bluuebunny/crossref_metadata_2025 huggingface dataset:
08.27: Steel‐timber composite (STC) beams: Numerical simulation of long‐term behaviour
Authors: Chiniforush Alireza A. , Valipour Hamid , Akbarnezhad Ali , Bradford Mark
Published: September 2017

Conventional steel‐concrete composite floors comprising of steel sections and sheeting, cast in situ concrete and embedded stud shear connectors are made from energy‐ and carbon‐intensive construction materials, viz. concrete and steel. Replacing conventional reinforced concrete floors with solid timber, in particular cross‐laminated timber (CLT) with improved stability and structural characteristics, can significantly increase the speed of construction, reduce the need for rigging and craneage and also lower the self‐weight of the building, the size of the columns and foundations and therefore the overall carbon footprint of the building. However, experimental data on the short‐ and long‐term structural performance of steel‐timber composite (STC) floors under service loading conditions are scarce and no long‐term theoretical analyses of steel‐timber composite floors have been reported hitherto in the literature. Accordingly, non‐linear 1‐D frame finite element models are developed in this paper, and validated against experimental data on timber and hybrid timber composite beams. The numerical tool is then employed to predict the long‐term stiffness and load‐deflection response of STC floors under service loading conditions. A parametric study is carried out and the influence of the stiffness of the shear connectors, timber shrinkage, creep, hydro‐expansion and mechano‐sorptive effect on the long‐term behaviour of the STC beams are investigated.
08.33: Full scale test on steel‐concrete composite beams: Investigation of innovative shear connectors
Authors: Kovács Nauzika , Kövesdi Balázs , Kachichian Mansour , Frank Máté Ferenc
Published: September 2017

Full scale tests on eight steel‐concrete composite beams have been executed in the Structural Laboratory of the Department of Structural Engineering, Budapest University of Technology and Economics in Hungary. The aim of the test series was to investigate the structural behavior of the new and innovative shear connections applied at the steel‐concrete interface. During the test the beams have been simple supported and tested under three point bending until the final failure following the Eurocode recommended testing procedure. The composite beams are built up of IPE 400 steel beams and 20×50 cm RC slab. The length of the beams was 6 m for each. The general layout and material grade of each beams are identical, however each has special shear connection: headed studs (as reference), perfobond plates, Y‐shaped perfobond, dove tale perfobond plates, trapezoidal perfobond plates. These connection types have been already tested by push‐out test in the same Laboratory in the previous years.

The main goal of the full scale tests was to investigate the force‐slip relationship for each connection types and verify the results of the push‐out tests. To determine the structural behavior of the shear connection both tests have been evaluated: the shear resistance of the connection is determined by the push‐out test and the initial stiffness by the beam tests. Further aims are to develop a test based calculation model for the design of the new innovative shear connections, and to build and verify and advanced FE model to perform virtual test on further connection configurations.
08.36: Numerical modelling of circular CFST members and assessment of multi‐axial stress state effects
Authors: Jiang Yadong , Kalemi Bledar , Silva António , Castro José Miguel , Monteiro Ricardo
Published: September 2017

Multi‐axial stress states, namely the concrete confinement effect and the bi‐axial stress state that develops on the steel profile, have a significant influence on the flexural behaviour of the circular Concrete‐Filled Steel Tubular (CFST) members. The results from an experimental investigation carried out at the University of Porto indicated that the combination of the two multi‐axial stress states contributes to an increase of the flexural capacity of circular CFST members. This paper presents the development of a 3D model in ABAQUS that has been validated against experimental data. A distributed plasticity model is also developed in OpenSees. It is shown that the 3D model, contrary to the distributed plasticity model, is able to simulate the multi‐axial stress states, hence reproducing the bending behaviour of circular CFSTs with fairly good accuracy. An extensive parametric study involving different CFST members is conducted with the aim of characterizing the concrete confinement effects as well as the bi‐axial stress states developing in the steel tube. A large database of results was generated and then employed in the derivation of modified uniaxial material strength properties. Relationships between the corrected material strength and the cross‐section factor, ζ, which depends on the cross‐section properties of the member, for both concrete and steel section, were derived as closed‐form expressions. These properties can be adopted both for cross‐section analysis and for the development of simplified distributed plasticity models. The accuracy of the distributed plasticity model was improved when the strength correction equations were applied.
08.44: Elastic buckling behavior of the surface material in sandwich structure
Authors: Yamanaka Moe , Ikarashi Kikuo , Inaba Toru
Published: September 2017

