Equivalent bending stiffness of simply supported preflex beam bridge with variable cross-section

In order to understand mechanical characters and find out a calculating method for preflex beams used in particular bridge engineering projects, two types of simply supported preflex beams with variable cross-section, preflex beam with alterative web depth and preflex beam with alterative steel flange thickness, are discussed on how to achieve the equivalent moment of inertia and Young’s modulus. Additionally, methods of calculating the equivalent bending stiffness and post-cracking deflection are proposed. Results of the experiments on 6 beams agree well with the theoretical analysis, which proves the correctness of the proposed formulas.     

疲劳荷载作用下栓钉连接件的抗剪承载力退化规律

为了解钢-混凝土组合结构中栓钉连接件在疲劳荷载后的力学特性,针对栓钉推出试件进行静载破坏试验、完全疲劳试验以及非完全疲劳破坏试验.在此基础上归纳了已有栓钉连接件的非完全疲劳破坏的相关试验数据,将疲劳循环次数和剩余抗剪承载力这两个参数作归一化处理,使得所有试验数据具备可比性;同时基于剩余强度理论,推导出适用于栓钉连接件的剩余承载力计算模型,并通过试验数据拟合确定其参数;最后通过若干文献的试验数据进行验证分析.结果表明:在疲劳荷载作用下,栓钉连接件的剩余承载能力呈现先慢后快的非线性退化趋势.所提出的栓钉连接件承载力幂指数退化模型可以较好地描述栓钉连接件的剩余承载力随疲劳循环次数的变化规律.