Shear resistance mechanism of prefabricated large-scale gerber girder

Abstract

In this study, shear tests were conducted to investigate the shear resistance mechanisms of Gerber precast concrete (GPC) girders consisting of PC end units, PC girder units, and cast-in-place concrete. To this end, individual PC end-member and mid-girder specimens were fabricated along with five GPC girder specimen with CIP concrete. The key test variables were overlapping (hanging) length and connection details of the mid-girder and end units. The test results showed that the shear performance of the composite GPC girder was significantly influenced by the connection details of the end-member and mid-girder. In the specimen where the mid-girder was simply assembled with the end-member without bolts, the failure was dominated by the damage concentrated on the bottom flange of the end-member. In contrast, in the specimen with the end-member and mid-girder assembled with bolts, there was no significant damage to the connection region, resulting in exerting full shear capacity. Additionally, based on the load–displacement response, crack pattern, and strain behavior measured from the experiment, the load-transfer mechanism of the GPC girder was estimated and reflected to propose a strut-and-tie model (STM) for the shear design of the GPC girder. The proposed STM was found to evaluate the shear strengths of the GPC girder specimens with a higher degree of accuracy than the shear strength evaluation method based on design code equations. Therefore, tied-arch mechanism can be assumed to dominate the main shear transfer mechanism when designing the GPC girder.