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High strain rate compressive strength behavior of cemented paste backfill using split Hopkinson pressure bar 被引量:7
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作者 Xin Chen Xiuzhi Shi +3 位作者 Jian Zhou Enming Li Peiyong Qiu Yonggang Gou 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2021年第3期387-399,共13页
The stability of cemented paste backfill(CPB)is threatened by dynamic disturbance,but the conventional low strain rate laboratory pressure test has difficulty achieving this research purpose.Therefore,a split Hopkinso... The stability of cemented paste backfill(CPB)is threatened by dynamic disturbance,but the conventional low strain rate laboratory pressure test has difficulty achieving this research purpose.Therefore,a split Hopkinson pressure bar(SHPB)was utilized to investigate the high strain rate compressive behavior of CPB with dynamic loads of 0.4,0.8,and 1.2 MPa.And the failure modes were determined by macro and micro analysis.CPB with different cement-to-tailings ratios,solid mass concentrations,and curing ages was prepared to conduct the SHPB test.The results showed that increasing the cement content,tailings content,and curing age can improve the dynamic compressive strength and elastic modulus.Under an impact load,a higher strain rate can lead to larger increasing times of the dynamic compressive strength when compared with static loading.And the dynamic compressive strength of CPB has an exponential correlation with the strain rate.The macroscopic failure modes indicated that CPB is more seriously damaged under dynamic loading.The local damage was enhanced,and fine cracks were formed in the interior of the CPB.This is because the CPB cannot dissipate the energy of the high strain rate stress wave in a short loading period. 展开更多
关键词 High strain rate Compressive strength behavior Cemented paste backfill Split Hopkinson pressure bar TAILINGS
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Shear Strength Behavior of Two Landfill Clay Liners 被引量:1
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作者 Jian Wenxing Engineering Faculty, China University of Geosciences, Wuhan 430074 Masashi Kamon Toru Inui Department of Global Environmental Engineering, Graduate School of Engineering, Kyoto University,Kyoto, 606 8501, Japan Takeshi Katsumi Department of Civil Engineering, Ritsumeikan University, Kusatsu, Shiga, 525 8577, Japan 《Journal of China University of Geosciences》 SCIE CSCD 2002年第3期260-265,共5页
Direct shear tests were conducted to obtain both the shear strength ofcompacted clay liners (CCLs) specimens and the interface shear strength between compacted clay linerand base soil. These experiments were conducted... Direct shear tests were conducted to obtain both the shear strength ofcompacted clay liners (CCLs) specimens and the interface shear strength between compacted clay linerand base soil. These experiments were conducted under the conditions of five different watercontents. The experimental results show that shear strength of both CCLs and CCLs/base interfacedecreases with the increase in the water content of CCLs and base soil. In addition, the considerateconcentration of NaCl in leachate has no deteriorating effect on the shear strength of liners.Triaxial shear tests were also conducted on clay liner specimens to obtain total and effective shearstrength under a fast compression. The shear strength parameters with total stress are φ=18. 5°and c=30 kPa for clay-bentonite, and φ=48. 5° and c=90 kPa for sand-bentonite and those witheffective stress are φ'= 27. 2° and c'=25 kPa for clay-bentonite, and φ'=35° and c'=100 kPa forsand-bentonite, respectively. These results indicate that the compacted clay-bentonite shows normalconsolidation, but that the compacted sand-bentonite exhibits over-consolidation. 展开更多
