EFFECT OF CONCRETE STRENGTH ON SHEAR RESISTANCE OF STUD CONNECTORS AND MOMENT RESISTANCE OF COMPOSITE BEAMS

摘要

In recent decades, composite steel-concrete beams have been more and more used in tall buildings. The mechanical connectors are commonly used to transfer longitudinal shear forces across the interface of die steel beam and concrete slab in composite beam design. The empirical equation for the shear strength of stud connectors, which was presented by Ollgaard et al in 1971, has been incorporated in codes of various countries. In this paper, based on experimental data of 95 push-out specimens and 11 composite beams with partial shear connection from home and abroad, the effects of concrete strength on the shear resistance of stud connectors and moment resistance of composite beams are analyzed and investigated. It was found that the shear strength calculated according to Ollgaard's empirical equation is lower than that of test results when the concrete strength is lower, while higher when the concrete strength is higher. And the same conclusions are got in composite beams with partial shear connection. A modified formula for the shear resistance of stud connectors is presented by means of regression analysis of the test data. From comparing calculated values with the results of push-out specimens and composite beams with partial shear connection, it is observed that the error of equation proposed by Ollgaard can be eliminated when used the modified formula proposed this paper. And the calculated value is in good agreement with the experimental results.