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Mechanical properties characterization of different types of masonry infill walls

André FURTADO, Hugo RODRIGUES, António ARÊDE, Humberto VARUM

《结构与土木工程前沿(英文)》 2020年 第14卷 第2期   页码 411-434 doi: 10.1007/s11709-019-0602-y

摘要: It is remarkable, the recent advances concerning the development of numerical modeling frameworks to simulate the infill panels’ seismic behavior. However, there is a lack of experimental data of their mechanical properties, which are of full importance to calibrate the numerical models. The primary objective of this paper is to present an extensive experimental campaign of mechanical characterization tests of infill masonry walls made with three different types of masonry units: lightweight vertical hollow concrete blocks and hollow clay bricks. Four different types of experimental tests were carried out, namely: compression strength tests, diagonal tensile strength tests, and flexural strength tests parallel and perpendicular to the horizontal bed joints. A total amount of 80 tests were carried out and are reported in the present paper. The second objective of this study was to compare the mechanical properties of as-built and existing infill walls. The results presented and discussed herein, will be in terms of strain-stress curves and damages observed within the tests. It was observed a fragile behavior in the panels made with hollow clay horizontal bricks, without propagation of cracks. The plaster increased the flexural strength by 57%.

关键词: masonry infill walls     experimental characterization     compression strength     shear diagonal strength     flexural strength    

Experiments on channel columns with inclined simple edge stiffeners under compression loading

WANG Chungang, ZHANG Yaochun, ZHANG Zhuangnan

《结构与土木工程前沿(英文)》 2007年 第1卷 第3期   页码 312-321 doi: 10.1007/s11709-007-0041-z

摘要: In order to investigate the compression behavior of pin-ended cold-formed channel columns with inclined simple edge stiffeners, a total of 30 pin-ended cold-formed channel columns with three sections (sloping lip stiffener turned at 45º, 90º, and 135º to the flange, respectively) and three different lengths (500 mm, 1 250 mm, and 2 000 mm) were tested. It was found that the inclination angles and loading positions have an obvious effect on compression ultimate load-carrying capacities and failure modes. All three sections have certain post-buckling strength, and the failure modes of most of the specimens contained distortional buckling. The capacity of the specimens with 45º inclined angle for bearing compression is appreciably higher than the other two types of specimens with 90º or 135º inclined angles at the same negative eccentricity, but obviously lower than the other two at the same positive eccentricity. Furthermore, tests were simulated by finite element analysis. Results from the analysis are in great agreement with the experimental data.

关键词: different     post-buckling strength     capacity     distortional buckling     Furthermore    

Axial compression behavior of CFRP-confined rectangular concrete-filled stainless steel tube stub column

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1144-1159 doi: 10.1007/s11709-021-0762-4

摘要: The mechanical properties of CFRP-confined rectangular concrete-filled stainless steel tube (CFSST) stub columns under axial compression were experimentally studied. A total of 28 specimens (7 groups) were fabricated for the axial compression test to study the influences of length-to-width ratio, CFRP constraint coefficient, and the thickness of stainless steel tube on the axial compression behavior. The specimen failure modes, the stress development of stainless steel tube and CFRP wrap, and the load–strain ratio curves in the loading process were obtained. Meanwhile, the relationship between axial and transverse deformations of each specimen was analyzed through the typical relative load−strain ratio curves. A bearing capacity prediction method was proposed based on the twin-shear strength theory, combining the limit equilibrium state of the CFRP-confined CFSST stub column under axial compression. The prediction method was calibrated by the test data in this study and other literature. The results show that the prediction method is of high accuracy.

关键词: CFRP     rectangular CFSST stub column     bearing capacity     limit equilibrium state     twin-shear strength theory    

Influence of steel corrosion on axial and eccentric compression behavior of coral aggregate concrete

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1415-1425 doi: 10.1007/s11709-021-0786-9

摘要: To study the behavior of coral aggregate concrete (CAC) column under axial and eccentric compression, the compression behavior of CAC column with different types of steel and initial eccentricity (ei) were tested, and the deformation behavior and ultimate bearing capacity (Nu) were studied. The results showed that as the ei increases, the Nu of CAC column decreases nonlinearly. Besides, the steel corrosion in CAC column is severe, which reduces the steel section and steel strength, and decreases the Nu of CAC column. The durability of CAC structures can be improved by using new organic coated steel. Considering the influence of steel corrosion and interfacial bond deterioration, the calculation models of Nu under axial and eccentric compression were presented.

