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multi-objective design method for seismic retrofitting of existing reinforced concrete frames using pin-supportedrocking walls

Yue CHEN; Rong XU; Hao WU; Tao SHENG

《结构与土木工程前沿(英文)》 2022年 第16卷 第9期   页码 1089-1103 doi: 10.1007/s11709-022-0851-z

摘要: Over the past several decades, a variety of technical ways have been developed in seismic retrofitting of existing reinforced concrete frames (RFs). Among them, pin-supported rocking walls (PWs) have received much attentions to researchers recently. However, it is still a challenge that how to determine the stiffness demand of PWs and assign the value of the drift concentration factor (DCF) for entire systems rationally and efficiently. In this paper, a design method has been exploited for seismic retrofitting of existing RFs using PWs (RF-PWs) via a multi-objective evolutionary algorithm. Then, the method has been investigated and verified through a practical project. Finally, a parametric analysis was executed to exhibit the strengths and working mechanism of the multi-objective design method. To sum up, the findings of this investigation show that the method furnished in this paper is feasible, functional and can provide adequate information for determining the stiffness demand and the value of the DCF for PWs. Furthermore, it can be applied for the preliminary design of these kinds of structures.

关键词: pin-supported rocking wall     reinforced concrete frame     seismic retrofit     stiffness demand     drift concentration factor     multi-objective design     genetic algorithm     Pareto optimal solution    

Seismic retrofit of existing SRC frames using rocking walls and steel dampers

Akira WADA, Zhe QU, Shojiro MOTOYUI, Hiroyasu SAKATA

《结构与土木工程前沿(英文)》 2011年 第5卷 第3期   页码 259-266 doi: 10.1007/s11709-011-0114-x

摘要: A retrofit of an existing 11-story steel reinforced concrete frame that features the innovative use of post-tensioned rocking walls and shear steel dampers is presented. The main components of the retrofitting plan and important design considerations are described. The retrofitting system is expected to effectively control the deformation pattern of the existing structure and significantly reduce damage to the existing structure during major earthquakes.

关键词: building structure     seismic retrofit     rocking wall     steel damper    

Influence of damages on static behavior of single-layer cable net supported glass curtain wall: full-scale

Gang SHI, Yongjiu SHI, Yuanqing WANG, Yongzhi ZUO, Xiaohao SHI, Zaoyang GUO,

《结构与土木工程前沿(英文)》 2010年 第4卷 第3期   页码 383-395 doi: 10.1007/s11709-010-0074-6

摘要: The single-layer cable net supported glass curtain wall has been applied in many building structures all over the world. In service, it will inevitably be subject to various damages. To study the influence of such damages on the static behavior of the single-layer cable net supported glass curtain wall, a full-scale model with the outside outline size of 4.85 m × 4.85 m and 4 × 4 grids is designed and tested. Two kinds of damages that are the cable prestress loss and cable anchorage end failure are led into the structure model during the test, and their influence has been investigated. The stiffness contribution of glass panels to the single-layer cable net supported glass curtain wall structure with or without damages and its change have been tested and analyzed. The results show that the maximum change rate of nodal deflection is 13.78% for the damage of cable prestress loss, while the change rate of nodal deflection is between 7% and 22% for the damage of cable anchorage end failure. The influence degree of the damages depends on the ratio of the structure initial stress stiffness change caused by damages to the total stiffness of the structure. The stiffness contribution of glass panels increases with the load increase. Under the same loading condition, the stiffness contribution of glass panels to the damaged structure is greater than that to the intact structure. The stiffness contribution of glass panels reduces the effect of the damages on the structural displacement and the cable tension force, but the glass panel could break if its stiffness contribution is too large.

关键词: single-layer plane cable net supported glass curtain wall     damage     cable prestress loss     cable anchorage end failure     stiffness contribution of glass panels    

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

《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    

Dynamic characteristics of a magnetorheological pin joint for civil structures

Yancheng LI,Jianchun LI

《机械工程前沿(英文)》 2014年 第9卷 第1期   页码 15-33 doi: 10.1007/s11465-014-0283-0

摘要:

