Abstract
In this study, straight composite steel-concrete beams were tested to investigate their mechanical performance under combined negative bending and torsional moments. Two specimens were used in this study, and different ratios between the applied negative bending and torsional moments were induced. Load and deflection relationships, strain development on the steel main girder and shear connectors (stud), and the slip development on the steel-concrete interface were recorded in the test and reported in this paper. The results indicate that increase of torsional moment will result in the significant decrease of the load-carrying capacities (e.g. yield load and ultimate load) of the specimens. It was also found that the normal strains of stud shear connectors in such beams are very large and non-negligible compared to their shear strains. In addition, the maximum interface slip was found occurring at around the 1/4 span, and the support conditions and serious crack of the concrete were considered to be the main causes. The research results obtained in this study can provide references for the design and analysis of steel-concrete composite beams subjected to the combined negative bending and torsional moments.
Highlights
The steel and concrete composite section is a popular structural form and has been widely used in many civil infrastructures, like buildings and bridges, due to its efficient use of material strengths of both structural steel and concrete in supported beams
The results obtained in this study indicate that there are non-negligible normal strains caused by bending moment as well as the axial forces in addition to the shear forces in steel-concrete composite beams subjected to combined negative bending and torsion, which can significantly affect the performance of the shear connectors thereby affect the global behavior of the composite beams
Detailed test results involving applied load versus displacement relationship, applied load versus strain relationships on steel main girder and shear connectors as well as slip on the steel-concrete interface were recorded in the test and reported in this paper
Summary
The steel and concrete composite section is a popular structural form and has been widely used in many civil infrastructures, like buildings and bridges, due to its efficient use of material strengths of both structural steel and concrete in supported beams. The structural behavior of steel-concrete composite beams under pure negative bending or torsion has been investigated by many researchers, such as Ko et al (2013), Ahmed and Ahmed (2015), Zivner et al (2016), Wang et al (2018), Liu et al (2019), and Liu et al (2019). Two overturned supported steel-concrete composite beams with different torsion/bending ratios were tested in this study, which were similar to specimens used in previous tests on steel-concrete composite beams under a pure hogging bending moment (Lin and Yoda, 2013; Lin et al, 2014b). Welded plate steel section is used in the steel girder
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