60m高度处单片露天超高混凝土悬臂墙的设计与施工

通过采用竖向预应力技术 ,解决了 60m高度处单片 8m高悬臂钢筋混凝土墙根部裂缝宽度超过规范限值的问题 ;采用将预应力钢绞线顶端锚固于墙高中段等结构和施工措施 ,控制墙体长细比不超过 3 0 ,减少了由于长细比过大对墙体承载力的不利影响     

无粘结预应力蛋形消化池的施工技术

石家庄市桥东污水处理厂有6座11500m3无粘结预应力混凝土蛋形消化池,本文介绍其非预应力钢筋、模板体系、混凝土和预应力工程等结构施工成套技术。     

缠绕型全自动液压压砖机机架钢丝预紧力的设计

通过建立钢丝缠绕型液压压砖机机架的力学模型，推导出钢丝绕层和钢丝预紧力的计算方法，并用有限元分析方法验算了某一缠绕型全自动液压压砖机机架钢丝预紧力的大小。     

Effects of prestressing the reinforcement on the behavior of reinforced granular beds overlying weak soil

The effects of prestressing the reinforcement on the strength improvement and settlement reduction of a reinforced granular bed overlying weak soil are being investigated through a series of laboratory scale bearing capacity tests. The influences of parameters such as strength of underlying weak soil, thickness of granular bed, magnitude of prestressing force, direction of prestressing forces and number of layers of reinforcement are being examined. Finite element analyses are carried out using the FE program PLAXIS to study the effect of prestressing the reinforcement. Results obtained from finite element analyses are found to be in reasonably good agreement with the experimental results.     

国家体育馆双向张弦结构预应力施工技术

国家体育馆屋面采用双向张弦网格结构,其预应力施工具有一定的难度。介绍了预应力施工方案及施工前期的一些准备工作,如施工仿真模拟计算、张拉工装的设计。简单介绍了预应力施工监测方案和张拉过程中的同步控制措施,并结合仿真计算结果和现场监测结果,提出了此类结构的预应力施工技术和特点。     

预应力锚索浆体胶结段承载能力的评定

本文根据非线性有限元计算成果及实验结果总结出预应力锚索浆体胶结段的受力特征、破坏机理。在此基础上,根据弹性理论,推导出一个弹性状态下的受力计算公式;给出一个能够反映胶结段破坏机理的承载近似计算公式,并说明采用此公式计算单孔锚固吨位时可获得安全系数的取值范围。     

Generation and application of prestress in redundantly full-actuated parallel manipulators

This paper addresses the inverse dynamics of redundantly actuated parallel manipulators. Such manipulators feature advantageous properties, such as a large singularity-free workspace, a high possible acceleration of the moving platform, and higher dexterity and manipulability. Redundant actuation further allows for prestress, i.e., internal forces without generating end-effector wrenches. This prestress can be employed for various goals. It can potentially be used to avoid backlash in the driving units or to generate a desired tangential end-effector stiffness. In this paper, the application of prestress is addressed upon the inverse dynamics solution. A general formulation for the dynamics of redundantly actuated parallel manipulators is given. For the special case of simple redundancy, a closed-form solution is derived in terms of a single prestress parameter. This yields an explicit parametrization of prestress. With this formulation an open-loop prestress control is proposed and applied to the elimination of backlash. Further, the generation of tangential end-effector stiffness is briefly explained. The approach is demonstrated for a planar 4RRR manipulator and a spatial heptapod.     

大跨度预应力混凝土结构施工质量控制研究

由于预应力混凝土的施工技术是一项专业性强、操作要求严、技术含量高的工作,所以预应力混凝土的质量控制对于结构施工的优劣起到至关重要的作用,进而影响到整个工程质量的好坏。鉴于此,本文从施工前、施工中和完工后三个阶段分析和归纳了预应力混凝土施工质量控制的要点,以期对工程实践起到参考和指导的作用。     

山西西龙池抽水蓄能电站地下厂房无粘结预应力对穿锚索工艺试验

无粘结预应力对穿锚索是保证山西西龙池抽水蓄能电站地下厂房顶拱薄层灰岩稳定的最主要支护方式，为验证施工工艺的可行性和正确指导施工，根据合同技术条款和施工图纸的要求，进行了地下厂房无粘结预应力对穿锚索工艺试验。     

夹片式锚具锚垫板荷载传递试验介绍——预应力锚固区安全探讨之七

意大利米兰市"材料检验试验室"作为官方机构,完成了一项夹片式锚具铸造型锚垫板的荷载传递试验,以确认此项锚垫板用于混凝土结构的负荷能力及安全性。它依据的标准是欧洲标准ETAG 013《预应力结构后张成套组件》和它的"理解文件"(2007年12月发布)。欧洲28个成员国都执行这项标准,域外工程单位也多有采用。我国即将实施的新版锚具国家标准(GB/T 14370)与欧洲标准基本一致。这份试验报告对我国当前情况很有参考价值。在我国预应力行业中,多数从业人员对"荷载传递试验"还比较陌生,不久将会遇到这种试验的工作要求。本文按试验报告原件的章节对试验过程进行了综合梳理和说明,并补充了欧洲标准的相关要点,希望减少读者疑问。