Existence theorems in the geometrically non-linear 6-parametric theory of elastic plates

In this paper we show the existence of global minimizers for the geometrically exact, non-linear equations of elastic plates, in the framework of the general 6-parametric shell theory. A characteristic feature of this model for shells is the appearance of two independent kinematic fields: the translation vector field and the rotation tensor field (representing in total 6 independent scalar kinematic variables). For isotropic plates, we prove the existence theorem by applying the direct methods of the calculus of variations. Then, we generalize our existence result to the case of anisotropic plates. We also present a detailed comparison with a previously established Cosserat plate model.Comment: 19 pages, 1 figur

Arch bridges under test loadings

According to the Polish bridge design code road bridges with spans over 20 m and all railway bridges, before they are given to public usage, all require the conduction of studies during a test loading. This paper is an illustration to the experience in arch bridge test loadings of the research team of Department of Structural Mechanics and Bridge Structures from the Gdansk University of Technology. It concerns the applied computational conceptions and researches on an example of three arch bridges, built between 2005 and 2007. The presented calculations results consists the analysis of spatial construction schemes made using the finite elements method (FEM) and its comparison to the field studies. The goal of the studies is to check the correctness of the construction 's work and of the design assumptions. Arch bridges with the longest spans, visualisation of the computational model, the displacement - deflection graphs of the arch bridge construction, generating the extreme span 's deflections, results of the calculations and field dynamic measurements of the some bridges, example of computation results and field dynamic measurements during the static tests are presented in the paper

Historical crane on the redesigned original trestle bridge as a memorial of Gdansk Shipyard

W pracy omówiono wybrane zagadnienia z przeprowadzonych badań mających na celu ocenę możliwości pozostawienia historycznego żurawia 642-24 na estakadzie B-5 w obecnej lokalizacji po modyfikacji jej schematu statycznego. Zmiana miałaby polegać na skróceniu konstrukcji jedenastoprzęsłowej do dwóch lub jednego przęsła. W referacie zawarto: ocenę aktualnego stanu technicznego obiektu, prezentację zakresu obliczeń MES, opis przyjętych schematów obciążeń, przedstawienie wyników obliczeń statycznych i wymiarowania elementów ustroju, sprawdzenie globalnej i lokalnej stateczności oraz charakterystyk dynamicznych konstrukcji.The paper includes selected aspects of the study, whose goal is to hold the historical crane 642-24 in its current location after the modification of trestle bridge static scheme. The scope of the paper includes the assessment of current technical condition of the object, a presentation of FEM analyses, a description of the assumed load cases, results of the static calculations, checking the effort of construction elements, global and local structure stability and its dynamic characteristics

Damage Analysis of Tensioning Cable Anchorage Zone of a Bridge Superstructure, Using CDP Abaqus Material Model

Numerical analysis of the tensioning cables anchorage zone of a bridge superstructure is presented in this paper. It aims to identify why severe concrete cracking occurs during the tensioning process in the vicinity of anchor heads. In order to simulate the tensioning, among others, a so-called local numerical model of a section of the bridge superstructure was created in the Abaqus Finite Element Method (FEM) environment. The model contains all the important elements of the analyzed section of the concrete bridge superstructure, namely concrete, reinforcement and the anchoring system. FEM analyses are performed with the inclusion of both material and geometric nonlinearities. Concrete Damage Plasticity (CDP) constitutive relation from Abaqus is used to describe nonlinear concrete behaviour, which enables analysis of concrete damage and crack propagation. These numerical FEM results are then compared with actual crack patterns, which have been spotted and inventoried at the bridge construction site

State of emergency of railway viaduct in Bydgoszcz

W artykule przedstawiono opis stanu awaryjnego wiaduktu kolejowego. Omówiono wyniki badań in situ oraz teoretycznych analiz statyczno-wytrzymałościowych ponad 100-letniego obiektu. Przedstawiono wnioski i zalecenia dotyczące doraźnego zabezpieczenia obiektu oraz warunki jego dalszej eksploatacji.The aim of this paper is to describe the damage of railway viaduct. The results of load tests and theoretical static analysis of over 100-years old viaduct are shown. Finally temporary preservation and the perspective of future exploitation are discussed

A novel formulation of 3D spectral element for wave propagation in reinforced concrete

The paper deals with numerical simulations of wave propagation in reinforced concrete for damage detection purposes. A novel formulation of a 3D spectral element was proposed. The reinforcement modelled as the truss spectral element was embedded in the 3D solid spectral finite element. Numerical simulations have been conducted on cuboid concrete specimens reinforced with two steel bars. Different degradation models were considered to study the real behaviour of bended beams

Composite GFRP u-shaped footbridge

The paper presents proposals for the use of glass fiber reinforced polymer composites for the construction of engineering objects, known and commonly used in the shipbuilding industry. An example of a pedestrian footbridge was used in this case, which, despite the considerable thickness of the structural material, was made using infusion technology in one production cycle. The designed and produced footbridge span is durable, dynamically resistant, incombustible, easy to install and maintain, resistant to weather conditions and also aesthetically interesting. For footbridge production environmentally friendly PET foam core may be used. It may come from recycling of used plastic packages and which is produced with less energy consumption process and much less CO2 emission. The load bearing part of the structure (skin) is made of polymer laminate reinforced with glass fabrics (GFRP)