A sandwich structure manufactured using a thin plate is lightweight, but has high bending stiffness. It is a very ideal structure from an environmental and structural point of view. It is very important to understand the buckling behavior of the surface material in this structure. Many arguments about it are based on in‐plane compression and in‐plane pure shear. When a steel sandwich panel is used on a roof or a wall, it is assumed that out‐of‐plane bending occurs owing to wind pressure and gravity. The purpose of this study is to understand the tendency of elastic buckling strength of the steel sandwich panel under out‐of‐plane bending and evaluate it using a simple formula.

The following conclusions are obtained: (1) Select assumptions that are considered the most appropriate for calculating the elastic buckling strength of the steel sandwich panel under out‐of‐plane bending. The theory proposed by Plantema corresponds well to the finite element analysis in scope of this study. (2) Calculate the elastic buckling strength of the steel sandwich panel under out‐of‐plane bending by the method expanded the theory proposed by Plantema. It converges to a constant value when the range of the thickness of the core material is large, and increases when this range is small. (3) Evaluate the elastic buckling strength of the steel sandwich panel under out‐of‐plane bending, and propose a simple approximation formula including the previous one.
08.51: An experimental study of composite beam‐column joints subject to impact loads
Authors: Chen Kang , Tan Kang Hai , Yang Bo
Published: September 2017

Beam‐column joints are one of the key elements in steel and composite frames. Till now, many research studies have focused on the behaviour of bare steel beam‐column joints and the influence of composite slabs subjected to quasi‐static loads. In this study, the research was extended to dynamic loading condition. Two beam‐column joint specimens with composite slabs, which were designed based on Eurocode 4, were tested using an MTS drop‐weight machine. This loading condition is probably more realistic for joints under progressive collapse scenario, which is a dynamic process. One of the specimens was a middle joint subject to sagging moment. The other specimen was a side joint subject to hogging moment. Behaviour of both joint specimens, including impact force, displacement of the middle column, strain and failure mode, was presented. Differences in the behaviour of the two joint specimens were observed and explained.
08.54: Behaviour of steel‐timber beam in bending
Authors: JURKIEWIEZ Bruno , DURIF Sebastien , BOUCHAIR Abdelhamid
Published: September 2017

The combination of timber elements and steel beams can be of high interest for fire protection and mechanical performances including the elastic instabilities. In this paper, experiments are performed to analyse the behaviour of various configurations of steel‐timber beams in bending. Each steel beam is connected to two timber beams at the web and the flanges. In order to define the material properties of the tested elements, each component (wood and steel) has been tested independently in the elastic field. Then, the timber and steel beams have been connected and tested until the failure. The observed behaviour show a significant effect of the reinforcement provided by the timber beams. In fact, the combination of timber‐steel elements improves the resistance to lateral buckling and local buckling of the steel profile.

This preliminary study, based on an experimental approach, is used to evaluate the performances of different means of connection and to define the possibilities of the combination of timber and steel elements for further developments.
08.60: Composite dowels in cracked concrete Experimental investigation
Authors: Classen Martin , Christou Georgios , Hegger Josef
Published: September 2017

