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摘要: 既有桥梁总会存在着不同程度的结构累积损伤, 这不但影响桥梁的正常运营, 而且会危及结构的使用安全。常规桥梁承载能力试验与新近发展起来的健康监测技术都很难独自对会导致桥梁脆性破坏的损伤累积进行有效检测。因此, 提出基于损伤机理的结构损伤安全评定方法的设想, 采用局部无损探测和整体、长期健康监测相结合的损伤判断、定位技术, 在正确诊断桥梁损伤基础上, 综合应用基于损伤力学、疲劳断裂、可靠度理论等多种方法和理论进行损伤安全评定。根据实时安全评定结果, 按照不同桥梁结构的损伤特点, 即时给出桥梁维护管理对策, 以便桥梁管理部门采取相应措施保障桥梁安全使用。以上海市外白渡桥为例简要介绍该方法的实际应用成果, 并对今后桥梁损伤安全评定研究提出了一些具体建议Abstract: Damage cumulation in existing bridges affects not only on normal service of bridges, but also on service safety of structures. Both load carrying capacity testing and health monitoring technology could not alone identify damage cumulation, which often leads to brittle fracture of bridges. A new approach of damage safety assessment based on damage mechanism is proposed, which combines local nondestructive inspection with global health monitoring technology to identify and localize damage. On the basis of accurate damage identification, damage mechanics, fatigue and fracture mechanics, reliability theory are applied for damage safety assessment. According to the online safety assessment results and the damage characteristics of different types of bridges, maintenance management strategy is timely suggested in order to help management department to ensure the service safety of bridges. The practice application of the new method is introduced through the example of Waibaidu Bridge in Shanghai. Finally, some suggestions about damage safety assessment of bridges in the future are given.
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Key words:
- bridge /
- damage /
- safety assessment /
- maintenance management strategy
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表 1 桥梁失效
Table 1. Tab.1 Bridge failure cases
桥名 桥型 事故时间 事故简况 失效原因 美国Kings桥 钢桥 1962 倒塌 疲劳脆断 美国Point Pleasant桥 吊桥 1967 倒塌 疲劳脆断 英国Yuys-y-Gwas桥 混凝土梁桥 1985 倒塌 预应力筋锈蚀 美国乔治·华盛顿桥 吊桥 1992 纽约侧锚锭内主缆近70%丝股腐蚀严重 主缆腐蚀 韩国圣水大桥 斜拉桥 1994 中孔崩塌 疲劳断裂 广州海印大桥 斜拉桥 1995 一根斜拉索突然断落 斜拉索锈蚀 帕劳岛桥 预应力混凝土梁桥 1996 倒塌 力筋腐蚀 重庆綦江彩虹桥 钢管混凝土拱桥 1999 倒塌 施工质量低下 宜宾小南门桥 劲性骨架箱肋拱 2001 桥面局部倒塌 吊杆断裂 表 2 桥梁无损检测技术
Table 2. Tab.2 Nondestructive (NDE) inspection technology
检测项目 检测技术 桥面板损伤检测 双频带红外自动温度成像系统和探地雷达成像技术 变形测量 水准仪、经纬仪、全站仪、相干激光雷达和GPS 超载检测 TRIP (transformation induced plasticity) 钢传感器 钢构件疲劳和裂缝检测 超声时程衍射、声发射、高分辨率热成像系统、无绳应变测量方法、无源疲劳荷载测量装置、涡流及交流场测量焊接裂缝、利用电磁声学传感器测量疲劳荷载 锈蚀检测 埋置式腐蚀微传感器、磁通泄漏检测系统、SoundPrint 1994声音监测系统 桥梁下部结构损伤检测 强迫振动法 索力测定 微型振动索力仪、相干激光雷达系统 混凝土强度无损检测 表面压痕法、回弹法、超声脉冲法、回弹-超声综合法、振动法、射线法 混凝土损伤检测 超声脉冲法、射线法、微波吸收和雷达扫描法、声发射法、透光法、介电法和电磁法等 表 3 剩余寿命及探测间隔
Table 3. Tab.3 Remaining fatigue life and inspection interval
杆号 超声波探测 观测 剩余寿命/a 探测间隔/a 剩余寿命/a 探测间隔/a A1E1 7.95 3.98 1.79 1.19 A1E2 36.34 18.17 11.11 7.41 A2E2 32.41 16.21 11.18 7.45 A2E3 37.36 18.68 11.51 7.67 A3E3 16.11 8.06 5.79 3.86 A3E4 27.93 13.97 7.73 5.15 A4E3 23.53 11.77 7.04 4.69 A4E4 22.45 11.23 5.76 3.84 A4E5 18.05 9.02 4.20 2.80 A5E4 50.72 25.36 8.82 5.88 A5E5 19.15 9.57 6.03 4.02 A5E6 20.87 10.44 5.62 3.75 A6E5 21.53 10.77 5.71 3.81 E5E6 534.14 267.07 219.45 146.30 -
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