Magnetorheological (MR) pin joint is a novel device in which its joint moment resistance can be controlled in real-time by altering the applied magnetic field. The smart pin joint is intended to be used as a controllable connector between the columns and beams of a civil structure to instantaneously shift the structural natural frequencies in order to avoid resonance and therefore to reduce unwanted vibrations and hence prevent structural damage. As an intrinsically nonlinear device, modelling of this MR fluid based device is a challenging task and makes the design of a suitable control algorithm a cumbersome situation. Aimed at its application in civil structure, the main purpose of this paper is to test and characterise the hysteretic behaviour of MR pin joint. A test scheme is designed to obtain the dynamic performance of MR pin joint in the dominant earthquake frequency range. Some unique phenomena different from those of MR damper are observed through the experimental testing. A computationally-efficient model is proposed by introducing a hyperbolic element to accurately reproduce its dynamic behaviour and to further facilitate the design of a suitable control algorithm. Comprehensive investigations on the model accuracy and dependences of the proposed model on loading condition (frequency and amplitude) and input current level are reported in the last section of this paper.

关键词: Magnetorheological pin joint     hyperbolic hysteresis model experimental testing frequency dependence    

Design considerations and experimental studies on semi-active smart pin joint

Yancheng LI, Jianchun LI, Bijan SAMALI, Jiong WANG,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 363-370 doi: 10.1007/s11465-009-0074-1

摘要: Hostile dynamic loadings such as severe wind storms, earthquakes, and sudden impacts can cause severe damage to many civil engineering structures. An intelligent structural system equipped with smart structural members that are controllable in real-time is an effective solution to structural damage and failure during such situations. Civil intelligent structures with controllable properties to adapt to any changes due to dynamic loadings can lead to effective protection of structures and their occupants. In this paper, design and testing of a semi-active magnetorheological (MR) pin joint, in which the moment resistance can be controlled in real-time by altering the magnetic field, is reported with the view of using it as a potential candidate for smart members in the development of intelligent structures. Design of prototype smart pin joints includes theoretical analysis related to the radius of the rotary plate, the property of MR fluids and the gap between the rotary plate and the casing based on the requirements of the dynamics of MR pin joints. FEM analysis was deployed to study the distribution of the magnetic field along the gap. It is found, from the theoretical analysis and experimental verification, that the MR pin joint with a diameter of 180 mm can produce a torque of up to 30 Nm, which meets requirements for semi-active members in a multi-storey prototype building model in the next stage of research and development.

关键词: magnetorheological (MR) fluids     smart pin joint     design consideration    

Antibiotics-mediated intestinal microbiome perturbation aggravates tacrolimus-induced glucose disorders in mice

Yuqiu Han, Xiangyang Jiang, Qi Ling, Li Wu, Pin Wu, Ruiqi Tang, Xiaowei Xu, Meifang Yang, Lijiang Zhang

《医学前沿(英文)》 2019年 第13卷 第4期   页码 471-481 doi: 10.1007/s11684-019-0686-8

摘要: Both immunosuppressants and antibiotics (ABX) are indispensable for transplant patients. However, the former increases the risk of new-onset diabetes, whereas the latter impacts intestinal microbiota (IM). It is still unclear whether and how the interaction between immunosuppressants and ABX alters the IM and thus leads to glucose metabolism disorders. This study examined the alterations of glucose and lipid metabolism and IM in mice exposed to tacrolimus (TAC) with or without ABX. We found that ABX further aggravated TAC-induced glucose tolerance and increased insulin secretion. Combined treatment resulted in exacerbated lipid accumulation in the liver. TAC-altered microbial community was further amplified by ABX administration, as characterized by reductions in phylum Firmicutes, family Lachnospiraceae, and genus . Analyses based on the metagenomic profiles revealed that ABX augmented the effect of TAC on microbial metabolic function mostly related to lipid metabolism. The altered components of gut microbiome and predicted microbial functional profiles showed significant correlation with hepatic lipid accumulation and glucose disorders. In conclusion, ABX aggravated the effect of TAC on the microbiome and its metabolic capacities, which might contribute to hepatic lipid accumulation and glucose disorders. These findings suggest that the ABX-altered microbiome can amplify the diabetogenic effect of TAC and could be a novel therapeutic target for patients.

