Volume 44 (2022): Edizione 2 (June 2022)

The paper presents the method and results of numerical simulations of the mutual dynamic interactions between vehicles and the bridge structure, which has defect in the form of excessive permanent deformations. The parametric analyses were carried out taking into account the following parameters: permanent deflections of spans, with a maximum value ranging from 0 to 150 mm, vehicle speed from 10 m/s (36 km/h) to 30 m/s (108 km/h), and two types of heavy vehicle suspension systems, each with very different properties. The presented analyses are based on the characteristics of real motorway bridge structure with permanent deflections of the multi-span main girders, constructed of steel beams and reinforced concrete slab. The proposed procedure of dynamic numerical analysis can also be useful in the assessment of the influence of permanent deflections on the interactions between vehicles and other types of bridge structures.

It is proved analytically that the complex growth rate σ= σ_r+iσ_i (σ_r and σ_i are the real and imaginary parts of σ, respectively) of an arbitrary oscillatory motion of neutral or growing amplitude in ferrothermohaline convection in a ferrofluid layer for the case of free boundaries is located inside a semicircle in the right half of the σ_rσ_i-plane, whose center is at the origin and radius = Rs[1−M1′(1−1M5)]Pr′, {\rm{radius}}\, = \,\sqrt {{{{R_s}\left[{1 - M_1^{'}\left({1 - {1 \over {{M_5}}}} \right)} \right]} \over {P_r^{'}}}}, where R_s is the concentration Rayleigh number, P_r^′ is the solutal Prandtl number, M₁^′ is the ratio of magnetic flux due to concentration fluctuation to the gravitational force, and M₅ is the ratio of concentration effect on magnetic field to pyromagnetic coefficient. Further, bounds for the case of rigid boundaries are also derived separately.

The paper presents designing due to the instability in-plane problem of the net-arch bridge. Firstly, three essential nonlinear examples are benchmarked in a finite element software. Secondly, linear and nonlinear buckling analyses are conducted, with the purpose of investigating the impact of nonlinear behavior of cables on steel arch instability, involving a comparison of the critical load factor and form from both the linear buckling and the post-critical third-order theory analyses. The impact of prestress and tension, elevation, and hanger failure on instability is discussed. Moreover, a new method for determining nonlinear buckling form for the net-arch structure is proposed in order to allow implementation of Unique Global and Local Imperfection method in cable structures. Calculations are conducted in the finite element software. The model of the network arch bridge is based on the bridge over Vistula River in Cracow.

According to Polish law, it is prohibited to perform excavations or locate buildings closer than 50 m from the embankment. In order to obtain exemption from this ban, filtration and stability analysis of the embankment and excavation in the flood conditions have to be performed. This paper presents results of the numerical investigations on interactions between excavations and embankment. Complex nature of the problem is presented. Methodology of numerical simulations and real case examples are described.

In today’s time, construction is the main key for development of any nation, but land resources are getting deplete. Thus, construction on compressible soil is left as a choice. Stone columns or granular piles (GPs) are broadly used to advance the bearing capacity of crummy ground and lessen the displacement of constructionserected on them. GP is the most efficient and cheap for ground improvement. Analysis of single partially strengthened (SPS) floating granular piled raft is presented in this paper in terms of several normalized aspects like vertical and radial displacement impact factors, settlement impact factor (SIF) for any depth, the normalized GP–soil interface shear and radial stresses, the load ratio, i.e., the percentage of the load taken by the GP and raft to the total load, and the normalized contact pressure distribution below the raft, which are evaluated for SPS floating granular piled raft. The SIF for top of GP is noticed to decline with the surge in the values of the strengthening parameters. The interfacial shear stresses get reorganized along the length of the GP.

The Youd etal liquefaction resistance curves developed in 2001 to characterize the cyclic resistance of soil based on SPT test are the most used in the context of the Seed and Idriss simplified procedure as a deterministic model. These curves were developed from a modified database of Seed etal. in 1985 with the assumption that the actual peak shear stress (τ_d) induced at depth h is always less than that predicted by the simplified procedure (τ_r) of Seed and Idriss (rd= τ_d/τ_r<1). By using a suite of equivalent linear site response analyses to adjust the dynamic and the simplified shear stress at depth h, Filali and Sbartai showed in 2017 that the dynamic peak shear stress for some earthquakes is greater than the simplified peak shear stress (rd>1). As in this case, the assumption of the simplified procedure is not verified, Filali and Sbartai have proposed a corrector factor (RC) in the range where r_d>1 to adjust the deformable and rigid body. In this paper, we will present a probabilistic study for the evaluation of the liquefaction potential using a database based on SPT measurement compiled after the Chi-Chi Taiwan earthquake, in which the cyclic stress ratio is evaluated using the proposed corrector factor. The objective of this study is to present a probabilistic shape of the cyclic resistance ratio (CRR) curves based on the original simplified method of Seed and Idriss and the corrected version and a new formulation for computing the probability of liquefaction.