摘要
钢管混凝土(CFST)构件因其具有良好的抗压、抗弯、抗剪能力,近年来被广泛用于各类型工程结构之中。鉴于CFST施工过程中,钢管与内部混凝土之间可能出现离析、剥离等缺陷,会降低或破坏钢管与混凝土的协同作用,导致承载力降低等问题。在受到极端荷载下,严重时会导致较大安全隐患和失效可能。因此,开展CFST剥离损伤检测十分必要。该文试制了采用超声能量扩散进行构件损伤检测的测试平台;对一批预设界面剥离损伤的方形截面CFST柱进行了不同频率超声波、考虑不同剥离尺寸影响的实测研究,得到归一化扩散及耗散系数,并以此作为管壁与内部混凝土剥离的检测指标;基于最佳激发频率提出CFST界面损伤判定依据,并采用COMSOL软件进行数值模拟验证。结果表明:归一化扩散及耗散系数对剥离损伤尺寸较敏感,可作为探明损伤规律性的重要参数。提出的CFST界面损伤判定模型与仿真试验吻合良好,最小误差为3.03%,平均误差小于10%,表明损伤判定模型能准确、有效定量识别钢管与核心混凝土间的界面剥离损伤,可拓展应用于同类型构件的损伤诊断和预判。
In recent years,concrete-filled steel tubular(CFST)composite members have been widely used in various engineering structures because of their excellent axial compression,bending and shear resistance capacities.For the construction process of CFST,the debonding defects between the steel tube and concrete will destroy the synthesis confined effect between them,leading to the reduction of bearing capacity.In serious cases,the structure will experience a large safety danger and high collapse probability under severe external excitations.Therefore,it is necessary to research the debonding detection of CFST.This study built the testing facility and framework with the ultrasonic energy diffusion test method.A series of tests were carried out for CFST with different dimensions of artificial debonding defects using ultrasonic waves at different frequencies.The linear fitting of the normalized diffusion and dissipation coefficients are chosen as the evaluation indexes,and the influence of different frequencies and the different sizes of debonding defects on the signals of the square CFST columns with debonding defects was studied.At last,based on the optimal excitation frequency,a model for determining the debonding defects of CFST was proposed,and COMSOL was used for numerical simulation verification.The results show that the diffusivity and dissipation coefficients are sensitive and varying with the size of the debonding defects,which can be chosen as important parameters for a defect detection.Based on the test and numerical verification,the test criteria has a favorite error,the minimum error is 3.03%,and the average error is less than 10%.The proposed model can quantitatively identify the debonding defects between the steel tube and the core concrete.Further,the proposed test method can do similar detection for CFST structural members.
作者
李宁
张海月
高树灵
李忠献
LI Ning;ZHANG Hai-yue;GAO Shu-ling;LI Zhong-xian(School of Civil Engineering,Tianjin University,Tianjin 300350,China;Key Laboratory of Coast Civil Structure Safety,Ministry of Education(Tianjin University),Tianjin 300350,China;Key Laboratory of Earthquake Engineering Simulation and Seismic Resilience of China Earthquake Administration(Tianjin University),Tianjin 300350,China)
出处
《工程力学》
EI
CSCD
北大核心
2023年第1期111-120,共10页
Engineering Mechanics
基金
国家重点研发计划项目(2019YFE0112500,2018YFC1504306)
国家自然科学基金面上项目(52178496,51678407)
天津市重点研发计划科技支撑重点项目(20YFZCSN00900)。
