带低屈服点钢材“延性保险丝”的钢框架盖板连接节点设计方法研究

采用屈服点低、高延性、高耗能能力的低屈服点钢材制作钢框架节点的连接组件，实现耗散地震能量与震后可更换功能叠加，为震后可恢复功能结构提供一种优质解决方案。为提出带低屈服点钢材“延性保险丝”的钢框架盖板连接节点的设计方法，首先采用通用有限元软件ABAQUS建立非线性计算模型，结合已有钢框架螺栓连接节点拟静力试验，验证数值模型的准确性和适用性。在此基础上，探讨不同影响因子对带低屈服点钢材“延性保险丝”的钢框架盖板连接节点工作性能的影响，获得各个影响因子与盖板“结构保险丝”作用的定量关系，最终提出了带低屈服点钢材“延性保险丝”的钢框架盖板连接节点的设计方法和设计流程，并采用实际工程设计算例进行验证。研究结果表明:拼接缝宽度、腹板盖板厚度与梁宽对节点实际承载力系数和盖板“结构保险丝”作用的影响较小；而拼接位置、梁高和翼缘盖板厚度是影响节点实际承载力系数的关键因子，设计不合理时会令“结构保险丝”作用提早失效；基于计算结果拟合得到节点设计承载力系数临界值与拼接位置和梁高的定量表达式，当设计承载力系数小于临界值时，低屈服点钢材盖板“结构保险丝”作用充分发挥；当设计承载力系数大于临界值时，随着设计承载力系数增大，低屈服点钢材盖板“结构保险丝”作用逐渐减弱。

DESIGN OF STEEL FRAME COVER PLATE CONNECTED JOINTS WITH LOW YIELD POINT STEEL “DUCTILE FUSES”

Low yield point steel with low yield strength,high ductility and high energy dissipation capacity is used for steel frame joints.It dissipates seismic energy,is replaceable after earthquakes and provides a high-quality solution for structures with resilience requirement.To propose a design for a steel frame connection with low yield point steel“ductile fuses”,a nonlinear numerical model was established by using ABAQUS.The model was verified by typical static tests of steel frame joints with bolted connections.The influence of different impact factors on the performance of this kind of joints was explored,and how these impact factors influenced the“structural fuse”was investigated.Subsequently,the design method was proposed and verified by using an example of practical engineering design.The results indicated that the width of the joint gap,the thickness of the web cover plate and the beam width had little influence on the actual bearing capacity coefficient of the joint andthe function of“structural”fuse effect.The position of splicing,the height of the beam and the thickness of theflange cover plate were the key factors of the actual bearing capacity coefficient of the joints.The“structuralfuse”will be prematurely ineffective if the design is nonviable.The relationship between the critical value of thedesign bearing capacity coefficient and the position of the joint and the height of the beam was established by datafitting.When the design bearing capacity coefficient is less than the critical value,the“structural fuse”worksnormally.When the design bearing capacity coefficient is larger than the critical value,the effect of‘structuralfuse’gradually decreases.