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Analysis of Load Carrying Capacity of Concrete-filled Square CFRP-steel Tubular Stub Column Under Axial Compression

- , 2015,
Abstract: 采用统一强度理论对CFRP-方钢管混凝土轴压短柱进行受力分析,并引入等效应力系数、混凝土强度折减系数和等效约束折减系数,将CFRP-方钢管混凝土转化为CFRP-圆钢管混凝土,进而建立了CFRP-方钢管混凝土轴压短柱的极限承载力计算公式。将所得理论公式的计算结果与文献资料数据进行对比,验证了该公式的正确性,并进行了影响因素分析。结果表明:随材料拉压比、统一强度理论参数和CFRP厚度的增加,CFRP-方钢管混凝土轴压短柱的极限承载力不断增大,但CFRP的约束效率却随其厚度的增加在减小;所得结论可为CFRP-方钢管混凝土轴压短柱的设计、施工及推广提供一定的理论依据。
Based on the unified strength theory, the load carrying capacities of concrete-filled square CFRP-steel tubular stub column under axial compression were analyzed. The concrete??filled square CFRP-steel tube was equivalent to concrete??filled circular CFRP-steel tube through introducing equivalent stress factor, concrete strength reduction factor and equivalent constraint reduction factor. Then authors established a formula for calculating ultimate bearing capacity of concrete-filled square CFRP-steel tubular stub column under axial compression. Through comparing the results of proposed formula with those of reference data, the correctness of proposed formula was proved. The influencing factors of formula were also discussed. The results show that the ultimate bearing capacity of concrete-filled square CFRP-steel tubular stub column under axial compression increases with increasing the tension and compression ratio of material, unified strength theory parameter and thickness of CFRP. However, the confinement rate of CFRP decreases with increasing its thickness. The obtained results can provide some theoretical references for the design, construction and extension of concrete??filled square CFRP-steel tubular stub column under axial compression
Experimental study on bonding behavior of CFRP-to-steel interface under early curing age

- , 2015, DOI: 10.3969/j.issn.1001-0505.2015.02.028
Abstract: 对低龄期下CFRP-钢双剪试件进行了轴向拉伸试验,研究了不同养护时间下CFRP-钢黏结界面峰值滑移量、黏结刚度、有效传力长度及极限承载力的变化规律.试验结果表明:CFRP-钢界面峰值滑移量随养护时间的增加而减小;养护1 d时界面具有比较稳定的承载力和维持自身稳定的刚度;养护3 d内强度和刚度迅速增加,有效传力长度迅速减小,5~7 d内各参数趋于稳定,由此认为合理养护时间应不少于3 d.基于此,推算出CFRP-钢界面的养护时间建议值及不同低龄期下CFRP-钢黏结承载力计算公式,为CFRP在钢结构中的加固设计提供依据.
The axial tensile tests of carbon fiber reinforced polymer(CFRP)-to-steel double shear specimen under early curing age were carried out. The variation laws of the peak slip value, the bonding rigidity, the effective force transmission length and the ultimate bearing capacity of the bonding interface of CFRP-to-steel under early curing age were ivestigated.The experimental results show that the peak slip values of the bonding interface of CFRP-to-steel decrease with the curing time passing by, and the interface has a stable bearing capacity and rigidity for self-stability with the curing age of 1 d. The strength and rigidity increase rapidly and the length of the effective force transmission decreases rapidly in 3 d. Meanwhile, these parameters tend to be stable in 5 to 7 d. Therefore, the reasonable curing age should be no less than 3 d. Based on these results, the recommended value of the curing age of CFRP-to-steel interface and the formulae of the bonding bearing capacity of CFRP-to-steel under different curing ages are put forward, providing a basis for strengthening design of CFRP in steel structures
Experimental study and numerical simulation for bond behavior of interface between CFRP and steel

- , 2018, DOI: 10.13801/j.cnki.fhclxb.20180316.001
Abstract: 碳纤维增强聚合物基复合材料(CFRP)与钢板的界面粘结性能为CFRP加固钢结构的关键问题之一。开展了17个CFRP板-钢板单搭接试件的拉伸剪切试验,研究了不同环氧粘结剂与CFRP材料的CFRP-钢界面力学行为和破坏模式;分析了粘结剂类型和CFRP材料对界面粘结滑移本构和界面剪切性能的影响,讨论了其承载力计算方法。结果表明:采用不同的粘结剂或CFRP材料,界面破坏形式和抗剪承载力均差异较大。采用Sika 330、Lica粘结剂的试件为CFRP板或钢板与胶层的界面破坏,采用Araldite粘结剂的试件为CFRP板浅表层离,采用Sika 30粘结剂的试件为胶层内聚破坏,采用SF(Sika S512/80)碳板的试件为CFRP板深层层离;Araldite试件的抗剪承载力为其他试件的1.7~2.9倍。Sika 330、Araldite及Lica试件粘结滑移曲线无明显下降段,属脆性破坏,而Sika 30与SF试件存在缓坡下降段,失效前有一定征兆;SF试件的粘结滑移本构可简化为三折线模型,其余试件则可简化为双线性模型。SF试件抗剪承载力需用Xia-a模型表征,其余试件则可用Xia-b模型表征。基于粘聚力模型对界面力学行为进行了数值模拟,结果表明,粘聚力模型可以较好地模拟界面的非线性力学行为,剥离应力对本单搭接试件的界面粘结强度影响很小。 