Xiamen Tianyuan Bridge
Engineering Service
In-Service Steel Bridge Condition Assessment & Minimally Invasive Reinforcement
在役钢桥病害检测评估与微创加固
Integrated condition inspection, fatigue assessment and minimally invasive reinforcement services for in-service orthotropic steel bridges. Robotic U-rib internal welding is used to improve fatigue-prone U-rib-to-deck details while minimizing disruption to normal bridge operation.
面向在役正交异性钢桥提供病害检测、疲劳性能评估及微创加固一体化服务，通过机器人U肋内焊改善易疲劳开裂的U肋与桥面板连接部位，并尽量降低施工对桥梁正常运营的影响。
Supplied by Wuhan Lixin Technology Co., Ltd.
Overview
Service overview
Fatigue cracks in single-sided U-rib-to-deck welded joints can remain hidden during their early development and may be difficult to detect before propagating into the deck plate.
Lixin provides an integrated service covering defect inspection, structural and fatigue assessment, reinforcement planning, robotic minimally invasive internal welding, construction monitoring and post-reinforcement evaluation.
For strengthening, controlled access openings are created in existing U-ribs. After internal cleaning and rust removal, compact robotic equipment is introduced into the U-rib to add an internal reinforcement weld. The resulting double-sided load-transfer detail reduces stress concentration at the original weld root.
The process is designed for implementation without full traffic closure, reducing disruption associated with conventional bridge rehabilitation.
采用U肋外侧单面焊结构的在役正交异性钢桥，其焊根疲劳裂纹在早期具有较强隐蔽性，在向桥面板内部扩展过程中通常较难发现。
锂鑫科技提供由病害检测、结构及疲劳性能评估、加固方案设计、机器人微创内焊施工、施工监测和加固效果评估组成的一体化服务。
实施加固时，在既有U肋适当位置开设工艺孔，经内部清理和除锈后，将小型机器人送入U肋内部增设加固焊缝，使内焊缝与原外焊缝形成双面受力结构，降低原焊根区域应力集中。
施工工艺可在不完全封闭交通的条件下实施，降低传统桥梁大修对交通运行的影响。
Scope
Service scope
Key components that may be provided for relevant engineering scenarios.
- Bridge defect inspection
- U-rib weld condition inspection
- Structural condition assessment
- Fatigue-life evaluation
- Reinforcement strategy and construction planning
- U-rib access-opening construction
- Internal cleaning and rust removal
- Laser or abrasive rust removal
- Robotic overhead internal welding
- Welding-process and structural monitoring
- Weld inspection and localized repair
- Access-opening restoration and recoating
- Post-reinforcement performance evaluation
- 桥梁病害检测
- U肋焊缝状态检查
- 结构状态评估
- 疲劳寿命评估
- 加固方案及施工组织设计
- U肋工艺孔施工
- 内部清理及除锈
- 激光或喷砂除锈
- 机器人仰位内焊
- 焊接过程及结构监测
- 焊缝检测及局部返修
- 工艺孔恢复及防腐涂装
- 加固后性能评估
Scenarios
Applicable project scenarios
Typical project conditions where this offering may be relevant.
- In-service orthotropic steel bridges with single-sided U-rib welds
- Bridges with suspected or confirmed fatigue cracking
- Preventive strengthening before deck-plate penetration
- Highway steel box-girder bridge rehabilitation
- Railway steel bridge rehabilitation
- Bridges requiring fatigue-life assessment
- Projects requiring minimized traffic interruption
- Long-term bridge maintenance and life-extension programs
- 采用U肋单面焊结构的在役正交异性钢桥
- 已发现或存在疲劳开裂风险的钢桥
- 裂纹贯穿桥面板前的预防性加固
- 公路钢箱梁桥维修加固
- 铁路钢桥维修加固
- 需要开展剩余疲劳寿命评估的桥梁
- 对交通中断控制要求较高的工程
- 桥梁长期养护及延寿项目
Offering Details
Technical Details & Applications
Condition assessment can combine weld inspection, structural stress monitoring, fatigue analysis and project-specific numerical evaluation to identify fatigue-prone U-rib-to-deck details and establish reinforcement priorities.
For completed reinforcement projects, strain and stress monitoring can be used to compare structural behaviour before and after strengthening and to evaluate changes in remaining fatigue life.
Minimally Invasive Reinforcement Process
- Condition inspection and reinforcement planning.
- U-rib access-opening positioning.
- U-rib opening.
- Internal cleaning and rust removal.
- Welding-area preparation.
- Robotic overhead internal welding.
- Weld inspection.
- Local grinding and supplementary welding.
- Access-opening restoration.
- Coating restoration.
