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.