The bond performance between carbon fiber reinforced polymer composites (CFRP) and steel plate is one of the key problems in strengthening steel structure with CFRP. Tensile-shear tests of 17 CFRP lamina-steel plate single-lap specimens were conducted, the mechanical behavior and failure modes of CFRP-steel interface of specimens with different epoxy adhesives and CFRP materials were studied. The influences of adhesive types and CFRP materials on interfacial bond-slip constitutive and shear bearing capacity were analyzed, and the calculation methods of interfacial shear capacity were discussed. Results show that interface failure modes and ultimate bearing capacity are significantly different for specimens with different adhesives or CFRP materials. The failure mode for specimens with Sika 330 and Lica adhesive is the mixed mode of CFRP-adhesive and steel-adhesive interface debonding, and failure modes for specimens with Araldite adhesive, Sika 30 adhesive, and SF (Sika S512/80) lamina are CFRP superficial delamination, adhesive failure, and CFRP deep layer delamination, respectively. The ultimate bearing capacity of Araldite specimen is 1.7~2.9 times of the other specimens. No descending branches are found in bond-slip curves for Sika 330, Araldite, and Lica specimens, which are characterized by brittle fracture of interfaces. However, low descending branches are found in bond-slip curves for Sika 30 and SF specimens, and forewarning signs occur before interfacial failure. The bond-slip constitutive model for the SF specimens can be simplified to trilinear model, while those for the other specimens can be simplified to bilinear models. The ultimate bearing capacity for SF specimens should be represented by Xia-a model, while those for the other specimens can be represented by Xia-b model. The mechanical behavior of the interface is numerically simulated based on cohesive zone model. Results show that the nonlinear mechanical behavior of the interface can be well simulated by the cohesive zone
Behaviour of stiffened concrete-filled steel composite (CFSC) stub columns
Bahrami, Alireza;Badaruzzaman, Wan Hamidon Wan;Osman, Siti Aminah;
Latin American Journal of Solids and Structures , 2013, DOI: 10.1590/S1679-78252013000200009
Abstract: this paper investigates the behaviour of axially loaded stiffened concrete-filled steel composite (cfsc) stub columns using the finite element software lusas. modelling accuracy is established by comparing results of the nonlinear analysis and the experimental test. the cfsc stub columns are extensively developed using different special arrangements, number, spacing, and diameters of bar stiffeners with various steel wall thicknesses, concrete compressive strengths, and steel yield stresses. their effects on the columns behaviour are examined. failure modes of the columns are also illustrated. it is concluded that the parameters have considerable effects on the behaviour of the columns. an equation is proposed based on the obtained results to predict the ultimate load capacity of the columns. results are compared with predicted values by the design code ec4, suggested equation of other researchers, and proposed equation of this study which is concluded that the proposed equation can give closer predictions than the others.
Hysteretic Behavior of Steel Column Strengthened With CFRP in Thermal Environment
Zhen-Guo Li
TELKOMNIKA : Indonesian Journal of Electrical Engineering , 2012, DOI: 10.11591/telkomnika.v10i5.1278
Abstract: This paper is concerned with analysis for the strengthening effect of carbon fiber-reinforced polymer (CFRP) on steel columns under cyclic lateral loading in thermal environment. Based on the finite element theory of thermo-elastic problem and steel structure stability theory, the hysteretic behavior of axial compression steel columns was studied by using Ansys software. The main variables investigated are: cyclic lateral loading, temperature, axial compression ratio and ductility. The results show that the CFRP wraps can improve the ultimate cyclic lateral loading and ductility of steel columns prominently in thermal environment which benefit to the anti-seismic capacity of steel structure. The effect of axial compression ratio on ultimate cyclic lateral loading is very obvious, more enhancements achieved with the axial compression ratio increased. While effect of temperature on ultimate cyclic lateral loading is not very obvious below 300℃.
Mechanism analysis on concrete-filled round-end steel tubular stub columns under axial load

福州大学学报(自然科学版) , 2015, DOI: 10.7631/issn.1000-2243.2015.04.0517
Abstract: 基于有限元软件ABAQUS对圆端形钢管混凝土轴压短柱进行分析. 分析表明:圆端形钢管对核心混凝土的约束效果介于圆钢管和矩形钢管之间;钢管对核心混凝土的约束作用主要分布于圆弧段;圆端形钢管混凝土柱的承载力、峰值应变和延性均介于圆钢管混凝土柱和矩形钢管混凝土柱之间;圆端形钢管混凝土构件承载力和延性随着钢管强度、含钢率、加劲肋厚度和加劲肋数量的提高而提高;随着混凝土强度的提高,其承载力提高但延性下降.