In steel‐concrete composite girders, composite dowel shear connectors can be used to transfer shear forces between the concrete slab and the steel section. In comparison to other shear connectors the composite dowels offer increased strength capabilities, higher deformation capacities both in normal and in high strength concrete and offer an efficient use of steel and concrete. Composite dowels gain increasingly acceptance and are more and more used especially for prefabricated constructions. In regions with negative bending moment – for example near the interior supports of continuous composite beams, where concrete cracking occurs, the shear capacity of composite dowels may be affected by transverse concrete cracks. So far, the internal shear carrying mechanisms of composite dowels in cracked concrete are not clarified and existing shear capacity models do not account for concrete cracking. Hence, the present paper summarizes the results of 38 shear tests, providing novel insights regarding the pry‐out failure of composite dowels in cracked concrete. The tests were performed in an innovative test setup, whereby concrete was cracked prior to the test allowing to investigate the impact of crack spacing and crack width.
09.15: Fatigue life prediction of New Little Belt Bridge steel deck under a cracked pavement section: Comparison between a monitoring‐based and a FE modelling approaches
Authors: Farreras‐Alcover Isaac , Sørensen Paw Lee , Bitsch Niels
Published: September 2017

This article is not available for publication.
09.17: Fatigue life of marked steel components
Authors: Jungbluth Dominik , Stranghöner Natalie
Published: September 2017

Steel components have to be identifiable and traceable during the whole manufacturing chain. The choice of the identification method is not specified consistently in international rules and standards. The European standard for the execution of steel structures EN 1090‐2 specifies that the use of durable marks may not result in producing damages without saying which damages are meant. Hard stamped marks are only permitted for steel grades up to S355 and only in areas where no effect on the fatigue life is expected. Otherwise the use of soft stamps should be verified. In other international standards hard stamped marks are explicitly required. These contradictions should be resolved.

In terms of durability and liability, markings should be resistant against particular manufacturing processes such as sandblasting, hot‐dip galvanizing or coating. For this reason, the following marking methods are used in practical applications: hard stamping, scribing, plasma marking and needling.

Nowadays the machinery manufacturers have developed machines in which the marking process can be automatically integrated in the manufacturing process of steel components so that manual layout scribing is not required anymore and components can be marked on the fly. However, the effect of the installed notch due to the marking process on the fatigue strength of the components has not been investigated yet. As a result, a classification of the resulting notched details according to the European detail categories of EN 1993‐1‐9 is in principle not possible.

For these reasons, the influence of durable marking methods on the fatigue strength of steel components needs to be clarified by experimental fatigue tests and numerical calculations which have been performed at the Institute for Metal and Lightweight Structures of the University of Duisburg‐Essen. Within these investigations the different marking methods hard stamped, scribed, plasma marked and needled as well as unmarked structural details have been examined. The experimental investigations have been carried out considering three different steel plate thicknesses 15 mm, 25 mm and 40 mm and two different steel grades S355J2 and S460N.

As expected the marked specimens show a decrease of the loading cycles until failure even though there are differences in fatigue life due to the different markings and their characteristic notch geometries.
10.23: Parametric study on the fire resistance of steel columns with thermal gradients
Authors: Correia António Moura , Rodrigues João Paulo , Kodur Venkatesh , Correia José Pedro
Published: September 2017

The current design Codes for steel columns under fire situation, are based on the assumption that the temperature distribution is uniform, and thermal gradients are neglected. However, nowadays this assumption is very rough, since several studies have been conducted in recent years, and the thermal gradients along the web or along the flange are quite well quantified, for cases with the column oriented with the web perpendicular or parallel to the adjacent walls.

The main issue to be discovered is whether in any case, the columns fail sooner during a fire event being only partially heated, than the columns totally engulfed in fire. This eventual behaviour may be provoked by the thermal bowing phenomenon. This is the purpose of this study. To find out in which cases, if any, the walls play a detrimental role in the fire resistance of the columns, a set of numerical simulations were carried out. A geometrical and material non‐linear analysis was performed, to assess the real influence of the surrounding walls on the fire behaviour of steel columns.

Moreover, the mechanism of failure can also be very different in steel columns embedded on walls, than the one observed in columns totally engulfed in fire. The post‐buckling behaviour of the column is of extreme importance in terms of global failure of a structure. This is also a very important issue analysed in the present study.

