Merely the fatigue strength in uniaxial tension or compression under constant - amplitude cyclic loading is given in the existing design code . the design result by using the fatigue strength in the code is apt to conservative under variable - amplitude or triaxial cyclic compression loadings , but sometimes apt to dangerous in uniaxial or triaxial tension - compression fatigue loadings 现行规范中,仅有混凝土单轴、等幅波动拉伸和抗压强度指标,采用这些指标进行设计,会导致设计结果有时偏于保守,如变幅及多轴压疲劳;而有时又偏于危险,如单轴及多轴波动拉-压疲劳。
In this dissertation , the effect of texture , heat - treatment , and hydrogen on the lcf behavior of zircaloy - 4 and the cyclic deformation behavior for zircaloy - 4 , n18 alloy and n36 alloy have been investigated systematically using fully - reversed tension - compression loading under strain control ( r = min / max = - 1 ) , while the evolvement of the friction and back stresses versus the number of repeated working cycles and the plastic strain amplitude has been studied , and the thorough discussion combined with the analysis result of fatigue sub - structure , friction and back stresses , and fatigue fracture has been given to the mechanism underlying the lcf behavior of alloys 本文采用对称拉压循环变形方法( r _ = _ ( min ) _ ( max ) = - 1 ) ,系统研究了织构、热处理状态、氢对zr - 4合金低周疲劳性能的影响, zr - 4合金、 n18合金和n36合金的循环变形行为,并研究了摩擦应力、背应力随循环周次、塑性应变幅的变化规律。结合疲劳亚结构和疲劳断口的分析结果,深入探讨了影响合金低周疲劳行为的作用机制。
Each unit anchor has its own individual tendon , its own unit fixed length of borehole , and is loaded with its own unit stressing jack which ensures that the load in all unit anchors is always identical . the total working load of the anchor is beard by each fixed anchor length of all units in staggered depth in the borehole and by means of respective bearing bodies , the tension loads applied to the plastic coated strands are changed into the compression loads on the grout of each fixed anchor length , then the total working load can be divided into several smaller loads and transmitted to the rock mass and soil in different locations in dispersed compression 压力分散型锚索是在一个钻孔中安装若干个锚索单元,每个单元都有自己的杆体和锚固段,在张拉时分别承受相同的工作荷载;锚索总的锚固力由分散布置于钻孔不同深度处的这些单元锚索的锚固段来共同承担,并利用各单元的承载体将无粘结锚索的拉力转化为对锚固段注浆体的压力,从而将锚索总的锚固力以压力形式分散作用于不同深度的岩土体上。