某超长地下室混凝土结构无缝设计计算研究

对沈阳某超长地下室混凝土结构的温度应力进行有限元计算分析,探讨了设置与不设置后浇膨胀加强带两种情况下地下室底板、顶板和外墙温度应力的大小和分布,并提出四种方案对施工二阶段的温度应力进行控制。结果表明,设置后浇膨胀加强带后施工一阶段的温度应力有了明显的减小,施工二阶段在方案四下的温度应力减小效果显著。通过合理设置后浇膨胀加强带和温度收缩钢筋,采用补偿收缩混凝土,采用方案四对施工二阶段进行控制及在环境温差、材料、混凝土生产技术和施工等角度做好控制,本超长地下室可不设置伸缩缝。     

微穿孔板吸声结构的研究进展

在介绍马大猷开创的微穿孔板吸声结构基础理论的前提下,综述了微穿孔板吸声结构的理论发展、吸声系数实验测量方法以及微穿孔板吸声结构在实际工程领域的一些应用。最后提出微穿孔板研究发展的方向。     

超长结构钢筋混凝土裂缝控制技术

浙江苍南县行政中心综合楼属超长结构,主体施工中采用ZY补偿收缩混凝土结构无缝设计施工,主要通过设置ZY膨胀加强带、ZY后浇膨胀加强带和后浇带,控制混凝土结构裂缝的产生,达到了设计要求。     

钛／钢爆炸焊接界面区形变特征研究

详细观察了钛／钢爆炸焊接界面区内的变形组织特征,研究了复合板的钢侧塑性变形层和钛侧绝热剪切线与焊接工艺参数的关系。结果表明,过大或过小的变形层都将导致界面区内产生有害缺陷。合理的变形层宽度应控制在５０μｍ￣２００μｍ之间,绝热剪切线长度不宜超过１０００μｍ。     

粉末烧结钨合金材料的绝热剪切变形局域化实验研究

在分离式Ｈｏｐｋｉｎｓｏｎ压杆装置上对斜圆柱粉末烧结钨合金试件进行了冲击实验,实验中观察到试件的宏观破断现象;用光学和扫描电子显微镜观察到钨合金中出现绝热剪切带这一变形局域化现象。实验结果表明,钨颗粒的形状和空间取向对钨合金剪切变形形式有明显的影响。     

超长地下箱基混凝土施工技术

以天津钢管公司不锈钢冷轧薄板工程退火酸洗机组设备基础为例,主要通过混凝土配合比控制、后浇带及施工缝的处理等,介绍超长地下箱基混凝土的施工技术,以解决超长超宽混凝土结构的施工问题,可供类似工程借鉴。     

混凝土后浇带的质量控制

介绍了晋城市开发区某办公楼工程的混凝土舌浇带施工新工艺，分析了因混凝土后浇带施工不当而产生裂缝的原习，提出了应采取的技术措施，并指出应制定企业工法，以确保工程质量。     

超长混凝土结构裂缝控制措施

介绍了超长混凝土结构裂缝常见的类型，从混凝土材料的选择、采取适当的养护及施工工艺、加强保温隔热等方面进行了论述，提出了超长混凝土结构控制裂缝的措施。     

Similar features in Z bands of both skeletal and cardiac muscle revealed by image enhancement

We have shown previously that the small square (ss) and basket weave (bw) states of the Z band lattice in cardiac and skeletal muscle are related to the contractile state of the muscle. We have used two-dimensional image processing techniques on digitized electron micrographs to enhance the structural features of each projected lattice form in cardiac and skeletal muscle. Four different processing techniques were employed to assess the effect of enhancement artifacts on the resulting Z band images. We observed only slight differences between enhanced images of a particular Z band form produced by the four different techniques. Every enhanced image showed an approximate four-fold symmetry independent of muscle type or Z band lattice form. Each enhanced image showed four cross-connecting Z-filaments which appeared to connect each axial filament to the four nearest axial filaments. In bw images from both cardiac and skeletal muscle, axial filaments had a greater apparent diameter and a greater interaxial filament spacing than in the ss images. In both muscle types, the cross-connecting Z-filaments appeared to overlap half-way between axial filaments in the ss images while the bw images showed no such overlap. These structural features are consistent with a dynamic Z band lattice that participates in muscle contraction.     

Coupled analysis of bifurcation and shear band in saturated soils

The focus of this study is the analysis of the onset of a shear band in saturated soils under biaxial stress conditions taking into account bifurcation in both pore pressure and soil skeleton. By considering the saturated soil as a two-phase medium, the inhomogeneous displacement and pore pressure fields are assumed to be nonlinear and satisfy the continuity conditions of displacements, displacement gradients and excess pore pressure on the boundaries of the band. It is shown that bifurcation may take place in loose, contractive soils in the form of two-phase diffuse mode or localized mode of soil skeleton deformation. For low permeability saturated soils, the onset of a shear band occurs at peak friction, with the shear band parallel to Coulomb's failure plane. Numerical examples using a simple stress–strain model are given to demonstrate the occurrence of the onset of a shear band and its inclination, as a function of the void ratio and the initial consolidation pressure.