One of the principle issues concerning the practical application of steel fiber reinforced concrete (SFRC) is the uncertainty related to its structural behavior, primarily caused by the partially random distribution and orientation of steel fibers in SFRC structural elements. This paper aims to provide a better understanding of how the variance of material properties of the SFRC affects the flexural behavior of SFRC beams. First, a distributed plasticity fiber finite element model of beam flexural behavior is proposed and validated. Then, probability distributions of selected material properties are defined based on existing probabilistic models and experimental results from the literature. Finally, a variance-based sensitivity analysis is performed using Sobol’ indices to identify uncertainties in material properties that contribute most to the uncertainties related to three characteristic points of a beam’s flexural behavior: first crack, yield, and collapse point. Sensitivity analysis is performed by surrogating the numerical model using polynomial chaos expansion. The variance in residual tensile strength is identified as the main contributor to the variance in the flexural behavior of an SFRC beam used in the case study.

Timber-concrete composite structures are innovative structural systems which have become the subject of extensive research and practical usage, primarily due to their attractive mechanical properties. This article deals with the experimental procedure and the analysis of the mechanical behavior of two different series of timber-concrete composite beams with the same span and geometry of cross-sections. In the first BF-series, the screws were used as a connecting system between the timber and concrete parts, whereas in the BN-series the combination of notches and screws, as a more complex system, was used for the same purpose. Both series were exposed to loading up to a failure by means of the standard four-point bending test. The mechanical behavior of the BF and BN-series beams was analyzed by a comparative analysis referring to: the correlation of the failure loading and the deflection, mechanisms of failure, the strain development across the height of mid-span’s and support’s cross-sections, the horizontal displacement in the timber-concrete interlayer at the support zones, the value of shear stresses and the calculated values of the effective bending stiffness of the beams. The differences in bearing capacity between both series of beams were negligible (about 5%), the effective bending stiffness of BF beams is lower for 32.86% compared to the BN-series and the average value of deflections in BF-series beams is twice as high than in the BN-series. The BN-series beams showed better mechanical behavior in aspects of development of shear stresses in support zones, exhibiting lower shear stress values with an average of 40%.

The aim of the research presented in this paper is the experimental confirmation of the numerically defined shapes of the Strut-and-Tie models, designed according to the EN 1992-1-1 recommendations, and obtained from the software “ST method”. Three reinforced concrete deep beams with openings were tested. Each of them had the same dimensions and quality of the material characteristics. The specimens, constructed as simply supported beams, were loaded with two concentrated forces and were tested for bending until failure. Each specimen was reinforced with different reinforcement layout determined by variation parameter β, incorporated in the software “ST method”. For the determination of the Strut-and-Tie models, all of the reinforcement layouts were equally favored in the first specimen (β = 1.0 for 0°, 45°, and 90°), only the horizontal direction was favored in the second (β = 1.0 for 0°), while in the third specimen the one at the angle of 45° (β = 1.0 for 45°). Based on the results of experimental research, it was concluded that the behavior of loaded members was in agreement with the proposed shapes of the Strut-and-Tie models that were used for their design, and it was confirmed that the program “ST method” can be used for obtaining Strut–and-Tie models.

Starting with the premise that the choice of the optimal method for strengthening reinforced concrete (RC) structures is a complex task and that ferrocement strengthening is comparable to other advanced strengthening technologies due to its cost-effectiveness, ease of construction, and durability, this paper presents a comparative study of the flexural bearing capacity of RC beams strengthened with ferrocement strips applied by gluing. An overview of the life cycle assessment (LCA) based on embodied energy or CO₂ is presented in the introduction, based on the existing literature review. The research includes tests of 15 RC beams of identical cross-sections (150/250 mm) and a span of 3000 mm. Strengthening was conducted by applying four types of ferrocement strips (different widths and wire mesh layers). Two factors were examined: the verification of the comprehensive FEM numerical model against the experimental results and the applicability of existing simplified calculation methods for sufficiently accurate results which could be used in regular practice. The results show that the failure forces obtained from numerical models and experimental models differ by no more than 3.94%. The increase in the bearing capacity of the strengthened models is up to 21.4%. The transformed area method for the cracked section showed good results when compared to the FEM and experimental models. The analytically calculated failure force is contingent upon the partial factor for variable action, which was explored within the 1.5–1.7 range.

This paper presents the experimental analysis that was conducted on small-scale 1g physical models of piled raft foundation structures with a group of 2 × 2 piles in loose sand. The purpose of the piles was to reduce the settlement of the raft. The test program included twelve experiments, three of which were conducted on a raft alone and nine on piled rafts at pile distances of 3d, 4d, and 5d and pile lengths of 10d, 20d, and 40d, where d is pile diameter. The test results show that the current conventional approach to design of piled raft foundations, at a high safety load factor in piles that assume to take the whole external applied load, is very conservative. Instead, it is more economical to apply a low bearing capacity factor for piles as settlement reducers and maximize use of raft bearing capacity to carry part of the external load.

The paper presents basic characteristics of pervious concrete and gives an overview of the most significant current researches in the world as well as the possibility of use of pervious concrete for road construction in Western...