Jacek Szafran

Lodz University of Technology · Department of Structural Mechanics

Sustainability, reliability, and durability are consistently key concerns in the construction industry. For the sake of development , new materials and structural solutions are constantly being invented. Modern approaches to structural design involve optimization techniques, which allow for the efficient use of the construction material. On the oth...

The main goal of this paper is to present the methodology of studies that were carried out to measure simultaneously lattice tower displacements together with wind velocity and direction as well as displacements of structural components of the tower to calculate stresses. Accelerations were also measured. The results were compared with the analytic...

This paper focuses on the optimization analysis of a 62-meter-high lattice tower structure with respect to the choice of its bracing system. The optimization aims at reducing the structure selfweight, which directly impacts its production costs, while maintaining an appropriate level of its load-carrying capacity. The cost optimization is particula...

Przedmiotem zgłoszenia jest stanowisko badawcze do badań belek żelbetowych pokrytych powłoką z polimocznika z wykorzystaniem technik optycznych i bezdotykowych metod pomiarowych, wyposażone w system optycznej korelacji obrazu (9), współpracujący z jednostką centralną do akwizycji i analizy danych, które posiada niezależną ramową konstrukcję stalową...

Przedmiotem zgłoszenia przedstawionym na rysunku jest sposób zabezpieczania belki żelbetowej warstwową powłoką z polimocznika, w którym w pierwszej kolejności przygotowuje się powierzchnię belki żelbetowej poprzez szlifowanie betonu. Następnie na wyszlifowaną powierzchnię belki aplikuje się grunt na bazie żywicy epoksydowej. Zagruntowaną belkę obsy...

Polyurea coatings as a possible structural reinforcement system” is a research project aimed at exploring possible applications of polyurea coatings for improving structural performance (including steel, concrete, wooden and other structures used in the construction industry). As part of the project, this paper focuses on evaluating the performance...

The paper presents a set of results concerning displacements of a 62-meter-high telecommunication tower. In total, 25 calculation models with different distances between tower legs were developed. In addition to the geometrical changes in the construction, the wind action for each model also considered a change in its aerodynamic drag and the upwin...

The paper discusses the results of laboratory experimental studies on reinforced concrete components (beams) with an outer polyurea layer. The main conclusion from this part of the research is that the beam elements covered with a polyurea layer are protected against corrosion processes even in an emergency state. The occurrence of scratches, even...

The paper discusses the results of laboratory experimental studies on reinforced concrete components (beams) with an outer polyurea layer. The important part of the study is the comparison of the results concerning the load-displacement relation for the reference beams (without the polyurea layer on their external surfaces) and those with the polyu...

The paper deals with evaluating the load-carrying capacity of industrial masonry chimneys used as structures supporting mobile telephony base stations. The goal of the research was to compare calculation approaches to the evaluation of wind actions according to two different methods provided for in standards and to emphasize significant discrepanci...

The paper addresses issues related to evaluating wind actions on complex antenna structures on telecommunications facilities. Looking for an analytical solution to such issues is challenging mainly because there are various types of towers with multiple support structures, many types of antennas in various arrangements, and different geometrical re...

The paper presents complex calculation analyses of a non-standard reinforcement of tower legs (made of L-sections). The construction of a combined cross-section (comprising L-sections and two round solid bars) and the influence of the additional elements on basic geometric characteristics of the elements are shown. Section forces resulting from win...

Link: https://repozytorium.p.lodz.pl/handle/11652/4391

The paper discusses the results of experimental research on polyurea. In authors' opinion, this material could be used to improve load-carrying capacity and integrity of structural elements made of various materials. The paper presents the results of research on basic mechanical properties of polyurea, its impact on integrity of cellular concrete s...

The experimental studies carried out by the author of this paper involved full-scale testing of six independent steel telecommunication towers. The assumptions of the tests, the equipment used, and details on how the tests were conducted and how measurements were taken are also provided in previous works. In this paper discussion of the failure m...

Designing of the structures using partial safety factors based on the SORM reliability indices allow to optimize these structures and to keep the necessary safety margins. This article is entirely devoted to a partial safety factors calibration procedure and its practical application on the examples of steel lattice towers chosen as the very slende...

“Polyurea coatings as a possible structural reinforcement system” is a research project aimed at exploring possible applications of polyurea coatings for improving structural performance (including steel, concrete, wooden and other structures used in the construction industry). As part of the project, this paper focuses on evaluating the performanc...

