Research on the Efficiency of Composite Beam Application in Multi-Storey Buildings

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 (A 1 ), Deltabeam (A 2 ), slim floor beam (A 3 ) and asymmetric slim floor beam (A 4 ) were chosen and evaluated according to nine assessment criteria (beam cost (K 1 ), initial preparation on site (K 2 ), installation time (K 3 ), complexity of installation technology (K 4 ), labour costs (K 5 ), fire resistance (K 6 ), load bearing capacity (K 7 ), beam versatility (K 8 ), and availability of beams (K 9 )). First, the significance of the rating criteria was selected and the order of the ranking criteria was obtained (K 1 ˃K 7 ˃K 3 ˃K 6 ˃K 4 ˃K 5 ˃K 2 ˃K 8 ˃K 9 ) 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 A 2 , 144 points to A 1 , 129 points to A 4 , and 111 points to A 3 . 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 A 2 was the best slim floor structure alternative for an eight-storey high-rise commercial residential building frame, A 1 ranked second, A 4 ranked third, and A 3 ranked fourth. In addition, the four composite beams were compared to a reinforced concrete beam (A 5 ) according to three assessment criteria (beam cost including installation (C 1 ), beam self-weight (C 2 ) and fire resistance (C 3 )). 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.