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Moment-curvature relationship of FRP-concrete-steel double-skin tubular members

Mingxue LIU, Jiaru QIAN

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 25-31 doi: 10.1007/s11709-009-0012-7

摘要： Tests were conducted on 3 specimens to study the flexural behavior of fiber reinforced polymer (FRP)-concrete-steel double-skin tubular members (DSTMs). The strip method was used to calculate the section moment-curvature curves of the 3 specimens and 12 models. A theoretical formula is presented for the flexural strength of DSTMs. The test results show that the tension zone of the specimen FRP tubes was in hoop compression while the compression zone was in hoop tension. The load-carrying capacity did not decrease even when the mid-span deflection reached about 1/24 of the span length. The tests, simulation and theoretical analysis resulted in a simplified formula for the flexural strength of DSTMs and a tri-linear moment-curvature model was expressed as a function of the section bending stiffness for DSTMs.

关键词： fiber reinforced polymer (FRP)     concrete     steel     double-skin tubular members (DSTMs)     moment-curvature curve     flexural strength    

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Heating energy savings potential from retrofitting old apartments with an advanced double-skin façade

Yeo Beom YOON, Byeongmo SEO, Brian Baewon KOH, Soolyeon CHO

《能源前沿（英文）》 2020年 第14卷 第2期   页码 224-240 doi: 10.1007/s11708-020-0801-1

摘要： Apartments account for over 60% of total residential buildings and consume a significant portion of primary energy in South Korea. Various energy efficiency measures have been implemented for both new apartment constructions and existing apartment retrofits. Old apartment structures have poor thermal performances, resulting in a high energy consumption. The South Korean government initiated retrofitting projects to improve the energy efficiency in old apartments. Apartment owners typically replace old windows with high-performance windows; however, there is still a demand for better and more innovative retrofit methods for a highly improved energy efficiency. This paper proposes an advanced double-skin façade (DSF) system to replace existing balcony windows in old apartments. Considering the cold climate conditions of Seoul, South Korea, it mainly discusses heating energy savings. Three case models were developed: Base-Case with existing apartment, Case-1 with typical retrofitting, and Case-2 with the proposed DSF system. The EnergyPlus simulation program was used to develop simulation models for a floor radiant heating system. A typical gas boiler was selected for low-temperature radiant system modeling. The air flow network method was used to model the proposed DSF system. Five heating months, i.e., November to March, and one representative day, i.e., January 24, were selected for detailed analysis. The main heat loss areas consist of windows, walls, and infiltration. The results reveal that the apartment with the DSF retrofit saves 38.8% on the annual heating energy compared to the Base-Case and 35.2% compared to Case-1.

关键词： double-skin façade     retrofitting     high-rise apartment     heating energy     building simulation    

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Behavior of concrete-filled double skin steel tubular columns with octagon section under axial compression

YANG Junjie, PENG Guojun, XU Hanyong

《结构与土木工程前沿（英文）》 2008年 第2卷 第3期   页码 205-210 doi: 10.1007/s11709-008-0035-5

摘要： Based on some conclusions of two kinds of concrete-filled double skin steel tube (CFDSST) members with circular or square sections, a new kind of CFDSST with octagonal section, where the outer tube has an octagonal section and the inner tube has a circular section, is proposed in this paper. Behaviors of the CFDSST members with octagon section subjected to axial compression are investigated, and some curves of load-strain of steel tubes and confined concrete and the bearing capacity of members are obtained. It is indicated that the bearing capacity of the columns with octagonal section is larger than that with square section and is smaller than that with circular section, and the bearing capacity of members is related to the ratio of the straight side to the bevelled one. Based on the proper stress-strain relationship, a couple of numerical analyses are made using the finite element software named ANSYS. Finally, a simplified formula is proposed in the paper, and the numerical results agree well with the experimental results and the mathematical solutions. The results are valuable for engineers.