关键词: coral aggregate concrete column     axial compression     eccentric compression     steel corrosion     calculation model    

Behavior of dam concrete under biaxial compression-tension and triaxial compression-compression-tension

WANG Huailiang, SONG Yupu

《结构与土木工程前沿(英文)》 2008年 第2卷 第4期   页码 323-328 doi: 10.1007/s11709-008-0043-5

摘要: In order to meet the requirement for nonlinear analysis and design of mass concrete structures, the deformation behavior and strength of three-graded concrete specimens 250 mm × 250 mm × 400 mm with a maximum aggregate size of 80 mm and the corresponding wet-screened concrete specimens 150 mm × 150 mm × 300 mm with a maximum aggregate size of 40 mm were studied experimentally. Specimens subjected to biaxial compression-tension (C-T) and triaxial compression-compression-tension (C-C-T) stress states. Test data indicate that both the deformation and strength of the mass concrete specimens are lower than those of the corresponding wet-screened concrete small specimens, but the initial tangent modulus of the stress-strain curve of the former is greater than that of the latter. Test results show that the wet-screened effect and size effect of the specimens under complex stress states are obvious such that these should be considered in the design of mass concrete structures. In addition, respective failure criteria for mass concrete in principal stress space and octahedron stress space are proposed.

关键词: requirement     wet-screened concrete     compression-tension     maximum aggregate     principal    

三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

《中国工程科学》 2007年 第9卷 第6期   页码 64-70

摘要:

对设计强度为10MPa的混凝土立方体试件进行三轴压缩试验,系统研究了等围压条件下混凝土的强 度和变形特性,围压分别为0,4,8,12,16MPa5个量级;同时研究了不等围压条件下混凝土强度变化特性, 试验表明,随着围压增加,混凝土的极限抗压强度有明显增强的趋势;随着小主应力的增加,中主应力的影响 有减弱的趋势;峰值应力处应变随围压增加幅度显著。得出了在不同恒定围压下混凝土的应力应变全过程曲线; 通过与当前文献资料的对比分析,指出了在混凝土结构计算中适用的强度及变形表达式,为工程实践提供了 依据。

关键词: 三向受力状态     不等围压     极限强度     变形     混凝土    

Effects of compression ratio on the combustion characteristics of a homogeneous charge compression ignition

SONG Ruizhi, ZHOU Longbao, LIU Shenghua, LI Wei, HU Tiegang

《能源前沿(英文)》 2007年 第1卷 第4期   页码 463-467 doi: 10.1007/s11708-007-0068-0

摘要: The effects of homogeneous charge compression ignition (HCCI) engine compression ratio on its combustion characteristics were studied experimentally on a modified TY1100 single cylinder engine fueled with dimethyl ether. The resul

关键词: homogeneous     cylinder     combustion     compression     dimethyl    

Numerical study of ignition mechanism of n-heptane direct injection compression-ignition engine

Xiaoping GUO, Zhanjie WANG,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 432-439 doi: 10.1007/s11708-009-0050-9

摘要: A detailed chemical dynamical mechanism of oxidation of n-heptane was implemented into kiva-3 code to study the ignition mechanism of a high-temperature, high-pressure, three-dimensional-space, transient turbulent, non-homogeneous, mono-component fuel in the engine. By testing the quantity of the heat released by the chemical reaction within the cylinder cell, the elementary reaction showing an obvious increase in the cell temperature was defined as ignition reaction and the corresponding cell as ignition position. The main pathway of the ignition reaction was studied by using the reverse deducing method. The result shows that the ignition in the engine can be divided into low-temperature ignition and high-temperature ignition, both of which follow the same rule in releasing heat, called the impulse heat releasing feature. Low-temperature ignition reaction, whose ignition reaction is c5h9o1-4=ch3cho+c3h5-a, follows the oxidation mechanism, while high-temperature ignition reaction, whose ignition reaction is c2h3o1-2=ch3co, follows the decomposition mechanism. No matter which ignition it is in, the chemical reaction that restrains the ignition reaction from lasting is the deoxidization reaction of alkylperoxy radicals.

