超音波法与敲击回音法检测钢筋混凝土梁柱接头

Detecting the reinforced concrete beam/column joints by ultrasonic wave and impact-echo methods

本文用超音波法及敲击回音法分别以斜向对打量测实体柱、不同厚度之块状试体、十字形试体及实体梁柱接头之压力波波速值,并与上述各试体之超音波直接对打量测的压力波波速值作比较,以评估斜向对打量测波速压力波之准确性,藉以探讨以斜向对打量测波速压力波值来检测梁柱接头混凝土质量之可行性.试验结果显示:超音波法于面宽40 cm之实体柱量测,当接收器偏距大于40 cm时,其波速值会明显下降;但敲击回音法以直径3 mm钢球作敲击源,接收器偏距超过70 cm波速值才会呈现下降趋势,以直径6mm钢球做量测则接收器偏距可达100cm,若以直径9mm钢球或铁锤做量测,接收器偏距达300 cm时,波速值仍未呈下降趋势.各试体之试验结果皆显示,超音波法之量测波速值基本上随接收器偏距增加而下降,但敲击回音法之波速值却不受偏距影响,其波速值与超音波直接对打值比较,误差皆在±3%以内.

This paper used an ultrasonic wave method and an impact-echo method to measure pressure wave velocities in full scale columns,block specimens with different thickness,cruciform specimens,and beam/column joints by obliquely placing transducers on the opposite faces.The results were then compared with those by direct measurement using an ultrasonic device to evaluate the accuracy of oblique measurement.The feasibility of quality evaluation for the concrete at the beam/column joint using the measured pressure wave velocities by oblique measurement was discussed.The test results showed that,the measured wave velocity went down sharply when the wave receiver deviated more than 40 cm for the measurement on a 40 cm width full scale column by the ultrasonic wave method.However,the measured wave velocity would begin to go down when the wave receiver deviated more than 70 cm using a 3 mm diameter steel ball as the impacting wave source by the impact-echo method.Using a 6 mm diameter steel ball,the deviation distance could reach up to 100 cm.Using a 9 mm diameter steel ball or a small hammer,the measured wave velocity would not go down even when the deviation distance was up to 300 cm.All test results on the specimens showed that,the wave velocity measured by the ultrasonic wave method basically went down when the deviation distance of the receiver increased,but the wave velocity measured by the impact-echo method was not affected.When compared with ultrasonic direct measurement,the wave velocity errors of the impact-echo method were well within ±3%.