关键词： mathematical     numerical     compression     stress-strain relationship     straight    

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Numerical study of thermal characteristics of double skin facade system with middle shade

Shaoning LIU, Xiangfei KONG, Hua YANG, Minchao FAN, Xin ZHAN

《能源前沿（英文）》 2021年 第15卷 第1期   页码 222-234 doi: 10.1007/s11708-017-0480-8

摘要： Architectural shade is an effective method for improving building energy efficiency. A new shade combined with the double skin façade (DSF) system, called middle shade (MS), was introduced and developed for buildings. In this paper, a 3D dynamic simulation was conducted to analyze the influence of MS combined with DSF on the indoor thermal characteristics. The research on MS for DSF involves the temperature, the ventilation rate, the velocity distribution of the air flow duct, and the indoor temperature. The results show that the angle and position of the shade in the three seasons are different, and different conditions effectively enhance the indoor thermal characteristics. In summer, the appearance of MS in DSF makes the indoor temperature significantly lower. The indoor temperature is obviously lower than that of the air flow duct, and the temperature of the air flow duct is less affected by MS. The influence of the position of blinds on indoor temperature and ventilation rate is greater than the influence of the angle of blinds. According to the climate characteristics of winter and transition season, in winter, early spring, and late autumn, the indoor temperature decreases with the increase of the position of blinds at daytime, but the opposite is true at night. The results found in this paper can provide reference for the design and use of MS combined with DSF in hot summer and cold winter zone.

关键词： middle shade     position     thermal characteristics     double skin facade    

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A numerical study of prestressed high strength steel tubular members

Michaela GKANTOU, Marios THEOFANOUS, Charalampos BANIOTOPOULOS

《结构与土木工程前沿（英文）》 2020年 第14卷 第1期   页码 10-22 doi: 10.1007/s11709-019-0547-1

摘要： The structural behavior of prestressed high strength steel (HSS) tubular members is investigated through the execution of advanced finite element modeling. Numerical models are developed and validated against published experimental data on HSS tubular members subjected to different levels of initial prestress and loaded either in tension or compression. The effect of the presence or absence of grouting on the strength and ductility of the members is also considered. To numerically replicate the structural response recorded in the tests, some key modeling features including the employed numerical solver, the adopted material models and the element types warrant careful consideration. Upon developing of the finite element models, the numerically generated ultimate loads, the corresponding failure modes and the full load-deformation curves are compared to the experimental ones, indicating a successful validation. As anticipated, prestressing enhances the load-bearing capacity for the tensile members, whereas it is detrimental for the compressive ones. A series of parametric studies is performed to assess the influence of key factors on the structural response of prestressed HSS members and the obtained results are discussed. Design guidance for tensile and compressive prestressed tubular members is also provided.

关键词： finite element     prestressing     tubular members     grout     high strength steel    

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Deformation analysis of shape memory polymer for morphing wing skin under airflow

Weilong YIN, Jingcang LIU, Jinsong LENG,

《机械工程前沿（英文）》 2009年 第4卷 第4期   页码 447-449 doi: 10.1007/s11465-009-0062-5

摘要： The method for analyzing the out-of-plane deformation of a flexible skin under airflow is developed in this paper. The aerodynamic analysis is performed using the CFD software, and the structural analysis is performed using finite element method. The chief aim of the present study is to investigate the out-of-plane deformation of the shape memory polymer (SMP) skin at different temperatures. Numerical results show that the maximum out-of-plane displacement of the SMP skin increases with increasing temperature. When the SMP skin is heated to 53°C, the maximum out-of-plane displacement is about 7 mm. It decreases by 72%, when the SMP skin is applied with a uniform pre-strain of 0.1.

关键词： aircraft     morphing     skin     shape memory polymer (SMP)     deformation     pre-strain    

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Experiment on aluminum alloy members under axial compression

Xiaonong GUO,Shuiping LIANG,Zuyan SHEN

《结构与土木工程前沿（英文）》 2015年 第9卷 第1期   页码 48-64 doi: 10.1007/s11709-014-0271-9

摘要： To improve the design methods of Chinese aluminum alloy members, experiment of 63 profiled aluminum alloy members, made of Chinese aluminum alloy 6061-T6, under axial compression is conducted in this paper. Valuable experimental data are obtained. At the same time, in order to obtain the relevant data, a large number of other experimental data from published papers and technical reports are collected and sorted out. 167 valid experimental data points are obtained finally. Furthermore, for the purpose of creating column curves, the aluminum alloy members under the axial compression, used in experiments, are analyzed by means of FEM. Based on the numerical results, 2 column curves are created by means of the numerical fitting method. The column curves are compared with the calculated data according to the experimental results for verification, and also are verified with the curves in design codes of several relevant countries. The numerical results show that the column curves obtained in this paper are valid and reliable.

