each element. By establishing the policy network, the agent outputs the Q value for each action after observing the state. Through numerical examples, it is confirmed that the trained agent can provide an accurate estimation of the Q values, and handle problems with different action spaces owing to utilization of graph embedding. Besides, different behaviors can be learned by varying hyperparameters in the reward function. By comparing the proposed method and the conventional sensitivity index-based methods, it is demonstrated that the computational cost is considerably reduced because the reinforcement learning model is trained offline. Besides, it is proved that the Q values produced by the reinforcement learning agent can make up for the deficiencies of existing indices, and can be directly used as the quantitative index for the decision-making for determining the most expected collapse scenario, i.e., the sequence of element removals.

关键词： progressive collapse     alternate load path     demolition planning     reinforcement learning     graph embedding    

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Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 318-330 doi: 10.1007/s11709-017-0420-z

摘要：

The objective of this study is, to interpret the influence of reinforced concrete walls addition in reinforced concrete frame structures considering behavior laws that reflects the actual behavior of such structures, by means of Castem2000computer code (pushover analysis). A finite element model is proposed in this study, using the TAKEDA modified behavior model with Timoshenko beams elements. This model is validated initially on experimental model. Then the work has focused on the behavior of a RC frame with 3 levels and three bays to better visualize the behavior of plastic hinges. Once the plastic hinge control parameters are identified (plastic rotation, ultimate curvature), a strengthening by introduction of reinforced concrete walls (RC/wall) at the ends of the reinforced concrete frame (RC/frame) has been performed. The results show that these RC walls significantly improve the behavior, by a relocation of efforts towards the central part of the beams.

关键词： RC/frame     RC/wall     moment curvature     plastic rotation     plastic hinge     pushover analysis     global models    

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Cyclic responses of three 2-story seismic concentrically braced frames

Ching-Yi TSAI, Keh-Chyuan TSAI, Chih-Han LIN, Chih-Yu WEI, Kung-Juin WANG, Yi-Jer YU, An-Chien WU,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 287-301 doi: 10.1007/s11709-010-0087-1

摘要： Three full scale two-story steel concentrically braced frames (CBFs) were tested at the National Center for Research on Earthquake Engineering (NCREE) in Taipei. The specimen is a single bay with the braces arranged in a two-story X-brace configuration. The main differences among the three tests are the brace types (hollow structural or wide-flange section) and the design criteria adopted for the gusset plate connections. Results of these three tests confirm that the two-story X-shape steel CBFs all have rather good energy dissipation characteristics up to a story drift of about 0.03 radians under the cyclically increasing lateral displacements. Severe brace local buckling and out-of-plane displacements were observed during each test. Tests confirm that both the 2-linear and 8-elliptical designs of the gusset plate connection provide satisfactory ductility for the steel CBF. Hollow structural section (HSS) braces fractured at a story drift smaller than that found using wide flange sections. The nonlinear fine element method (FEM) program ABAQUS was used to simulate the responses of the specimen. The base shear versus the story drift relationships obtained from the tests and the FEM analytical results are quite agreeable in various levels of lateral frame displacement. The analytical results confirm that the severe out-of-plane buckling of the braces can be accurately simulated. FEM analyses also illustrate that the steel moment resisting frame takes about 40% story shear when the inter-story drift is greater than 0.02 radians.

关键词： concentrically braced frame (CBF)     full-scale test     finite element (FE) analysis     flexural buckling     local buckling    

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Seismic behavior experimental study of frame joints with special-shaped column and dispersed steel bar

Shuchun LI, Bo DIAO, Youpo SU,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 378-383 doi: 10.1007/s11709-009-0064-8

摘要： To overcome the problem that steel bars are put too close at a flame joint with special-shaped beam and column, mechanical performance of three groups of six RC flame joints with special-shaped (L, T and+) column and dispersed-steel bars-beam on the top floor under cyclic loads were studied. Experimental comparison was conducted between special-shaped (L, T and+) column and normal beams. The cracking load, yielding load, ultimate bearing capacity, failure patterns, and hysteretic properties at joint core area were investigated. The seismic behaviors of the joints with different proportions of dispersed-steel-bar beams were analyzed. The results of experimental analysis indicate that the mechanical and seismic behaviors of frame joints with T-shaped and+-shaped column are nearly not changed when suitable proportion steel bars are dispersed to flange plane. Stiffness degeneration of flame joint with L-shaped column is rather serious due to concrete damage stiffness. Theoretical result indicates that distributing area of the dispersed steel-bar beams in the flange plate should be strictly controlled to avoid anchor destroy.

