PSI - Issue 59

Valentin Aleksiievets et al. / Procedia Structural Integrity 59 (2024) 710–717 Valentin Aleksiievets et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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The samples were loaded in stages, each applying a load increment of 1 kN to all samples. Readings of indicators were taken at the beginning and end of each stage. Loading continued until the average shear deformation of the connection reached Δ u =2 mm. A hold was performed at each loading stage, lasting approximately 5 to 10 minutes. Clock-type indicators were used to measure the shear deformations of the nail connections attached to opposite sides of the connection. 3. Methodology of theoretical research The calculated load-bearing capacity of the nailed connection according to the regulatory documents (DBN B.2.6-161: 2017, Eurocode 5: 2004) can be determined by the following formulas (1-4) ; (1)

;

(2)

√ ) ) ;

(3)

√ √

.

(4)

The minimum value from (1-4) is accepted . All elements of the nail connections are made of the same wood, so the expression can be written as:

.

(5)

The design bending moment is determined by the formula:

.

(6)

It is proposed to calculate the design bearing capacity of the nail connection using the following expression:

.

(7)

4. Results and discussion The experimental tests were conducted on symmetrical nail connections of wooden structures in the first series under shear along the fibers under static loading. Necessary information about the behaviour of the test samples was recorded during the tests. Key indicators, particularly focused on during the tests, included failure loading (bearing capacity of the element) and shear deformations of the connection elements. The loss of bearing capacity was considered when the shear deformation of the connection elements reached the limit value, which is Δu=2 mm. Based on the test results, graphs of the dependencies of shear deformations of the connections on the load were constructed (Fig. 4a,b). The loading at which sample no. 1 lost bearing capacity according to the second group of limit states was 13.5 kN. Subsequently, a slight increase in bearing capacity was observed in the testing of connections 2, 3 and 4 with larger thicknesses of middle elements. The failure of connection 2 occurred at a load of 13.95 kN. Samples of nail connections 3 and 4 were also tested with incrementally applied longitudinal force. The destructive loads were 14.4 and 14.5 kN, respectively. The destructive loads for nail connections 5 and 6 were 14.53 and 14.55 kN, respectively.