关键词： aluminum alloy     column curve     compression members     overall stability coefficient    

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Performance study on T-stub connected semi-rigid joint between rectangular tubular columns and H-shaped

Guochang LI, Hongping YU, Chen FANG

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 296-303 doi: 10.1007/s11709-013-0217-7

摘要： This paper investigates the performance of T-stub connected semi-rigid joint of rectangular tubular columns and H-shaped steel beams. The finite element analysis software ABAQUS is used to analyze the nonlinear performance of the joint under monotonic loading. Meanwhile, the dimensions of T-stub, column and beam are considered as analytic parameters to discuss the performance of the joint. The analysis shows that the thickness and the length of T-stub webs, the height of beam section, bolt diameter, shear connector and the preloaded force affect the performance of the joint largely, and the thickness of the steel tube, the thickness and length of T-stub flange, bolt spacing have relatively little influences on the performance of the joint. The research results indicate that this joint is semi-rigid joint.

关键词： rectangular tubular columns     T-stub     semi-rigid     nonlinear finite element analysis     moment-rotation curves    

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The critical importance of epigenetics in autoimmune-related skin diseases

《医学前沿（英文）》 2023年 第17卷 第1期   页码 43-57 doi: 10.1007/s11684-022-0980-8

摘要： Autoimmune-related skin diseases are a group of disorders with diverse etiology and pathophysiology involved in autoimmunity. Genetics and environmental factors may contribute to the development of these autoimmune disorders. Although the etiology and pathogenesis of these disorders are poorly understood, environmental variables that induce aberrant epigenetic regulations may provide some insights. Epigenetics is the study of heritable mechanisms that regulate gene expression without changing DNA sequences. The most important epigenetic mechanisms are DNA methylation, histone modification, and noncoding RNAs. In this review, we discuss the most recent findings regarding the function of epigenetic mechanisms in autoimmune-related skin disorders, including systemic lupus erythematosus, bullous skin diseases, psoriasis, and systemic sclerosis. These findings will expand our understanding and highlight the possible clinical applications of precision epigenetics approaches.

关键词： epigenetics     autoimmune-related skin diseases     DNA methylation     histone modifications     noncoding RNAs    

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Estimating moment capacity of ferrocement members using self-evolving network

Abdussamad ISMAIL

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 926-936 doi: 10.1007/s11709-019-0527-5

摘要： In this paper, an empirical model based on self-evolving neural network is proposed for predicting the flexural behavior of ferrocement elements. The model is meant to serve as a simple but reliable tool for estimating the moment capacity of ferrocement members. The proposed model is trained and validated using experimental data obtained from the literature. The data consists of information regarding flexural tests on ferrocement specimens which include moment capacity and cross-sectional dimensions of specimens, concrete cube compressive strength, tensile strength and volume fraction of wire mesh. Comparisons of predictions of the proposed models with experimental data indicated that the models are capable of accurately estimating the moment capacity of ferrocement members. The proposed models also make better predictions compared to methods such as the plastic analysis method and the mechanism approach. Further comparisons with other data mining techniques including the back-propagation network, the adaptive spline, and the Kriging regression models indicated that the proposed models are superior in terms prediction accuracy despite being much simpler models. The performance of the proposed models was also found to be comparable to the GEP-based surrogate model.

关键词： ferrocement     moment capacity     self-evolving neural network    

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Intermediate HSS bracing members during seismic excitations: modeling, design, and behavior

Madhar HADDAD

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 148-162 doi: 10.1007/s11709-016-0375-5

摘要： Concentric hollow structural section (HSS) bracing members are used frequently in steel framed structural systems to resist seismic excitations. Finite element modeling of the HSS braces that utilizes the true stress-strain curves produces hysteresis responses that are reasonable matches to the experimental response. True stress-strain curves are obtained from coupon tests or stub-column tests while utilizing an exponential function or strain hardening rule with a trial and error procedure to obtain the hysteresis behavior. In the current study, the true stress-strain curves are directly obtained from tests on stub-columns extracted from the full scale HSS bracing members away from the mid-length plastic hinge after cyclic testing. Two experimental tests (Shaback 2001 and Haddad 2004) were used to validate the model. Results indicate that the stress-strain curves for these braces are not unique. A refined damage accumulation model for ultra-low-cycle fatigue is implemented to predict fracture of the brace tests. The refined damage model is then used in the finite element modeling to predict fracture of braces in a chevron braced frame of an eight-storey building subjected to selected ground motions analyzed using OpenSees program. Results indicate that all braces could sustain the selected earthquake records without fracture.

