Abstract
A total of 32 Four-point bending tests on grout-filled steel micropile were performed on casings with nominal outer diameters of 178, 194, 244, and 346 mm and threaded joints of nominal lengths varying between 51 and 76 mm. Specimens presented different thread shapes, including 'V threads' and 'square threads, as well as, variations in the pin- and box-ends wall-thickness with considered wall taper slopes of 0.0625, 0.0521, and 0 (no wall-taper). Displacements at the mid-span joint, loading points, and end-supports were measured using string potentiometers, along with rotations of the supports measured with inclinometers. Detailed distributions of the axial and hoop strains around the threaded connections were assessed via digital image correlation techniques.