Screening for internal defects of timber members based on impact evaluation method

摘要

This paper proposes a screening method and quantitative criteria for screening the internal defects of ancient timber members. Based on the impact evaluation (IE) method, two parameters, i.e. time of impact (TI) and proportion of integral area (PIA), were used to assess the internal defects. Impact tests were also conducted to study the effects of different influencing factors on the parameters (TI and PIA). The results demonstrated the satisfactory screening ability of PIA when the optimal proportion for the boundary value (f(b)) in the frequency domain was set as 50%. TI had a strong correlation with both the length of internal defects (I-d) and the surface hardness (R-2 = 0.74 and 0.93); however, PIA only had a significant correlation with I-d (R-2 = 0.84). The validation test results revealed that the proposed method and quantitative criteria could be used to detect the internal defects of ancient timber when the distance between internal defects and the surface (h(a)) was less than 35 mm. (C) 2020 Elsevier Ltd. All rights reserved.