The influence of stress ratio on maximum crack width of specimens is obvious , and the larger the stress ratio is , the longer the fatigue life is , it can influence the mechanical property of specimens directly 应力比对试件梁的最大裂缝宽度影响显著,应力比越大,疲劳寿命越长,直接影响试件梁在疲劳荷载作用下的性能。
But because the rigidity of the flat - beam is small , sometimes we need to use the prestressed steel to control the flexibility of the flat - beam and the width of the crack 但是由于扁梁的刚度小，往往需要在扁梁中配置预应力筋，以控制扁梁的挠度和裂缝宽度，同时也带来了位移反应较大、结构耗能较低、延性能力较差的弱点。
Abstract : simplifying the formula in code for concrete structure design ( gbj10 - 89 ) , we obtaine the appoximate formula of crack width , that is used to the beam of rectangular section in design 文摘:对《混凝土结构设计规范》 ( gbj10 - 89 )中的裂缝宽度计算公式进行化简，得出矩形截面梁裂缝宽度实用计算公式，供工程设计时使用。
Test and analysis results indicate that some little polypropylene fiber in cement concrete can not only reinforce the load _ carrying capacity and rigidity , but also control the crack width and strengthen the ductibility of beams 对比分析结果表明，适量聚丙烯纤维的掺入能够提高梁的承载能力和刚度，并能限制裂缝宽度，增加梁的延性。
Since the influence of crack on the durability of segments is uncertain and fuzzy , this paper established the durability damage membership functions for the segment surface crack width , length , orientation and density respectively 同时，鉴于表面裂缝对管片结构的耐久性影响具有模糊性的特点，分别建立了用于计算评价管片表面裂缝宽度、长度、方向和密度等因素对管片结构耐久性损伤的模糊隶属度函数。
In this article , grid - beam structure by simply supported on foursides in the engineering is discussed . its calculated method of internal force and displacement under uniform load and choosing section to control the wide of crack is studied also 本文针对工程中常见的四边简支、正交的井字梁结构进行讨论，研究了该结构受均布荷载作用下的内力及位移的计算方法，以及截面选择、裂缝宽度控制方法等。
The formulas on crack width of rc beams and src beams are analyzed at home and abroad too . the calculation formulas on the maximum crack width of src beam under short time load are suggested . the calculation result tallies that of tests well 分析比较了国内外钢筋混凝土梁和劲性钢筋混凝土梁裂缝计算公式，提出了劲性钢筋混凝土梁在短期荷载作用下的最大裂缝宽度计算公式，其计算值与试验值吻合较好。
Many factors can be concluded in this model . meanwhile the model is simple and feasible . the trial example shows the results of assessment of the degree of reinforcement corrosion coincide well with that of the experiment 建立了钢筋锈蚀量评估的bp网络模型，该模型可以同时考虑混凝土强度、保护层厚度、钢筋直径、裂缝宽度等多种影响因子，算例表明： bp网络模型的评估结果与实测结果较为一致，该模型应用简便。
Abstract : through an example ' s calculation of crack width , the calculation formula adopted by the new and old design specification for hydraulic concrete structures and design specification for concrete structures used in industrial and civil buildings were analysed and compared with each other 文摘:通过实例对新、旧水工混凝土结构设计规范及工业与民用建筑混凝土结构设计规范所采用的裂缝宽度计算公式进行分析比较。
The main conclusions are as following : 1 . specimens have four kinds of fatigue failure characteristics such as normal section crack width and truncated section crack width beyond the limit , the fatigue damage of steel bars . specimens ’ fatigue life is from 15 thousand to 1800 thousand 主要结论如下: 1 、试件出现了正截面裂缝宽度达到限值、斜截面裂缝宽度达到限值、钢筋疲劳断裂等疲劳破坏特征,疲劳寿命介于1 . 5万次180万次。
