摘要
为正确估计桥梁结构船撞下的需求,以中国通航水域广泛采用的高桩承台桥梁为对象,从荷载模式的角度开展了驳船等效侧向荷载研究。在构建船撞等效侧向力作用模式过程中,考虑了高桩承台基础的动力特点,将其简化成两自由度体系。基于两自由度模型的振动模态、驳船冲击谱及模态组合方法,推导出了确定驳船撞下桥梁等效荷载的新方法,并在算例中运用提出的方法与现有规范静力法进行了比较。结果表明:基于模态的等效荷载作用模式与规范静力法单点集中力形式存在显著差异;规范静力法精度低,仅简单放大荷载大小,但不改变作用模式时误差仍然较大,说明荷载作用模式在确定桥梁船撞需求与能力时至关重要;采用所提出的荷载模式计算时,结构响应与动力结果吻合较好,且其计算精度对质量比和墩身-桩基刚度比不敏感。
To accurately estimate the collision-induced demand of bridge structures,the equivalent lateral barge impact load was investigated from the view of the load pattern for the elevated pilecap bridge that has been extensively used in Chinese navigable waters.By considering the dynamic characteristics of the elevated pile-cap foundation,it was simplified into two degree-offreedom（2-DOF）system in the development of the equivalent lateral barge impact load pattern.Based on the vibration modes of the 2-DOF model,the barge shock spectrum and the modal combination rule,an innovative method was derived to determine equivalent loads on the bridge subjected to barge collisions.The developed method was applied to the practical example and compared with the code-prescribed static method.The results show that there are significant differences between the mode-based equivalent load pattern and the concentrated force of single point commonly recommended by the design specification;the accuracy of the code-prescribed method is very low and its error is still large if the magnitude of the barge-impact load is simply increased but the load pattern is not adjusted,indicating that the load pattern plays a crucial rolein determining the demand and capacity of bridge structures under barge impacts;the structural response results obtained from the proposed method are in good agreement with the dynamic results,and its accuracy is not sensitive to the mass ratio and the pier to pile-group stiffness ratio.
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2016年第7期72-80,共9页
China Journal of Highway and Transport
基金
国家自然科学基金项目(51308202
51408208)
湖南省自然科学基金项目(14JJ3056)
教育部高等学校博士学科点专项科研基金项目(20130161120026)
中央高校基本科研业务费专项资金项目(531107040698)
关键词
桥梁工程
高桩承台基础
模态分析法
船桥碰撞
等效侧向力模式
bridge engineering
elevated pile-cap foundation
modal analysis method
barge bridge collision
equivalent lateral load pattern