Niestandardowe wzmocnienia stalowych konstrukcji przestrzennych – przykłady realizacji i obliczeń.

The study is a description of the research carried out as part of the research project “Polyurea coatings as possible reinforcement system”. The main assumption of the article is to assess the suitability of polyurea coatings to improve the performance characteristics of building structure elements. For the purposes of the study, basic polyurea stu...

This paper describes studies completed under the research project "Polyurea coatings as a possible reinforcement system". It primarily aims at assessing the usability of polyurea coatings for improving the performance of components of building structures. Basic studies on polyurea, simple physical tests and full-scale experiments were carried out f...

The main goal of this paper is to present the results of the buckling resistance analysis of two types of unconventional reinforcement of legs of a telecommunications tower by means of equal-leg angle sections. The key reinforcing elements are round solid bars that are connected with the angle section in various ways. Two types of connection betwee...

The paper emphasizes aspects that have to be addressed when analyzing monopole structures, such as vortex excitation occurring due to a repeating pattern of vortex shedding in the flow of air around a tower (von Kármán vortex street). The fatigue analysis is discussed in detail in the paper and it presents solutions that were introduced on the basi...

The main goal of this paper is to provide recommendations for designing state‐of‐the‐art and lightweight steel lattice telecommunication towers which offer the highest possible load‐carrying capacity. The design rules presented in the paper are based on experimental results obtained for two independent tower structures. Full‐scale facilities, namel...

The article presents basic information on the use of polyurea membranes as a highly effective system protecting steel structures against corrosion. The basic advantages and disadvantages of this type of insulation are described, with particular emphasis on their use as an anti-corrosion coating. Two implementation cases were presented: a steel silo...

The use of polyurea systems to improve the strength and durability of structural elements used in construction.

The paper describes a part of studies under the research project “Polyurea coatings as a possible structural reinforcement system”. The main goal of the experimental investigation is to explore possible applications of polyurea coatings for reinforcing structures (including steel, concrete, wooden and other structures used in building industry). Th...

The article presents basic information on building corrosion processes and the use of polyurea systems as a functional method of protecting structures against corrosion. The basic advantages and disadvantages of this type of insulation are described, with particular use as an anti-corrosion coating and a positive effect on the strength parameters o...

This work concerns the stochastic finite-element method (SFEM) reliability analysis of a skeletal, very slender steel telecom-munication tower calibrated with a full-scale pushover experiment carried out for the same tower. The basic SFEM implementation is completed with common application of the generalized stochastic perturbation technique (SPT)...

Given the large number of steel lattice tower structures that have been erected (on average, for the mobile telephony alone, between 50 and 100 facilities are erected each year across Poland), their operation, manufacturing, and design requirements are slightly more complex than in the case of traditional steel structures. Due to the number of...

The main goal of this work is to present numerical analysis of time-dependent reliability of a steel slender lattice tower subjected to the given stochastic atmospheric corrosion.

29 th Meeting Winchester 8-12 September 2019 IASS Working Group No. 4 – Technical Expert Group for Masts and Towers

This work concerns the Stochastic Finite Element Method (SFEM) reliability analysis of the skeletal, very slender steel telecommunication tower calibrated with the full scale pushover experiment carried out for the same tower. The basic SFEM implementation is completed with common application of the generalized stochastic perturbation technique (SP...

Modern construction aims at making new and self-sufficient buildings. This also applies to the heating demand for heating system, which actually increases the requirements for insulation of partitions. This is closely related to the search for new materials and polyurethane foam PUR is a perfect example of modern insulating material. It is importan...

The main aim of this paper is to present a reliability estimation procedure for steel lattice telecommunication towers based on tensioned joint reliability. The experiment, which involved doing a full-scale pushover test of a 40 m high lattice tower, constituted the starting point for further analyses. Experimental data served as bases for finite e...

Modern construction generates new and demanding requirements regarding building materials. This also applies to products used for thermal insulation, waterproofing and damp proofing. The solution here might be modern spray insulation in the form of PUR foam and polyurea. The article presents their basic properties, while emphasising their competiti...

