Influence of imperfections on ultimate strength of girders

缺陷对梁极限强度的影响

• 批准号: 13650521
• 负责人: OKURA Ichiro
• 金额: $ 2.18万
• 依托单位: OSAKA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650521/
• 关键词: girder; robot welding; stiffener-end-gap; fatigue crack; ultimate strength; elasto-plastic large-deflection analysis; bending; shear; 補剛材端ギャップ; 弾塑性有限変位解析; 垂直補剛材端ギャップ; 終局強度; 静的載荷試験; 有限要素法

In this study, regarding stiffener-end-gaps and fatigue cracks as imperfections against the state that these do not exist, the following researches are completed in order to clarify how much these influence the ultimate strength of girders1. Effects of stiffener-end-gaps on ultimate strength of girdersPlacing a large gap at horizontal-stiffener-ends and vertical-stiffener-ends is desirable to improve the movability of welding robots., The relation between the decrease of the ultimate strength of girders and the gap size at the vertical-stiffener-ends are investigated by the statically loading tests and the elasto-plastic large-deflection analysis with FEM for shear loading and combined loading of bending and shear. From this, the mechanism that the rigidity and gap size of vertical stiffeners as well as the shapes of the initial deflection of webs decrease the ultimate strength of girders is given clear2. Influence of cracks on the ultimate strength of girders under bendingThere are many instances of fatigue cracks occurring in steel bridges. Now it is not clear how much the fatigue cracks decrease the ultimate strength of girders. The effects of cracks on the deflection and the ultimate strength of girders under bending are investigated by the static loading tests of four plate girders with different cracks induced. The web cracks on the tension side of bending decrease a little the ultimate strength, but the drop of the load after the maximum load is smaller than that of the girders without such cracks. The cracks between a web and a top flange suddenly drop the load under the yield moment

在这项研究中，考虑加劲肋端部的差距和疲劳裂纹的缺陷对状态，这些都不存在，完成了以下研究，以澄清这些影响梁的极限强度有多大1。加劲肋端部间隙对梁极限承载力的影响为了提高焊接机器人的可移动性，在水平加劲肋端部和垂直加劲肋端部设置较大的间隙是可取的。通过静载试验和剪切加载及弯剪联合加载下的弹塑性大挠度有限元分析，研究了竖向加劲肋端部差距大小与极限承载力降低的关系。由此，阐明了竖向加劲肋刚度、加劲肋间隙大小以及腹板初始挠度形状降低主梁极限承载力的机理。裂缝对受弯构件极限承载力的影响钢桥中出现疲劳裂缝的情况很多。目前尚不清楚疲劳裂纹对主梁极限强度的影响程度。通过4根不同形式的板梁静载试验，研究了裂缝对板梁挠度和极限承载力的影响。受拉侧腹板裂缝对极限承载力的影响较小，但最大荷载后的荷载下降幅度小于无裂缝梁。腹板与上翼缘之间的裂纹在屈服弯矩作用下使荷载突然下降

项目成果

I.Okura, Y.Ohta, Y.Fujimori: "Effects of vertical-stiffener-end-gaps on ultimate strength of girders under shear"International Journal of Steel Structures. Vol.3, No.1. (2003)

I.Okura、Y.Ohta、Y.Fujimori：“垂直加强筋端间隙对剪力梁极限强度的影响”国际钢结构杂志。

Y.Ohta, Y.Fujimori, I.Okura: "Influence of web initial deflection shapes on ultimate strength of girders under shear"JSCE, Kansai Branch, Annual Conference in 2002. I-2. (2002)

Y.Ohta、Y.Fujimori、I.Okura：“腹板初始挠度形状对剪力梁极限强度的影响”JSCE，关西分会，2002 年年会。I-2。

大倉一郎: "Effects of vertical-stiffener-end-gaps on ultimate strength of girders under shear"Stability and Ductility of Steel Structures, Budapest, Hungary. 473-480 (2002)

Ichiro Okura：“垂直加强筋端间隙对剪切梁极限强度的影响”钢结构的稳定性和延展性，匈牙利布达佩斯 473-480 (2002)。

大倉一郎, 大田欣史, 瓦林誠: "Effects of vertical-stiffener-end-gaps on ultimate strength of girders under shear"Proceedings of Sixth Pacific Structural Steel Conference, Beijing, China. 272-277 (2001)

Ichiro Okura、Yoshifumi Ota、Makoto Kawarashi：“垂直加强筋端部间隙对剪切梁极限强度的影响”第六届太平洋结构钢会议论文集，中国北京 272-277 (2001)。

Okura, Y.Ohta, M.Kawarabayashi: "Effects of vertical-stiffener-endgaps on ultimate strength of girders under shear"Proceeding of Sixth Pacific Structural Steel Conference, Beijing, China. 272-277 (2001)

Okura、Y.Ohta、M.Kawarabayashi：“垂直加强筋端间隙对剪力梁极限强度的影响”第六届太平洋结构钢会议论文集，中国北京。