Attila László Joó

Budapest University of Technology and Economics · Department of Structural Engineering

Since cold-formed steel (CFS) elements are susceptible to complex buckling phenomena that decrease their structural capability, many strengthening trends have been developed so far. One of these methods is the use of polystyrene aggregate concrete (PAC) as bracings in order to restrain the global and distortional buckling modes of CFS members, wher...

Orthotropic steel decks are widely used in the bridge engineering practice due to light weight, high performance and high ultimate strength-to-weight ratio. Purpose of the current paper is developing the first residual stress model for orthotropic steel decks (OSDs) with U-shaped stiffeners based on residual stress measurement results. The proposed...

A promising design concept, the performance-based wind engineering methodology is adopted, implementing a finite element model (FEM) to analyse the structural behaviour of a telecommunication steel lattice mast. The integration of site-specific wind loading models into the standardized FEM-based design can be a powerful tool for design engineers. T...

The study adopts the Performance‐Based Design concept to analyse the structural behaviour of a telecommunication steel lattice tower equipped with wind speed and strain sensors located in Central Hungary. Bayesian updating is utilised to combine the information from the relatively short measurement collected at the site with a longer dataset from a...

Jelen cikk a 2017-1.3.1-VKE-2017-00040 számú "Hálózatosodott technológiák alkalmazása acélszerkezetek gyártása, szerelése, fenntartása és kapcsolódó szolgáltatások területén" című pályázati tevékenység fő eredményeit összefoglaló MAGÉSZ folyóirat különszám bevezető cikke. Célja, hogy röviden bemutassa az elvégzett munkát, összefoglalja az eredménye...

Welded T-joints are commonly used in manufacturing of stiffened panels or crossbeams. However, welding of web-to-flange joint induces residual stresses and distortions resulting in significant challenges during both manufacturing and service. These issues can ultimately impact the structural performance, including fatigue and stability, and lifetim...

Several breakthroughs have appeared in different applications due to deep learning which can be applied in Bridge Weigh-In-Motion (BWIM) systems as well. Therefore, deep learning applications should be examined in BWIM systems. However, some deep learning-based solutions have already been proposed in the international literature, they cannot be com...

All the available information and uncertainties should be taken into account in a model to give correct answer to a stated problem and evaluate the performance of a structure. This study deals with the impact of parameter estimation uncertainty in extreme wind speeds on the assessed reliability index using frequentist approach. The peak-over-thresh...

With the increasing demand for using cost‐effective structures in the construction field, more and more novel structural systems have been developed. One of these new efficient systems is cold‐formed steel (CFS) members encased in polystyrene aggregate concrete (PAC). In this study, a simplified numerical model has been proposed, using ANSYS softwa...

The utilization of cold-formed steel (CFS) elements has become more popular recently, due to their cost efficiency and feasibility in constructional work. Nevertheless, since such elements are subjected to a variety of complex stability issues, numerous approaches of strengthening have been examined. Namely, CFS members were braced by using lightwe...

In order to investigate the stabilization effect of distinct steel members by steel cladding system including trapezoidal sheeting and sandwich panels in fire using advanced analysis techniques, the computer models and modeling techniques must be validated by available experiment tests. However, the fire tests in this area are scarce. As part of a...

Sandwich panel constructions are getting popular from the second half of the 20th century however, the restraint provided by sandwich panels in regards to the instability of structural members was not investigated at elevated temperature, which became the scope of the research introduced in this paper. An experimental test series was conducted at t...

The use of thin‐walled structures has been increasingly spread in the last few decades due to their big advantages in both structural design and construction methods. Therefore, the recent researches have discussed a wide range of thin‐walled structures applications. However, the resistance of such structures will be decreased by buckling effect; h...

By the wider spread of sandwich panels as a cladding system on industrial steel buildings, the research on various design aspects is evolving as well. The principal aim of the research introduced in this paper is to study the rotational restraint provided by sandwich panels at both ambient and elevated temperatures, and derive the temperature depen...

This paper presents the results of a theoretical-numerical study of laterally-restrained thin-walled steel rectangular hollow flange beams subjected to bending, shear and bending and shear interaction. Finite element analyses were carried out by using ANSYS software, and validated by previous experimental tests. Furthermore, the effect of intermedi...

Nowadays, the use of probabilistic modeling for the design of engineering structures is becoming more and more widespread due to the advances in computer technology. In order to have a comprehensive picture about a meteorological phenomenon, e.g., wind actions on structures, uncertainties must be taken into account. From structural ngineering and...

Lightweight roof and wall structural systems are widely used for cladding of steel portal frames. It is a well-known fact, that assembled systems of profiled sheeting and purlins show significant stiffness to in-plane loads, which action is referred to as stressed skin effect. This research aimed to investigate the influencing parameters of stresse...

The paper introduces experimental tests in order to examine the stability behaviour of members supported by sandwich panels at elevated temperature. The test specimens were 3.0 m x 3.0 m sized diaphragms, constructed of three HEA120 beams with sandwich panels installed on the outer face. After reaching desired temperature level, the middle beam was...

