某流塑状冲填土软基CPT测试结果与分析

利用CPT测试方法对流塑状软土地基进行测试，并根据测试结果对地基土的各项物理力学指标进行分析，据此考察CPT测试方法在流塑状软土地基上应用的实用性与可靠性。     

剪力墙结构中连梁设计

高层建筑剪力墙结构中的连梁在水平荷载作用，内力较大，常出现超限，因而连梁设计是剪力墙结构设计中的重点，也是难点。本文就连梁内力分析提出几种内力调整方法。供设计同行参考。     

碳纤维布加固损伤混凝土梁的抗剪疲劳试验

对钢筋混凝土受剪梁疲劳损伤后进行了粘贴U型碳纤维布加固钢筋混凝土损伤梁的疲劳试验。试验结果表明：钢筋混凝土梁粘贴U型碳纤维布后箍筋应变减小了20％～40％，斜裂缝宽度减小了34％～39％，且碳纤维布用量越大效果越明显。因此，粘贴碳纤维布可以较大提高损伤混凝土梁的抗剪疲劳性能，延长损伤混凝土结构的使用寿命。     

三剪应力统一屈服准则研究

为克服单剪屈服准则仅考虑最大主切应力和双剪准则只考虑两个较大主切应力的缺点，以菱形十二面单元体为依据，同时考虑单元体上的三个主切应力τ13、τ12、和τ23、对材料屈服的影响，认为这三者的组合达到某一极值时，材料即出现屈服．提出了三剪应力统一屈服准则，三剪屈服准则可更大限度地发挥材料的强度潜力．该屈服准则比单剪屈服准则和双剪屈服准则更具有一般性．它还可以考虑单元体上所作用的全部剪应力的不同组合，从而构成外凸和非凸两大族屈服面．     

层状土中考虑剪切变形的单桩水平振动解析解

针对桩基水平振动分析问题，建立了能够同时考虑桩体弯曲和剪切变形的桩土计算模型.采用与频率相关的刚度系数和阻尼系数来模拟土对桩的动反力，简化桩体为Timoshenko梁，得到了层状黏弹性地基中能同时考虑桩体弯曲和剪切变形的单桩的水平振动解析解.研究了桩土模量比、桩体长径比、地基成层性以及激振频率对桩基动力响应的影响.并且在给定桩土参数的情况下，把同时考虑桩体弯曲和剪切变形的解析解与只考虑弯曲变形的解进行了比较.结果表明，忽略桩体水平振动时的剪切变形可能会带来较大的误差.     

组合剪力墙单元

由许多小壳单元凝聚而成的四边形组合剪力墙单元,专门用于剪力墙的力学分析.单元的外边界上的4个角结点带有平面内的转动自由度,并且每条外边界上有2个中间结点的位移是由两端正角结点位移的Hermit插值表示.组合剪力墙单元的优点是:(1)高精度,一个单元可以模拟一个开间的剪力墙;(2)容易处理开洞引起的一些问题;(3)与梁柱单元位移模式协同.     

Intermetallic reactions in reflowed and aged Sn-9Zn solder ball grid array packages with Au/Ni/Cu and Ag/Cu pads

During the reflowing of Sn-9Zn solder ball grid array (BGA) packages with Au/Ni/Cu and Ag/Cu pads, the surface-finished Au and Ag film dissolved rapidly and reacted with the Sn-9Zn solder to form a γ₃-AuZn₄/γ-Au₇Zn₁₈ intermetallic double layer and ε-AgZn₆ intermetallic scallops, respectively. The growth of γ₃-AuZn₄ is prompted by further aging at 100°C through the reaction of γ-Au₇Zn₁₈ with the Zn atoms dissolved from the Zn-rich precipitates embedded in the β-Sn matrix of Sn-9Zn solder BGA with Au/Ni/Cu pads. No intermetallic compounds can be observed at the solder/pad interface of the Sn-9Zn BGA specimens aged at 100°C. However, after aging at 150°C, a Ni₄Zn₂₁ intermetallic layer is formed at the interface between Sn-9Zn solder and Ni/Cu pads. Aging the immersion Ag packages at 100°C and 150°C caused a γ-Cu₅Zn₈ intermetallic layer to appear between ε-AgZn₆ intermetallics and the Cu pad. The scallop-shaped ε-AgZn₆ intermetallics were found to detach from the γ-Cu₅Zn₈ layer and float into the solder ball. Accompanied with the intermetallic reactions during the aging process of reflowed Sn-9Zn solder BGA packages with Au/Ni/Cu and Ag/Cu pads, their ball shear strengths degrade from 8.6 N and 4.8 N to about 7.2 N and 2.9 N, respectively.     

