PSI - Issue 81

Mykola Roshchuk et al. / Procedia Structural Integrity 81 (2026) 499–503

500

study of the performance of solid-section timber beams under service conditions in freshwater and marine environments is a topical issue. The aim of this study is to conduct experimental investigations of solid-section spruce and pine timber beams under conditions of long-term immersion in freshwater and marine environments and to analyze the features of their performance under such service conditions. 2. Methods of experimental research For the experimental program, 12 solid- section beams with dimensions of 50 × 80 × 1650 mm and a moisture content of 12% were manufactured. The beams were produced under factory conditions (DSTU EN 336 – 2003). The bending elements were made of coniferous timber - pine and spruce. Subsequently, 8 of the manufactured beams were immersed in freshwater and saline environments in special tanks for 180 days (Fig. 1). After immersion, the timber moisture content exceeded 30%. The moisture content of the test specimens was monitored using a pin-type moisture meter (DSTU 4922:2008).

Fig. 1. Impregnation of beams in a marine environment

The characteristics of the test beams are presented in Table 1.

Table 1. Characteristics of the test beams.

Timber species

Beam cross section, mm

Immersion duration, days

Timber moisture content, %

Loading type

Number of specimens, pcs

Without wetting

Pine

50x80x1650 50x80x1650

- -

12 12

Single short-term Single short-term

2 2

Spruce

Wetting in freshwater environment

Pine

50x80x1650 50x80x1650

180 180

>30 >30

Single short-term Single short-term

2 2

Spruce

Wetting in marine environment

Pine

50x80x1650 50x80x1650

180 180

>30 >30

Single short-term Single short-term

2 2

Spruce

Full-scale experimental tests of wetted and non-immersed solid-section timber beams were carried out using a dedicated test setup under a single short-term load in accordance with current standards (DBN B.2.6-161:2017; Eurocode 5:2004; DSTU EN 380-2008) (Fig. 2). Strains were measured using strain gauges, while deflections were measured with deflectometers. The strain gauges were bonded prior to wetting onto a surface previously treated with epoxy adhesive. After bonding, an additional epoxy layer was applied to the gauges to prevent moisture ingress into the gauge body.