Acél fegyverzetű, különböző töltetű – kőzetgyapot, PIR, PUR - szendvicspaneleket gyakran alkalmaznak acél csarnokok burkolataként kedvező hőszigetelő adottságuk miatt, épületek stabilizálására való alkalmazásuk viszont újszerű, ennek vizsgálatára először a XXI. sz. elején került sor. A szendvicspanelek stabilizáló hatására vonatkozó első tanulmány...

Dedicated to Univ.‐Prof. Dr.‐Ing. habil. Frank Werner on his 70th birthday Zusammenarbeit zwischen Weimar und Budapest bei der rechnergestützten Modellierung von Stahl‐ und Verbundkonstruktionen Der Beitrag gibt einen Überblick über die langjährige Zusammenarbeit zwischen der Bauhaus‐Universität Weimar und der Budapester Universität für Technik und...

The Part II of this two-part paper evaluates the results of the experimental test series introduced in Part I. This research aimed to examine the major influencing parameters of stressed skin effect in industrially applied, nonstandard diaphragm configurations. As no international study was executed in state of art, in order to study the role of di...

Previous studies on stressed skin effect of industrial steel buildings showed discrepancies between the ECCS formulae and experimental results. To clarify the discrepancies full-scale experimental test program was planned and executed by the Budapest University of Technology and Economics, Department of Structural Engineering. The aims of the full-...

The opportunities of improvement in stressed skin design formulae in the European Convention for Constructional Steelwork (ECCS) publication are reviewed in this paper. Stressed skin effect is the diaphragm action provided by the in‐plane stiffness of a diaphragm assembly. The diaphragm is composed of panel assemblies transmitting in‐plane forces t...

In the past few years we have been executed a wide research program at the Structural Engineering Department of BME examining the joints of thin walled sections made with self-drilling screws. During our research program which has been included more than 100 tests we have been examining the static and dynamic behaviour, stiffness and load bearing c...

Lightweight roof and wall structural systems are widely used for industrial type steel buildings and it has been recognised that assembled systems of profiled sheeting and purlins show strong resistance to loads acting in their own plane. In our experimental research the purpose was to determine the stiffness and strength in widely used structural...

A szelemenből és trapézlemezből álló burkolati rendszerek jelentős mértékben ellenállnak a saját síkjukban keletkező erőknek is, ezen hatást az Eurocode-ban " stressed skin effect "-nek nevezik. Ezen merevítő hatás elhanyagolása földrengésveszélyes területeken a biztonság kárára történik a szerkezet merevségének alulbecslése miatt. A hatás figyelem...

Assembled systems of profiled sheeting and purlins show strong resistance to loads acting in their own plane, this effect is called " stressed skin effect " in the Eurocode. We have executed a cyclic panel test series with 18 tests to define the possible degradation of this resistance and stiffness as well.

This paper discusses mode identification for buckling modes calculated by shell finite element analyses. An automatic mode identification method has been previously proposed by the authors that uses a special system of modal base functions, referred to as cFSM base functions. Earlier studies proved the applicability of the approach, but also highli...

The objective of this paper is to provide a method for applying modal identification, (i.e. the separation of general deformations into fundamental buckling deformations classes: local, distortional, global, shear, and transverse extension) to collapse analysis of thin-walled members modeled using material and geometric nonlinear shell finite eleme...

The objective of this paper is to provide a method for applying modal identification, (i.e. the separation of general deformations into fundamental buckling deformations classes: local, distortional, global, shear, and transverse extension) to collapse analysis of thin-walled members modeled using material and geometric nonlinear shell finite eleme...

The objective of this paper is to demonstrate an approximate method whereby eigen buckling modes from a shell finite element method (FEM) analysis of a thin-walled member can be quantified in terms of the fundamental buckling classes, namely, global, distortional, local, or other. The buckling classes are defined using the mechanical definitions em...

This paper presents a new design approach for the stability design of thin-walled members. The proposed approach is based on the buckling modes and critical forces/moments determined by a linear buckling analysis performed on a regular shell finite element model. A fully automatic buckling mode identification technique is applied, by using the moda...

The paper deals with the numerical fatigue analysis of the steel orthotropic bridge decks. The main focus is on the welded connection of the longitudinal rib and the deckplate. Advanced numerical model is developed to predict the fatigue-life of this structural detail on the basis of hot-spot-stresses, using the recommendations of the IIW and Euroc...

The aim of the ongoing research work is to analyze the composite action of the structural elements of composite floors by experimental and numerical studies. The mechanical and frictional interlocks result in a complex behaviour and failure under horizontal shear. This is why the design characteristics can be determined only by standardized experim...

This paper presents the first results of an attempt to identify buckling modes calculated by a regular shell finite element analysis via the modal base functions produced by the constrained finite strip method, a method recently proposed by the Authors. The paper gives the mechanical criteria which are used for mode definition, as well as briefly s...

Javaslatot tettünk vékonyfalú szelvények stabilitásvesztési módjainak új, mechanikai alapon történő definiálásra. Kidolgoztuk a cFSM (constrained Finite Strip Method) eljárást. A cFSM-mel tetszőleges nyitott keresztmetszetű két-csuklós prizmatikus rúd rugalmas stabilitásvizsgálata elvégezhető: tetszőleges tiszta vagy interakciós módhoz tartozó krit...