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This paper presents an experimental testing of two short‐fiber reinforced composites (SFRC). The two materials are a polyphthalamide with 33% glass fiber inclusion (PPA‐GF33) and a polyphenylene sulfide with 40% glass fiber inclusion. Rectangular plates were obtained from these two materials by injection molding. Specimens, type 1BA, according to ISO 527‐2, were cut out with orientations of 0°, 15°, 30°, 45°, 60°, and 90°, with respect to the longitudinal direction of the plate. The cutting was conducted using a CNC water jet machine. Tension tests were performed at room temperature, in order to determine the mechanical behavior. Results are presented in the form of stress–strain curves, considering different orientations of the specimens. The experimental results were processed in order to assess the differences that appear due to fiber orientation. A comparison between the two materials was performed in terms of Young's modulus, tensile strength, and tensile strain. The experimental data were used to calibrate the Tsai–Hill fracture criterion.

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Background:Studies have shown that the flexibility of the connections has an important role in the distribution of forces and moments in the structure. This also applies for the displacements, deformations and the stability of the structure. Objective:The objective of the present study is to investigate the influence of the stiffness of column web-panel and connection on the ultimate response of Moment Resisting Frames (MRFs). Methods:A comprehensive parametric study was carried out. In particular, a set of one hundred and twenty planar frames was analyzed, considering three approaches for modelling the joints. Results:The results highlight that neglecting the influence of the connection and column web panel leads to significant over-estimation of the global instability factor α cr , which can lead to unconservative design and assessment of steel frames, especially for those cases subjected to severe horizontal forces as the seismic actions. Conclusion:Accounting for the joint deformability in MRFs is important even for the cases with connection stiffness (k b ) larger than 25 times the beam stiffness where EN1993-1-8 allows neglecting the model of the connection stiffness. Indeed, the comparison of cases with k b ≥ 25 between the models with and without the connection deformability show that of α cr can decrease from 5% to 16%, depending on the refinement of the modelling assumptions. This decrease also lead to higher second order effects and thus to higher design forces but also the overall stiffness of the frame is overestimated.