The main goal of this paper is to present coupled Computational Fluid Dynamics and structural analysis for the precise determination of wind impact on internal forces and deformations of structural elements of a longspan roof structure. The Finite Volume Method (FVM) serves for a solution of the fluid flow problem to model the air flow around the s...

The study is the next part of the research project related to the possibilities of application polyurea coating in civil engineering. This project focus on the impact of polyurea coating applications mainly on steel, concrete and reinforced concrete components currently used in civil engineering. The main goal of the paper is a presentation of stru...

Modern building industry generates new and extraordinary demands on the building materials used. It is also the case for construction materials used for thermal insulation, waterproofing and anti-waterproofing. The solution to the new demands can be the spray insulation in the form of PUR foam and polyurea, which is undoubted advantage of ease of a...

The main aim of this paper was to present the influence of full-scale experiments under breaking load on design process. The main attention is focused on mechanisms of destruction of steel lattice telecommunication towers, which are widely used in Poland. The basis of analysis was results obtained by full scale tests. This approach allow to include...

This work is focused on the experimental-based Stochastic Finite Element Method analysis of the steel lattice telecommunication structure exposed to the wind pressure, whose average value is treated as the Gaussian random variable. The Least Squares Method is provided here for symbolic recovery of the polynomial responses of this structure in addit...

The main aim of this paper is a presentation of the results obtained for the stochastic analysis of structural joints. The starting point constituted full-scale pushover test of the 40 m lattice tower. Experimental data served for FE model calibration (entire tower), assignment of steel mechanical properties and results confirmation for structural...

The main objective of the presented paper is to discuss chosen lattice tower joint behavior under structure ultimate load. Joint numerical modelling considerations are enriched with comparison to the full-scale tower pushover test results. Two independent load cases were examined: 1) where the L-sections (diagonal bracings) are loaded by the axial...

The main aim of this paper is to present a Stochastic Finite Element Method analysis with reference to principal design parameters of bridges for pedestrians: eigenfrequency and deflection of bridge span. They are considered with respect to random thickness of plates in boxed-section bridge platform, Young modulus of structural steel and static loa...

The main aim of this study was to analyze the behaviour of steel circular hollow sections which are widely used in engineering structures such as masts or towers. The laboratory tests consisted of a series of axial compression trials which were executed until the moment of global stability loss has been reached. The tests were performed with nine s...

The main aim of this study was to estimate structural reliability of a steel lattice telecommunication tower by determining the reliability index β with a SORM approach using full dynamic analysis. A properly calibrated FE computational model created based on tower experimental data, which were obtained from a full-scale test, was used for this pur...

The main goal of the paper is to present the current state of knowledge about polyurea coating system. The emphasis was placed here on presentation of two topics: material which is polyurea and its present applications, and a device for spraying polyurea coating systems. The work, in the next parts, focuses on explaining why polyurea is uncommon an...

Steel lattice towers are frequently used in wide range of civil engineering activities like telecommunication an the power industry. The main type of load in case of the high, slender tower structures is a wind action. Geometrical properties like: cross section of the tower (square, triangular, rectangular), spacing of the supports, convergence of...

The main aim of this paper is presentation of the wind impact analysis results for the structure having complex geometry, where a modular space grid constitutes the roof shell surface. The wind load has been estimated using the pressure coefficients calculated according to the Eurocode standards. The results have been subsequently compared with num...

The main aim of this paper is a presentation of the results obtained for the stochastic analysis concerned steel chimney with the height equal to 40 meters and subjected to the random wind loading. Analysis was performed with using generalized stochastic perturbation technique based on a Taylor expansion and traditional Finite Element Method. Polyn...

The main aim of this paper is to present results of a full-scale pushover test of a 40 meter telecommunication tower under breaking load. A detailed description of the studied tower has been presented with emphasis on the geometrical imperfections of the selected members of the structure. The results of the experiment consisting of the axial forces...

The main aim of this article is a global, conceptual analysis of a speedway stadium which is an adaptation of an existing sports object: Beira Rio in Porto Alegre. The following elaboration includes a selection process of the primary elements' geometries for the concerned structure: truss girders, and presentation of geometric parameters for the wh...

This article encompasses a presentation of preparation works and full-scale experiments of three different steel lattice telecommunication towers. The emphasis was placed here on the way how these experiments were performed and particularly on the experimental site selection, foundation site preparation, equipment application as well as an impact o...