关键词： beam with dispersed steel bar     flame joints with special-shaped beam and column     seismic behavior     scale of dispersed steel bars    

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Truss-arch model for shear strength of seismic-damaged SRC frame columns strengthened with CFRP sheets

Sheng PENG, Chengxiang XU, Xiaoqiang LIU

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1324-1337 doi: 10.1007/s11709-019-0557-z

摘要： Carbon fiber reinforced polymer (CFRP) materials are important reinforcing substances which are widely used in the shear strengthening of seismic-damage steel reinforced concrete (SRC) frame structures. To investigate the shear strength of SRC frame columns strengthened with CFRP sheets, experimental observations on eight seismic-damaged SRC frame columns strengthened with CFRP sheets were conducted at Yangtze University and existing experimental data of 49 SRC columns are presented. Based on the existing experiments, the theories of damage degree, zoning analysis of concrete, and strengthening material of the column are adopted. To present the expression formula of the shear strength of SRC frame columns strengthened with CFRP sheets, the contributions of strengthening material and transverse reinforcement to shear strength in the truss model are considered, based on the truss-arch model. The contribution of arch action is also considered through the analysis of the whole concrete and that of the three zones of the concrete are also considered. The formula is verified, and the calculated results are found to match well with the experimental results. Results indicate that the proposed whole analysis model can improve the accuracy of shear strength predictions of shear seismic-damaged SRC frame columns reinforced with CFRP sheets.

关键词： carbon fiber reinforced polymer material     steel reinforced concrete frame column     seismic-damaged     trussed-arch model     shear strength    

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视频分层组织方案和技术

章毓晋,陆海斌

《中国工程科学》 2000年 第2卷 第3期   页码 18-22

摘要：

数字视频是多媒体信息系统中重要的数据类型。传统的视频表示方法仅是一个时间序列一媒体流， 所以对计算机来说，很难在内容层次上认知视频。为了有效地访问和利用视频信息，合适的视频数据组织非常 重要。文章提出将视频划分成四个层次即视频节目、情节、镜头和图像帧的组织方法。这样一种分层结构提供了紧凑和有意义的视频目录，方便了视频非线性浏览和基于内容的检索。为了得到这样一种组织，不仅要检测 出镜头和情节这些视频单元的边界，还要提取镜头关键帧和选择情节有代表性的镜头和代表帧。文章介绍一系 列分割视频和组织视频的准则和方法，并把它们结合起来组成了一个原型实验系统。文中还给出了一些对实际 视频进行组织的结果，它们表明该组织形式是非常有效的。

关键词： 视频组织     浏览     镜头     关键帧     情节     代表帧    

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扫描格式转换的自适应帧频提升算法 及其FPGA实现

吴勇,张光烈,郑南宁,张霞

《中国工程科学》 2001年 第3卷 第4期   页码 56-62

摘要：

文章提出了一种新的自适应帧频提升算法，并深人研究了它的快速硬件实现方法。该算法通过引入 内部参数和加权块匹配误差，来进行自适应运动补偿，因而它可以有效地消除噪声的影响，并便于硬件实现。最后，通过建立对应于可变参数的因子査找表和采用现场可编程逻辑器件（FPGA)快速实现了扫描格式转换中的帧频提升算法，并应用在实际系统中，实验结果表明该算法十分有效。

关键词： 扫描格式转换     帧频提升     块匹配     运动补偿    

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Experimental research on seismic behavior of recycled concrete frame under varying cyclic loading

SUN Yuedong, XIAO Jianzhuang, ZHOU Deyuan

《结构与土木工程前沿（英文）》 2008年 第2卷 第4期   页码 302-308 doi: 10.1007/s11709-008-0050-6

摘要： A study is conducted on the seismic behavior of one natural concrete frame and two recycled concrete frames with 100% recycled coarse aggregate whose scales are 1:2 entirely, and a comparative study is conducted under low-reversed cyclic lateral loading and different vertical loading. This work aims to estimate the failure mechanism, hysteresis loops, displacement ductility, deterioration of strength and stiffness and energy dissipation of recycled concrete frames under low-reversed cyclic loading as well as the influence of different vertical loading. Analysis on the basis of the experiment proves that it is entirely feasible to apply recycled concrete to practical engineering for the sake of its good seismic behaviors. Theoretical base is provided for further study and practical application of recycled concrete structure.

关键词： different     aggregate     stiffness     practical application     % recycled    

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Cyclic behavior of prefabricated reinforced concrete frame with infill slit shear walls

Kui XIAO,Qilin ZHANG,Bin JIA

《结构与土木工程前沿（英文）》 2016年 第10卷 第1期   页码 63-71 doi: 10.1007/s11709-015-0294-x

摘要： A composite structural system consisting of prefabricated reinforced concrete frame with infill slit shear walls (PRCFW), with good ductility, is a new type of earthquake resistant structure. Pseudo-static tests were performed to evaluate the seismic behavior of the PRCFW system. Two one-bay, two-story PRCFW specimens were both built at one-half scale. Additional computational research is also conducted to enhance the nonlinear analytical capabilities for this system. Combined with the concrete damaged plastic (CDP) model provided by finite element program ABAQUS and the constitutive model of concrete proposed by Chinese code, the damage process of the PRCFW structure under cyclic load is simulated. The simulated results show a good agreement with the test data, the dynamic behavior of the PRCFW system can be simulated sufficiently accurate and efficient to provide useful design information. The experimental and numerical study show that this system has the potential to offer good ductility and energy absorption capacity to dissipate input energy, and stiffness adequate for controlling drift for buildings located in earthquake-prone regions.