关键词 shear strength behavior direct shear test CU triaxial compression test compacted clay liner LANDFILL
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Evidence for the Reliability and Validity of the Arabic Version of the Student Risk Screening Scale for Internalizing and Externalizing Behaviors (SRSS-IE)
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作者 Sumayah A. Alrubayie Keetam D. F. Alkahtani 《Journal of Behavioral and Brain Science》 2024年第1期32-45,共14页
School-based universal screening for behavioral/emotional risk is a necessary first step to providing services in an educational setting for students with emotional and behavioral disorders (EBDs). Psychometric proper... School-based universal screening for behavioral/emotional risk is a necessary first step to providing services in an educational setting for students with emotional and behavioral disorders (EBDs). Psychometric properties are critical to making decisions about choosing a screening instrument. The purpose of the present study was to examine the psychometric properties of the student risk screening scale for internalizing and externalizing behaviors (SRSS-IE). Participants included 3145 students and their teachers. Item-level analyses of the current sample supported the retention of all items. The internal consistency of the SRSS items ranged from 0.83 to 0.85. Convergent validity between the SRSS-IE and a well-established screening tool, the strength and difficulties questionnaire (SDQ), was found for the total score (r = 0.70). Additionally, the results of this study demonstrate strong social validity, suggesting the SRSS-IE to be a useful and functional screening tool. We conclude that the SRSS-IE is a valid and reliable instrument for assessing the level of emotional and behavioral difficulties among elementary students. 展开更多
关键词 The Student Risk Screening Scale for Internalizing and Externalizing behaviors (SRSS-IE) strength and Difficulties Questionnaire (SDQ) Emotional and behavioral Difficulties Screening Tools Systematic Screening
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High Strength Silicon Carbide Foams and Their Deformation Behavior 被引量:11
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作者 Chong TIAN Jinsong ZHANG Xiaoming CAO Qiang LIU Wanping HU 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2006年第2期269-272,共4页
Silicon carbide (SIC) foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 a... Silicon carbide (SIC) foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 2.3 g/cm^3, with corresponding compressive strengths ranging from about 23 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading. 展开更多
关键词 Silicon carbide foams Apparent density strength Deformation behavior Linear-elastic behavior
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Effects of chromium on the corrosion and electrochemical behaviors of ultra high strength steels 被引量:13
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作者 Jin-yan Zhong Min Sun +2 位作者 Da-bo Liu Xiao-gang Li Tian-qi Liu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2010年第3期282-289,共8页
