Search Results (8)

The use of steel-concrete composite slim-floor beams with dowel shear connectors is uncommon, and the design rules provided in Eurocode 4 for composite construction are not directly applicable to the slim-floor composite beam. In this paper, a finite element model is developed, followed by a parametric study that examines the effects of various shear connector parameters on the structural behaviour of composite beams. The comparison and analysis show that the load-bearing capacity increases with a bigger concrete dowel, as long as the shear connection degree is less than 100% and the dowel diameter is not greater than 80 mm; the load-bearing capacity goes up about 5–10% for every 10 N/mm² increase in concrete strength and about 2% for every 4 mm increase in rebar diameter in the dowel; also, the dowel central spacing has a big impact on the structural behaviour. The composite beams showed great flexibility, with the end slip at the highest load being more than 6 mm and the maximum load declining by less than 15% when the midspan deflection reached L/30. The proposed calculation method for bending moment resistance is more than 90% accurate for composite beams that have a shear connection degree greater than 40%. The findings from this research provided more profound insights into the behaviour of this type of slim-floor composite beam. Full article

The paper concerns the numerical modelling of a new slim-floor system with innovative steel–concrete composite beams called “hybrid beams”. Hybrid beams consist of a high-strength TT inverted cross-section steel profile and a concrete core made of high-performance concrete and are jointed with prestressed hollow core slabs by infill concrete and tie reinforcement. Such systems are gaining popularity since they allow the integration of the main structural members within the ceiling depth, shorten the execution time, and reduce the use of concrete and steel. A three-dimensional finite element model is proposed with all parts of the system taken into account and detailed geometry reproduction. Advanced constitutive models are adopted for steel and concrete. Special attention is paid to the proper characterisation of interfaces. The new approach to calibration of damaged elastic traction–separation constitutive model for cohesive elements is applied to concrete-to-concrete contact zones. The model is validated with outcomes of experimental field tests and analytical calculations. A satisfactory agreement between different assessment methods is obtained. The model can be used in the development phase of a new construction system, for instance, to plan further experimental campaigns or to calibrate simplified design formulas. Full article

In this study, the bending behavior of Slim-Floor beams was analyzed using FE models developed in the ABAQUS software. The validity of these models was demonstrated by comparing the numerical results obtained with experimental data found in the literature. Through parametric evaluations, the following findings were verified: (i) the connection mechanisms adopted (concrete dowels, reinforcing steel bars, and adherence) were able to activate the composite behavior between steel and concrete; (ii) the spacing between the openings, the number of openings, and the diameter of the reinforcing steel bars determine the behavior of the connection; (iii) adherence contributes little to the strength of the connection, and therefore, its contribution can be neglected; (iv) the connection mechanisms adopted in this study can promote the ductile behavior of the Slim-Floor beams. Full article

Efficient use of energy in the construction sector is a pillar of the European Union’s 2050 climate protection goals, yet legislation makes no explicit reference to urban morphology or building form, which are recognized as key to energy performance in buildings. Rapidly changing energy standards and new requirements for on-site energy production demand a vigorous scrutiny of established urban typologies that are largely the product of an older energy regime. The research explores a set of 312 building shapes with floor-to-area ratio (FAR) of 3 within a given plot to identify emerging trends, ranges, and correlations between geometric variables, visual comfort, and energy indicators. Cases are grouped and evaluated in relation to three main urban typologies to highlight unique features related to each typology. The paper also compares two groups of results related to passive and active solar potential, respectively, to identify formal traits that are specific to each of these two design strategies. Finally, the research ranks design options based on total energy use taking into account the energy need for artificial lighting as well as contributions from both passive energy savings and active energy production. Results show that energy demand across cases varies by a factor 2 for passive strategies and a factor 5 when active potential is considered based on shape alone. Best results are clearly positioned at the two extremes of the geometric and proportional range. On the one hand, low-rise compact bar and courtyard buildings that are perhaps most prevalent in our cities today may be effectively retrofitted to meet active energy targets. On the other hand, extremely tall and slim towers appear to be the only typology in the study with the potential to achieve zero-energy status by virtue of their form alone. The work sheds light on the formal implications of EU energy mandates and offers a glimpse of how buildings may adapt to the combined selective pressures of high on-site energy fraction and low energy use to shape our future cities. Full article

