（太原理工大学建筑与土木工程学院， 太原 030024）

［摘要］为研究往复荷载作用下网架平板支座超低周疲劳破坏，设计了长圆孔平板支座试件。在进行了平板支座大位移往复加载的超低周疲劳试验后，对锚栓破坏过程、变形特征、宏观断面特征展开研究。试验结果表明：平板支座在往复加载过程中，锚栓受到拉-弯双重作用产生不可恢复的塑性变形并逐渐积累成为试件的“薄弱”区域；随着根部裂纹产生并在加载过程中不断扩展，在锚栓开裂处产生应力集中最终发生疲劳断裂；平板支座锚栓断后的伸长率与缩颈率能直观反映其变形范围与塑性损伤累积程度；锚栓断口表面沿加载方向存在两个裂纹源，断面可见半月形贝纹线，断面中间区域比较粗糙，锚栓断口均呈现明显的疲劳源区、扩展区和瞬断区，具有疲劳断口的宏观基本特征，属于典型的疲劳破坏。

［关键词］网架结构；超低周疲劳试验；平板支座；锚栓；破坏特征

中图分类号：TU391文献标识码：A文章编号：1002-848X(2021)04-0119-05

Experimental study on ultra-low cycle fatigue failure of anchor bolt for plate bearing of grid under reciprocating load

ZHANG Ziqiang, LI Haiwang, SONG Xiayun, WANG Xingyu

(College of Architecture and Civil Engineering, Taiyuan University of Technology, Taiyuan 030024, China)

Abstract:In order to study the ultra-low cycle fatigue failure of plate bearing of grid under reciprocating loading, long circular hole plate bearing specimens were designed. After the ultra-low cycle fatigue test of plate bearing under large displacement reciprocating loading was carried out, the failure process, deformation characteristics and macroscopic section characteristics of anchor bolt were studied. The test results show that in the reciprocating loading process of plate bearing, the anchor bolt is subjected to the dual action of  tension and bending to produce irreparable plastic deformation and gradually accumulate into a “weak” region of the specimen. With the initiation of root crack and the continuous propagation in the loading process, the fatigue fracture occurs when the stress concentration occurs at the crack of anchor bolt. The extension rate and necking rate of plate bearing anchor bolt after breaking can directly reflect the deformation range and the accumulation degree of plastic damage. There are two crack sources along the loading direction on the fracture surface of anchor bolt. The middle area of the fracture surface is rough, and the half-moon-shaped shell lines can be seen in the fracture surface. The fracture surface of anchor bolt shows obvious fatigue source zone, expansion zone and transient fracture zone. It has the macroscopic basic characteristics of fatigue fracture and belongs to typical fatigue failure.

Keywords:space truss structure;ultra-low cycle fatigue test;plate bearing;anchor bolt;failure characteristics

*国家自然科学基金(51578358)。

作者简介：张子强，硕士，助理工程师，Email：735325723@qq.com；通信作者：李海旺，博士，教授，博士生导师，Email：lhwtut@126.com。