The main aim of this paper is a presentation of the results obtained for the stochastic analysis concerned steel chimney with the height equal to 40 meters and subjected to the random wind loading. Analysis was performed with using generalized stochastic perturbation technique based on a Taylor expansion and traditional Finite Element Method. Polyn...

The main focus of this paper is the presentation of the capabilities of the numerical analysis dedicated to cable structures affected by random parameters. The main tool of the analysis carried out is the Generalized Stochastic Perturbation Method. It allows to determine numerically the statistical data for horizontal reaction of a single cable wit...

The main aim of this paper is to present how informative, and relevant in advancing the current state of knowledge, destructive experiments can be, particularly when carried out in a controlled manner on full-scale objects. All the considerations presented in the manuscript are based on the results of the experiments that were fully devoted to the...

Computational determination of aerodynamic resistance for high truss structures like telecommunications towers is the subject of this study. Normalized procedures were presented with an example of an existing structure concerning the total wind coefficient. The results of calculations along with their broad elaboration and interpretation have been...

The main purpose of this work is to verify the influence of the weighting procedure in the Least Squares Method on the probabilistic moments resulting from the stability analysis of steel skeletal structures. We discuss this issue also in the context of the geometrical nonlinearity appearing in the Stochastic Finite Element Method equations for the...

The main objective of this paper is to present and discuss failure mechanism, failure mode, as well as plastic deformation of a lattice telecommunication tower obtained during a full-scale pushover test. The manuscript consists of a detailed description of the tested structure and the experimental site. Displacements of particular nodes of the towe...

The main purpose of this work is to verify the influence of the weighting procedure in the Least Squares Method on the probabilistic moments resulting from the stability analysis of steel skeletal structures. We discuss this issue also in the context of the geometrical nonlinearity appearing in the Stochastic Finite Element Method equations for the...

The main aim of this paper is a presentation of computational analysis of the forced vibration of the steel telecommunication tower resulting from the uncertain wind blows with the use of the Stochastic Finite Element Method. This approach is based upon the Taylor expansion with random coefficients of a general order for all input and output random...

The main aim of this paper is to present the problems related to the design of steel chimneys according to former PN-B and current PN-EN standards. The selected research material is useful particularly in the analysis of already existing structures designed and erected several years ago. Carrying capacity recalculations of chimney structures are ve...

The main aim of the work is to show an application of the generalized stochastic perturbation technique based on Taylor expansion to the Finite Element Method implementation in structural elastodynamic problems. This is worked out thanks to the symbolic derivation provided in computer algebra MAPLE and thanks to the Least Squares Method embedded in...

The main aim of this paper is to present a mathematical model and its numerical realization for the composite material with stochastic interface defects employing the perturbation-based stochastic finite elements. The defects are modeled as the semicircular micro-cavities (“bubbles”) lying with their diameters on the reinforcement-matrix interface...

The main issue in this article is computational probabilistic analysis and reliability assessment of the steel telecommunication towers subjected to material and environmental uncertainty. Such a discussion is important since very wide, frequent and relatively modern application of these structures, which are subjected to various sources of uncerta...

This paper addresses the important question in structural analysis how to efficiently model the eigenvibrations of the steel footbridge structures with random geometrical and/or physical parameters. Numerical analysis is based here on the traditional Finite Element Method enriched with the stochastic perturbation technique in its generalized nth or...

This paper addresses an important question in structural analysis how to efficiently model the uncertain temperature influence on the internal forces in particular structural elements of the steel telecommunication towers. The computational methodology proposed here is based on the traditional Finite Element Method enriched with the generalized sto...

The main aim of this paper is to make a comparison of the eigenfrequencies of the high telecommunication towers alternatively manufactured using the stainless steel and the aluminium components. It is provided each time assuming that the Young modulus of the applied material is the Gaussian input random variable and using the general-ized stochasti...

This paper addresses the important question in structural analysis how to efficiently model the eigenvibrations of the spatial structures with random physical and/or geometrical parameters. The entire computational methodology is based on the traditional Finite Element Method enriched with the stochastic perturbation technique in its generalized nt...

The main aim of this paper is to demonstrate the application of the generalized stochastic perturbation technique to model the lognormal random variables in structural mechanics. This is done to study probabilistic characteristics of the eigenvibrations for the high telecommunication towers with random stiffness, which are modeled as the linear ela...