基于分形理论的玻璃纤维增强树脂复合材料-混凝土组合梁损伤特性  

Damage characteristics of glass fiber reinforced polymer-concrete composite beams based on fractal theory

作　　者：宋广信 杨丽辉[1] 胡春阳 苏晗 张浩天 SONG Guangxin;YANG Lihui;HU Chunyang;SU Han;ZHANG Haotian(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]北京交通大学土木与建筑工程学院,北京100044

出　　处：《复合材料学报》2021年第6期1870-1881,共12页Acta Materiae Compositae Sinica

基　　金：基本科研业务费(2017JBM088)。

摘　　要：工程实际中,玻璃纤维增强树脂复合材料(GFRP)-混凝土组合梁往往出现较大的损伤而破坏,有必要对其破坏过程进行研究。为了研究此类构件的损伤特性,通过声发射仪器对1片GFRP工字梁和6片不同螺栓连接的GFRP-混凝土组合梁的四点弯曲试验加载的全过程进行了监测。并基于分形理论对试验梁加载过程的声发射能量信号进行了相空间重构,计算了试验梁各加载阶段的声发射能量信号分形维数值。研究表明,试验梁的声发射能量时间序列具有分形特征,且关联维数可很好地描述GFRP-混凝土组合梁损伤破坏的整个阶段;归纳各试验梁的声发射能量时间序列分维曲线的演化模式:纯弯段区域的损伤演化模式为"早期峰"至"低幅波动";剪跨区的损伤演化模式为"低幅波动"至"持续高幅波动";将试验梁加载过程的试验现象与分维值的演化相对照,则可将分维值的"持续高幅波动"作为试验梁失稳的前兆。根据关联维数,提出"损伤预警"的可能。其相应的分维值出现"持续高幅波动",则损伤"预警点"出现,结构的承载力已达到其极限的70%左右,需要加强监测。In engineering practice, glass fiber reinforced polymer(GFRP)-concrete composite beams usually fail as a result of larger damages, and hence it is of great significance to study the damage process. In order to study the damage characteristics of such components, four-point bending loading tests were carried out for a GFRP I-beam and six GFRP-concrete composite beams connected by different bolts, and the whole process was monitored by an acoustic emission(AE) device. On the basis of the phase-space reconstruction of the AE energy signals, the fractal dimension of AE energy signals were calculated in each loading stage. The results show that the time serials of AE energy is of fractal characteristics. The dimension can well describe the complete damage stages;The evolution of the fractal dimension curve of AE energy time series is summarized: the mode in pure bending section is "early peak" to "low amplitude fluctuation";the mode in shear span area is "low amplitude fluctuation" to "continuous high amplitude fluctuation";by comparing the phenomenon of loading process of test beam with the evolution of fractal dimension value, the "sustained high amplitude fluctuation" of the fractal dimension can be regarded as the precursor of the instability of the test beam. According to the dimension, the possibility of "early warning" was proposed. Early warning points can be identified when there is enduring high-amplitude fluctuation for corresponding fractal dimension. The bearing capacity of the structure has reached about 70% of the allowableextreme, suggesting necessary intensified monitor.

关 键 词：桥梁工程 损伤预警 GFRP-混凝土组合梁 声发射(AE) 分形理论 

分 类 号：TB332[一般工业技术—材料科学与工程] TU37[建筑科学—结构工程]