关键词: compression-ignition engine     ignition mechanism     elementary reaction     n-heptane    

Three-dimensional numerical simulation for plastic injection-compression molding

Yun ZHANG, Wenjie YU, Junjie LIANG, Jianlin LANG, Dequn LI

《机械工程前沿(英文)》 2018年 第13卷 第1期   页码 74-84 doi: 10.1007/s11465-018-0490-1

摘要:

Compared with conventional injection molding, injection-compression molding can mold optical parts with higher precision and lower flow residual stress. However, the melt flow process in a closed cavity becomes more complex because of the moving cavity boundary during compression and the nonlinear problems caused by non-Newtonian polymer melt. In this study, a 3D simulation method was developed for injection-compression molding. In this method, arbitrary Lagrangian-Eulerian was introduced to model the moving-boundary flow problem in the compression stage. The non-Newtonian characteristics and compressibility of the polymer melt were considered. The melt flow and pressure distribution in the cavity were investigated by using the proposed simulation method and compared with those of injection molding. Results reveal that the fountain flow effect becomes significant when the cavity thickness increases during compression. The back flow also plays an important role in the flow pattern and redistribution of cavity pressure. The discrepancy in pressures at different points along the flow path is complicated rather than monotonically decreased in injection molding.

关键词: injection-compression molding     simulation     injection molding     melt flow     cavity pressure    

Improvement of engine performance with high compression ratio based on knock suppression using Miller

Haiqiao WEI, Jie YU, Lei ZHOU

《能源前沿(英文)》 2019年 第13卷 第4期   页码 691-706 doi: 10.1007/s11708-019-0621-3

摘要: In theory, high compression ratio has the potential to improve the thermal efficiency and promote the power output of the SI engine. However, the application of high compression ratio is substantially limited by the knock in practical working process. The objective of this work is to comprehensively investigate the application of high compression ratio on a gasoline engine based on the Miller cycle with boost pressure and split injection. In this work, the specific optimum strategies for CR10 and CR12 were experimentally investigated respectively on a single cylinder DISI engine. It was found that a high level of Miller cycle with a higher boost pressure could be used in CR12 to achieve an effective compression ratio similar to CR10, which could eliminate the knock limits at a high compression ratio and high load. To verify the advantages of the high compression ratio, the fuel economy and power performance of CR10 and CR12 were compared at full and partial loads. The result revealed that, compared with CR10, a similar power performance and a reduced fuel consumption of CR12 at full load could be achieved by using the strong Miller cycle and split injection. At partial load, the conditions of CR12 had very superior fuel economy and power performance compared to those of CR10.

关键词: high compression ratio     knock     Miller cycle     split injection     engine performance    

Efficient controller area network data compression for automobile applications

Yu-jing WU,Jin-Gyun CHUNG

《信息与电子工程前沿(英文)》 2015年 第16卷 第1期   页码 70-78 doi: 10.1631/FITEE.1400136

摘要: Controller area networks (CANs) have been designed for multiplexing communication between electronic control units (ECUs) in vehicles and many high-level industrial control applications. When a CAN bus is overloaded by a large number of ECUs connected to it, both the waiting time and the error probability of the data transmission are increased. Thus, it is desirable to reduce the CAN frame length, since the duration of data transmission is proportional to the frame length. In this paper, we present a CAN message compression method to reduce the CAN frame length. Experimental results indicate that CAN transmission data can be compressed by up to 81.06% with the proposed method. By using an embedded test board, we show that 64-bit engine management system (EMS) CAN data compression can be performed within 0.16 ms; consequently, the proposed algorithm can be successfully used in automobile applications.

