This paper addresses the problem of road safety regarding barrier placement as relative to the curb. A short summary of existing regulations is presented. Numerical simulations using the explicit finite element system Ls-Dyna are shown. In the analysis, variable distance between the barrier and the curb is assumed. The obtained result reveals that the distance has little impact on the working width of the barrier.

The use of the passivity-based control (PBC) properly fits stability problems related to multilevel converters. Two approaches for

the PBC design have been proposed and will be reviewed in the present paper. Particularly the second is developed by splitting the system into n subsystems and controlling them independently. The partition of the multilevel converter is done on the basis of energy considerations. The main advantage of the second approach is the separate control of the different DC-links and a flexible loading capability.

A finite element (FE) model of the straight guideway bridge under monorail train has been built in this research in order to investigate dynamic interactions of the coupled system in the vertical and longitudinal direction. A limited length of the straddle monorail bridge including five continuous spans is modeled in three dimensions by using FE method. A 3D model of the monorail train system, built in the multibody analyzer MSC ADAMS, is assembled over the bridge. The entire model, consisting of the vehicle and bridge subsystems, is numerically analyzed by performing dynamic simulation in time domain. The braking forces between the train tires and guideway beams are activated in the analysis, in addition to the dead weights of the components and the train live loads. Dynamic forces in the tires are obtained for the case of the emergency braking in the system. The reaction forces, appeared in the bridge piers, are reported as the input forces for the purpose of the bridge design.

The paper presents selected aspects of dynamic numerical simulations of an orthotropic steel railway bridge loaded by high-speed trains. The model of moving loads was adopted in accordance with the models set out in the applicable standards. The current European code requirements are referred in which the computer calculations of the dynamic response of the structure are the basis for assessing the suitability of the structure to carry high-speed rail traffic ( v > 160 km/h ). In this research the calculations are based on the author's method of generating traffic roads in Abaqus FEM environment. lt is emphasized in the paper that in most commercial FEM codes (including Abaqus), moving loads are not implemented in modules responsible for defining of loads. The author's approach to this issue allowed to obtain results confirming its adequacy. In the longer term, the authors will develop a plan to adapt this algorithm in order to generale traftic loads on bridges discretized as spatial and plane numerical models.

On the 14th of February, 2015, a huge fire broke out on Łazienkowski Bridge; a five span bridge, 423 m long and 28 m wide, built in the years 1972-74. It was a fully steel structure with four plate girders and orthotropic deck. The fire started under the first span during the replacement of wooden service decks. The next day, the Department of Bridges of the Warsaw University of Technology was designated to conduct an expertise material investigation, geometrical verification, and FEM model analysis. The subject of this paper concentrates on geometrical issues. The main difficulty of this task was the lack of full reference data regarding the bridge's original structure. The old design was incomplete and there was no actual surveying results for the undamaged structure. As a conclusion, some remarks focused on surveying measurements and on the final decision regarding this bridge are given. It was eventually exchanged into a brand new one and put into public use on the 28th of October, 2015.

Arch bridges are built since two thousand years at least. Structural materials changed during this time. The design methods were changed also. The biggest impact was noted with development of Finite Element Method and graphical methods of preparation of technical drawings which is strictly combined with development of computers. These processes appeared also in Polish construction industry, especially from the beginning of 90-ties XX century.

But in this paper we do not consider mentioned above problems. We would like to present development of arch bridges from construction technology point of view. This aspect of creation of bridge structures is not very often the subject-matter of analysis. For many investors, design engineers and contractors optimization of structures is most important issue. For most of them the reduction of volume (weight) of structural material is only solution. But sometimes it is not true – the construction technology gives much more efficient results.

We present below examples of realization in Poland medium and large span arch bridges – steel, concrete and hybrid structures.

The paper presents descriptions of bridge disintegration types and contact mass loss in the bridge stage. There is presented Matlab solvers to solve equation describing dynamic changes of temperature in the bridge region. The final result of program calculations is the mass loss and the volume of the metal of contacts which was lost during the bridge stage.

This paper presents the design, fabrication and testing of an improved thin-film thermal converter based on an electro-thermally excited and piezo-resistively detected micro-bridge resonator. The resonant thermal converter comprises a bifilar heater and an opposing micro-bridge resonator. When the micro-bridge resonator absorbs the radiant heat from the heater, its axial strain changes, then its resonant frequency follows. Therefore the alternating voltage or current can be transferred to the equivalent DC quantity. A non-contact temperature sensing mechanism eliminates heat loss from thermopiles and reduces coupling capacitance between the temperature sensor and the heater compared with traditional thin-film thermal converters based on thermopiles. In addition, the quasi-digital output of the resonant thin-film thermal converter eliminates such problems as intensity fluctuations associated with analogue signals output by traditional thin-film thermal converters. Using the fast-reversed DC (FRDC) method, the thermoelectric transfer difference, which determines the frequency-independent part of the ac-dc transfer difference, is evaluated to be as low as 1.1 · 10−6. It indicates that the non-contact temperature sensing mechanism is a feasible method to develop a high-performance thermal converter.