复合砂浆钢筋网加固RC简支梁抗剪性能的试验研究

复合砂浆钢筋网薄层加固是一种有效的新型加固方法,能够显著地提高钢筋混凝土梁的抗剪承载力以及抗裂性能.在6根复合砂浆钢筋网加固RC简支梁和1根对比梁的试验基础上,研究了加固梁各种参数对梁极限抗剪承载力的影响,并分析对比了各组加固梁的破坏形态、斜裂缝、荷载-跨中挠度曲线的变化规律.给出了复合砂浆钢筋网加固RC梁的极限抗剪承载力计算公式,计算结果与试验结果吻合较好.     

Unified analytical stress- strain curve for quasibrittle geomaterial in uniaxial tension, direct shear and uniaxial compression

Considering strain localization in the form of a narrow band initiated just at peak stress, three analytical expressions for stress - strain curves of quasibrittle geomaterial （such as rock and concrete） in uniaxial tension, direct shear and uniaxial compression were presented, respectively. The three derived stress - strain curves were generalized as a unified formula. Beyond the onset of strain localization, a linear strain-softening constitutive relation for localized band was assigned. The size of the band was controlled by internal or characteristic length according to gradient-dependent plasticity. Elastic strain within the entire specimen was assumed to be uniform and decreased with the increase of plastic strain in localized band. Total strain of the specimen was decomposed into elastic and plastic parts. Plastic strain of the specimen was the average value of plastic strains in localized band over the entire specimen. For different heights, the predicted softening branches of the relative stress- strain curves in uniaxial compression are consistent with the previously experimental results for normal concrete specimens. The present expressions for the post-peak stress - deformation curves in uniaxial tension and direct shear agree with the previously numerical results based on gradient-dependent plasticity.     

Entire deformational characteristics and strain localization of jointed rock specimen in plane strain compression

Shear band （SB）, axial, lateral and volumetric strains as well as Poisson＇s ratio of anisotropic jointed rock specimen （JRS） were modeled by Fast Lagrangian Analysis of Continua （FLAC）. Failure criterion of rock was a composited Mohr-Coulomb criterion with tension cut-off. An inclined joint was treated as square elements of ideal plastic material beyond the peak strength. Several FISH functions were written to automatically find the addresses of elements in the joint and to calculate the entire deformational characteristics of plane strain JRS. The results show that for moderate joint inclination （JI） , strain is only concentrated into the joint governing the behavior of JRS, leading to ideal plastic responses in axial and lateral directions. For higher JI, the post-peak stress-axial and lateral strain curves become steeper as JI increases owing to the increase of new SB＇s length. Lateral expansion and precursor to the unstable failure are the most apparent, resulting in the highest Poisson＇s ratio and even negative volumetric strain. For lower JI, the entire post-peak deformational characteristics are independent of JI. The lowest lateral expansion occurs, leading to the lowest Poisson＇s ratio and positive volumetric strain all along. The present prediction on anisotropic strength in plane strain compression qualitatively agrees with the results in triaxial tests of rocks. The JI calculated by Jaeger＇s formula overestimates that related to the minimum strength. Advantages of the present numerical model over the Jaeger＇s model are pointed out.