The effects of chromium on the corrosion and the electrochemical behaviors of ultra high strength steels were studied by the salt spray test and electrochemical methods. The results show that ultra high strength steel... The effects of chromium on the corrosion and the electrochemical behaviors of ultra high strength steels were studied by the salt spray test and electrochemical methods. The results show that ultra high strength steels remain martensite structures and have anodic dissolution characteristic with an increase of chromium content. There is no typical passive region on the polarization curves of an ultra high strength stainless steel, AerMet 100 steel, and 300M steel. However, chromium improves the corrosion resistance of the stainless steel remarkably. It has the slowest corrosion rate in the salt spray test, one order of magnitude less than that of AerMet 100 and 300M steels. With the increase of chromium content, the polarization resistance becomes larger, the corrosion potential shifts towards the positive direction with a value of 545 mV, and the corrosion current density decreases in electrochemical measures in 3.5wt% NaCl solutions. Because of the higher content of chromium, the ultra high strength stainless steel has a better corrosion resistance than AerMet 100 and 300M steels. 展开更多
关键词 ultra high strength steel corrosion rate CHROMIUM electrochemical behavior
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Experimental Behavior of Partially Prestressed High Strength Concrete Beams 被引量:3
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作者 Shady H. Salem Khalid M. Hilal +1 位作者 Tarek K. Hassan Ahmed S. Essawy 《Open Journal of Civil Engineering》 2013年第3期26-32,共7页
In the last few decades, prestressed concrete has been rapidly used in bridge engineering due to the enormous development in the construction techniques and the increasing need for long span bridges. High strength con... In the last few decades, prestressed concrete has been rapidly used in bridge engineering due to the enormous development in the construction techniques and the increasing need for long span bridges. High strength concrete has been also more widely spread than the past. It currently becomes more desirable as it has better mechanical properties and durability performance. Major defect of fully prestressed concrete is its low ductility;it may produce less alarming signs than ordinary reinforced concrete via smaller deflection and limited cracking. Therefore, partially prestressing is considered an intermediate design between the two extremes. So, combining high strength concrete with partial prestressing will result in a considerable development in the use of prestressed concrete structures regarding the economical and durability view points. This study presents the results of seven partially prestressed high strength concrete beams in flexure. The tested beams are used to investigate the influence of concrete compressive strength, prestressing steel ratio and flange width on the behavior of partially prestressed beams. The experimentally observed behaviors of all beams were presented in terms of the cracking load, ultimate load, deflection, cracking behavior and failure modes. 展开更多
关键词 PARTIALLY PRESTRESSED High strength Concrete BEAMS SERVICEABILITY behavior Failure Modes
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Experimental Study on Flexural Behavior of Post-Tensioning Bonded Partially Prestressed Ultra-High Strength Concrete Beams
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作者 Jinqing Jia Gang Meng 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2015年第2期94-102,共9页
