双层套管同心跟管成孔工艺在复杂地层的应用

猴子岩水电站格宗移民场平工程子格里料场开挖时,其后边坡地质结构复杂,基岩为强风化强卸荷带,预应力锚索施工成孔难度大,常规单层套管偏心跟管、同心跟管和固壁灌浆成孔方式不能满足成孔要求,进度慢、成本高。采取双层套管同心跟管工艺有效地解决了在复杂地层预应力锚索成孔难题。     

大直径筒仓中无粘结预应力混凝土结构的应用

大直径混凝土筒仓采用普通钢筋混凝土结构设计时，常常需要较大幅度地增加钢筋用量，有时甚至加大钢筋用量仍无法满足规范对裂缝宽度的要求。故采用无粘结预应力混凝土结构筒仓，可有效地控制裂缝的出现，并减小钢筋用量，取得了良好的效果。以工程实例对无粘结预应力混凝土结构筒仓的设计、施工作了介绍。     

重钢预应力SWRH82B盘条的生产分析

介绍采用150 mm×150 mm连铸坯、高速线材轧机生产Φ12.5 mm规格预应力82B盘条的试生产情况,对试生产中出现的问题进行分析,并提出了改进意见.     

有粘结预应力外包角钢混凝土梁施工阶段弹性受力分析

外包钢混凝土结构构造简单、联接方便、承载力高、延性好。但作为受弯构件,其抗裂性能及抗弯刚度等优势不是很明显。对其施加预应力,形成有粘结预应力外包角钢混凝土结构,可以进一步提高构件的承载能力、抗弯刚度、抗裂性能、耐久性。文章对有粘结预应力外包角钢混凝土梁进行施工阶段弹性受力分析,并给出其相应应力、应变计算公式。     

浅议预应力锚索高边坡防护技术

由于预应力锚索防护施工技术大大减轻结构物的自重、节约工程材料并确保工程的安全和稳定,具有显著的经济效益和社会效益,因而目前在工程中得到极其广泛的应用.     

预应力梁板预制施工质量控制

本文通过对预应力梁板的原材、施工工艺和施工质量的控制的介绍,保证了预应力梁板施工的施工质量。     

预应力片材加固负载RC梁受弯承载力分析

分析有初始弯矩作用时,预张纤维片材粘贴加固混凝土梁中加固材料相对该处混凝土滞后应变或超前应变的计算方法和纤维片材中有效预应力的取值;对预应力FRP粘贴加固梁构成的复合截面,分析各种可能应变组合下的受弯极限状态,给出两大弯曲破坏类型(分别由片材拉断和混凝土压碎引发)的界限判别条件和极限承载力计算表达式.试验分析表明,极限承载力试验值与计算值比值的均值为0.99,变异系数为0.047.     

控制索原长求解索张拉力的反分析法

为对预应力空间钢结构的施工成形进行系统的研究,提出了基于控制索原长求解索张拉力的反分析法.从预应力状态开始,通过控制每一级张拉索的原长,进行非线性有限元迭代计算,求出索在分级分批施工时的控制力.方法的优点在于计算简单,省去了通用有限元需要反复试算的缺点.应用编制的程序对一弦支穹顶模型进行了施工过程的模拟分析,结果表明:反分析法能精确模拟结构的施工成形过程,且在整个过程中,每根索只需张拉一次,简化了施工工艺.     

Nonlinear behavior of concrete beams with hybrid FRP and stainless steel reinforcements

The full-range behavior of partially bonded, together with partially prestressed concrete beams containing fiber reinforced polymer (FRP) tendons and stainless steel reinforcing bars was simulated using a simplified theoretical model. The model assumes that a section in the beam has a trilinear moment—curvature relationship characterized by three particular points, initial cracking of concrete, yielding of non-prestressed steel, and crushing of concrete or rupturing of prestressing tendons. Predictions from the model were compared with the limited available test data, and a reasonable agreement was obtained. A detailed parametric study of the behavior of the prestressed concrete beams with hybrid FRP and stainless steel reinforcements was conducted. It can be concluded that the deformability of the beam can be enhanced by increasing the ultimate compressive strain of concrete, unbonded length of tendon, percentage of compressive reinforcement and partial prestress ratio, and decreasing the effective prestress in tendons, and increasing in ultimate compressive strain of concrete is the most efficient one. The deformability of the beam is almost directly proportional to the concrete ultimate strain provided the failure mode is concrete crushing, even though the concrete ultimate strain has less influence on the load-carrying capacity. Foundation item: Project (50478502) supported by the National Natural Science Foundation of China     

预应力混凝土斜拉桥施工抗风性能计算分析

根据某预应力混凝土斜拉桥的悬臂施工过程,运用桥梁设计专用软件Midas/civil计算分析了索塔浇筑完成以及最大悬臂状态两种情况下主梁及索塔的抗风性能,得出了一些有益的结论,为以后其他同类桥梁的设计和建设提供参考.