关键词: Controller area network (CAN)     Electronic control units (ECUs)     Data compression     Signal rearrangement    

Schedule Compression Impact on Construction Project Safety

Curt Webb,Lu Gao,Ling-guang Song

《工程管理前沿(英文)》 2015年 第2卷 第4期   页码 344-350 doi: 10.15302/J-FEM-2015059

摘要: Many construction projects are met with stringent timelines or the threat of exorbitant liquidated damages. In addition, construction schedulers are frequently forced to incorporate aggressive schedule compression techniques. As already discussed by previous researchers, these schedule compression techniques have direct impacts on project productivity and quality defects. Researchers have also pointed out that schedule compression will affect safety incidents such as Occupational Safety & Health Administration recordable injuries and near misses over long project durations. However, most of the existing studies treated safety as a subcategory of project productivity and project quality, and minimal research has been done to directly quantify the effect of schedule compression on safety at the project level. Therefore, in this research, we conducted a survey and statistical analysis to investigate the relationship between schedule compression and safety in construction projects. We interviewed various members of the Houston construction community from both industrial and non-industrial roles. Statistical analysis was used to identify factors that have significant impacts on the occurrence of safety incidents at an industry specific level.

关键词: construction safety     schedule compression     overtime     work shift     Hurdle model    

Performance analysis of solar absorption-subcooled compression hybrid refrigeration system in subtropical

Xiangyang YE,Liming LIU,Zeyu LI

《能源前沿(英文)》 2019年 第13卷 第1期   页码 185-192 doi: 10.1007/s11708-017-0452-z

摘要: Solar absorption-subcooled compression hybrid refrigeration system is a new type of efficient and economical solar refrigeration device which always meets the demand of cooling load with the change of solar irradiance. The performance of the hybrid system is higher due to the improvement of evaporator temperature of absorption subsystem. But simultaneously, the variation of working process as well as performance is complicated since the absorption and compression subsystems are coupled strongly. Based on the measured meteorological data of Guangzhou, a subtropical city in south China, a corresponding parametric model has been developed for the hybrid refrigeration system, and a program written by Fortran has been used to analyze the performance of the hybrid system under different external conditions. As the condensation temperature ranges from 38°C to 50°C, the working time fraction of the absorption subsystem increases from 75% to 85%. Besides, the energy saving fraction also increases from 5.31% to 6.02%. The average COP of the absorption subsystem is improved from 0.366 to 0.407. However, when the temperature of the absorption increases from 36°C to 48°C, the average COP of hybrid system decreases from 2.703 to 2.312. Moreover, the working time fraction of the absorption subsystem decreases from 80% to 71.7%. The energy saving fraction falls from 5.67% to 5.08%. In addition, when the evaporate temperature increases from 4°C to 14°C, the average COP of the absorption subsystem decreases from 0.384 to 0.365. The work of the compressor decreases from 48.2 kW to 32.8 kW and the corresponding average COP of the absorption subsystem is improved from 2.591 to 3.082.

关键词: solar     absorption-subcooled     compression hybrid     dynamic simulation     performance analysis    

Primary spinal epidural non-Hodgkin’s lymphoma presented with spinal cord compression syndrome

Chunquan CAI MD, PhD, Qingjiang ZHANG BM, Changhong SHEN MD, PhD,

《医学前沿(英文)》 2009年 第3卷 第4期   页码 499-502 doi: 10.1007/s11684-009-0075-9

摘要: The spinal epidural space is an uncommon presenting site in primary non-Hodgkin’s lymphomas, especially for children. A boy suffered spinal cord compression syndrome caused by primary spinal epidural non-Hodgkin’s lymphoma. Thoracolumbar magnetic resonance imaging (MRI) demonstrated an intraspinal mass. An operation was performed with gross total tumor removal. Histological examination revealed a non-Hodgkin’s B-cell lymphoma. Bone marrow aspiration was negative for lymphoma involvement. No other therapies (chemotherapy and/or radiotherapy) were performed according to the parents’ opinion. The patient died approximately one year after the operation due to brain metastases. The clinical course and imaging features were discussed with a review of literatures.