This paper presents the results of four partially prestressed ultra-high strength concrete beams in flexure. The test results are used to evaluate the effects of prestressing tendon depth and area on flexure behavior ... This paper presents the results of four partially prestressed ultra-high strength concrete beams in flexure. The test results are used to evaluate the effects of prestressing tendon depth and area on flexure behavior of specimen beams. The test results indicate that: the cracking load,yielding load,peak load and stiffness postcracking of specimen beams are enhanced by reducing prestressing tendon depth or increasing prestressing tendon area, and the flexural ductility is improved by increasing prestressing tendon depth or reducing prestressing tendon area. The effect of complex reinforcement index considering the strength of the equivalence principle and the reinforcement position on loading levels under serviceability limit state,flexural strength and displacement ductility factor are studied. The influence coefficient of prestressing tendon kpis introduced in the complex reinforcement index. As the complex reinforcement index increases, the loading levels under serviceability limit state and flexural strength increases linearly,and the displacement ductility factor decreases linearly. The test results also verify the conventional beam flexural theory based on the plane cross-section assumption for predicting ultimate flexural strength of partially prestressed ultra-high strength concrete beams is valid. After the introduction of the coefficient kp,the calculation method of cracks in code for design of concrete structure in china are appropriated for the specimen beams. 展开更多
关键词 partially prestressed ultra-high strength concrete flexural behavior DUCTILITY serviceability limit state
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Ultra-high cycle fatigue behavior of high strength steel with carbide-free bainite/martensite complex microstructure 被引量:5
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作者 Xue-xia Xu Yang Yu Wen-long Cui Bing-zhe Bai Jia-lin Gu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2009年第3期285-292,共8页
The ultra-high cycle fatigue behavior of a novel high strength steel with carbide-free bainite/martensite (CFB/M) complex microstructure was studied. The ultra-high cycle fatigue properties were measured by ultrason... The ultra-high cycle fatigue behavior of a novel high strength steel with carbide-free bainite/martensite (CFB/M) complex microstructure was studied. The ultra-high cycle fatigue properties were measured by ultrasonic fatigue testing equipment at a frequency of 20 kHz. It is found that there is no horizontal part in the S-N curve and fatigue fracture occurs when the life of specimens exceeds 10^7 cycles. In addition, the origination of fatigue cracks tends to transfer from the surface to interior of specimens as the fatigue cycle exceeds 10^7, and the fatigue crack originations of many specimens are not induced by inclusions, but by some kind of "soft structure". It is shown that the studied high strength steel performs good ultra-high cycle fatigue properties. The ultra-high fatigue mechanism was discussed and it is suggested that specific CFB/M complex microstructure of the studied steel contributes to its superior properties. 展开更多
关键词 high strength steel ultra-high cycle fatigue BAINITE MARTENSITE fatigue behavior
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The relationship between microstructure and stress-strain behavior in tension in high strength pipeline steel
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作者 CUI Tiancheng,ZHENG Lei and Li Bing Research Institute of Baoshan Iron & Steel Co.,Ltd.,Shanghai 201900,China 《Baosteel Technical Research》 CAS 2010年第S1期57-,共1页
