钢-超薄UHPC轻型组合桥面短钢筋连接件抗剪性能研究

It is difficult to apply the structure of steel-ultra thin UHPC lightweight composite deck due to the adoption of the ultra-thin UHPC layer. To solve this problem, an innovative shear connector fabricated from short rebar is proposed. In this work, the shear performance of the short rebar connectors is revealed through static and fatigue tests on push-out specimens. The static tests disclosed that: ① Two failure modes, namely, the break of connector-to-steel deck weld and the localized damage of UHPC, were observed; ② The capacity of the short steel rebar increased with the length of the connector-to-steel deck weld; ③ The shear capacity of the short steel rebar was higher than that of headed stud, but it was lower than that of welded steel mesh. The fatigue tests showed that under a nominal shear stress range of 80 MPa, the fatigue lives of three specimens were 1.942, 2.710, and 1.958 million cycles, respectively. By removing the maximum value, the mean fatigue life of the remaining two specimens was 1.95 million cycles, which is slightly lower than 2 million, a value defined in related design specifications. Based on the fatigue theory of welded structures, the fatigue strength corresponding to a fatigue life of 2 million can be calculated as 79.6 MPa. Furthermore, a detailed finite-element analysis was performed to reveal the response of the proposed short rebar connectors on an orthotropic steel deck bridge. The analysis results indicated that when the spacing of the short rebar connector was 200×200 mm (longitudinal×transverse), both the connector and the connector-to-deck plate weld met the fatigue design requirement. The research results in this work provide theoretical basis for the application of real bridges in the future.