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Andrei Gîrbacea
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1
Composite beams are commonly used in current design practice due to their efficient material use and competitive execution. The shear connection is mainly achieved by means of headed studs welded on the top flange. However, the welded connectors obstruct the possibility of a non‐destructive disassembly required to reuse the steel beams and concrete slabs. Raised concern regarding sustainability aspects drive the construction sector to introduce a shear connector which enables the demountability of the flooring. Composite action can be enabled by a bolted connection consisting of an embedded bolt and coupler connected by an external injection bolt through the top flange of the steel beam. This paper aims to assess the initial investment costs and economic viability of two demountable steel‐concrete composite beam solutions. The investigated systems comprise of two different concrete flanges: a prefabricated solid deck and an in‐situ casted profiled sheeting slab. The cost inputs of the analysis were defined by industry experts based on assumed labour and material requirements. The unit price of the novel connector is significantly higher (approx. 15 times) compared to the regular headed welded stud. This justifies the need to optimize the connector arrangement in order to keep the cost per square meter as low as possible. Non‐uniform connector arrangements can be used to reduce construction time and costs with minor decrease in beam stiffness. A tool was developed to generate a batch of 13500 composite beam designs which were later analysed in terms of costs.
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Composite beams are commonly used in current design practice due to their efficient material use and competitive execution. The shear connection is mainly achieved by means of headed studs welded on the top flange. However, the welded connectors obstruct the possibility of a non‐destructive disassembly required to reuse the steel beams and concrete slabs. Raised concern regarding sustainability aspects drive the construction sector to introduce a shear connector which enables the demountability of the flooring. Composite action can be enabled by a bolted connection consisting of an embedded bolt and coupler connected by an external injection bolt through the top flange of the steel beam. This paper aims to assess the initial investment costs and economic viability of two demountable steel‐concrete composite beam solutions. The investigated systems comprise of two different concrete flanges: a prefabricated solid deck and an in‐situ casted profiled sheeting slab. The cost inputs of the analysis were defined by industry experts based on assumed labour and material requirements. The unit price of the novel connector is significantly higher (approx. 15 times) compared to the regular headed welded stud. This justifies the need to optimize the connector arrangement in order to keep the cost per square meter as low as possible. Non‐uniform connector arrangements can be used to reduce construction time and costs with minor decrease in beam stiffness. A tool was developed to generate a batch of 13500 composite beam designs which were later analysed in terms of costs.
Steel-concrete composite beams are widely used in practice because of their simple construction sequence and economic cross-section design. Reuse of traditional composite beams is not possible due to the permanent connection between the steel beam and concrete deck established by welded headed studs. To allow for fast construction, demountability and reuse of composite beams, various demountable shear connectors can be used. In this paper the results of experiments carried out on demountable and reusable tapered composite beams, consisting of a tapered steel beam and large-scale prefabricated concrete decks, are presented. The performance of various arrangements of resin-injected bolt-coupler shear connectors was considered to optimize the beneficial effect of composite action whilst minimizing the number of shear connectors. An advantage of resin-injected bolted shear connectors is that composite action is obtained instantaneously and simultaneously for all connectors. Demountability and reusability of the composite beam were successfully demonstrated experimentally. Experimental and numerical results indicated that the number of shear connectors necessary to fulfil deflection and end-slip limits can be reduced by concentrating them near the supports of a simply-supported beam. Results obtained using finite element models closely matched the experimental results in terms of deflection, stresses and curvature.
