CONNECTION TECHNOLOGIES FOR FAST ERECTION OF STEEL STRUCTURES FOR BUILDINGS (FEOSBUILD)

Steel-concrete hybrid building systems offer sustainable and effective structural solutions for multi-story and high-rise buildings considering that steel is a completely recyclable material and that the most advantageous mechanical properties of steel and concrete could be used simultaneously against the effects of tension and compression stress resultants. On the other hand, a small percentage of multi-story buildings and a small number of high-rise structures are actually constructed using steel-concrete hybrid building technologies. This is mostly a result of general contractors’ orientation toward the completion of construction projects using traditional reinforced-concrete construction techniques. Therefore, they generally do not employ a sufficient and competent workforce to execute labor-intensive and complex on-site manufacturing activities such as welding of fin plates and pre-tensioning applications for high-strength bolts required to assemble steel beams and reinforced-concrete columns and walls of steel-concrete hybrid building systems. In order to reduce labor-intensive on-site tasks, general construction contractors typically utilize conventional construction approaches using only reinforced concrete building systems. As a result, the structural and environmental benefits of steel-concrete hybrid building systems could not be widely adopted by the construction industry. This research project proposes three different novel structural joint configurations with cutting-edge saw-tooth interface mechanical interlock bolted connection, bolt-less plug-in connection, and grouted joint details for beam-to-column joints of steel-concrete hybrid building systems. The proposed joint configurations eliminate on-site welding and enable the accommodation of construction and manufacturing tolerances in three spatial directions to achieve fast erection strategies for the construction of steel-concrete hybrid building systems. Therefore, the outcomes of the research project make it possible for general construction contractors to use their existing workforce to complete construction tasks for steel-concrete hybrid building systems without the requirement of specialized tools or training. In this study, a total of six separate experimental test campaigns were established to determine the load-deformation behaviors of the proposed joint configurations and to identify their load-bearing components. In order to show that the suggested joint configurations are appropriate for mass production without the utilization of special equipment or machinery, the experimental test prototypes of the proposed joint configurations were produced in partnership with commercial producers. The experimental test campaigns were simulated with numerical models by means of advanced computer-aided finite element analyses for the identification of the ultimate deformation limits of the proposed joint components and to clarify their progressive failure mechanisms under quasi-static loading conditions. A set of analytical resistance models were developed to estimate the load-bearing capacities of the proposed joint configurations based on the failure modes identified by the observations made during the experimental tests and in accordance with the output results of the numerical simulations. Based on the analytical expressions, the most significant, in other words, the basic variables impacting the load-bearing capacities of the proposed joint configurations were identified. Additionally, the load-deformation behaviors of the proposed joint configurations were further investigated with numerical parametric studies by parametrizing the basic variables to understand their impact on the load-deformation behaviors of the proposed joint configurations. To verify the accuracy of the analytical resistance models of the proposed joint configurations, the estimations of the analytical expressions were compared with the output results of the numerical parametric studies. Based on the distribution of the estimations of the analytical expression against the output result of the numerical parametric studies, characteristic and design partial safety factors were established according to EN1990, Annex D for the analytical resistance models of the saw-tooth interface mechanical interlock bolted connection and bolt-less plug-in connection. The estimations of the analytical resistance model of grouted joint details for beam-to-column joints of steel-concrete hybrid building systems were also compared with the output results of a numerical parametric study but no partial safety factor was established for this joint detail