Effects of reinforcement slippage on the non‐linear response under cyclic loadings of RC frame structures

This paper discusses the importance of including the bond‐slip effects in assessing the response under cyclic loads of reinforced concrete frames. The discussion is based on analyses performed using numerical models which are simple, computationally efficient and capable of representing the salient features of reinforced concrete frames under both static and dynamic loads. The numerical models comprise a displacement‐based, reinforced concrete frame element with bond‐slip and a rigid beam column joint element with bond‐slip. Two applications illustrate the model accuracy and show the importance of including bond‐slip. The first application considers a reinforced concrete beam‐column subassemblage experimentally tested under cyclic loads. The second application considers the shaking table test of a two‐story one‐bay reinforced concrete frame In both cases the analytical results correlate well with the experimental results in terms of strength, displacement demands and hysteretic energy dissipation. Furthermore, the paper shows how the analyses that include bond‐slip yield a better correlation with the experimental results with respect to the analyses that assume a perfect bond. Copyright © 2003 John Wiley & Sons, Ltd.     

超声反射法套管-地层环空间介质波阻抗反演方法与成像实例

针对套管井反射式超声波水泥固井质量检测问题,本文利用超声反射波频谱中套管共振透射窗内的复合反射系数,提出了定量反演套管-地层环空间内介质的波阻抗的方法. 利用复合反射系数中多个频率点的相移反正切函数主值,给出了波阻抗的计算公式,并把套管-地层环空间介质中波的相移的整、实特性作为波阻抗反演收敛的判据. 针对井下实际测井环境中超声换能器性能受温度和压力等的影响而发生变化,导致的声源波形（子波）和复合反射系数不确定的困难,提出了用井下原地（in situ）实测波形定量估计声源波形和复合反射系数的方法. 通过对合成数据的处理,分别考察了已知介质的声学和几何参数存在的偏差对套管-地层环空间内介质的波阻抗反演结果的影响. 本文对多组模型井检验数据进行了目的层介质的波阻抗反演与成像,成像结果与真实情况吻合,验证了反演方法的有效性. 最后对现场实测资料进行了套管-地层环空间内介质的波阻抗定量反演与成像.     

Effects of orientation on the diffusive properties of fluid-filled grain boundaries during pressure solution

An unresolved issue in the study of pressure solution in rock materials is the dependence of grain boundary structure and diffusive properties on the mutual orientation of neighbouring grain lattices. We report electrical measurements yielding the diffusivity of differently oriented halite–glass and halite–halite contacts loaded in the presence of brine. The halite–glass contact experiments show pressure solution of the halite and an effect of halite lattice orientation on grain boundary transport. Post-mortem observations show an orientation-dependent grain boundary texture controlled by the periodic bond chains in the halite structure. It is inferred that this texture determines the internal grain boundary structure and properties during pressure solution. In the halite–halite experiments neck-growth occurred, its rate depending on twist-misorientation. The results imply that deformation by pressure solution may lead to lattice-preferred orientation development, and that polymineralic rocks may deform faster at lower stresses than monomineralic rocks.     

黄铁矿含金机理探讨

在大多数金矿床中,黄铁矿是金的主要载体矿物之一.本文从黄铁矿的晶体结构化学角度出发,分析了黄铁矿的晶体结构特点;探讨了金以An+和An-离子形式分别替代Fe2+离子和S2-离子的形成机理以及以可见金方式在黄铁矿中的赋存机制.通过分析,认为金在黄铁矿中的富集主要与黄铁矿的晶体结构有关,特别是与黄铁矿中的Fe-S、S-S、An-S和Fe-Au键的电子结构特点有关.     

A combined local damage index for seismic assessment of existing RC structures

A new local damage index for existing RC structures is introduced, wherein deterioration caused by all deformation mechanisms (flexure, shear, anchorage slip) is treated separately for each mechanism. Moreover, the additive character of damage arising from the three response mechanisms, and the increase in degradation rate caused by their interaction, are fully taken into consideration. The proposed local damage index is then applied, in conjunction with a finite element model developed previously by the authors, to assess seismic damage response of several RC column and frame test specimens with substandard detailing. It is concluded that in all cases and independently from the prevailing mode of failure, the new local damage index describes well the damage pattern of the analysed specimens. Copyright © 2012 John Wiley & Sons, Ltd.     