In this paper the relationship between microstructure and stress-strain behavior in tensile test of high strength pipeline steel was investigated.The steel with polygonal ferrite-bainite(PF + B) microstructure has a &... In this paper the relationship between microstructure and stress-strain behavior in tensile test of high strength pipeline steel was investigated.The steel with polygonal ferrite-bainite(PF + B) microstructure has a "round-house" type tensile stress-strain curve with low Y/T ratio,highly uniform elongation and high n-value,which means PF + B microstructure has the best deformability(i.e.Ideal stress-strain behavior) among the four microstructures.The steel with acicular ferrite-martensite&austenite(AF + MA) microstructure has a "continuous-yielding" type tensile stress-strain curve,whose deformability is worse than that of PF + B microstructure.Both the steels of polygonal ferrite-acicular ferrite(PF + AF) and polygonal ferrite-pearlite (PF+P) microstructure have "luders elongation" type tensile stress-strain curve with high Y/T ratio,low uniform elongation and low n-value,which means PF + AF and PF + P microstructures have the worst deformability among the four microstructures. 展开更多
关键词 high strength pipeline steel tension stress-strain behavior MICROSTRUCTURE
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Experimental research on behavior of 460 MPa high strength steel I-section columns under cyclic loading 被引量:5
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作者 Wang Jiaojiao Shi Gang Shi Yongjiu 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2014年第4期611-622,共12页
To investigate the seismic behavior of I-section columns made of 460 MPa high strength steel (HSS), six specimens were tested under constant axial load and cyclic horizontal load. The specimens were designed with di... To investigate the seismic behavior of I-section columns made of 460 MPa high strength steel (HSS), six specimens were tested under constant axial load and cyclic horizontal load. The specimens were designed with different width-to-thickness ratios and loaded under different axial load ratios. For each specimen, the failure mode was observed and hysteretic curve was measured. Comparison of different specimens on hysteretic characteristic, energy dissipation capacity and deformation capacity were further investigated. Test results showed that the degradation of bearing capacity was due to local buckling of flange and web. Under the same axial load ratio, as width-to-thickness ratio increased, the deformation area of local buckling became smaller. And also, displacement level at both peak load and failure load became smaller. In addition, the full extent of hysteretic curve, energy dissipation capacity, ultimate story drift angle decreased, and capacity degradation occurred more rapidly with the increase of width-to-thickness ratio or axial load ratio. Based on the capacity of story drift angle, limiting values which shall not be exceeded are suggested respectively for flange and web plate of 460 MPa HSS I-section columns when used in SMFs and in IMFs in the case of axial load ratio no more than 0.2. Such values should be smaller when the axial load ratio increases. 展开更多
关键词 high strength steel width-to-thickness ratio axial load ratio seismic behavior I-section column
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超高强Ti-15Mo-2.7Nb-3Al-0.2Si钛合金的强化行为及模型
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作者 石晓辉 张琪 +3 位作者 荆镇 范智渊 刘江林 乔珺威 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第4期1136-1149,共14页
基于XRD、OM、SEM和TEM分析,研究超高强Ti-15Mo-2.7Nb-3Al-0.2Si钛合金的组织演变及强化行为。结果表明,位错强化和析出强化效应对该合金的屈服强度影响较大。冷轧+再结晶+冷轧+双时效组合工艺可获得1518 MPa的最高屈服强度,这主要归因... 基于XRD、OM、SEM和TEM分析,研究超高强Ti-15Mo-2.7Nb-3Al-0.2Si钛合金的组织演变及强化行为。结果表明,位错强化和析出强化效应对该合金的屈服强度影响较大。冷轧+再结晶+冷轧+双时效组合工艺可获得1518 MPa的最高屈服强度,这主要归因于显微组织中的高密度残存位错及密集而细小的次生α相。建立复合强化模型,其预测误差在16.6%以内。此外,研究发现次生α相体积分数的增加可以不断强化晶内区域,这使得沿晶断裂开始出现并逐渐占据整个断裂面。 展开更多
关键词 强化模型 超高强 强化行为 钛合金 Ti-15Mo-2.7Nb-3Al-0.2Si