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Steel-concrete composite beams are widely used in practice because of their simple construction sequence and economic cross-section design. Reuse of traditional composite beams is not possible due to the permanent connection between the steel beam and concrete deck established by welded headed studs. To allow for fast construction, demountability and reuse of composite beams, various demountable shear connectors can be used. In this paper the results of experiments carried out on demountable and reusable tapered composite beams, consisting of a tapered steel beam and large-scale prefabricated concrete decks, are presented. The performance of various arrangements of resin-injected bolt-coupler shear connectors was considered to optimize the beneficial effect of composite action whilst minimizing the number of shear connectors. An advantage of resin-injected bolted shear connectors is that composite action is obtained instantaneously and simultaneously for all connectors. Demountability and reusability of the composite beam were successfully demonstrated experimentally. Experimental and numerical results indicated that the number of shear connectors necessary to fulfil deflection and end-slip limits can be reduced by concentrating them near the supports of a simply-supported beam. Results obtained using finite element models closely matched the experimental results in terms of deflection, stresses and curvature.
Environmental concerns steerthe construction industry towards more sustainable developmentssuch asdemountable and reusablestructures. Composite structures are a frequent solution for multi-story buildings and bridges, however the use of welded shear connectors requires labour and energy intensive disassembly. Two bays of a demountable flooring systemfor a multi-storey car park building were erected in the laboratory. The flooring system consists of large prefabricated concrete decks connected to taperedsteelbeams. The feasibility of assembly and disassemblyof the flooring system was tested under laboratory condition. Shear interaction was achieved by an embedded bolt and coupler which areconnected to the top flange of the steel beam by an external injection bolt. Oversized holes are used in thetopflangeof the steel beamto accommodate fabricationand executiondeviationsandthedeformations occurringduring construction. Extensive imperfection measurements and finite element models were used to design the oversized hole diameter to 32 mm. Thehole clearance must be compensated either by pretensioning or injecting the bolt-to-hole clearance with an epoxy resinto enable instantaneous composite action underlive loads.Experimental injection of 150 injection bolts confirmsthat epoxyresin can reliably fill the hole clearance, and that the injectionprocess takes30 seconds per bolt.Various non-uniform shear connector arrangementswere considered to minimizeconstruction costs and maximize the speed of execution. The mechanical behaviour of the demountable composite beam was tested experimentally and numerically.
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Environmental concerns steerthe construction industry towards more sustainable developmentssuch asdemountable and reusablestructures. Composite structures are a frequent solution for multi-story buildings and bridges, however the use of welded shear connectors requires labour and energy intensive disassembly. Two bays of a demountable flooring systemfor a multi-storey car park building were erected in the laboratory. The flooring system consists of large prefabricated concrete decks connected to taperedsteelbeams. The feasibility of assembly and disassemblyof the flooring system was tested under laboratory condition. Shear interaction was achieved by an embedded bolt and coupler which areconnected to the top flange of the steel beam by an external injection bolt. Oversized holes are used in thetopflangeof the steel beamto accommodate fabricationand executiondeviationsandthedeformations occurringduring construction. Extensive imperfection measurements and finite element models were used to design the oversized hole diameter to 32 mm. Thehole clearance must be compensated either by pretensioning or injecting the bolt-to-hole clearance with an epoxy resinto enable instantaneous composite action underlive loads.Experimental injection of 150 injection bolts confirmsthat epoxyresin can reliably fill the hole clearance, and that the injectionprocess takes30 seconds per bolt.Various non-uniform shear connector arrangementswere considered to minimizeconstruction costs and maximize the speed of execution. The mechanical behaviour of the demountable composite beam was tested experimentally and numerically.
One of the increasingly important parameters in the construction sector is the time required for the execution and easy demounting of a structure. The goal of this paper is to provide insight into an on-going research focusing on structural performance of large prefabricated concrete decks connected by a demountable shear connectors. A large bolt-to-hole clearance is used to accomplish both requirements. The holes are injected by an epoxy resin to ensure composite action. The demountability and reusability of the composite beam system was successfully tested.
...
One of the increasingly important parameters in the construction sector is the time required for the execution and easy demounting of a structure. The goal of this paper is to provide insight into an on-going research focusing on structural performance of large prefabricated concrete decks connected by a demountable shear connectors. A large bolt-to-hole clearance is used to accomplish both requirements. The holes are injected by an epoxy resin to ensure composite action. The demountability and reusability of the composite beam system was successfully tested.