砂浆受腐蚀锚固体的锚固特性试验研究

采用室内加速腐蚀试验方法,研究了砂浆受腐蚀后砂浆锚杆锚固体的锚固特性变化情况。通过对不同腐蚀阶段砂浆锚杆锚固体中锚杆-砂浆界面以及砂浆-基体界面的黏结强度及荷载-位移关系的测试及分析,得到了界面黏结特性随砂浆腐蚀时间的变化关系。结果表明：随着砂浆受腐蚀程度的增加,锚杆-砂浆-基体三者界面间的黏结强度均呈线性下降,锚杆-砂浆界面间剪切刚度随着腐蚀时间的增加而减小,而砂浆-基体界面间的剪切刚度受砂浆腐蚀程度的影响不大,但界面间的化学胶着力会随砂浆腐蚀程度的增加而降低。     

基于CAD平台开发的悬挂点检查与自动处理

简要介绍了基于CAD平台开发悬挂点检查与自动处理的程序开发技术、技术路线、实现方法、主要源代码。主要用于地籍测量数据入库前悬挂点检查,并用实例进行了验证,取得了满意的效果,达到了设计的目的,为作业单位提高了效率。     

谷氨酸插层镁铝水滑石微观结构与性能:实验与理论研究

采用共沉淀法合成了谷氨酸插层镁铝水滑石(LDHs-Glu),并使用XRD表征技术以及分子动力学模拟方法对其微观结构与性能进行了研究。结果表明随着LDHs-Glu中水分子数量增加,层间距d003逐渐增大。XRD表征得到其层间距为1.328 nm,与理论模拟得到的当水分子数Nw=7时的水滑石层间距d003=1.323 nm相近。随着层间水分子数量增加,水合能逐渐增大,最终趋于流体水的特征值(-41.8 kJ/mol)。水合过程中,水滑石层板与阴离子间的氢键逐渐减少,而层板与水分子间的氢键逐渐增多,说明水分子与层板间的亲和力更强。实验表征与理论模拟相结合的研究方法,有望成为插层复合材料微观结构研究的重要手段。     

A new ultrasonic interferometer for the determination of equation of state parameters of sub-millimeter single crystals

A new giga-Hertz ultrasonic interferometer has been developed, based on ultrasonic microscopy technology. The interferometer operates from 0.3 GHz to 1.5 GHz. The high frequency and associated small wavelengths together with the large bandwidth make it possible to measure travel times in samples with thicknesses of several microns and allow for unprecedented accuracy in bond corrections. An absolute accuracy of 1 part in 10⁵ in travel time measurements is achievable in single crystals (thickness of 200 microns) or glasses of interest to the earth sciences. The high precision travel time data, combining with sample length measurements using a laser interferometer built in our laboratory, yield very high precision ultrasonic velocities.The interferometer is intended for use in conjunction with a newly developed 4 GPa gas piston cylinder apparatus (Getting andSpetzler, 1993) for equation of state measurements under simultaneous pressure and temperature. A separate correction for the bond will be made for each datum at every point in temperature pressure space.     

针对黏性土胶质联结特征的SEM-EDS试验研究

采用 “整区→微区→胶结点”的逐步分区测试方法,对湛江原状黏土与重塑土开展SEM-EDS试验研究,观察土体微观结构的胶质联结特征,确定胶结物质的元素组分及其空间分布状态,建立微观结构-化学物质-宏观力学行为的相互关系与灵敏性分析。结果表明,土的基本性质很大程度上取决于微观层面的颗粒联结特征。湛江黏土的结构单元实际上是以许多黏土矿物薄片堆叠而成的黏土畴,开放式的絮凝结构加上以游离氧化铁为主要成分的胶质联结特征是导致湛江黏土具有高灵敏性、强结构性的根本原因。当应力水平超过土体的结构屈服应力后,力学性能迅速劣化,结构单元体逐步转为联结强度弱,分散性强的凝聚体或叠聚体。研究还表明,土的颗粒联结强度、结构形态特征及其对结构强度的贡献是导致原状土与重塑土性质差异的本质,天然状态下的湛江黏土土性受控于微观结构特征,而重塑土土性受控于黏土矿物颗粒本性。