关键词: antibiotics     tacrolimus     glucose disorders     microbiome    

Association of the genetic polymorphism of EPHX1 and EPHX2 with the susceptibility to chronic benzene poisoning

SUN Pin, ZHANG Zhongbin, WU Fen, WAN Junxiang, JIN Xibeng, XIA Zhaolin

《医学前沿(英文)》 2007年 第1卷 第3期   页码 320-326 doi: 10.1007/s11684-007-0062-y

摘要: The aim of this study was to explore the association of the genetic polymorphism of and with the susceptibility to chronic benzene poisoning (CBP). A case-control study of 268 patients with CBP and 268 healthy workers matched by age and sex, all of whom were occupationally exposed to benzene, was conducted. The single nucleotide polymorphisms (SNPs, rs2854451, rs3738047, rs2234922 and rs1051741) of gene and the SNP (rs751141) of gene were tested by the TaqMan PCR method. In the subjects carrying the genotype of rs3738047 GG, the risk of CBP was decreased in the individuals simultaneously carrying rs2234922 G ( = 0.02). Alternatively, in the subjects carrying the genotype of rs2234922 AA, the risk of CBP was increased in the individuals simultaneously carrying the allele of rs751141A ( = 0.03). It was also found that there were potential interactions between alcohol consumption and the polymorphism of rs1051741 ( = 5.28, = 0.02) or rs2234922 (= 6.71, = 0.01). Compared to individuals with rs1051741 CC or rs2234922 AA genotype in the drinkers, the risk of CBP in those carrying genotypes of rs1051741 CT+TT or rs2234922 AG+GG was decreased, respectively ( = 0.04, 〈0.01). Haplotype analysis of polymorphisms in showed that the risk of CBP was increased in the subjects with haplotype 2 (rs2854451-A, rs3738047-G, rs2234922-A, rs1051741-C) or haplotype 4 (rs2854451-G, rs3738047-A, rs2234922-G, rs1051741-T), but decreased in those with haplotype 6 (rs2854451-G, rs3738047-G, rs2234922-G, rs1051741-T) or haplotype 10 (rs2854451-A, rs3738047-A, rs2234922-G, rs1051741-T), respectively. Logistic regression analysis revealed that smoking might play a role in modifying the risk of CBP (OR = 0.313, 95% CI: 0.123 0.794, = 0.015). The genetic polymorphism in may be associated with the risk of CBP in the Chinese occupational population and further research is needed for the association between the genetic polymorphism in and the susceptibility to CBP.

关键词: case-control     rs2854451     regression analysis     haplotype     further research    

Modal analysis of acoustic leak signal in pipelines using time-frequency analysis

JIAO Jing-pin, FEI Ren-yuan, HE Cun-fu, WU Bin

《机械工程前沿(英文)》 2006年 第1卷 第2期   页码 146-150 doi: 10.1007/s11465-006-0013-3

摘要: It is important to analyze the propagation characteristics of guided waves in acoustic leak location in pipelines. In this paper, the acoustic leak signal is analyzed in the time-frequency domain. Based on the relation of time-frequency distribution of the acoustic leak signal and the dispersion curves of guided waves, the mode components of acoustic leak signals were obtained. The research can provide a guideline for the mode selection in pipeline leak location, and help improve the accuracy of leak location.

关键词: dispersion     selection     guided     research     time-frequency    

Numerical simulation of squat reinforced concrete wall strengthened by FRP composite material

Ali KEZMANE,Said BOUKAIS,Mohand Hamizi

《结构与土木工程前沿(英文)》 2016年 第10卷 第4期   页码 445-455 doi: 10.1007/s11709-016-0339-9

摘要: The advanced design rules and the latest known earthquakes, have imposed a strengthening of reinforced concrete structures. Many research works and practical achievements of the application of the external reinforcement by using FRP composite materials have been particularly developed in the recent years. This type of strengthening seems promising for the seismic reinforcement of buildings. Among of the components of structures that could affect the stability of the structure in case of an earthquake is the reinforced concrete walls, which require in many cases a strengthening, especially in case where the diagonal cracks can be developed. The intent of this paper is to present a numerical simulation of squat reinforced concrete wall strengthened by FRP composite material (carbon fiber epoxy). The intent of this study is to perform finite element model to investigate the effects of such reinforcement in the squat reinforced concrete walls. Taking advantage of a commercial finite element package ABAQUS code, three-dimensional numerical simulations were performed, addressing the parameters associated with the squat reinforced concrete walls. An elasto-plastic damage model material is used for concrete, for steel, an elastic-plastic behavior is adopted, and the FRP composite is considered unidirectional and orthotropic. The obtained results in terms of displacements, stresses, damage illustrate clearly the importance of this strengthening strategy.

