The paper presents results of a study on T-shaped composite concrete beams with a variously located interface. Damage to tested beams was caused by shear. The crack patterns and the value of the force causing interface cracking were analysed. Conclusions concerning the failure mechanism were formulated. Moreover, the influence of the interface location and of the difference between the moduli of elasticity of joint materials on stress in the interface was also analysed.

The study presented constitutes the next step of authors’ investigations on the concrete composite T-shaped beams. The comparison of the failure modes and crack patterns of numerical models and beams tested was performed previously. In this paper, analyses concentrate on determination the proper values of cohesive surface parameters ensuring the high conformity of deformation and strains of the numerical model to the experimental results. In the particular series of beams the interfaces between concrete parts are varied as follows: reinforced joint with normal and tangential interactions only (BZ/S2/A), non-reinforced joint with adhesion (BZ/P), and reinforced joint with adhesion (BZ/P+S). Material properties used in numerical model are based on obtained in the laboratory ones. Furthermore, the ‘traction–separation’ law in the ABAQUS software defining the cohesion surface is used and analysis of the cohesive parameters response to interface roughness is carried out. The results show a strong dependence between the cohesion surface parameters and the response of the composite beam. A very good convergence of the numerical model with the experimental results in terms of ‘force-displacement’ relationship is achieved. Finally the parameters defined in the ABAQUS are determined, which have a key impact on the beams response.

The tests results of composite reinforced concrete T-shaped beams with an interface between the web and the flange are presented. The interface in the beams differed in the degree of the adhesion activity and the joining reinforcement ratio. Five series of beams were tested for deflection, displacement of composite parts in relation to each other, strain of main and transverse reinforcement, and crack pattern. The results were compared with the theoretical forces, at which interface cracks and achieves the bearing capacity, calculated in accordance with fib Model Code 2010.

The two‐electron relaxation processes in Rydberg hollow atoms (RHA), formed in collisions of slow highly charged ions (HCI) of Xe (q = 23–36) with metallic Be surface, were studied experimentally by means of X‐ray spectroscopy. The pulsed beams of HCI were delivered by the electron beam ion source while the emitted X‐rays were observed by a silicon drift detector. From the measured spectra of M‐X‐rays, dominated by the Paschen series of nf3d one‐electron‐one photon radiative (R) transitions, the relaxation processes involving two electrons, namely, the internal dielectronic excitation, interatomic Coulombic decay, two‐electron‐one photon transitions and the Auger transition (A), were extracted. The dead‐time effect in X‐ray detector for a pulsed ion beam of HCI was considered in order to estimate the Auger decay rates. Finally, we demonstrate that the present results give access to estimate a time‐scale of relaxation of RHA in solids.