Ultimate strength analysis of partially composite and fully composite open-web steel joists

Abstract

The behavior of composite steel joists with various degrees of shear connection is investigated. The results of eight full-size composite joist tests, conducted as a portion of the study, are presented. Joist spans range from 24 ft. to 30 ft. and depths from 8 in. to 18 in. Six types of mechanical connectors provide horizontal shear transfer capacity. Steel deck supported slabs, from 3 in. to 4 in. thick, are used for all tests. The results of the experiments are used to evaluate the flexural strength and associated failure modes of partially composite and fully composite joists.

The results of each test are compared to theoretical calculations based on an ultimate strength flexural model. The joists are classified by how the provided amount of shear connection compares to the bottom chord yield force and by how the provided amount of shear connection in conjunction with the top chord capacity compares to the bottom chord yield force. Behavior typical of each classification is discussed. Correlation with previously conducted composite joist tests of similar configuration is also discussed.