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型钢高强自密实混凝土黏结滑移性能试验研究
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作者 陈宗平 梁延 +1 位作者 许瑞天 覃伟恒 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第7期215-226,共12页
为研究型钢与高强自密实混凝土界面黏结滑移性能,以混凝土保护层厚度和型钢埋置长度作为变化参数,设计9个型钢高强自密实混凝土试件进行推出试验.观察试件破坏过程、破坏形态和裂缝发展形式,获取了试件加载端的荷载-滑移全过程曲线,研... 为研究型钢与高强自密实混凝土界面黏结滑移性能,以混凝土保护层厚度和型钢埋置长度作为变化参数,设计9个型钢高强自密实混凝土试件进行推出试验.观察试件破坏过程、破坏形态和裂缝发展形式,获取了试件加载端的荷载-滑移全过程曲线,研究不同变量对其黏结性能的影响规律.结果表明:型钢高强自密实混凝土组合结构界面极限黏结强度随着混凝土保护层厚度的增加而增大,最大增幅94.9%;随着型钢埋置长度的增加而减小,最大削减为38.1%.界面黏结抗剪刚度随着型钢保护层厚度的增加先增大后减小,最大增幅85.1%;随着型钢埋置长度的增加而增大,最大增幅为30%.界面耗能能力与其变量相关性较弱;随保护层厚度的增加,界面损伤发展越晚;随型钢埋置深度的增加,界面损伤速度减缓.提出了型钢高强自密实混凝土黏结强度的计算公式,能较好地预测型钢高强自密实混凝土黏结强度. 展开更多
关键词 型钢 高强自密实混凝土 滑移性能 界面损伤 黏结强度
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基于GISSMO损伤模型的高强度钢碰撞失效行为研究
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作者 张健 谭嘉伟 +1 位作者 姬贺港 刘仁伟 《船舶工程》 CSCD 北大核心 2024年第7期111-121,共11页
为了研究不同失效模型对碰撞仿真结果的影响,以期准确描述材料的失效行为。以船用高强度钢EH36为研究对象,设计2个温度下不同应力状态的材料拉伸试验,得到其不同温度下的力学性能、载荷和位移数据,将试验结果与拉伸仿真联合,反求出广义... 为了研究不同失效模型对碰撞仿真结果的影响,以期准确描述材料的失效行为。以船用高强度钢EH36为研究对象,设计2个温度下不同应力状态的材料拉伸试验,得到其不同温度下的力学性能、载荷和位移数据,将试验结果与拉伸仿真联合,反求出广义增量应力状态依赖损伤模型(GISSMO)的参数;构建冰体与船体板架的碰撞仿真,对比不考虑失效,考虑V-M失效准则以及GISSMO损伤模型的仿真结果。结果表明,考虑GISSMO损伤模型相比于V-M失效准则,碰撞力峰值和板架吸能情况都有所减小。由于GISSMO损伤模型考虑了不同应力三轴度对材料失效的影响,所获得的损伤形态更接近于真实情况,因此GISSMO损伤模型能较好预测EH36钢材的变形及失效行为。 展开更多
关键词 GISSMO损伤模型 高强度钢 碰撞 失效行为
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考虑残余强度影响的输电线路装配式锚杆基础有限元仿真分析
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作者 邓长征 胡鑫 阎晓铭 《电工材料》 CAS 2024年第2期66-73,共8页
针对现有装配式基础仿真的不足,以新型装配式锚杆基础为对象,进行ABAQUS有限元仿真计算。对材料本构、荷载施加方式、接触行为加以改进,提出了一种可有效反映出在考虑残余强度影响的情况下,装配式锚杆基础的承载能力和各部件的受力情况... 针对现有装配式基础仿真的不足,以新型装配式锚杆基础为对象,进行ABAQUS有限元仿真计算。对材料本构、荷载施加方式、接触行为加以改进,提出了一种可有效反映出在考虑残余强度影响的情况下,装配式锚杆基础的承载能力和各部件的受力情况的有限元建模方法。仿真结果表明,该方法能有效地反映接触界面损伤后仍存在的残余剪切强度特征,且基础整体受力变化过程符合实际工况,证明了建模方法的合理性和正确性,为装配式锚杆基础和相似结构设计、施工提供可靠有效的依据。 展开更多
关键词 装配式锚杆基础 ABAQUS 粘结接触 残余强度
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U型组合再生混凝土-高强混凝土梁抗火性能
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作者 肖建庄 陈子璇 《工程力学》 EI CSCD 北大核心 2024年第6期9-18,共10页
为突破单一混凝土材料在受力和抗火两方面的性能难以协同优化的难题,该文创新性地提出U型组合再生混凝土-高强混凝土梁(简称为RAC-HSC组合梁),系统地开展了火灾试验和常温、火后受弯试验,综合分析了不同工况下组合梁的性能表现。研究表... 为突破单一混凝土材料在受力和抗火两方面的性能难以协同优化的难题,该文创新性地提出U型组合再生混凝土-高强混凝土梁(简称为RAC-HSC组合梁),系统地开展了火灾试验和常温、火后受弯试验,综合分析了不同工况下组合梁的性能表现。研究表明:火灾下,RAC-HSC组合梁的耐火性能显著优于高强混凝土整浇梁,其梁内温度较低,跨中挠度较小,跨中未出现明显裂缝,且未观察到爆裂现象;常温及高温后的受弯试验中,RAC-HSC组合梁的屈服荷载、极限承载力及初始刚度均显著优于再生混凝土梁,基本达到或超过普通混凝土整浇梁和高强混凝土整浇梁的水平。该文所提出的U型组合再生混凝土-高强混凝土梁是混凝土构件“抗火-受力一体化设计”的有益尝试。 展开更多
关键词 组合混凝土梁 再生混凝土 高强混凝土 抗火性能 受力性能
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钢管高强再生混凝土叠合柱偏压性能
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作者 牛海成 尚天宇 +1 位作者 李博涵 黄明晖 《建筑钢结构进展》 CSCD 北大核心 2024年第8期1-10,共10页
为研究钢管高强混凝土叠合柱偏心受压性能,以混凝土类型和偏心距为参数,完成了6根叠合柱偏心受压试验,研究了不同参数对钢管高强混凝土叠合柱损伤发展过程、破坏特征、承载力和延性的影响,并基于《钢管混凝土叠合柱结构技术规程》(T/CEC... 为研究钢管高强混凝土叠合柱偏心受压性能,以混凝土类型和偏心距为参数,完成了6根叠合柱偏心受压试验,研究了不同参数对钢管高强混凝土叠合柱损伤发展过程、破坏特征、承载力和延性的影响,并基于《钢管混凝土叠合柱结构技术规程》(T/CECS 188—2019)和相关学者提出的公式对16根钢管混凝土叠合柱的偏压承载力进行了计算。研究结果表明:再生混凝土叠合柱与普通混凝土叠合柱的受力过程均经历了弹性、带裂缝工作和破坏3个阶段,表现出外围混凝土保护层被压碎脱落、纵筋鼓曲和箍筋外鼓等破坏特征;与普通混凝土叠合柱相比,再生混凝土叠合柱的初始刚度和变形能力有所降低,但承载力略高;随着偏心距的增加,钢管混凝土叠合柱的初始刚度和承载力迅速降低,而位移延性系数迅速增大,中和轴逐渐向受压区移动,与平截面假定的吻合度有所降低;钢管混凝土叠合柱偏压承载力计算应考虑钢管自身承载力以及钢管对核心混凝土约束效应的影响。 展开更多
关键词 钢管混凝土叠合柱 高强再生混凝土 偏压性能 承载力计算
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Experimental study on the seismic behavior of high strength concrete fi lled double-tube columns 被引量:13
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作者 Qian Jiaru Li Ningbo +1 位作者 Ji Xiaodong Zhao Zuozhou 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2014年第1期47-57,共11页
