Ludovic Alexandru Fϋlöp

VTT Technical Research Centre of Finland | vtt · Infrastructure Health

We investigate probabilistic seismic hazard analysis (PSHA) in low-seismicity regions in which epistemic uncertainties are largely due to the sparsity of data, with a focus on Finland, northern Europe. We investigate the sensitivity of site-specific PSHA outcomes to different choices of basic input parameters, starting from preexisting PSHA models...

Air entrained concrete is used for outdoor structures in cold climate to enhance freeze-thaw resistance. A well dispersed air void system is incorporated in the fresh concrete, consisting of spherical air voids that provide expansion space for freezing water and thus act as pressure-relief. The amount of air entrainment (AE), which results from add...

Steel-concrete (SC) is a structural typology and construction method in which continuous steel plates are used on the surfaces of concrete walls or slabs, having dual role of formwork and longitudinal reinforcement. The continuous steel-plates on both sides of the concrete element improve economy by prefabrication, but hinder the use of traditional...

We present a modeling technique for generating synthetic ground motions, aimed at earthquakes of design significance for critical structures and ground motions at distances corresponding to the engineering near field, in which real data are often missing. We use dynamic modeling based on the finite-difference approach to simulate the rupture proces...

A method for condition monitoring and maintenance of short and medium span concrete bridges has been developed in Japan. The method is based on the acceleration response of the bridge, measured when a bus or other heavy vehicle is crossing it. The characteristic displacement (deflection) of each bridge-span is calculated based on the acceleration i...

Timber bridges are economical, easy to construct, use renewable material and can have a long service life, especially in Nordic climates. Nevertheless, durability of timber bridges has been a concern of designers and structural engineers because most of their load-carrying members are exposed to the external climate. In combination with certain tem...

We propose a ground-motion prediction equation (GMPE) for probabilistic seismic hazard analysis of nuclear installations in Finland. We collected and archived the acceleration recordings of 77 earthquakes from seismic stations on very hard rock (VHR, i.e., the shear-wave velocity in the upper 30 m of the geological profile=2800 m/s according to the...

This paper presents the development of the method for predicting the reusability of building components and whole structures and a pilot study of three different single‐storey steel buildings in Finland. The method enables various building parts and products to be classified through a procedure to calculate their reusability index. These values can...

This paper presents the development of the method for prediction of reusability of building components and whole structures. The method was developed especially for single-storey steel buildings, but can be applied with some modifications for any component (or cluster of components) reclaimed from a demolished or refurbished building. It enables cl...

SCIENCE investigated the use of steel-concrete composite (SC) modular systems for use in industrial applications. This form of construction offers many advantages over traditional reinforced concrete (RC), including speed of construction and structural efficiency. The project focused on generating experimental and numerical data to fill gaps in the...

This paper introduces a new method for the assessment of reusability of components and structures of steel-framed buildings. It enables classification of various building parts and products through a procedure to calculate, weight and aggregate recyclability indicators and thus it helps to explore their potential to a second life. In connection wit...

Structural steels used in buildings and infrastructures have to meet ductility requirements of the design codes to ensure the constructional steelwork ability to resist localized stress concentration in details and cyclic loads. Such requirements are usually minimum ultimate-to-yield strength ratio, uniform elongation and elongation at failure. Whi...

Floor vibration of a reactor building subjected to seismic loads was investigated, with the aim of quantifying the variability of vibrations on each floor. A detailed 3D building model founded on the bedrock was excited simultaneously in three directions by artificial accelerograms compatible with Finnish ground response spectra. Dynamic simulation...

Steel concrete steel (SC) is a structural typology and construction method. Continuous steel plates are used on the surfaces of concrete walls/slabs, having both the roles of formwork and tensile reinforcement. The steel plates completely replace the longitudinal reinforcement, but shear reinforcement may still be present. SC gained popularity in i...

Structural steels need to demonstrate certain ductility in order to be used in buildings design. Fulfilling these criteria of design codes may be difficult especially for new high-strength steels where ductile fracture of tensile coupons appears at relatively low deformation. The goal of our study is to develop a calculation method of alternative d...

De-aggregation of probabilistic hazard assessment (PSHA) results show that the dominating source of vibrations with engineering significance to NPP safety is from mid-magnitude earthquakes located at close distances to the plant. This region is called the “near-field” and is known for its particularities when compared to “far-field”. For example, s...

