碳纤维束铆钉锚固下CFRP布加固梁的力学性能

粘贴碳纤维布(CFRP)加固梁时,通常需对其进行锚固,避免发生因CFRP布过早剥离而无法充分利用其抗拉强度。但当梁施工空间较小,梁侧面形状不规则时,CFRP布锚固较困难,采用新型碳纤维束铆钉锚固的方式能够很好地解决这一弊端。本文通过对四组不同锚固方式下的CFRP布加固梁进行四点受弯承载力试验,对比分析加载过程中各梁的力学性能和破坏规律,研究表明碳纤维束铆钉锚固下CFRP布加固梁强度和刚度都有显著增强。进一步对碳纤维束铆钉锚固方法优化,得到最佳碳纤维束铆钉锚固深度约为80mm,最佳锚固间距约为200mm。     

A comparison between wet and cryogenic drilling of CFRP/Ti stacks

This paper compares conventional and cryogenic cooling in the deep hole drilling of carbon fiber reinforced polymer (CFRP)/Ti stacks. Various parameters are taken into account to find if the use of cryogenic coolant is justified by the improvement of the final results. Both the thrust and the torque were acquired continuously during the machining operations and compared both in average and distribution. The use of a cryogenic coolant brings a reduction in thrust force and torque without any sensible drawback. Overall the results prove that cryogenic drilling is a suitable technology for CFRP/Ti stack drill.     

预应力CFRP布加固混凝土大偏心受压柱试验研究

为改善被加固混凝土大偏心受压柱的受力性能,提出在柱周缠绕粘贴CFRP布、柱受拉侧粘贴CFRP布复合加固技术。设计了四根尺寸、材料与配筋均相同的混凝土大偏心受压柱,分别采用不同加固方式加固,通过静力加载试验,研究预应力CFRP布加固柱的受力性能,分析不同加固方式的加固效果。研究表明,大偏压柱在纵、横向分别粘CFRP布加固后,柱的承载力有了明显的提高,裂缝分布均匀且裂缝宽度小,延性明显提高。     

二次受力CFRP布加固混凝土矩形柱抗压强度计算方法研究

在一次受力下CFRP布加固混凝土矩形柱抗压强度理论公式的基础上,按照叠加原理和强度代换原理推导了二次受力下CFRP布加固混凝土矩形柱抗压强度理论公式,并采用ANSYS软件对CFRP布加固混凝土柱的二次受力性能进行了数值模拟,将试验值与理论值及ANSYS值进行对比,结果基本吻合,证明了理论推导的科学性,为加固工程提供了一定的理论参考．     

CFRP-薄壁圆钢管混凝土组合短柱的非线性有限元分析

利用ANSYS软件建立了CFRP-薄壁圆钢管混凝土组合短柱、钢管混凝土柱、素混凝土柱对比柱的三维有限元模型,并对比分析上述3种构件在轴压作用下的延性和极限承载力的差异.研究结果表明:CFRP-薄壁圆钢管混凝土柱的极限承载力比钢管混凝土柱有较大提高(模拟的单层粘贴构件约提高11％,双层粘贴构件约提高25％),且整体刚度好,表现为弹性阶段轴向位移小,当CFRP断裂后,钢管能继续提供塑性支持;钢管混凝土柱的极限承载力比素混凝土柱提高约4倍,延性也得到很大改善;ANSYS模拟值与文献[1]中的试验值和计算值吻合较好.     

碳纤维布加固超役混凝土电杆的破坏机理及力学性能

以某电网某路段超过服役期的钢筋混凝土电杆为研究对象,选取电杆杆身与跨中带钢圈接头的杆身试件各6根,其中各取3根试件采用碳纤维布（CFRP）沿杆件纵向进行加固,并对其进行抗弯承载力试验,对比研究在不同的碳纤维布黏贴层数下加固电杆的受力性能和破坏机理。基于试验实测数据,对强度及刚度计算方法进行了研究,并提出了刚度退化的数学表达式。研究结果表明：采用碳纤维布加固电杆后,其破坏表现为混凝土与碳纤维布的表面粘脱失效所致,纵向碳纤维布被拉断作为最终破坏形态,破坏过程迅速,脆性明显;试件的截面应变分布符合平截面假定。加固前杆身试件的承载力退化严重,加固后混凝土电杆的承载能力和刚度均有显著提高,但加固电杆的损伤发展较加固前提早,且快而集中,综合多方面考虑,建议在混凝土电杆接头附近的一定距离内采取双层、杆身其余部位采用单层的碳纤维布加固方法。     

重力式桥台开裂原因的有限元分析与加固措施

本文针对公路上中、小桥台普遍存在的开裂问题,结合实际工程,借助大型通用有限元软件ANSYS对某公铁立交桥斜交U型重力式桥台在侧墙与前墙接缝处开裂的原因进行了分析,且提出了开裂成因和防治办法,供设计、施工参考．     

Numerical analysis of multilayered CFRP retrofitted RC beams with partial interaction

This paper presents a theoretical model to simulate the behaviour of RC beams strengthened with multilayered CFRP matrix allowing for inter-layer slip. An element of the composite beam is assumed to be subjected to a system of forces that satisfy equilibrium and compatibility of deformations. The inter-layer slip is allowed for by relating the differential strain at the interfaces between the CFRP layers and the concrete to the longitudinal shear flow at the corresponding interface through the shear stiffness of the adhesive layer. The basic differential equations are derived in terms of displacement variables and solved numerically using finite differences. The results of the numerical simulation included slip values along the interfaces, maximum slip values, stresses and strains and deflections. The results compare reasonably well with experimental findings.     

Numerical simulation of hypervelocity impact on CFRP/Al HC SP spacecraft structures causing penetration and fragment ejection

A representative carbon fiber reinforced plastic/aluminum honeycomb sandwich panel (CFRP/Al HC SP) spacecraft structure has been modeled in the hydrocode AUTODYN using the state-of-the-art ADAMMO material model [Riedel W, Harwick W, White D, Clegg R. Advanced material damage models for numerical simulation codes. ESA CR(P) 4397, 2003] to study the performance of the structure during impact events that cause perforation and fragment ejection. A new procedure combining a series of existing theoretical methods has been developed and applied to derive a full set of coarse material data. The data set has been implemented in AUTODYN, and the results of the numerical simulation have been compared to experimental impact test data. For impact tests performed near the structural ballistic limit, quantitatively accurate results were obtained over a range of impact velocities and angles. A further increase in the projectile size resulted in significant destruction of the sandwich panel front face-sheet and diversion from the experimental damage measurements. Inspection of the numerical model has shown non-localized propagation of inter-laminar delaminations, possibly caused by an under-prediction of the laminate dynamic inter-laminar tensile strength. The effects of the delamination propagation occur over an extended time scale and were not found to affect the state and trends of the fragment cloud ejected into the satellite interior. Accordingly, experimental trends of fragment cloud dispersion have been qualitatively reproduced.     

碳纤维布与钢板复合加固钢筋混凝土梁抗弯承载力的计算分析

碳纤维布与钢板复合加固钢筋混凝土梁是一种新型的加固方法,作者通过12根试件的试验研究碳纤维布和钢板以及两者复合加固钢筋混凝土梁的破坏特征、受力性能和破坏机理。在试验的基础上,本文分析了混凝土强度、纵筋率、CFRP与钢板的加固量等因素对复合加固梁正截面极限承载力的影响,提出了与现行规范相符合的实用承载力计算公式,并与试验结果进行对比。对比结果表明,计算值与试验值吻合较好,本文建议的实用计算公式对实际工程有一定的参考价值。