Abstract Laterally loaded pile foundations are more commonly employed in geotechnical engineering due to their widespread utilisation in contemporary construction projects, with examples including wind turbines. The most effective method for estimating pile lateral capacity is a static load test conducted in a natural scale. However, there are some challenges associated with field performance tests, which can be avoided by conducting them on model piles in a laboratory scale. This article presents the initial results from a series of lateral static load tests conducted on steel pipe piles in a laboratory scale. Based on the retrieved results, an analysis of the loaddisplacement pile lateral behaviour was performed, and the pile lateral bearing capacities were estimated with approximation methods. In addition, an approximation error analysis was performed.

Abstract The aim of this research was to determine the optimal dimensions of a tapered, bisymmetric, thin-walled, I-shaped cantilever for which, at a constant mass, the critical load causing the buckling of the beam reaches the maximum value. Optimal solutions were sought in a discrete set of admissible values of the taper coefficients of the I-bar’s web and/or flanges. A model of a thin-walled bar with an open cross-section, whose mathematical description was derived on the basis of the momentless theory of shells, was used to analyse the considered problem described by a system of four coupled differential equations with variable coefficients. The equations were solved using Chebyshev series of the first kind to approximate the generalized displacement functions, and the recurrence algorithm presented in earlier publications by the author(s). A tapered cantilever with a bisymmetric cross-section, subjected to the action of a uniformly distributed load, was analysed. The load can be applied to the I-bar’s upper flange or to its lower flange, or it can act in the centre of the web. The obtained critical load values were compared with those obtained using the finite element method and the commercial Sofistik software. In the set of linearly tapered cantilevers with a bisymmetric double-tee cross section, the cantilevers with the highest taper coefficients of the web and the flanges (the free end having the smallest possible dimensions) were found to be optimal (in their case, at a constant mass, the critical buckling load reaches its maximum value).

Abstract The work presents a method of automatic stabilisation of unstable multi-degree-of-freedom linear parametric systems. The publication is a continuation and extension of the subject matter described in Wójcicki’s earlier work ‘Application of first-order sensitivity analysis to stabilization of unstable continuous MDOF parametric periodic systems’ ( Studia Geotechnica et Mechanica). While in that paper first-order sensitivity analysis was used, in this paper it was extended to the second-order sensitivity analysis. The algorithm of the presented method of stabilisation of an unstable continuous in time parametric system has become significantly more complicated, but the new formulas allow for better (nonlinear) prediction of extrapolated changes in the values of design parameters, which should accelerate the system stabilisation procedure. The obtained formulas were verified and validated using the same examples that were used in the study cited earlier. The method’s innovation is the idea to achieve the non-homogeneous parametric sensitivity equation by evaluating analytically the first and second derivatives of the parametric homogeneous equation of motion with respect to design parameter. Then, by solving the obtained sensitivity equation, the first and second derivatives of monodromy matrix and finally the first and second derivatives of multipliers are evaluated. Ultimately, this method is based on sensitivity analysis of absolute values of multipliers. Furthermore, the sensitivity analysis method was improved and generalised to allow to correctly determine the eigenderivatives also with respect to those system parameters on which the parametric excitation period depends. In particular, it becomes possible to use the parametric excitation period as a design parameter.

Abstract The article describes an existing and pioneering measurement system, which can be called a geotechnical monitoring system. This system has string sensors measuring strains, stresses and forces and was installed in concrete columns strengthening weak soil subgrades. Concrete columns using full displacement technology strengthen the ground under the embankment of the expressway No. S7 between Gdańsk and Elbląg in Poland. In terms of geological structure, the area where the measuring columns were made is characterized by the presence of low-bearing, large-thickness organic soils, such as peats and soft plastic silts, and a high groundwater level. The described geotechnical monitoring system consists of a total of eight measurement columns in four test areas. This article is a presentation of the measurement system and the first results of measurements carried out during column load-bearing tests.

Abstract From a practical point of view, the most important feature of a parametric periodic system is the instability phenomenon. Unlike in systems with constant coefficients, in which only points of instability exist, in parametric systems, whole areas of instability occur. This study presents a method of automatic stabilisation of unstable multi-degree-of-freedom linear continuous-in-time parametric systems. In this method, a parametric excitation can only be a continuous function of time. This paper concerns the sensitivity analysis of multipliers – complex eigenvalues of the monodromy matrix. The method is an alternative approach to that proposed in all other previous works on this subject. A procedure based on sensitivity analysis and directional derivative was used. The method's innovation is achieving the non-homogeneous parametric sensitivity equation by evaluating analytically the derivative of the homogeneous parametric equation of motion with respect to the design parameter. Then, by solving this sensitivity equation, evaluating the first derivative of the monodromy matrix, and finally, the first derivatives of multipliers. Ultimately, this method is based on a sensitivity analysis of the absolute values of multipliers. Furthermore, the sensitivity analysis method was improved and generalised to allow to correctly determine the eigenderivatives also with respect to those system parameters, on which the parametric excitation period depends. In particular, it becomes possible to use the parametric excitation period as a design parameter, which was not possible in the works of other authors. Examples of this method's implementation are also presented. This work continues the topics developed by the author in his earlier works.

