Application of Acoustic Emission Method and Impact Echo Method to Structural Rehabilitation

Abstract

The paper is concerned with the technical aspects of the appraisal and retrofitting process of fire damaged reinforced concrete structures. The assessment of fire damaged structures is carried out along lines similar to those of the appraisal of existing structures. In practice, constructions are most often assessed by destructive tests in-situ and on core bore specimens. In addition to destructive tests, damaged structures are also assessed by non-destructive ones. The present paper shows the use of non-destructive methods of measurement using the acoustic-emission and impact-echo methods. Acoustic emission provides valuable data on the structural integrity of a material. This method has a significant potential to be used for in-situ monitoring and evaluation of the current state of structures. An impact-echo method is based on impact-generated stress waves that propagate through concrete and are reflected by internal flaws and external surfaces. Impact-echo can be used to determine the location and extent of flaws such as crack delamination, voids, honeycombing and deboning in plain, reinforced, and post-tensioned concrete structures. The paper presents a possible rehabilitation plan based on the potential results obtained by these non-destructive methods.

Interpretation of Impact-Echo Testing Data from a Fire-Damaged Reinforced Concrete Slab Using a Discrete Layered Concrete Damage Model

“…Figure 10 shows typical time signals measured by IE testing on the surface of reinforced concrete slab specimens before and after the 3-h standard fire testing. Consistent with the observations made by previous researchers [15,16,19,22,25], the time signals measured on the concrete surface exposed to fire (Figure 10b) were dominated by waves with longer wavelengths than those measured on the sound concrete (Figure 10a). Furthermore, some differences were also observed in the time signal measured on the surface opposite the fire exposure side, compared to that measured on the sound concrete.…”

“…Impact-echo testing was also used successfully to evaluate the post-fire condition of the concrete structures by measuring the resonance frequencies of circular, thin-disk shaped concrete samples obtained from the core samples [ 20 ]. In addition, some researchers performed condition assessments of fire-damaged concrete samples from reinforced concrete elements using the same conventional IE testing setup as that shown in Figure 1 a [ 21 , 22 , 23 , 24 , 25 ]. It has been demonstrated in the studies that the spectral responses of fire-damaged concrete manifested as shifts of the peak frequencies to frequencies lower than those measured on sound concrete.…”

Investigations of AE Signals Emitted From Dropped Indenter on Steel Pipes’ Surface

“…AE technique has been demonstrated as an effective method for detecting growing flaws and fatigue in structures by monitoring their AE signals [1][2][3][4][5][6][7][8]. AE monitoring technique utilizes the energy released from the structural flaws for its operation and does not require extrinsic energy sources [4] and hence, it is considered as a passive monitoring technique [9,10].…”