The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient

Several previous investigations on failure of a certain type lattice girders railway bridge (on so called BJD line) have not convincingly explained reasons nor have they described potential hazards. This paper attempts to provide an answer, employing static, dynamic, and fatigue analysis of the structure, focusing on previously not analyzed vibrations of elements constituting a lattice node. Detailed models of two types of such nodes – damaged and non- damaged were compared, inside carefully defined limits of applicability.

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.

This study was carried out on the background of Sutong Bridge project based on fracture mechanics, aiming at analyzing the growth mechanism of fatigue cracks of a bridge under the load of vehicles. Stress intensity factor (SIF) can be calculated by various methods. Three steel plates with different kinds of cracks were taken as the samples in this study. With the combination of finite element analysis software ABAQUS and the J integral method, SIF values of the samples were calculated. After that, the extended finite element method in the simulation of fatigue crack growth was introduced, and the simulation of crack growth paths under different external loads was analyzed. At last, we took a partial model from the Sutong Bridge and supposed its two dangerous parts already had fine cracks; then simulative vehicle load was added onto the U-rib to predict crack growth paths using the extended finite element method.

The analysis was focused on three post-tensioned slab bridges, constructed in 1950s. Two of them function normally and will probably achieve the life span of 100 years required by the relevant regulations. The third one will likely be demolished soon and replaced with a new reinforced concrete frame bridge. To its degradation contributed the faulty diagnosis of its technical condition during its periodic technical inspections. The introduction briefly characterises the development of the prestressed structure theories reviewing papers on concrete rheology and monographs looking into prestressing. The paper is based on the existing fragments of the technical design documents concerning the bridges in question. The bridges were designed by Polish civil engineers.

The new topology of three-winding welding transformer is proposed. Each secondary winding is connected in parallel through the separate bridge rectifier to the welding arc. The main feature of the proposed device is parallel working of two secondary windings with different rated voltage. The advantage is nonlinear transformation ratio of current that provides unprecedented power efficiency. The self- and mutual leakage inductances, which are important in power conversion, are calculated by 2D FEA model. The operational current of the device is modelled numerically via P-Spice simulator. The proposed topology is up to 30% more power effective than conventional welding transformer provided that the leakage inductances of primary and secondary windings are correctly fitted. This transformer is used for manual arc welding.

The effects of friction were observed in electric guitar strings passing over an electric guitar saddle. The effects of changing the ratio of the diameter of the winding to the diameter of the core of the string, the angle through which the string is bent, and the length on either side of the saddle were measured. Relative tensions were deduced by plucking and measuring the frequencies of vibration of the two portions of string. Coefficients of friction consistent with the capstan equation were calculated and were found to be lower than 0.26 for wound strings (nickel plated steel windings on steel cores) and lower than 0.17 for unwound (tin plated steel) strings. The largest values of friction were associated with strings of narrower windings and wider cores and this may be due to the uneven nature of the contact between the string and saddle for wound strings or due the surface of the windings deforming more, encouraging fresh (and therefore higher friction) metal to metal contact. It is advised to apply lubrication under the saddle to string contact point after first bringing the string up to pitch rather than before in order to prevent this fresh metal to metal contact.

Prof. Przemysław Perlikowski, a mechanical engineer, and his wife Asst. Prof. Renata Perlikowska, who studies opioid peptides used in medicine, discuss the challenges of research work and life.

Development of the transport infrastructure in Poland has contributed to the implementation of various technologies of construction of bridges and their components. Use of reinforced soil for construction of embankments, retaining structures (RSS walls) and abutments is one of the solutions which has been frequently used for the past twenty years. Shortly after its development, the technology proposed by Henri Vidal in 1966 also gained appreciation in Poland [4]. Reinforced soil bridge abutments started to be widely used in Poland at the turn of the 20th century. The bridge facilities at the junction of Trasa Siekierkowska route and Wał Miedzeszyński Street in Warsaw, which were built in the years 2000÷2002, are an example of structures from that period. The authors of this paper have been particularly interested in the outermost supports of the reinforced concrete flyovers which were constructed in the form of intermediate reinforced soil abutments. Offsets – the vertical displacements, in the range of 15÷25mm, emerging between the level of the road surface and the steel elements of the expansion joints which separate the flyover’s structure from the embankment – were observed in 2015, in the course of regular inspections. While accounting for the observations which have been made, the surveying measurements and the ground investigation, the paper diagnoses and describes the mechanism which led to the emergence of the offsets. Potential patterns of the occurrence of additional settlements, as the reason for emergence of the offsets, were identified and analyzed. The settlement of the outermost support (abutment), as a result of increase of relative density of alluvial sands due to the dynamic interaction of the roadways of Wał Miedzeszyński Street, was analyzed. Analytical and numeric approaches were used in the course of analysis while relying on PLAXIS and MIDAS software.