低温下早龄期混凝土爬模连接件受剪性能研究OA

During winter construction,early-age concrete is partially exposed when formwork is lifted,exposing it to the risk of frost damage.This could affect the shear performance of the connection joints between the formwork and the structure,thereby impacting the safety of construction operations.To study the shear performance of early-age concrete formwork connection joints under low temperatures,six specimens were designed for push-out tests.Based on the constitutive relationships of concrete and steel under low temperatures.Finite element models of the push-out test for formwork connection specimens were established using ABAQUS software.The study parameters included temperature,concrete age,shear bolt diameter and strength.Analysis of test results and numerical simulations showed that under low temperatures,the members experienced brittle failure.Lowering the temperature increased the shear bearing capacity and initial stiffness of the members,but reduced their ductility.Increasing the concrete age was beneficial for the bearing capacity of the formwork connection specimens,but reduced their ductility.Enhancing the strength of high-strength bolts had a minor impact on the shear bearing capacity of the formwork connection specimens,but improved their ductility.Finally,comparisons were made between the specifications of various countries and the test results,revealing that the specifications of all countries could conservatively estimate the shear bearing capacity of early-age concrete formwork connection joints under low temperatures.