关键词: simulation     strengthening     reinforced concrete wall     squat wall     FRP composite material     damage     Abaqus    

Nonlinear analysis of pre-tensioned glass wall facade by stability function with initial imperfection

Siu-Lai CHAN, Yaopeng LIU, Andy LEE,

《结构与土木工程前沿(英文)》 2010年 第4卷 第3期   页码 376-382 doi: 10.1007/s11709-010-0086-2

摘要: Pre-tensioned high strength trusses using alloy steel bar are widely used as glass wall supporting systems because of the high degree of transparency. The breakage of glass panes in this type of system occurs occasionally, likely to be due to error in design and analysis in addition to other factors like glass impurity and stress concentration around opening in a spider system. Most design does not consider the flexibility of supports from finite stiffness of supporting steel or reinforced concrete beams. The resistance of lateral wind pressure of the system makes use of high tension force coupled with the large deflection effect, both of which are affected by many parameters not generally considered in conventional structures. In the design, one must therefore give a careful consideration on various effects, such as support settlement due to live loads and material creep, temperature change, pre-tension force, and wind pressure. It is not uncommon to see many similar glass wall systems fail in the wind load test chambers under a design wind speed. This paper presents a rigorous analysis and design of this type of structural systems used in a project in Hong Kong, China. The stability function with initial curvature is used in place of the cubic function, which is only accurate for linear analysis. The considerations and analysis techniques are believed to be of value to engineers involved in the design of the structural systems behaving nonlinearly.

关键词: tension system     glass wall     nonlinear analysis     pre-tensioning     second-order analysis    

Diaphragm wall-soil-cap interaction in rectangular-closed- diaphragm-wall bridge foundations

Hua WEN, Qiangong CHENG, Fanchao MENG, Xiaodong CHEN

《结构与土木工程前沿(英文)》 2009年 第3卷 第1期   页码 93-100 doi: 10.1007/s11709-009-0015-4

摘要: Rectangular-closed-diaphragm-wall foundation is a new type of bridge foundation. Diaphragm wall-soil-cap interaction was studied using a model test. It was observed that the distribution of soil resistance under the cap is not homogeneous. The soil resistance in the corner under the cap is larger than that in the border; and that in the center is the smallest. The distribution of soil resistance under the cap will be more uniform, if the sectional area of soil core is enlarged within a certain range. Due to the existence of cap, there is a “weakening effect” in inner shaft resistance of the upper wall segments, and there is “enhancement effect” in the lower wall segments and in toe resistance. The load shearing percentage of soil resistance under the cap is 10%-20%. It is unreasonable to ignore the effects of the cap and the soil resistance under the cap in bearing capacity calculations.

关键词: diaphragm wall     bridge foundation     low cap     interaction    

Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-plane

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1128-1143 doi: 10.1007/s11709-021-0753-5

摘要: This paper provides insight into the seismic behavior of a full-scale precast reinforced concrete wall under in-plane cyclic loading combined with out-of-plane loading replicated by sand backfill to simulate the actual condition of basement walls. The tested wall exhibited flexural cracks, owing to the high aspect ratio and considerable out-of-plane movement due to lateral pressure from the backfill. The wall performed satisfactorily by exhibiting competent seismic parameters and deformation characteristics governed by its ductile response in the nonlinear phase during the test with smaller residual drift. Numerical analysis was conducted to validate experimental findings, which complied with each other. The numerical model was used to conduct parametric studies to study the effect of backfill density and aspect ratio on seismic response of the proposed precast wall system. The in-plane capacity of walls reduced, while deformation characteristics were unaffected by the increase in backfill density. An increase in aspect ratio leads to a reduction in in-plane capacity and an increase in drift. Curves between the ratio of in-plane yield capacity and design shear load of walls are proposed for the backfill density, which may be adopted to determine the in-plane yield capacity of the basement walls based on their design shear.

关键词: precast wall     basement wall     out-of-plane response     quasi-static test     sand backfill     seismic parameters    

Prediction of shield tunneling-induced ground settlement using machine learning techniques

Renpeng CHEN, Pin ZHANG, Huaina WU, Zhiteng WANG, Zhiquan ZHONG

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1363-1378 doi: 10.1007/s11709-019-0561-3

摘要: Predicting the tunneling-induced maximum ground surface settlement is a complex problem since the settlement depends on plenty of intrinsic and extrinsic factors. This study investigates the efficiency and feasibility of six machine learning (ML) algorithms, namely, back-propagation neural network, wavelet neural network, general regression neural network (GRNN), extreme learning machine, support vector machine and random forest (RF), to predict tunneling-induced settlement. Field data sets including geological conditions, shield operational parameters, and tunnel geometry collected from four sections of tunnel with a total of 3.93 km are used to build models. Three indicators, mean absolute error, root mean absolute error, and coefficient of determination the ( ) are used to demonstrate the performance of each computational model. The results indicated that ML algorithms have great potential to predict tunneling-induced settlement, compared with the traditional multivariate linear regression method. GRNN and RF algorithms show the best performance among six ML algorithms, which accurately recognize the evolution of tunneling-induced settlement. The correlation between the input variables and settlement is also investigated by Pearson correlation coefficient.