关键词： HSS     FEM     stress-strain curves     damage model    

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Hyperthermia on skin immune system and its application in the treatment of human papillomavirus-infectedskin diseases

null

《医学前沿（英文）》 2014年 第8卷 第1期   页码 1-5 doi: 10.1007/s11684-014-0309-3

摘要：

Hyperthermia is a condition characterized by increased body temperature as a consequence of failed thermoregulation. Hyperthermia occurs when a body produces or absorbs more heat than it dissipates. Hyperthermia also elicits various effects on the physiology of living cells. For instance, fever-range temperature (39β°C to 40β°C) can modulate the activities of immune cells, including antigen-presenting cells, T cells, and natural killer cells. Heat shock temperature (41β°C to 43β°C) can increase the immunogenicity of tumor cells. Cytotoxic temperature (>43β°C) can create an antigen source to induce an anti-tumor immune response. The immunomodulatory effect of hyperthermia has promoted an interest in hyperthermia-aided immunotherapy, particularly against tumors. Hyperthermia has also been used to treat deep fungal, bacterial, and viral skin infections. We conducted a series of open or controlled trials to treat skin human papillomavirus infection by inducing local hyperthermia. More than half of the patients were significantly cured compared with those in the control trial. A series of challenging clinical cases, such as large lesions in pregnant patients or patients with diabetes mellitus, were also successfully and safely managed using the proposed method. However, further studies should be conducted to clarify the underlying mechanisms and promote the clinical applications of hyperthermia.

关键词： hyperthermia     HPV     immune response     virus     tumor    

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Risk stratification system for skin and soft tissue infections after allogeneic hematopoietic stem cell

《医学前沿（英文）》 2022年 第16卷 第6期   页码 957-968 doi: 10.1007/s11684-021-0910-1

摘要： Skin and soft tissue infections (SSTIs) refer to infections involving the skin, subcutaneous tissue, fascia, and muscle. In transplant populations with hematological malignancies, an immunocompromised status and the routine use of immunosuppressants increase the risk of SSTIs greatly. However, to date, the profiles and clinical outcomes of SSTIs in hematopoietic stem cell transplantation (HSCT) patients remain unclear. This study included 228 patients (3.67%) who developed SSTIs within 180 days after allogeneic HSCT from January 2004 to December 2019 in Peking University People’s Hospital. The overall annual survival rate was 71.5%. We compared the differences between survivors and non-survivors a year after transplant and found that primary platelet graft failure (PPGF), comorbidities of acute kidney injury (AKI), and hospital-acquired pneumonia (HAP) were independent risk factors for death in the study population. A PPGF–AKI–HAP risk stratification system was established with a mortality risk score of 1×PPGF+1×AKI+1×HAP. The areas under the curves of internal and external validation were 0.833 (95% CI 0.760–0.906) and 0.826 (95% CI 0.715–0.937), respectively. The calibration plot revealed the high consistency of the estimated risks, and decision curve analysis showed considerable net benefits for patients.

关键词： skin and soft tissue infections     hematopoietic stem cell transplantation     risk stratification system     mortality    

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Numerical modelling of reinforced concrete flexural members strengthened using textile reinforced mortars

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 649-668 doi: 10.1007/s11709-023-0919-4

