Mechanical Properties of Stainless Steel Rod-Shaped Connectors for Precast Concrete Sandwich Panels

To study the mechanical properties of the stainless steel rod-shaped connectors， three pull-out tests and twelve push-off tests were conducted. The research parameters included the thickness of the insulation layer （50 mm and 70 mm） and whether the insulation layer was present during testing. The test results showed that the tensile specimens experienced concrete cone failure， and the pull-out load-displacement curve was approximately linear before peak load. The average tensile bearing capacity was 8.52 kN， and the peak slip between concrete wythes ranged from 1.49 mm to 1.61 mm. In the push-off tests， the connectors underwent bending followed by pull-out， but no concrete cone was pulled out. During the early loading stage， the push-off load-slip curve was approximately linear. After the connector experienced bending， the load-slip curve exhibited a distinct nonlinear relationship. The average shear bearing capacity of a single connector ranged from 2.48 kN to 6.45 kN， with corresponding slips between wythes ranging from 1.3 mm to 5.4 mm. The shear bearing capacity decreased as the insulation layer thickness increased. The shear bearing capacity of the connectors decreased as the thickness of the insulation layer increased. When the insulation layer thickness increased from 50 mm to 70 mm， the shear bearing capacity of the specimens without the insulation layer decreased by 79.8%， while that of the specimens with the insulation layer decreased by 8.4%. The presence of the insulation layer had a significant effect on the shear bearing capacity of the connectors， and the shear bearing capacity of the specimens with the insulation layer was 1.4 to 2.4 times that of the specimens without it.