A local and global finite element analysis of the stringer-floor beam connection of a 19th century riveted railway bridge in Spain made of puddle iron were performed to obtain the maximum principal strains in the riveted connecting angles corresponding to bending moments from train loading on the bridge. Due to the anisotropic nature of puddle iron, the connecting angles were modelled using Hill anisotropic plasticity potential and a parametric study in the local FE model of the connection was performed. A laboratory specimen fabricated with original stringers dismantled from the railway bridge was tested to calibrate the numerical models, so the yield stress ratio that best fitted experimental results was obtained. Based on the method of constant fatigue-life diagram and modified Goodman fatigue failure criterion, it was detected that the connecting angles were prone to fatigue crack initiation, as the combination of mean stress and alternating stress amplitude at the toe of the angle fillet remained outside the infinite fatigue-life region. An innovative strengthening system based on adhesively-bonded carbon-fiber reinforced polymer (CFRP) angles was designed to prevent fatigue crack initiation in the connecting angles of the stringer-floor beam connection. Different CFRP laminate layouts were numerically evaluated and a proper configuration was obtained that reduced both the mean stress and the alternating stress amplitude in the connecting angle to shift from finite fatigue-life region to infinite fatigue-life region in the constant fatigue-life diagram. To validate the effectiveness of the proposed CFRP strengthening method, its application on a second laboratory specimen fabricated with original stringers was evaluated experimentally and compared with numerical results. The research study conducted showed that the use of adhesively-bonded CFRP angles was an effective strengthening system in reducing the stress level in the fillet region of the puddle iron connecting angles (where fatigue cracks are prone to initiate) and consequently could increase fatigue life of the stringer-floor beam connection.

中文翻译：

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19世纪铆接铁路桥纵梁-地梁连接处CFRP疲劳强度的数值和实验评估

进行了一个19世纪西班牙水坑铁制铆钉铁路桥梁纵梁-底板梁连接的局部和全局有限元分析，以得出对应于火车荷载作用在桥上的弯矩的铆接连接角的最大主应变。 。由于熔池铁的各向异性特性，使用希尔各向异性可塑性势对连接角进行建模，并在局部有限元模型中进行了参数研究。测试了用从铁路桥梁上拆下的原始桁条制成的实验室标本，以校准数值模型，从而获得了最适合实验结果的屈服应力比。基于恒定疲劳寿命图和修正的Goodman疲劳破坏准则的方法，检测到连接角易于疲劳裂纹萌生，这是因为平均应力和角部圆角脚趾处的交替应力振幅的组合仍处于无限疲劳寿命区域之外。设计了一种基于粘合碳纤维增强聚合物（CFRP）角的创新加固系统，以防止在纵梁-地板梁连接的连接角度中出现疲劳裂纹。对不同的CFRP层压板布局进行了数值评估，并获得了一种适当的配置，该配置可以减小连接角中的平均应力和交变应力幅度，从而从恒定疲劳寿命图中的有限疲劳寿命区域过渡到无限疲劳寿命区域。为了验证所提出的CFRP加固方法的有效性，通过实验评估了其在第二个使用原始纵梁制造的实验室标本上的应用，并与数值结果进行了比较。进行的研究研究表明，使用粘结CFRP角钢是一种有效的增强系统，可以降低水坑铁连接角（容易产生疲劳裂纹）的圆角区域的应力水平，因此可以延长轮胎的疲劳寿命。纵梁与横梁的连接。