The main conclusion of this work, intend to ascertain for different values of slenderness and load levels, if in any case, the walls presented a detrimental role, meaning that the fire resistance of the column was lower in the case it was in contact with walls.
11.26: The seismic design of a building having a dual type structural system in Romania
Authors: Vlad Ion , Vlad Mirela Nausica
Published: September 2017

The March 4, 1977 earthquake was the last major seismic event that struck Romania. 1,600 persons were killed, over 11,000 were injured, and 33,000 buildings collapsed or were severely damaged. The great majority of these injuries were in masonry and reinforced concrete buildings. The few existing steel structures behaved very well during the earthquake, excepting the situation when inadequate structural concepts were met. Even if the number of steel buildings was not so high, steel was used especially for long span roofs of industrial buildings. Starting with that period, the design practice proved that steel is an excellent material for seismic‐resistant structures thanks to its performance in terms of strength and ductility. The bulk of the paper consists in presenting the design of a dual type structural system having in the horizontal plane the shape of the letter “Y” and in the vertical plane two basements, a ground floor and 14 stories. Trying to realize a building virtually immune to earthquake action the superstructure of the building, of composite type, was conceived to have two different parts: (a) a reinforced concrete structural subsystem formed by the three structural cores placed in the peaks of the equilateral triangle, their main role being that of assuring the lateral strength of the building to the seismic loads; (b) a steel structural subsystem, having a structural role mainly towards the gravity loads. The steel structural subsystem is placed in the central zone of the building and is connected to the three reinforced concrete cores placed in the peaks of the equilateral triangle. It consists of three moment resisting frames and composite type floor structures. The paper also contains information about the results of some in‐situ dynamic investigations performed after each stage during the construction, in order to validate the structural models of analysis and the contribution of the steel structural subsystem on the overall dynamic characteristics of the building.
11.54: A proposal to improve the seismic behaviour of eccentrically braced structures
Authors: Köber Helmuth , Stoian Marina
Published: September 2017

The present paper is intended to relieve the behaviour under severe seismic actions of some eccentrically bracing systems equipped with additional vertical connection elements (vertical truss elements between the ends of all dissipative members that are not connected directly to columns) compared to the seismic behaviour of traditional eccentrically bracings. Each considered structural type (with and without additional vertical truss elements) was subjected to three dynamic nonlinear analyses using Vrancea earthquakes acceleration records.

The values of different parameters recorded during nonlinear analyses were compared: extreme base shear forces, maximum plastic deformations in the dissipative members, greatest member forces in different structural elements, extreme horizontal floor displacements. The amount of dissipated energy and the estimated steel consumption for each considered frame was analyzed.
11.64: Seismic behaviour of steel Chevron bracing systems by non‐linear dynamic analyses
Authors: Faggiano Beatrice , Formisano Antonio , Castaldo Carmine , Canicattì Luca , Landolfo Raffaele , Mazzolani Federico Massimo
Published: September 2017

The paper focuses on steel Chevron concentric bracing systems (CBF‐V) as seismic resistant structures, presenting the evaluation of the structural seismic performance through dynamic analyses, aimed at improving the design methods.

A wide numerical study is carried out. Different CBF‐V configurations are designed, for a total number of 12 structures, by varying number of storeys (3, 6, 10), design methods (linear and dynamic analysis) and braces sections (H‐shaped and circular hollow sections). Nonlinear Incremental Dynamic Analyses (IDA) are performed by the SeismoStruct software, considering 7 earthquakes records, in order to investigate the seismic response. The most relevant evaluation parameters are shown and discussed, IDA curves are caught and the behavior factors calculated. Results show that expected collapse modes, involving the braces only, according to the Capacity Design, are not in agreement with the noted mechanisms, in which damage also involves non‐dissipative elements, in particular the beams. Hence, it is needed to deepen such key issue, through further experimental and numerical investigations in order to optimize the design procedure.
11.65: An axial type self‐centering energy dissipation device with shape memory alloy for seismic mitigation
Authors: Li Ran , Shu Ganping , Liu Zhen , Lyu Xiao , Chen Meihe
Published: September 2017