- Post-reinforcement evaluation.
Fatigue Testing
In fatigue testing of a single-sided welded specimen, a weld-root crack developed after 287,000 loading cycles. Without removing the existing crack, an internal reinforcement weld was added. A further 585,000 loading cycles were then applied before a new crack developed at the external weld toe, while the original weld-root crack did not continue to propagate.
Full-Scale Safety Verification
A 6 m orthotropic steel deck specimen was tested under a longitudinal prestress of 70 MPa to evaluate structural response during U-rib access opening and internal welding.
The measured deflection-to-span ratio above the opening was 1/751. The maximum measured stress near the opening during cutting was 180.965 MPa, below the yield limit of the base steel. Deck-plate temperature remained below 180°C during overhead welding.
Selected Project — Junshan Yangtze River Bridge
The reinforcement trial involved 56 U-ribs in Segment No. 24. Structural strain monitoring was conducted before, during and after reinforcement.
At one monitored detail on the ERE-surfaced side, fatigue-life evaluation showed an increase in estimated remaining fatigue life from 3.9 years before reinforcement to 40.8 years after internal welding. On the UHPC side, the corresponding estimate increased from 28.5 years to 69.0 years.
Selected Project — Xiamen Haicang Bridge
The project included three U-rib reinforcement zones with a total internal weld length of approximately 2,753 m.
Stress monitoring showed no yielding at monitored points during opening and internal welding. After completion, stresses generally returned close to their initial levels.
The maximum measured temperature during internal welding was 173°C and decreased from peak temperature to near ambient conditions within less than 0.5 hour.
Other Applications
- Xiamen Tianyuan Bridge
- Watang–Rizhao Railway Bridge
Standards
The internal-welding reinforcement technology has been incorporated into technical requirements related to highway bridge strengthening and steel bridge maintenance, including:
- *Guidelines for Improving Highway Safety and Resilience*
- *Specifications for Strengthening Design of Highway Bridges* (JTG/T 5431-2025)
- *Technical Specifications for Maintenance of Highway Steel Bridges* (JTG/T 5123-2025)
技术说明与应用案例
检测与评估
在役钢桥状态评估可结合焊缝检测、结构应力监测、疲劳分析及项目专项计算，识别U肋与桥面板连接部位的疲劳风险，并为加固范围和实施顺序提供依据。
加固工程可通过施工前后的应变及应力监测，对结构受力状态变化和剩余疲劳寿命改善情况进行评价。
微创加固流程
- 病害检测与加固方案制定。
- U肋工艺孔定位。
- U肋开孔。
- 内部清理除锈。
- 待焊区域处理。
- 机器人仰位内焊。
- 内焊缝检测。
- 局部修磨及补焊。
- 工艺孔恢复。
- 防腐涂装恢复。
- 加固效果评估。
疲劳试验
相关疲劳试验中，单面焊试件加载28.7万次后在焊根处出现疲劳裂纹。在未处理原有裂纹的情况下增设内焊加固焊缝，继续加载58.5万次后外侧焊趾出现新的疲劳裂纹，而原有焊根裂纹未继续扩展。
足尺安全性验证
采用6 m长正交异性板足尺构件，在70 MPa纵向预应力条件下，对U肋开孔及内焊过程中的结构响应进行验证。
工艺孔上方实测挠跨比为1/751；开孔过程中切口附近实测最大应力为180.965 MPa，低于母材屈服极限；U肋仰位内焊过程中桥面顶板温度低于180℃。
代表项目 — 军山长江大桥
军山长江大桥内焊加固试验选择24号节段，共涉及56根U肋，并在加固前、施工期间及加固后开展结构应变监测。
其中ERE铺装侧一处监测细节的剩余疲劳寿命评估值由加固前3.9年提高至40.8年；UHPC铺装侧相应评估值由28.5年提高至69.0年。
代表项目 — 厦门海沧大桥
厦门海沧大桥设置3个U肋内焊加固区域，内焊焊缝总长度约2753 m。
施工期间开展结构应力监测，开孔及内焊全过程监测点均未出现屈服状态，施工完成后测点应力基本恢复至初始水平。
内焊过程中实测最高温度为173℃，由最高温度下降至接近环境温度的时间小于0.5 h。
其他应用
- 厦门天圆大桥
- 瓦日铁路桥
规范应用
U肋内焊加固技术已纳入公路桥梁安全韧性提升、桥梁加固及钢结构桥梁养护相关技术文件，包括：
- 《公路安全韧性提升技术指南》
- 《公路桥梁加固设计规范》（JTG/T 5431-2025）
- 《公路钢结构桥梁养护技术规范》（JTG/T 5123-2025）
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