关键词: non-Hodgkin’     s lymphoma     primary     spinal cord compression syndrome     epidural space    

Differential diagnosis of cervical nerve compression syndrome of the external intervertebral foramen

WANG Jinwu, NI Weifeng, XU Jianguang, ZHU Haibo, GUO Shangchun, ZENG Bingfang, ZHAO Binghui

《医学前沿(英文)》 2007年 第1卷 第2期   页码 177-180 doi: 10.1007/s11684-007-0033-3

摘要: The aim of the present research is to study the mechanism of cervical nerve compression syndrome of the external intervertebral foramen and its differential diagnosis with cervical spondylosis. Diagnostic treatment with muscle relaxant, vasodilator, neurotrophic medicine and celecoxib (COX)-2 inhibitor were performed in 20 patients with cervical nerve compression syndrome of the external intervertebral foramen and 20 patients with cervical spondylosis confirmed by operation. Diagnostic local block therapy was performed additionally in cases showing little effect after diagnostic treatment. All the patients were followed up postoperatively for more than one year. Fifteen cases with cervical nerve compression syndrome of the external intervertebral foramen were healed by the diagnostic treatment. The other five cases had a short-term remission and there was no recurrence after diagnostic local block therapy. Diagnostic treatment led to short-term alleviation of the symptom in 20 cases with cervical spondylosis confirmed by operation, the results of which was far from satisfactory and operation was undertaken finally in all the 20 cases. The etiology of cervical nerve compression syndrome of the external intervertebral foramen lies in the compression of the cervical plexus, brachial plexus and cervical dorsal rami by the tendinous decussating fibers of the scalenus anticus, medius, minimus and the posterior muscles of the neck. Diagnostic treatment was propitious to differentiate cervical nerve compression syndrome of the external intervertebral foramen from cervical spondylosis.

关键词: satisfactory     COX     minimus     operation     compression syndrome    

标题 作者 时间 类型 操作

Mechanical properties characterization of different types of masonry infill walls

André FURTADO, Hugo RODRIGUES, António ARÊDE, Humberto VARUM

期刊论文

Experiments on channel columns with inclined simple edge stiffeners under compression loading

WANG Chungang, ZHANG Yaochun, ZHANG Zhuangnan

期刊论文

Axial compression behavior of CFRP-confined rectangular concrete-filled stainless steel tube stub column

期刊论文

Influence of steel corrosion on axial and eccentric compression behavior of coral aggregate concrete

期刊论文

Behavior of dam concrete under biaxial compression-tension and triaxial compression-compression-tension

WANG Huailiang, SONG Yupu

期刊论文

三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

期刊论文

Effects of compression ratio on the combustion characteristics of a homogeneous charge compression ignition

SONG Ruizhi, ZHOU Longbao, LIU Shenghua, LI Wei, HU Tiegang

期刊论文

Numerical study of ignition mechanism of n-heptane direct injection compression-ignition engine

Xiaoping GUO, Zhanjie WANG,

期刊论文

Three-dimensional numerical simulation for plastic injection-compression molding

Yun ZHANG, Wenjie YU, Junjie LIANG, Jianlin LANG, Dequn LI

期刊论文

Improvement of engine performance with high compression ratio based on knock suppression using Miller

Haiqiao WEI, Jie YU, Lei ZHOU

期刊论文

Efficient controller area network data compression for automobile applications

Yu-jing WU,Jin-Gyun CHUNG

期刊论文

Schedule Compression Impact on Construction Project Safety

Curt Webb,Lu Gao,Ling-guang Song

期刊论文

Performance analysis of solar absorption-subcooled compression hybrid refrigeration system in subtropical

Xiangyang YE,Liming LIU,Zeyu LI

期刊论文

Primary spinal epidural non-Hodgkin’s lymphoma presented with spinal cord compression syndrome

Chunquan CAI MD, PhD, Qingjiang ZHANG BM, Changhong SHEN MD, PhD,

期刊论文

Differential diagnosis of cervical nerve compression syndrome of the external intervertebral foramen

WANG Jinwu, NI Weifeng, XU Jianguang, ZHU Haibo, GUO Shangchun, ZENG Bingfang, ZHAO Binghui

期刊论文