Serve earthquake often cause large deformation to structures which might deteriorated or degraded seismic performance level. Installing shape memory alloy (SMA) dampers to the structure is one of the most effective approaches to mitigate earthquake disasters. The mechanical behaviour of superelastic Ni‐Ti shape memory alloy wire is tested and a multi‐linear constitutive model which appropriately describes and elucidates the mechanical property and material characteristics is obtained by simplifying the hysteretic response. A new axial type SMA damper with energy dissipation and self‐centering property is proposed. The structure, the design method, the working principle and the model of the recovery force are introduced. The energy dissipation capacity and the self‐centering property are examined by low cyclic loading processes. Both the two properties reach an excellent effect. The result indicate that SMA has a great potential to be used in structures to mitigate seismic displacement response and improve the self‐centering performance of structures.
11.67: Cyclic backbone curves for steel wide‐flange columns: A numerical study
Authors: Ozkula Gulen , Harris John , Uang Chia‐Ming
Published: September 2017

Experimental and analytical studies on the cyclic behaviour of deep, slender wide‐flange steel beam‐columns funded by the National Institute of Standards and Technology (NIST) is ongoing at the University of California at San Diego (UCSD). In parallel with full‐scale column tests, numerical simulations of columns under monotonic and cyclic loading conditions were conducted to generate a wide‐ranging database of results. A correlation study using results from the full‐scale tests was conducted to validate the numerical simulation procedure. The simulated columns covered a wide range of cross‐sectional (local) and member (global) slenderness ratios, axial force level, and yield stress. Regression analyses were conducted to construct moment‐rotation responses, ‘backbone curves’, for use in performance‐based evaluations of steel moment frames. The database is divided into three groups based on observed buckling modes. Computational expressions for the key parameters that define the backbone curves are presented.
I.11.61: Full scale tests on moment‐resistant‐frames under cyclic loading
Authors: Avgerinou Stella , Lignos Xenofon , Thanopoulos Pavlos , Vayas Ioannis
Published: September 2017

Three large scale tests on two‐story Moment Resistant Frames (MRF) under cyclic loading were conducted in the Laboratory of Steel Structures of NTUA in the frame of the RFCS‐supported project MATCH. Selected joints of the frames were formed with Reduced Beam Sections (RBS), in order to achieve plastic hinge formation away from the welded connections and the heat affected zones. In addition, holes were drilled in the flanges in order to study the crack initiation and crack propagation under large plastic deformations.

The experimental set‐up consisted of a rigid test rig frame providing horizontal support to the hydraulic actuator, a base girder on which rested the test frame and a supporting frame, which prevented the out‐of‐plane movement of the test frames. The base girder was attached to the test rig so that no net horizontal force was transferred to the ground. The experimental set‐up was anchored to the Laboratory's strong floor. The test frames were simply supported on the base girder.

The test frames were designed with weak beams and strong columns. The beam–to–column joints were realized with all‐around fillet welds. In the two‐bay frames the beams of a selected joint were designed with RBS near the connection regions while the rest of the connection regions were locally reinforced with stiffeners and beam haunches in order to ensure plastic deformation would occur in the selected joint. In the one‐bay frame all beams were designed with RBS sections towards the joints. The distance of the RBS sections from the column faces as well as the geometry of the flange reduction was specified in accordance with the provisions of EN 1998–3.

The tests were performed under displacement control using a computer controlled hydraulic actuator. A cyclic load of increasing amplitude was applied according to ECCS provisions while the maximum interstory drift reached was approximately 5%.

The actuator's force was applied through a vertical spread beam, which ensured that the load was applied in an inverted triangular pattern, in accordance with the anticipated seismic forces.