An alternative ductility requirement for steels subjected to diffuse necking in details.

Significant number of reinforced concrete building frames executed in the ‘50’s-60’s in Europe need seismic upgrading. At those times understanding of earthquake effects was insufficient and quality control on construction sites lacking. This combination resulted in buildings framed in reinforced concrete with bad quality materials and inadequate r...

The paper summarises the main outcomes of the project carried out in the period 2011-2014. It is a continuation of the material published in the Interim Report of the SAFIR 2014 program (L. Fülöp et al., 2013), with a general shift from hazard prediction towards focus on qualification of systems, structures and components (SSC’s). This shift result...

The paper presents some essential aspects regarding the design of an energy efficient school building in Romania, in which both the passive house concept and the renewable energy solutions are applied to optimize the cost in the use phase and the global cost of the investment. In order to improve the real-time energy consumption of the building and...

ISBN 978-951-38-7918-1 ISSN 2242-1211

This report is deliverable for 2013 of Subproject 2 in the project SESA “Seismic Safety of Nuclear Power Plants – Targets for Research and Education”, part of the SAFIR 2014 program on nuclear safety. A number of building typologies, interesting from the point of view of seismic vulnerability have been selected during 2012 by the Ad-Hoc group in SE...

This report is deliverable for 2014 of Subproject 3 in the project SESA “Seismic Safety of Nuclear Power Plants – Targets for Research and Education”, part of the SAFIR 2014 program on nuclear safety. In 2014, in Subproject 3, the review task for an emergency diesel generator day-tank has been carried out and reported. The day-tank has been one c...

In Romania, after the changes in 1989, most flats in existing buildings were sold to the occupants. This was a sort of getting back for those people who lost their private property, but another reason of this decision was the missing centralized management capacity of the administration. Looking back now and analyzing from the point of view of how...

Low-rise buildings are used for industrial and commercial activities. Most of these buildings are built by prefabricated-concrete elements characterised by low efficiency of connections and a lower ductility performance when subjected to earthquake loading. The proposal aim is defining prefabricated steel solutions for single-storey and low-rise bu...

As more metallic alloys are introduced in engineering structures, the demand for the proper utilisation of their nonlinear stress–strain relationship is increasing. This paper discusses the inelastic buckling of members from such materials with a special focus on ferritic stainless steels. Here we introduce an alternative approach for the overall s...

This report is deliverable for 2011 of Subproject 2 in the project SESA “Seismic Safety of Nuclear Power Plants – Targets for Research and Education”, part of the SAFIR 2014 program on nuclear safety. The aim of the task was to present a state-of-the-art overview of accepted seismic design methods for the nuclear field, versus those for ordinary st...

In Romania, after the changes in 1989, most flats in existing buildings were sold to the occupants. This was a sort of "getting back" for those people who lost their private property, but another reason of this decision was the missing centralized management capacity of the administration. Looking back now and analyzing from the point of view of ho...

This paper introduces new modelling and evaluation algorithms for automated virtual testing of cold-formed structural members. These algorithms are integrated in Abaqus CAE plugin and verified against real tests of stainless steel hollow sections. Our tool is capable of creating finite element models including complex material behaviour, residual s...

This study brings new insights into the advantages of using more sophisticated design methods for steel portal frames (e.g. geometrically and materially nonlinear analysis with imperfections or GMNIA, and the general method introduced in Eurocode 3), compared to the commonly used member checks with interaction formulae. The differences between the...

The document presents description of two software tools for optimization of portal frames (AP Frame and EV Frame). Both tools use the methods from Eurocode 3 (EN 1993-1-1 [7]) for the design part, and genetic algorithm methods for optimization. The optimization tool developed for Abaqus (AP-Frame) models the frame with “Shell” type finite elements...

The document presents portal frame design, and optimization results, obtained using two software tools developed at VTT. Both tools use analytical methods from Eurocode 3 (EN 1993-1-1 [7]) for design, and genetic algorithms for optimization. The tool developed for Abaqus (AP-Frame) models the frame with “Shell” type finite elements for out-of-plane...

This study brings new insights into the advantages of using more sophisticated design methods for steel portal frames (e.g. geometrically and materially nonlinear analysis with imperfections or GMNIA, and the general method introduced in Eurocode 3), compared to the commonly used member checks with interaction formulae. The differences between the...