关键词： slit shear wall     constitutive model     cyclic     seismic     damage    

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Displacement-based seismic design of high-strength concrete frame columns

ZHANG Guojun, LIU Jianxin, LU Xilin

《结构与土木工程前沿（英文）》 2008年 第2卷 第1期   页码 93-101 doi: 10.1007/s11709-008-0006-x

摘要： Based on the testing results of 108 high-strength concrete columns under constant axial loading and horizontal cyclic loading, the relations between the drift ratio at yield, the maximum displacement drift, the limiting displacement drift, the ductility ratio of testing columns and shear span-to-depth ratio, axial compression ratio, confining reinforcement characteristic values, the ratio of cover area to confined core area as well as longitudinal reinforcement ratio are discussed in this paper. Then the relations between limiting displacement drifts and axial compression ratio, confining reinforcement characteristic values and the ratio of cover area to confined core area are analytically regressed. Subsequently the relations between confining reinforcement characteristic values and axial compression ratio, the limiting displacement drift, and the practical formula used to calculate confining reinforcement characteristic values are put forward. In the end the minimum confining reinforcement characteristic values in the dense hoop regions of high-strength concrete columns are presented by comparatively analysis, and compared with ones in the design code (GB 50010-2002, P. R. China).

关键词： horizontal cyclic     longitudinal reinforcement     design     loading     constant    

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Numerical simulation and analysis for collapse responses of RC frame structures under earthquake

Fuwen ZHANG, Xilin LU, Chao YIN,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 364-369 doi: 10.1007/s11709-009-0061-y

摘要： In this paper, a discrete element model for collapse simulation of RC frame structure is constructed by discretizing the structure into a few elements and spring groups. This model introduces special hysteretic models of connected springs for arbitrary loading path and also takes into account reasonable failure criteria for springs considering coupling effect of shear and axial force. Based on the discrete element model, a computer program is developed to simulate the whole process of RC frame structures from initial state to collapse under earthquakes. Particularly, the contact-impact problem between discrete elements has been treated with effective measures. Then, the program is employed to study the collapse mechanism of a real building in Wenchuan earthquake-hit area; the result of which shows that the simulation program developed based on the new model can realistically simulate the seismic collapse process of RC frame structures.

关键词： discrete element method     failure criteria     contact-impact     simulation program    

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标题 作者 时间 类型 操作

Seismic tests of post-tensioned self-centering building frames with column and slab restraints

Chung-Che CHOU, Jun-Hen CHEN

期刊论文

Development of rocking constraint device with vertical damping capacity for three-dimensional base-isolated frame

期刊论文

Seismic performance of moment resisting steel frame subjected to earthquake excitations

Fadzli M. NAZRI, Pang Yew KEN

期刊论文

Tests on impact effect of partial fracture at steel frame connections

CHEN Yiyi, BIAN Ruoning

期刊论文

Deep reinforcement learning-based critical element identification and demolition planning of frame structures

Shaojun ZHU; Makoto OHSAKI; Kazuki HAYASHI; Shaohan ZONG; Xiaonong GUO

期刊论文

Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

期刊论文

Cyclic responses of three 2-story seismic concentrically braced frames

Ching-Yi TSAI, Keh-Chyuan TSAI, Chih-Han LIN, Chih-Yu WEI, Kung-Juin WANG, Yi-Jer YU, An-Chien WU,

期刊论文

Seismic behavior experimental study of frame joints with special-shaped column and dispersed steel bar

Shuchun LI, Bo DIAO, Youpo SU,

期刊论文

Truss-arch model for shear strength of seismic-damaged SRC frame columns strengthened with CFRP sheets

Sheng PENG, Chengxiang XU, Xiaoqiang LIU

期刊论文

视频分层组织方案和技术

章毓晋,陆海斌

期刊论文

扫描格式转换的自适应帧频提升算法 及其FPGA实现

吴勇,张光烈,郑南宁,张霞

期刊论文

Experimental research on seismic behavior of recycled concrete frame under varying cyclic loading

SUN Yuedong, XIAO Jianzhuang, ZHOU Deyuan

期刊论文

Cyclic behavior of prefabricated reinforced concrete frame with infill slit shear walls

Kui XIAO,Qilin ZHANG,Bin JIA

期刊论文

Displacement-based seismic design of high-strength concrete frame columns

ZHANG Guojun, LIU Jianxin, LU Xilin

期刊论文

Numerical simulation and analysis for collapse responses of RC frame structures under earthquake

Fuwen ZHANG, Xilin LU, Chao YIN,

期刊论文