The safety of steel bridges around capital region under severe conditions

本研究综合了首都圈地区钢结构桥梁在恶劣条件下的疲劳和屈曲极限承载力、风荷载、地震荷载和严重交通活荷载的估算以及抗震设计等不同方面的研究。为确保首都圈地区钢桥的安全，进行了以下研究。(1)关于疲劳;钢桥疲劳开裂数据库的建立。气孔疲劳裂纹扩展的评估。公路桥梁疲劳裂纹扩展模拟。角焊接头疲劳裂纹检测的可行性研究。用tig电弧重熔法修复疲劳裂纹接头。(2)关于极限承载能力;加筋钢板极限强度的估算。钢柱受力性能的简化分析与优化。非均匀支承斜拉桥的分析。(3)严重交通活载.移动车辆重量的测量。公路桥梁交通活载极值评估的仿真研究。公路桥梁疲劳评估的应力折减系数。车辆多处存在对桥梁疲劳损伤的影响。(4)柔性地基上柔性结构的动力上举。圆形容器调谐液体阻尼器的实验研究。(5)设计方法;安全系数对桥梁设计的影响分析。粗差对确定安全系数的影响。从统计数据中确定分位值的一种方法。

In the present study we synthesize investigations for steel bridges around capital region under severe condition on different aspects such as ultimate load carrying capacity subjected to fatigue and buckling, estimation of wind load, earthquake load, and severe traffic live load, and anti-earthquake design. With a purpose to ensure the safety of steel bridges around capital region, the following studies are carried out.(1) On fatigue; Establishment of data base for fatigue cracking in steel bridges. The evaluation of fatigue crack growth from blowholes. Simulation of fatigue crack growth in highway bridges. Feasibility study on detection of fatigue crack in fillet welded joint. Retrofitting fatigue-cracked joints by tig arc remelting.(2) On ultimate load carrying capacity; Estimation of ultimate strength of stiffened steel plates. Simplified analysis and optimality on the steel column behavior. Analysis of cable-stayed bridges subjected to nonuniform support.(3) On severe traffic live load; Measurement of weigth of moving vehicles. Simulation for evaluating extremes of traffic live load on highway bridges. Stress reduction factor for fatigue assessment of highway bridges. Effect of multiple presence of vehicles on fatigue damage of bridges.(4) On dynamic problems; Dynamic uplifting of flexible structure on compliant ground. Experimental study on tuned liquid damper using circular containers.(5) On design method; Influence analysis of the factors of safety on the design of bridges. Effects of gross errors for determining the factors of safety. A Method to determine fractile values from statistical data.