Abstract In an era marked by rapid growth and diminishing natural resources, including land, ground improvement has become imperative, particularly for civil engineers dealing with soft soils. This study explores the potential of granular piles (GPs) and granular piled rafts (GPRs) as cost-effective and sustainable solutions for overcoming resource-related challenges. The research focuses on a comparative analysis of the settlement interaction factor (SIF) within groups of GPRs and GPs as foundation systems. By evaluating and comparing the settlement magnification effects induced by adjacent foundation elements, the study aims to uncover insights into the influence of spacing and relative stiffness on the SIF. These findings offer valuable information for engineers, enabling them to optimize designs and address potential settlement-related issues in a resource-conscious manner

Abstract This paper presents a numerical analysis of the shrinkage of reinforced concrete foundations on the ground, known as mat foundations. It presents Finite Element Method (FEM) calculations of a beam and its verification with analytical solutions. Two numerical models of mat foundations have been adopted for the purpose of this study. The first model is a foundation resting directly on the ground, that is, on an elastic Winkler base. The second numerical model consists of layers, that is, a mat foundation and a substructure (lean concrete), taking into account the frictional forces between these layers. The Mohr–Coulomb model was used in the analyses. Conclusions were drawn from the numerical analyses on the influence of the soil substrate on the magnitude of the shrinkage stresses. Modelling the interaction between the foundation and a concrete sole using elastic bonds is clearly suboptimal. Using friction to model this connection is a better approach as it avoids underestimating shrinkage stresses. The differences can be up to an order of magnitude.

Abstract Danamic vibration absorbers (DVAs) are used to suppress the excessive structural response due to dynamic loading. To maximize their effectiveness, the placement and characteristics of DVAs need to be carefully chosen. To address this challenge, a methodology that enables this task to be accomplished by means of an evolutionary algorithm is presented in this paper. A beam subjected to a sequence of forces with random amplitudes, which move at random time instances with a constant velocity, is considered. The beam has either one or a set of two arbitrarily located DVAs. The loading is modeled using a filtered Poisson process, while the DVAs are modeled as single-degree-of-freedom (SDOF) systems. It is shown that the proposed algorithm can serve as a powerful tool when selecting an arrangement of DVAs, in turn effectively mitigating any undesired structural response. Moreover, the optimization of DVAs leads to the asymmetry of the absorber’s position along the length of a bridge’s beam. The obtained results can be used to evaluate the correctness of calculations conducted for the purpose of assessing structural damping requirements.

Abstract According to Eurocode 7, limit state design codes generally draw more attention to ultimate limit states than to serviceability limit states. This paper presents the problem of settlement assessment of spread foundations on clays when the foundation design is governed by the serviceability limit state requirements. The paper presents the test results of geotechnical parameters for heavily preconsolidated boulder clays (sandy clay saCl and silty sandy clay sasiCl), which prevail on the Warsaw University of Life Sciences – SGGW campus. The test results were used for settlement calculations of spread foundations. Based on the results of field and laboratory tests, the problem of spatial variability assessment and determination of the characteristic value of soil parameters was addressed. Classical statistics and Bayesian analysis were used in the statistical analysis of the test results. Settlements of spread foundations were calculated based on the soil parameters obtained from cone penetration tests (CPTs) and dilatometer tests (DMTs). Special attention was drawn to the selection of the characteristic values of soil parameters. Determination of the characteristic value of the constrained modulus Mk was performed using two methods: according to the well-known and frequently used formula proposed by Schneider (1997; 1999) and according to the European draft standard prEN 1997-1:2022-09. Settlement calculations of spread foundations were carried out taking into account changes in the stresses and the constrained modulus in the subsoil. The calculated settlements were verified by field measurements performed during the construction of the object. Comparison of settlements obtained from the characteristic values of the constrained modulus Mk estimated according to prEN 1997-1:2022-09 with the measured settlements indicates that the calculated values were significantly higher than the measured values. Smaller differences between the measured and calculated settlements were obtained when the characteristic values of the constrained modulus Mk were determined from Schneider's formula, while smaller differences were obtained when the mean values of the constrained modulus M mean were used.

Abstract Due to their effectiveness, environmental friendliness, and economic benefits, geosynthetics are increasingly utilized in civil engineering, especially woven geotextiles for soil stabilization reinforcement. Standard strength testing assumes a constant rate of elongation for samples, but in practice, the loading rate of geosynthetics in the field is much lower. Selecting appropriate materials is crucial for the effectiveness and durability of structures. For polymeric materials like woven geotextiles, the strain rate affects their properties. Understanding these properties is essential for safe design and construction. This article explores the potential application of polypropylene geotextiles for soil reinforcement in embankments. The polymer properties are discussed, along with the methodology for strength testing of geosynthetics and the results of the research. The findings allowed for the calculation of the long-term strength of samples at different elongation rates, which was used to verify changes in the factor of safety for a slope model. The highest tensile strength was 33.44 kN/m at a stretching speed of 20 mm/min. At 2 mm/min, it was 30.35 kN/m, and at 0.2 mm/min, it was 28.70 kN/m. These results determined the factor of safety: F = 2.08 for the fastest stretched sample and F = 1.97 for the slowest. Theoretical approaches to understanding changes in strength parameters due to variations in strain rate have been presented, as well as computational approaches using the Bishop method in GEO5 software, based on the results from tensile strength tests.