Latin Hypercube Sensitivity Analysis and Non-destructive Test to Evaluate the Pull-out Strength of Steel Anchor Bolts Embedded in Concrete

Abstract

Anchor bolts are extensively employed in the various industries such as construction, mechanical and mining. Their applications range from installing permanent objects such as hybrid structures, lighting piles, direction signs to structures installed for serving temporary purpose. Several destructive testing methods have been proposed to investigate the pull-out strength of anchor bolts. However, the first real non-destructive testing method that used Schmidt hammer rebound number to estimate the load carrying capacity of anchor bolts was successfully proposed by the authors. In this method the authors successfully relate the pull-out strength of the steel anchors, N, embedded in the concrete with the Schmidt hammer rebound number, R. The research team was successful in identifying anchor bolts with improper installation resulting in lower pull-out strength. It was observed during experimentation that strength of steel anchor bolts depends upon several factors such as concrete strength, embedment length, bolt diameter, its alignment and rebound number. The cut-off value, R, of 56, 61 was identified for steel anchors of 8 mm, 10 mm diameters with embedment lengths of 50 mm and the R value of 55, 53 and 51 was identified as cut-off for 12 mm, 16 mm and 20 mm diameters with embedment lengths of 50 mm and 70 mm, respectively. Anchors depicting higher rebound values can be considered as properly installed while anchors with lower rebound value indicate defects in installation and quality of surrounding concrete. Furthermore, a detailed random parametric analysis employing Latin Hypercube Sampling method to conduct sensitivity analysis of 144 anchor bolts test data. Five diameter anchor bolts with two embedment depths were tested and analyzed. Through the analysis of experimental data, the influence of each parameter was investigated in order to ascertain its impact on the load carrying capacity of the anchor bolts. It is confirmed that the alignment of the anchor bolt is most dominant factor among all random factors considered in the analysis. Furthermore, the embedment length holds a larger influence on the pull-out strength as compared to the bolt diameter.