The analysis on concrete-filled round-end steel tubular (CFREST) stub column under axial compression were carried out using finite element software ABAQUS. The analysis results indicate that:the confinement effect provided by the round-end steel tube is between those provided by circular and rectangular steel tubes. The confinement effect provided by the round-end steel tube on the core concrete is mainly distributed in arc segment. The strength,peak strain and ductility of the CFREST column are between those of the CFST column with circular and rectangular cross-sections. For CFREST columns,the strength and ductility increase with the increasing of the steel strength,steel ratio,stiffener thickness and the number of stiffeners. As the concrete strength increases,the strength increases but the ductility drops
CFRP与钢组合斜拉索斜拉桥方案研究  [PDF]
哈尔滨工业大学学报 , 2011, DOI: 10.11918/j.issn.0367-6234.2011.04.024
Abstract: 针对现阶段斜拉索设计所面临的难题,提出了一种新型的基于碳纤维增强塑料(CFRP)与钢组合斜拉索的斜拉桥方案.该方案将CFRP斜拉索与传统钢斜拉索分别应用于斜拉桥恒载活载状态,发挥CFRP材料高强轻质,钢材料弹性模量大的优势而同时又弥补各自缺点.介绍了该组合方案的设计方法和关键力学参数,并利用参数分析给出推荐取值.通过构造和全桥研究可以得出:与全钢斜拉索斜拉桥相比,该组合斜拉索斜拉桥垂度效应小,自重轻;而与全CFRP斜拉索斜拉桥相比,其整体刚度大,价格便宜.从理论上证明了这种组合斜拉索的力学优势和替代传统钢斜拉索或全CFRP斜拉索应用在斜拉桥上的可行性.
Factors effect on the effective length in a double strap joint between steel plates and CFRP  [cached]
Majid Mohammed Ali
International Journal of Advances in Applied Sciences , 2012, DOI: 10.11591/ijaas.v1i1.484
Abstract: This paper presents the behavior of axially loaded flat steel plates strengthened using carbon fiber reinforced polymer sheets. Two steel plates were joined together with adhesive and followed by the application of carbon fiber sheet double strap joint with different bond lengths. The effective length of CFRP sheet has been study by using commercially available finite element analysis software ANSYS V12.1. A parametric study has been performed by numerical modeling with the variables of CFRP sheet thickness, adhesive layer thickness, steel plate thickness and number of CFRP sheet layer.
CFRP与钢组合拉索斜拉桥经济性能分析  [PDF]
哈尔滨工业大学学报 , 2011, DOI: 10.11918/j.issn.0367-6234.2011.08.024
Abstract: 为克服大跨径斜拉桥整体刚度降低,提出一种新型斜拉桥方案,即CFRP与钢组合拉索斜拉桥,介绍碳纤维增强塑料CFRP与钢组合拉索斜拉桥的设计理念,并提出斜拉索构造以及斜拉桥结构的设计方法,研究了CFRP与钢组合拉索斜拉桥经济性能,并推导出该类斜拉桥的材料用量与造价公式.基于所推导公式,对其跨长、塔高以及价格比分别进行经济性能参数分析,得到CFRP与钢组合拉索斜拉桥的经济性能变化规律,为该类斜拉桥设计提供理论依据,从理论上证明CFRP与钢组合拉索斜拉桥的经济性能优势和未来替代传统斜拉索应用在斜拉桥上的可行性.
Experimental and Analytical Investigations on the Structural Behaviour of Steel Plate and CFRP Laminate Flexurally Strengthened Reinforced Concrete Beams  [PDF]
M.Z. Jumaat,A. Alam
Journal of Applied Sciences , 2008,
Abstract: This study presents an experimental and analytical investigation to compare the structural behaviour of externally bonded steel plates and Carbon Fiber Reinforceed Polymer (CFRP) laminates flexurally strengthened r.c. beams. For the experimental investigation, three r.c. beams were cast. One beam was tested in the un-strengthened condition to act as the control beam. The second beam was strengthened using steel plate while the third beam was strengthened using CFRP laminate. The strengthened beams were designed to have the same strength with the assumption that they would fail in a ductile manner. The test results indicated that although both beams were designed for the same strength, the CFRP laminate strengthened beam recorded a slightly higher failure load compared to the steel plate strengthened beam. The steel plate strengthened beam recorded a higher cracking load and less deflections, reinforcement bar strains, concrete strains and crack widths compared to the CFRP laminate strengthened beam. Results also showed that the CFRP laminate strengthened beam failed by premature concrete cover separation failure, whereas the steel plate strengthened beam failed by premature plate end interfacial debonding followed by concrete cover separation. The beams were also modelled using a Finite Element Method (FEM) package. The numerical results seemed to agree well with the experimental results.
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