The slim floor beams, characterized by the steel profile embedded in the concrete slab, may be found in different configurations, based on the shape of the steel profile cross-section, which can vary from a rectangular to double-T section. While the most common shape used nowadays is the double-T cross-section, the Eurocodes do not provide a simplified method for the fire resistance assessment. The literature offers a simplified method for computation of bending resistance under elevated temperature, based on existing research on thermal models, and was validated for a particular type of slim floor beams (SFB). The current study extends the scope of application of this method, for different types of slim floor beam, which include an asymmetric double-T steel cross-section. The objective was reached through a numerical procedure, by analyzing 162 configurations subjected to four different fire requirements (R30, R60, R90, R120), resulting in a total of 648 analyses, performed with a validated numerical model in SAFIR software. The results in terms of bending resistance showed that the simplified method represents a strong tool for the fire design of slim floor beams. Full article

Slim floor systems are very common nowadays and various types are currently being used for the construction of high-rise buildings and car parks. Concrete in slim floor beams encases the steel beam section which helps to improve their fire resistance. Despite their higher fire resistance, several fire protection materials like intumescent coatings are often used to achieve a higher fire resistance where desired. The thermal properties and behaviour of various intumescent coating materials were previously studied through experimental investigations. This paper presents finite element analyses to simulate the response of unprotected and protected slim floor beams in fire using different simulation tools. For this purpose, fire tests conducted on unprotected slim floor beams and intumescent coating materials are modelled using research and commercial software. Results from the analyses are compared and verified with the available test data. These validated models are later combined to study the behaviour of protected slim floor beams in fire. Results from the study show that the research and the commercial software replicate the behaviour of slim floor beams and protection materials with good accuracy. Due to the presence of the intumescent coating, the protected slim floor beams displayed a better fire resistance as the temperature of the steel part remained below 400 °C even after 60-min of standard heating. The protected slim floor beams continued to support the external loads even after 120 min of heating. Full article

Trapezoidal-shaped thin-walled metallic profiled sheets are used in composite floor construction to enable rapid construction and reduce reinforcement and formwork requirements in concrete casting. However, relevant literature reported the early failure of steel sections due to the buckling and shear of existing trapezoidal and re-entrant decking profiles. There are also limitations regarding design rules for composite flooring systems. Current work aims to develop a new type of composite top-hat section for possible use in composite slim-floor construction. Sinusoidal metallic corrugated sheets that are widely used in building construction were utilized and a new bending technique was used to produce deck components, in which transverse corrugations were introduced along the main direction of the corrugated profile. This paper investigates the structural response of these new sections for several loading and support conditions using a pilot experimental scheme. The developed top-hat sections demonstrated considerable resistance to bending as well as buckling through effective stress re-distributions under considered construction stage loading for single span and continuous span conditions. Currently available design equations recommended by Australian Standards for a similar type of corrugated decks were used to predict the design strength and to compare it with those obtained experimentally. It was concluded that the expressions proposed by the code were inadequate for single span loading cases and would require modifications before being applied to the new profile. Full article

Over the past decade, several types of composite slim floor constructions have been used in multi-storey buildings in Lithuania. In order to study the efficiency of composite beam application in steel-framed multi-storey buildings, Thorbeam (A₁), Deltabeam (A₂), slim floor beam (A₃) and asymmetric slim floor beam (A₄) were chosen and evaluated according to nine assessment criteria (beam cost (K₁), initial preparation on site (K₂), installation time (K₃), complexity of installation technology (K₄), labour costs (K₅), fire resistance (K₆), load bearing capacity (K₇), beam versatility (K₈), and availability of beams (K₉)). First, the significance of the rating criteria was selected and the order of the ranking criteria was obtained (K₁˃K₇˃K₃˃K₆˃K₄˃K₅˃K₂˃K₈˃K₉) by means of a survey questionnaire. Second, the beams were ranked according to the points given by the questionnaire respondents as follows: 160 points were given to A₂, 144 points to A₁, 129 points to A₄, and 111 points to A₃. Deltabeam is considered to be the most rational alternative of the four beams compared. Calculations done using the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) analysis method revealed that composite beam A₂ was the best slim floor structure alternative for an eight-storey high-rise commercial residential building frame, A₁ ranked second, A₄ ranked third, and A₃ ranked fourth. In addition, the four composite beams were compared to a reinforced concrete beam (A₅) according to three assessment criteria (beam cost including installation (C₁), beam self-weight (C₂) and fire resistance (C₃)). Deltabeam was found to be efficient for use as a slim floor structure in a multi-story building due to having the lowest cost, including installation, and self-weight, and the highest fire resistance compared to other composite beams studied. Although Deltabeams are 1.4 times more expensive than reinforced concrete beams, including installation costs, they save about 2.5% of the building’s height compared to reinforced concrete beams. Full article