钢管混凝土脱粘缺陷无损检测新方法及其在赛格大厦中的应用

Non-destructive testing of interfacial debonding defects in concrete-filled steel tubes and its application to the SEG Building

钢管混凝土结构具有良好的力学与抗震性能,被广泛应用于超高层建筑与大跨度桥梁的建设中。然而随着服役时长增加,钢管与核心混凝土之间形成的脱粘缺陷会对建筑的服役性能产生不利影响。该研究提出了超声相控阵法与叩诊法对钢管混凝土脱粘缺陷进行半定量检测,并开发了相应的检测装置。对于超声相控阵法,采用全聚焦成像对超声全矩阵捕获数据进行成像,并提取钢管-混凝土界面反射的幅值,通过反射系数曲线评估钢管混凝土脱粘缺陷的严重程度;对于叩诊法,基于敲击而产生的两种不同结构振动模态,采用小波变换分析回声数据中的能量分布,并采用振动模态能量比检测脱粘缺陷是否存在。这两种方法成功应用于深圳赛格大厦异常晃动事件后的结构安全评估中,对赛格大厦钢管混凝土外框柱的脱粘缺陷进行了全面检测,并计算了综合脱粘率。检测结果表明,赛格大厦钢管混凝土外框柱整体脱粘率约为50.0%,脱粘情况严重。通过对比分析两种方法的检测结果可知:超声相控阵法与叩诊法均可对钢管混凝土中的脱粘缺陷进行半定量检测;两者相比,叩诊法具有更高的检测效率,而超声相控阵法具有更高的检测分辨率与检测精度。

Concrete-filled steel tube structures have been widely applied to the construction of high-rise buildings and large-span bridges due to their excellent mechanical and seismic performance.However,with the increase of service time,the debonding defects between steel tube and core concrete will adversely affect the building safety.In the paper,the ultrasonic phased array method and the acoustic impact method were proposed to detect the debonding defects in concrete-filled steel tubes,and two special-designed inspection instruments were developed.In the ultrasonic phased array method,the total focusing method was applied for image reconstruction,and the reflection coefficient at the steel-concrete interface was extracted for debonding evaluation.In the acoustic impact method,the energy distribution of the flexural vibration mode and thickness mode in the echo data was analyzed by the wavelet transform.The two proposed methods were successfully applied to the health evaluation of the Shenzhen SEG Building after the abnormal shaking incident.The debonding defects of the concrete-filled steel tube columns of the SEG Building were detected and the comprehensive debonding ratio was calculated.The results of the field tests show that the comprehensive debonding rate of the SEG Building is about 50.0%,showing a serious debonding degree.The comparative analysis on the detection results by these two methods shows that both the ultrasonic phased array method and the impact acoustics method can be used for semi-quantitative detection of debonding defects in concrete-filled steel tube columns.The impact acoustics method has a higher detection efficiency,while the ultrasonic phased array method has a higher detection resolution and detection accuracy.