The aim of the study was to optimize the shape of welded-tapered frames to achieve the lowest mass while all limit states conditions are satisfied according to the Eurocodes. The AP-Frame optimization tool developed in VTT was used to produce results presented in this report. Together with the detailed optimized frame configurations, frame mass and...

Rouhiainen, Veikko (ed.), Scientific activities in Safety & Security 2009, 44-46

Rouhiainen, Veikko (ed.), Scientific activities in Safety & Security 2009, 48-50

In recent years important research activity has been undertaken in order to determine the earthquake performance of light problem of earthquake performance through experiments on wall panels gauge steel house structures. Usually, studies approach the problem of earthquake through experiments on wall panels conducted either under monotonic or cyclic...

For the proper design of cold-formed steel-framed houses in earthquake regions, the behavior of the shear walls has to be known. Besides the structural walls the behavior of a house is influenced, at least in the early stage of the shaking, by the non-structural elements which are not accounted in the design. These supplementary finishing elements...

The paper summarises the results of an experimental program carried out at the Politehnica University of Timisoara in order to evaluate the performance of eaves (knee) and ridge (apex) joints of pitched roof cold formed steel portal frames under monotonic and cyclic loading. Three different configurations of ridge and knee joints have been tested....

Thin-walled steel structures are usually made by sections of class 4 or 3 and they can be obtained either by cold-forming or thin plate welding. Traditionally these structures, being slender, are considered non-ductile and not allowed for plastic design. As a consequence a reduction factor q=1 and elastic design can be applied only. Present paper s...

The ever-increasing need for housing generated the search for new and innovative building methods to increase speed, efficiency and enhance quality, one direction being the use of light thin steel profiles as load bearing elements and different materials for cladding. The same methodology can be employed to build small steel structures for offices,...

The main components to provide earthquake performance of a light-gauge steel house are the shear walls. Understanding shear wall behaviour and finding suitable hysteretic models is important in order to be able to build realistic finite element models and assess structural performance in case of earthquake. As for any building structure expected to...

The paper summarises the results of an experimental program carried out at the Politehnica University of Timisoara in order to evaluate the performance of ridge (apex) and eaves knee joints of pitched roof cold formed steel portal frames under monotonic and cyclic loading. Three different configurations of apex and knee joints were tested. The beha...

Şuruburile autofiletante au o popularitate deosebită ca elemente de îmbinare a barelor de oţel formate la rece. Această popularitate se datorează în primul rând uşurinţei şi rapidităţii cu care acestea se pot monta, simplificând montajul elementelor. Diversitatea de forme, soluţii şi domenii de aplicare a elementelor de oţel formate la rece a tras...

The ever-increasing need for housing generated the search for new and innovative building methods to increase speed, efficiency, and to enhance quality, with one direction being the use of light steel profiles as load bearing elements and the use of different materials for cladding. Wind and seismic behavior of these structures is influenced by the...

The ever-increasing need for housing generated the search for new and innovative building methods to increase speed, efficiency and enhance quality, one direction being the use of light steel profiles as load bearing elements and different materials for cladding. Wind and seismic behavior of these structures is influenced by the hysteretic characte...

Shear walls made of light gauge (LG) steel skeleton in combination with different cladding materials, represent the basic load bearing element of LG structures exposed to horizontal loading (ie. Wind and Earthquake). For earthquake loading, besides load bearing capacity, factors like ductility and overstrength play are important parameters. In this...

Two new structural systems, MSBS and PRPF, made of cold-formed steel sections based on LINDAB roofing and cladding solutions are presented. These systems have been developed in Romania which is a seismic and heavy snow territory. Main constructional features and seismic performance of both these systems is summarised in the paper.

The seismic performance of two single storey steel buildings is analysed in this paper. They are an office building and a light industrial building, respectively. The buildings are located in heavy snow and seismic zones and are fully made by cold-formed steel sections. General design principles of old-formed design and building technology are pres...

Cold-formed steel sections are used more and more as structural members. Compared with hot-rolled ones, there are important technical advantages of these sections, but there are also some structural problems, mainly due to their slenderness, which impose limits of using such sections in heavy buildings and, particularly, in buildings located in sei...