PSI - Issue 81

Petro Gomon et al. / Procedia Structural Integrity 81 (2026) 411–416

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conditions (Drobyshynets et al., 2024). T-shaped sections are typically used to reduce concrete consumption or to limit the height of the cross-section, while reinforcement is arranged to fully utilize the compressed concrete zone. An important research task is the experimental evaluation of the influence of low-cycle loading on reinforced concrete T-beams – specifically, on the load-bearing capacity of normal and inclined sections due to variation in the physical and mechanical properties of concrete, as well as on beam deflection and crack development. Nomenclature ε b relative deformations of concrete F load η load level 2. Methods of research All specimens were produced in accordance with recommendations for testing reinforced concrete structures (Eurocode 2:2004; DBN B.2.6-98:2009). The experimental program included 12 beams , 12 prisms, and 3 cubes (Table 1). The samples were manufactured in laboratory conditions. The concrete was cured in the laboratory. The concrete was 6 months old at the time of testing.

Table 1. Volume of experimental studies Experimental specimens Quantity

Dimensions, cm Research object

15×15×15 15×15×60 23 × 40 × 200 23 × 40 × 200 23 × 40 × 200

С ube specimens

12 12

С ube strength

Prismatic specimens

Prismatic strength

Beam B-1 Beam B-2 Beam B-3

4 4 4

Strength of a reinforced concrete T-beam under single static and low-cycle loading with variable flange thickness. Deformation of concrete and reinforcement, and measurement of beam deflections.

To determine the influence of low-cycle loading on flange behaviour in T-shaped sections, three variants of beam cross-sections were adopted (Fig. 1), differing only in flange thickness: 3 cm (B-1), 4 cm (B-2), and 5 cm (B-3). The beams were deliberately over-reinforced to study the behaviour of the compressed concrete zone and the failure mechanism. The average longitudinal reinforcement ratio was 3.4%.

O32A400C

O32A400C

Fig. 1. Structural layout of the experimental beam

All beams were made of factory-mixed concrete of class C32/40 and reinforced with longitudinal A400C bars of 32 mm diameter and transverse A240C stirrups of 10 mm diameter (Fig. 2). The flange reinforcement consisted of 3 mm wire reinforcement (Vr1) to prevent flaking. Reinforced concrete T-beams, prisms, and cubes were fabricated in the laboratory of the Department of Structural Engineering using the same concrete batch.

Fig. 2. Structural layout of the reinforcement cage

The main objective of the study is to determine the influence of low-cycle loading on the behaviour of concrete within a T shaped cross-section. To achieve this, two loading schemes were adopted (Fig. 3). The first scheme involved monotonic loading, during which the beams were brought to failure to determine the ultimate load. The second scheme involved applying high-level low-cycle loading; under this regime, the beams were subjected to 10 loading cycles, followed by loading to failure during the 11th