关键词: EPB shield     shield tunneling     settlement prediction     machine learning    

A new acoustic emission source location technique based on wavelet transform and mode analysis

JIAO Jing-pin, HE Cun-fu, WU Bin, FEI Ren-yuan, WANG Xiu-yan

《机械工程前沿(英文)》 2006年 第1卷 第3期   页码 341-345 doi: 10.1007/s11465-006-0006-4

摘要: For wave propagation in dispersive media, the arrival time of the acoustic emission signal to the sensor is dependent on the setting of the threshold voltage, which results in the inaccuracy of the acoustic emission location. Based on the wavelet transform and the theory of modal acoustic emission, a new method is proposed to improve the accuracy of acoustic emission source location. It is believed that the acoustic emission signal propagation in the structure has the characteristics of multi-mode and dispersion, and the acoustic emission source location should use the arrival time to sensors obtained from the output signals not only at the same mode but also at the same frequency. The wavelet transform is used to resolve the problem. By utilizing the time-frequency data of the wavelet, the frequency-dependent arrival time traveling is easily obtained; by numerical computation of the wave s propagation in structure, the group velocity of the guided mode is also obtained, therefore the accuracy source location is realized. The acoustic emission source location experiments were conducted in a thin steel plate and results show that the technique is an effective tool for acoustic emission source location.

关键词: s propagation     frequency     emission signal     signal propagation     dispersive    

标题 作者 时间 类型 操作

multi-objective design method for seismic retrofitting of existing reinforced concrete frames using pin-supportedrocking walls

Yue CHEN; Rong XU; Hao WU; Tao SHENG

期刊论文

Seismic retrofit of existing SRC frames using rocking walls and steel dampers

Akira WADA, Zhe QU, Shojiro MOTOYUI, Hiroyasu SAKATA

期刊论文

Influence of damages on static behavior of single-layer cable net supported glass curtain wall: full-scale

Gang SHI, Yongjiu SHI, Yuanqing WANG, Yongzhi ZUO, Xiaohao SHI, Zaoyang GUO,

期刊论文

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

期刊论文

Dynamic characteristics of a magnetorheological pin joint for civil structures

Yancheng LI,Jianchun LI

期刊论文

Design considerations and experimental studies on semi-active smart pin joint

Yancheng LI, Jianchun LI, Bijan SAMALI, Jiong WANG,

期刊论文

Antibiotics-mediated intestinal microbiome perturbation aggravates tacrolimus-induced glucose disorders in mice

Yuqiu Han, Xiangyang Jiang, Qi Ling, Li Wu, Pin Wu, Ruiqi Tang, Xiaowei Xu, Meifang Yang, Lijiang Zhang

期刊论文

Association of the genetic polymorphism of EPHX1 and EPHX2 with the susceptibility to chronic benzene poisoning

SUN Pin, ZHANG Zhongbin, WU Fen, WAN Junxiang, JIN Xibeng, XIA Zhaolin

期刊论文

Modal analysis of acoustic leak signal in pipelines using time-frequency analysis

JIAO Jing-pin, FEI Ren-yuan, HE Cun-fu, WU Bin

期刊论文

Numerical simulation of squat reinforced concrete wall strengthened by FRP composite material

Ali KEZMANE,Said BOUKAIS,Mohand Hamizi

期刊论文

Nonlinear analysis of pre-tensioned glass wall facade by stability function with initial imperfection

Siu-Lai CHAN, Yaopeng LIU, Andy LEE,

期刊论文

Diaphragm wall-soil-cap interaction in rectangular-closed- diaphragm-wall bridge foundations

Hua WEN, Qiangong CHENG, Fanchao MENG, Xiaodong CHEN

期刊论文

Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-plane

期刊论文

Prediction of shield tunneling-induced ground settlement using machine learning techniques

Renpeng CHEN, Pin ZHANG, Huaina WU, Zhiteng WANG, Zhiquan ZHONG

期刊论文

A new acoustic emission source location technique based on wavelet transform and mode analysis

JIAO Jing-pin, HE Cun-fu, WU Bin, FEI Ren-yuan, WANG Xiu-yan

期刊论文