In the present paper, the design of the test specimens and the experimental set‐up is described in detail, and the preparation and results of the experimental investigations are presented.
12.06: Numerical analysis of stainless steel, concrete encased and carbon steel double skin tubular stub columns
Authors: de Araújo Raphaella Oliveira , de Lima Luciano Rodrigues Ornelas , da Silva Vellasco Pedro Colmar Gonçalves , da Silva André Tenchini
Published: September 2017

The use of stainless steel as formwork for concrete columns provides several benefits for the structure, including the high corrosion resistance, durability, fire resistance, ease of maintenance and high aesthetic value. The use of composite systems in columns has been a major breakthrough in bridges and viaducts. A particular advantage of the composite columns is the reduction of cross sectional area, speed of construction, easy maintenance and material saving when compared to conventional reinforced concrete structures. These advantages are related to the idea that the columns are concrete filled eliminating the use of forms and the need for extra steel reinforcing bars. The investigated system adopts a second carbon steel tube inside the primary stainless steel tube composing the structural system made of concrete‐filled double skin composite tube columns (CFDSCT). This study aims to develop numerical models, using the finite element method and considering geometric imperfections. The structural behaviour was assessed through a nonlinear analysis and was later compared to compressive tests performed in the laboratory. After the completion of the numerical models calibration, a parametric analysis was performed to investigate the influence of parameters like the diameter, thickness and height of the stainless steel tube (outer) while its results were also compared to predictions made by traditional design equations.
12.07: Numerical assessment of stayed austenitic steel columns
Authors: Ribeiro Danielle M. , da S. Vellasco Pedro C. G. , de Araujo Ricardo R. , de Lima Luciano R. O. , da Silva André T.
Published: September 2017

The use of prestressed steel stayed columns systems in construction has numerous advantages related to its light weight, load bearing capacity and assembly process flexibility. A practical application of these structural systems could be recently observed in Brazil for the erection of the Rock in Rio III world stage. In this event the use of prestressed stayed carbon steel columns were used for temporary shoring, optimizing the erection sequence. The main stage had a 82 meters span with a 40 m clear height and a 4500 m2 area. Two stayed column were used, both with a 20 m length. Up to the present the majority of investigations of these stayed systems have been focused on carbon steel columns. In view of these facts the present paper aimed to present an investigation of the structural behaviour of columns made with the austenitic stainless steel. Numerical models were developed in the Ansys software, focusing on the structural system load carrying capacity and the optimal level of prestress to be used. The optimal level of prestress to be used was also determined considering the influence of initial imperfections. The results confirmed that the use of prestress in the cables significantly enhance the ultimate loads and ductility capacity of the columns.
12.09: Weathering steel – 30 years of experience in Banedanmark
Authors: Holmstrøm Peter , Nielsen Mogens G. , Cero Dritan
Published: September 2017

Banedanmark has used weathering steel for more than 30 years and has gathered unique information about corrosion of weathering steel during this period. Not only has the corrosion rates been noted – but also the good and poor detailing. The conclusions of this will be given in this paper. Based on the information gathered from the tests, a method for estimating the corrosion lifetime for the specific type of structure is given.

Since 1986 weathering steel has been widely used on the Danish rail network for overhead line equipment structures such as masts and frames etc. As these structures now represent a very large investment to the owner of the rail net, it is crucial to follow if the expected lifetime from design is valid.

These structures are based on a ‘standard‐design’ developed by Ramboll in the mid 80ti'es. At that time the knowledge on how weathering steel would behave on these specific structures was limited, hence a test‐programme was carried out from 1988 to 1994, in order to verify the corrosion rate in general, along with the suitability of the design philosophy of details. This test‐programme was carried out using designated test‐masts that was located along the rail track at selected locations.

After seven years of studying the test‐masts, the test‐programme was stopped, as these results indicated that the required service life would be met. And there was not observed any critical items on the detailing used.

Now, after almost 30 years of service, the designated test‐masts are still available, and as results from the first test‐regime indicated some conservatism in design assumptions, it might be the case that the existing structures can be considered safe beyond the original design life of 50 years.

