Coped steel beams have been commonly adopted in steel frame structure construction, but the existence of coped regions severely limits the ultimate load carrying capacity and will even lead to unfavorable failure modes. This paper aims to study the reinforcing strategies of carbon fiber reinforced polymer (CFRP) plates for coped steel beams against local web buckling. A total of four single coped steel beams with and without reinforced CFRP plates were fabricated and experimentally tested under different reinforcing strategies. Typical failure modes, the influence of CFRP plate layers, and pasting inclination angles were investigated and discussed. It has been found that the CFRP plate was efficient in improving ultimate load carrying capacities and prohibiting local web buckling of coped beams. The reinforcing effect was more prominent with more layers of CFRP plates, and CFRP plates with inclined pasting angles could also provide higher post-peak ductility compared to horizontal pasting. A finite element model was also established and validated against the experimental results. A subsequent parametric analysis was conducted to quantitively characterize the influence of various reinforcing strategies. The simplified calculation model was proposed based on the experimental and simulation results, which is hoped to provide further insights into the design of singled coped beams in practical engineering.

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The building sector is actively researching and reviewing technical solutions for de-construction, driven by the increasing importance of sustainability requirements, as outlined in the EU Commission's ‘Green Deal,‘ which aims to achieve net-zero greenhouse gas emissions by 2050. Two key research areas in efficient structural design strategies are the performance of hybrid structures, which combine mechanical properties and architectural appearance of different materials, and the techniques and mechanical properties of connections between structural components that enable deconstruction and reuse. However, there is a scarcity of studies and methods focused on demountable and hybrid structural systems, limiting the understanding of their overall structural performance at a real-structure floor level. In this paper, a finite element model is presented to conduct a comparative study between the traditional floor system with welded stud connections and the demountable floor system with coupler-embedded bolted connectors. The numerical results showed that the serviceability loading capacity of the demountable floor system was 8% lower, and the difference in ultimate resistance was further enlarged. Reusing a demountable floor system, analysed in the case study, had little effect on the ultimate resistance, but it is difficult to exclude local plastic deformation after the first life cycles.@en

Ultra-high performance geopolymer concrete (UHPGC) has been favored due to its excellent sustainability and outstanding mechanical properties. This study was conducted to explore the mechanical and durability properties of slag/metakaolin-based UHPGC with steel fibers reinforcement. The uniaxial compression test and rapid chloride migration test were conducted to measure the compressive strength and chloride penetration resistance of UHPGC. A total of nine groups of mixture proportions were designed and tested to investigate the influences of steel fiber dosage and sodium hydroxide (NaOH) solution concentration. The results showed that an increased steel fiber dosage and alkali concentration can improve compressive strength, and the maximum compressive strength can reach more than 140 MPa. In addition, the rapid chloride migration test showed that the chloride penetration resistance of the slag/metakaolin-based concrete was moderate, with a non-steady chloride migration coefficient ranging from 6.5 × 10⁻¹² m²/s to 14.1 × 10⁻¹² m²/s. The increase in steel fiber volume content slightly enlarged chloride penetration depth, while the higher concentration of sodium hydroxide solution was beneficial as it improved chloride penetration resistance. The results suggest that although ultra-high compressive strength can be achieved, the durability issues of steel fiber reinforced slag/metakaolin-based geopolymer concrete still need considerable attention.

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The steel coped beams are commonly seen in steel structures since slotting and coping are inevitable for the fitting of steel beams. The steel coped beams with slender web, however, are prone to local web buckling, which results in decreased load carrying capacity and catastrophic failure modes. This paper is intended to investigate the feasibility of reinforcing single-coped beam with carbon fiber reinforced polymer (CFRP) plate. Totally five single-coped steel beams with or without CFRP plate reinforcement were tested. The failure processes and influences of different parameters were discussed and compared. It was found that the application of CFRP plate is effective to prohibit the development of buckling line. Thus, the load carrying capacity of CFRP reinforced single-coped beam could be three times higher than its control group. A novel finite element (FE) model was proposed and verified with experimental results. Based on the FE model, the failure mechanisms of CFRP reinforced single-coped beam were investigated. The parameter analysis was also conducted to acquire the optimal size of the CFRP plate considering its reinforcement effects. Based on both experimental and simulational results, the simplified design method of CFRP reinforced single-coped beam was also proposed.

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The rounded corners have significant influences on the buckling processes and carrying capacity of thin-walled steel structures. This paper was intended to investigate the influences of rounded corners on the performance of single-coped beam with slender web. The mechanical behaviours of two typical single-coped beams with different coped depths were experimentally investigated first. The finite element (FE) model was proposed and the accuracy was verified by comparing it with the experimental results. Based on the proposed FE model, the influences of different radius for rounded corners (R_c) were investigated. It was concluded that the application of rounded corners has great impacts on the failure modes and buckling processes of single-coped beams. It was also found that the energy-dissipating capacity as well as load carrying capacity increased significantly with the application of round corners, especially for single-coped beam with deep coped depth. The round corner index, which considered the influences of both rounded corner and coped depth, was proposed via fitting with the simulational results. A typical design example considering the round corner index was also provided and a more accurate result was achieved.

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