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有人知道这个怎么翻译吗?(急用)
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作者： G3318
01-01 08:00
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2.3.5 Behavior of Concrete under Biaxial Stresses
For prestressed concrete bridge girders, in order to consider cracking due to steel expansion, it is necessary to consider a biaxial stress since the cover is subjected to a biaxial stress produced by prestressing stress and the stress which comes from corrosion product. Kupfer and Hilsdorf investigated the behavior of concrete under a biaxial stress[1969]. According to their study, in the region of combined compression and tension, tensile strength decreases as compressive stress increases (see Figure 2.3.13 and Figure2.3.14).
2.4 Effect of Crack Width on Diffusion of Chloride Ions
2.4.1 Crack Width Prediction
There have been many studies of the relationship between crack width and the corrosion rate. Although longer crack width can result in a greater corrosion rate, several researchers found a weak relationship between crack width and corrosion rate. Several design codes limit the crack width to control the corrosion rate, while other codes do not.
The American Concrete Institute (ACI) used the crack width limit [the ACI 318 code 1971, 77, 83; ACI Committee 224 1980]. However, the current ACI code 318[2002] limits the spacing of reinforcement closest to concrete surface since crack width in structures can vary. The new code also eliminated the distinction between interior and exterior exposures because corrosion is not strongly correlated with surface crack width for a typical stress range in reinforcement at service load levels.
In the ACI 318 code [1971, 77, 83] and ACI Committee 224 [1980], the predicted crack width is determined by the following formula:
where is service load stress in reinforcement, is the distance from the neutral axis to
the bottom fiber, divided by the distance to the reinforcement, is the distance from the
extreme tension fiber to the center of the reinforcing bar located closest to it, and is
the effective tension area of concrete surrounding the tension reinforcement, and having the same centroid as that reinforcement, divided by the number of bars or wires. It should be noted that Equation 2.4.1 is given in inches (1 inch=25.4mm).
The AASHTO LRFD code uses the following Equation, instead of crack width,
where Z is the crack width parameter.
However, the AASHTO LRFD code also mentions that using a certain value of the crack width parameter results in a limiting surface crack width of about 0.40mm (0.016 inch). This Equation was introduced considering the scatter in crack width, and thus it can be concluded that the origins of Equations 2.4.1.1 and 2.4.1.2 are the same. |
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回复：有人知道这个怎么翻译吗?(急用)
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作者： wogannima521
01-01 08:00
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2.3.5钢筋混凝土双向应力下的预应力混凝土梁桥, 为了考虑裂缝导致钢筋扩张 既要考虑一个双轴应力以来的封面,是受到了双轴应力产生预应力 紧张和压力,来自腐蚀产品. kupfer和hilsdorf调查钢筋混凝土在双轴应力〔1969〕. 根据他们的研究,在该地区的合并压缩和紧张, 抗拉强度随压应力增大(见图2.3.13和figure2.3.14). 2.4影响裂缝宽度diffusion氯离子2.4.1裂缝宽度预报已有许多研究 关系裂缝宽度和腐蚀率. 虽然长裂缝宽度可能造成更大的腐蚀速度, 若干研究人员发现一种微弱的关系裂缝宽度和腐蚀率. 几个设计规范,限制裂缝宽度控制腐蚀率,而其他的代码不. 美国混凝土学会(ACI)和使用的裂缝宽度限制[防疫代码318,1971年,77个,83个; 防疫委员会2241980〕. 不过, 目前防疫代码318[2002]界限间距最接近钢筋混凝土表面自裂缝宽度结构 也不尽相同. 新法还取消了区分内部和外部风险的侵蚀,因为没有强烈的相关曲面 裂缝宽度为一典型的应力范围,强化服务,在负荷水平. 在aci318码[1971年,77,83]和防疫委员会224〔1980〕, 预测裂缝宽度是由下列公式:那里是服务的荷载应力钢筋 就是距中性轴至底部的纤维,再除以距离的增援, 是距极度紧张纤维为中心的钢筋位于最接近, 是有效的地区紧张局势的具体周边紧张加固 并有相同的心作为增援,除以钢筋或电线. 应当指出的方程式2.4.1是英寸(1英寸=25.4mm). 该aashtolrfd代码使用下列公式计算,而不是裂缝宽度,这里Z是裂缝宽度参数. 不过, 该aashtolrfd典也提到,使用一定价值的裂缝宽度参数结果限制 表面裂缝宽度约0.40mm(0.016英寸). 这个方程被引入考虑散射的裂缝宽度 因此可以断定,起源方程2.4.1.1和2.4.1.2都一样 |
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