PSI - Issue 13

Barbara Šubic et al. / Procedia Structural Integrity 13 (2018) 503–510 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

505

3

Reinforcing materials are placed in the mullion (thicknesses of 68 mm and width of 105 mm). Design of reinforcements was defined by numerical analysis of the profiles which considered optimal dimensions, orientation and positioning of reinforcements to achieve the best bending stiffness of the profile. Two additional criteria were considered in this analysis: the reinforcements should not be visible when window is completed and the dimensions of reinforcements should correspond to those available on the market. Two basic scheme of reinforcement positioning (WB1 and WB2) were selected for further static and thermal analysis, Fig. 2. WB1 and WB2 had 20 % and 22 % of reinforcing material, respectively.

Fig. 2. Selected reinforcements position and dimension (mm) in mullion 1 (WB1-left) and mullion 2 (WB2-right).

Compariso n of modulus of elasticity (E), thermal conductivity (λ) and density (ρ) of materials used in this study are presented in Table 1.

Table 1. Characteristics of spruce, glass and reinforcing materials. E [GPa]

λ ]W/mK]

ρ [kg/m 3 ]

Spruce GFRP Glass CFRP

12 38 70

0.11

460

0.3

2000 2500 1420 7850 2800

1 5

120 190

Steel

17

Aluminium

70

160

Mechanical properties of the materials were obtained either from European standards ( EN 338:2016 ; ISO 10077 2: 2017 ) or from technical sheets provided by manufacturers (Voßedelstahlhandel GmbH & Co. KG 2014; Exel composites 2017; Saint Gobain 2017; Azo Materials 2017)

2.2. Calculation of thermal transmittance

U w was calculated with WinUwFassade 5.5 (Sommer Informatik GmbH) software according to EN ISO 10077-1: 2017 and Equation 1. U w is calculated based on the geometric parameters of the windows; surface area of frame - A f , surface area of glass - A g and length of glass edge - l g , as well as U f , U g and Ψ g (0.039 W/mK). U g was 0.6 W/m 2 K in all cases. The size of window was parametric component of calculations. Linear thermal transmittance of material or sequence of materials (U) is the rate of heat transfer through one square meter of a structure, divided by the difference in temperature across the structure and was defined by WinIso 2D software.