摘要： Externally bonded (EB) and near-surface mounted (NSM) bonding are two widely adopted and researched strengthening methods for reinforced-concrete structures. EB composite substrates are easy to reach and repair using appropriate surface treatments, whereas NSM techniques can be easily applied to the soffit and concrete member sides. The EB bonded fiber-reinforced polymer (FRP) technique has a significant drawback: combustibility, which calls for external protective agents, and textile reinforced mortar (TRM), a class of EB composites that is non-combustible and provides a similar functionality to any EB FRP-strengthened substrate. This study employs a finite element analysis technique to investigate the failing failure of carbon textile reinforced mortar (CTRM)-strengthened reinforced concrete beams. The principal objective of this numerical study was to develop a finite element model and validate a set of experimental data in existing literature. A set of seven beams was modelled and calibrated to obtain concrete damage plasticity (CDP) parameters. The predicted results, which were in the form of load versus deflection, load versus rebar strain, tensile damage, and compressive damage patterns, were in good agreement with the experimental data. Moreover, a parametric study was conducted to verify the applicability of the numerical model and study various influencing factors such as the concrete strength, internal reinforcement, textile roving spacing, and externally-applied load span. The ultimate load and deflection of the predicted finite element results had a coefficient of variation (COV) of 6.02% and 5.7%, respectively. A strain-based numerical comparison with known methods was then conducted to investigate the debonding mechanism. The developed finite element model can be applied and tailored further to explore similar TRM-strengthened beams undergoing debonding, and the preventive measures can be sought to avoid premature debonding.

关键词： fiber reinforced polymer     textile reinforced mortar     finite element analysis     concrete damage plasticity     calibration and validation     parametric study    

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Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1071-1088 doi: 10.1007/s11709-022-0879-0

摘要： For open car park structures, adopting a performance-based structural fire design is often justified and allowed because the fire does not reach flashover. However, this design approach requires an accurate assessment of temperatures in structural members exposed to car fires. This paper describes a numerical study on the thermal exposure on steel framing members in open car park fires. Steel temperatures are computed by the coupling of computational fluid dynamics and finite element modeling, and by analytical models from the Eurocodes. In addition, the influence of galvanization on the steel temperature evolution is assessed. Results show that temperatures in unprotected beams and columns are influenced by the section geometry, car fire scenario, modeling approach, and use of galvanization. Galvanization slightly delays and reduces peak temperature. Regarding the different models, CFD-FEM (CFD: computational fluid dynamics, FEM: finite-element method) coupled models predict lower temperatures than the Hasemi model, because the latter conservatively assumes that the fire flame continuously touches the ceiling. Further, the Hasemi model cannot account for the effect of reduced emissivity from galvanization on the absorbed heat flux. Detailed temperature distributions obtained in the steel members can be used to complete efficient structural fire designs based on the member sections, structure layout, and use of galvanization.

关键词： open car park     localized fire     steel frame     numerical modeling     computational fluid dynamics    

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标题 作者 时间 类型 操作

Moment-curvature relationship of FRP-concrete-steel double-skin tubular members

Mingxue LIU, Jiaru QIAN

期刊论文

Heating energy savings potential from retrofitting old apartments with an advanced double-skin façade

Yeo Beom YOON, Byeongmo SEO, Brian Baewon KOH, Soolyeon CHO

期刊论文

Behavior of concrete-filled double skin steel tubular columns with octagon section under axial compression

YANG Junjie, PENG Guojun, XU Hanyong

期刊论文

Numerical study of thermal characteristics of double skin facade system with middle shade

Shaoning LIU, Xiangfei KONG, Hua YANG, Minchao FAN, Xin ZHAN

期刊论文

A numerical study of prestressed high strength steel tubular members

Michaela GKANTOU, Marios THEOFANOUS, Charalampos BANIOTOPOULOS

期刊论文

Deformation analysis of shape memory polymer for morphing wing skin under airflow

Weilong YIN, Jingcang LIU, Jinsong LENG,

期刊论文

Experiment on aluminum alloy members under axial compression

Xiaonong GUO,Shuiping LIANG,Zuyan SHEN

期刊论文

Performance study on T-stub connected semi-rigid joint between rectangular tubular columns and H-shaped

Guochang LI, Hongping YU, Chen FANG

期刊论文

The critical importance of epigenetics in autoimmune-related skin diseases

期刊论文

Estimating moment capacity of ferrocement members using self-evolving network

Abdussamad ISMAIL

期刊论文

Intermediate HSS bracing members during seismic excitations: modeling, design, and behavior

Madhar HADDAD

期刊论文

Hyperthermia on skin immune system and its application in the treatment of human papillomavirus-infectedskin diseases

null

期刊论文

Risk stratification system for skin and soft tissue infections after allogeneic hematopoietic stem cell

期刊论文

Numerical modelling of reinforced concrete flexural members strengthened using textile reinforced mortars

期刊论文

Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

期刊论文