Experimental research on pull-out behavior of steel-UHPC composite beams with new composite dowels connectors

Abstract

In order to study a new type of steel-UHPC composite connector, a total of 16 steel-UHPC composite connectors with steel dowels and studs and steel-UHPC composite connectors with steel dowels without studs were designed and manufactured, and the pull-out test, finite element simulation and theoretical analysis were carried out. The load-slip curve, ultimate pull-out bearing capacity, crack development law of the UHPC layer and crack growth trend of the steel-UHPC interface were experimentally studied. The influence of the type of connector, the height of the steel dowel and the inclination angle of the steel dowel on the ultimate pull-out bearing capacity and failure mode of the specimens were compared by parameter analysis. The test results are compared with the finite element analysis results to verify the accuracy of the finite element model. A simplified calculation formula for the pull-out bearing capacity was proposed. The results showed that the failure modes of 16 specimens were the shear failure and axial tensile failure of the UHPC, both of which were ductile failures. The bearing capacity in the elastic stage and ultimate bearing capacity of the steel dowel connector with headed studs were higher than those of the steel dowel connector. After adding headed studs, the pull-out bearing capacity of the specimens could be increased by about 49% ∼ 84%. When the longitudinal steel bars were added to the bottom of the steel dowel connector with headed studs, the ductility in the loading stage and ultimate bearing capacity of the specimen could be improved. The steel dowel composite connector with headed studs with a steel dowel height of 100 mm and an inclination angle of 65° had better pull-out resistance.