Using Impact-Echo Method to Detect Void around the Steel Rebar in Structural Concrete after Severe Earthquake

• Main Authors: Hsiu-Chu Chiou, 邱秀珠
• Other Authors: Chia-Chi Cheng
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/92001664253191847752

碩士 === 朝陽科技大學 === 營建工程系碩士班 === 89 === Abstract Three major subjects were studied in the paper. (1) study the effects of different steel diameter and the cover thinkness to the steel amplitude in the transfer function of the impact-echo response. The affective range of the steel signals was also studied by applying impact-echo tests along the lines besides the bar-position. the steel amplitude is linearly proportional to the steel diameter-to-depth ratio. By linear regression the relation as equation, This equation can be used to predict the steel amplitude for any arrangement of steel bar in the situation without earthquake. (2) study the magnitude of the ground motion, the age of concrete during the earthquake, and diameter to depth ratio to the steel bond in newly cast concrete. (3) study the bond condition damaged by the resonant vibration of the steel bar. The bond conditions were tested by both non-destructive impact-echo tests and the destructive pullout tests. Most of the specimens were failed by pullout modes. The results show no apparent damage were created by the large difference of mass inertia between the steel bar and early-aged concrete for ground acceleration up to 0.773 g and vibrated at the age as early as 4 hours. For the second study, the voids and cracks were created by the resonant frequency. The relation between the average steel amplitude in the impact-echo response and the bond-loss was established for bars failed by pullout modes.