To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column sp... To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column specimens were conducted.The test variables included the width-to-thickness ratio(β1) and the area ratio(β2) of the square steel tube,the wall thickness of the circular steel tube,and the axial force(or the axial force ratio) applied to the CFDT columns.The test results indicate that for CFDT columns with a square steel tube with β1 of 50.1 and 24.5,local buckling of the specimen was found at a drift ratio of 1/150 and 1/50,respectively.The lateral force-displacement hysteretic loops of all specimens were plump and stable.Reducing the width-to-thickness ratio of the square steel tube,increasing its area ratio,or increasing the wall thickness of the internal circular steel tube,led to an increased fl exural strength and deformation capacity of the specimens.Increasing the design value of the axial force ratio from 0.8 to 1.0 may increase the fl exural strength of the specimens,while it may also decrease the ultimate deformation capacity of the specimen with β1 of 50.1. 展开更多
关键词 high strength concrete fi lled double-tube(CFDT)column seismic behavior area ratio of the square steel tube width-to-thickness ratio of the square steel tube axial force ratio quasi-static test
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聚乙烯管材专用料耐高温水浴老化性能研究 被引量:1
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作者 高蔓彤 刘德俊 +2 位作者 刘亚明 张阿昱 鲜林云 《现代塑料加工应用》 CAS 北大核心 2024年第1期8-10,26,共4页
以3种聚乙烯(PE)管材专用料(PEX-1,PE100,PERT-I)为研究对象,在95℃下进行水浴老化试验,通过差示扫描量热仪(DSC)、维卡软化温度测定仪、万能试验机研究了其耐热氧老化性能、热变形行为和拉伸性能。结果表明:在95℃下水浴老化1 440 h后,... 以3种聚乙烯(PE)管材专用料(PEX-1,PE100,PERT-I)为研究对象,在95℃下进行水浴老化试验,通过差示扫描量热仪(DSC)、维卡软化温度测定仪、万能试验机研究了其耐热氧老化性能、热变形行为和拉伸性能。结果表明:在95℃下水浴老化1 440 h后,3个样品中,PERT-I的结晶度变化率最小(2.16%),氧化诱导时间(OIT)变化率最小(2.70%),维卡软化温度变化率最小(0.28%),表现出优异的耐热氧老化性能和热变形性能,同时,PERT-I的拉伸强度变化率和屈服强度变化率分别为15.06%,15.16%,可作为耐高温PE管材内衬层的备选材料。 展开更多
关键词 聚乙烯 水浴老化 耐热氧老化性能 热变形行为 拉伸性能
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新型热处理方法制备超高强度Inconel 718合金
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作者 冉蓉 王洋 +5 位作者 任富强 张元祥 方烽 张维娜 袁国 王国栋 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第7期2204-2218,共15页
为改善Inconel718合金的组织并优化性能,提出一种980℃,1 min高温超短退火和随后的双时效相结合的新型热处理方法。结果表明,超短退火处理产生了部分再结晶组织,KAM图表明即使在变形晶粒中也形成了再结晶晶核。因此,高温超短退火克服了... 为改善Inconel718合金的组织并优化性能,提出一种980℃,1 min高温超短退火和随后的双时效相结合的新型热处理方法。结果表明,超短退火处理产生了部分再结晶组织,KAM图表明即使在变形晶粒中也形成了再结晶晶核。因此,高温超短退火克服了再结晶势垒,使得后续的再结晶过程可以在较低温度的时效处理过程中完成,从而获得了均匀细化的组织(~3.59μm)。980-1min-aged样品具有优异的拉伸性能,室温极限强度和总伸长率分别为1600 MPa和19%。650℃热拉伸条件下的极限强度和伸长率分别约为1350 MPa和26%。因此,高温超短退火能有效提高Inconel718合金的性能。 展开更多
关键词 Inconel 718合金 超高强度 δ相析出相 再结晶行为 时效处理
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久坐与社区老年人下肢肌力:跌倒恐惧与年龄的中介和调节作用
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作者 洪金涛 王晶晶 +2 位作者 李岩松 王晨 弭守玲 《中国组织工程研究》 CAS 北大核心 2025年第17期3566-3571,共6页
背景:人体老龄化进程中,下肢肌肉力量会随着年龄的增长呈现显著的生理性下降,久坐、跌倒恐惧、年龄与下肢肌力之间可能存在一定关联,但它们之间的影响路径与效应关系尚不明确。目的:探究社区老年人久坐和下肢肌肉力量之间的关系,并探讨... 背景:人体老龄化进程中,下肢肌肉力量会随着年龄的增长呈现显著的生理性下降,久坐、跌倒恐惧、年龄与下肢肌力之间可能存在一定关联,但它们之间的影响路径与效应关系尚不明确。目的:探究社区老年人久坐和下肢肌肉力量之间的关系,并探讨跌倒恐惧和年龄在上述两者关系中的作用。方法:共招募331名60岁及以上的上海市社区老年人。采用问卷调查法收集基本信息、人口学资料等;采用国际身体活动问卷-短卷评估久坐时间,采用30 s坐站测试测量下肢肌力,采用中文版国际跌倒效能量表测评跌倒恐惧。对数据进行描述统计、相关分析、基于回归的路径分析和中介效应检验。结果与结论:最终以318名老年人[78.9%为女性,平均年龄(67.8±5.5)岁]的有效数据纳入分析,其中久坐时间≥3 h的185名,<3 h的133名。①久坐和跌倒恐惧呈正相关关系(P<0.01),下肢肌力和久坐(P<0.01)、跌倒恐惧(P<0.001)均呈负相关关系。②久坐显著负向预测下肢肌力(β=-0.125,P<0.05),久坐显著正向预测跌倒恐惧(β=0.182,P<0.01);跌倒恐惧显著负向预测下肢肌力(β=-0.293,P<0.001)。③跌倒恐惧在久坐和下肢肌力之间起中介作用(β=-0.053,95%CI:-0.100至-0.018)。④久坐对跌倒恐惧的预测效应具有统计学意义(β=0.164,P<0.01),这说明年龄调节了久坐对跌倒恐惧的影响。 展开更多
关键词 老年群体 老龄化 肌肉萎缩 肌肉力量 久坐 跌倒恐惧 中介效应 调节作用
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