To investigate this further a pilot test‐has been carried out, to check if the test‐regime is still suitable for gathering new information after almost 30 years of exposure. This initial test showed that it might be possible to increase the expected service life from 50 to perhaps 80–100 years of existing structures.

In addition it was evident that the design philosophies of details are suitable for long time exposure. It even indicated some conservatism in the philosophy of detailing too.

The tests have gathered unique knowledge of how mast structures for overhead lines of weathering steel behaves after long time exposure.
12.12: Influence of welding on mechanical properties of high strength steel butt joints
Authors: Chen Cheng , Zhao Ming‐Shan , Fung Tat‐Ching , Chiew Sing‐Ping , Lee Chi‐King
Published: September 2017

In view of the fact that welding thermal cycle could adversely affect the mechanical properties of heat affected zone (HAZ) for quenched and tempered (QT) high strength steel (HSS) due to the transformation of microstructures, experiments were conducted to find out the correlation of welding heat input, hardness, microstructure and the tensile strength of HSS butt joints. Two S690 QT HSS butt joints were welded with 8mm thickness plates by shielded metal arc welding (SMAW), and 3.2mm and 5.0mm diameter electrodes were employed to achieve the conditions of different heat inputs. During welding, the thermal cycles near the weld bead were recorded by thermocouples. After the welding, the test specimens were cut out from the welded joints. Then, coupon tests were carried out to measure the tensile strength of joints. In addition, hardness tests and microstructure observation of HAZ on the well‐polished specimens were conducted. The test results reveal that a soft layer was generated in the fine grain heat affected zone (FGHAZ) with a lower hardness value. Eventually, it affects tensile strength of S690 QT HSS to some extents. Additionally, it was also found that increase of heat input leads to longer cooling time and consequently higher degree of HAZ softening.
13.10: Angles connected by one leg in tension
Authors: Može Primož
Published: September 2017

The paper deals with bolted connections of angles connected by one leg subjected to tension force. These connections are characterized by the eccentricity of the tension force and are dealt with in the EN 1993‐1‐8 standard that provides the design resistance for block tearing, for bolt bearing and for reduced effective net cross‐section that is based on β factors. A closer look on the design resistance of the reduced effective net cross‐section shows that the calculation of β may lead to inconsistencies. An addition of a bolt may lead to decrease of the net cross‐section resistance. Moreover, the formulas for the calculation of the reduced net cross‐section resistances are only a different presentation of the formulas for the block tearing resistance. Analysis of 631 test results from literature shows that the calculation of the block tearing resistance is sufficient and that equations 3.12 and 3.13 of EN 1993‐1‐8 are redundant. The study will also show that a constant distribution of stress on the tension face may be assumed in the formula for the block tearing resistance of the angles connected by one leg in tension (eq. 3.9, EN 1993‐1‐8), similarly to the provisions in American standard AISC 360–05. A modified bolt bearing strength function is also presented and statistically analysed on 631 test results. It is simpler and less conservative than the one in EN 1993‐1‐8.
13.14: Seismic assessment and strengthening of existing steel moment‐resisting frame buildings: the European EC8‐3 and current challenges
Authors: Araújo Miguel , Macedo Luís , Castro José Miguel
Published: September 2017

In Europe, the revision of part 3 of Eurocode 8 (EC8‐3), which is the part of the Eurocodes that specifically addresses the seismic assessment and strengthening of existing structures, has been set as a first priority in the preparation of the new generation of Eurocodes that are expected to be released in 2020. However, and although EC8‐3 has been the focus of extensive research in the case of existing reinforced concrete buildings, very few works focused on the seismic assessment of existing steel buildings. The aim of this paper is hence to provide a discussion on the applicability of EC8‐3 to steel moment‐resisting frame (SMRF) buildings, to highlight the code main limitations and inconsistencies and present new steps taken forward in order to overcome them. Various issues regarding the definition of the performance requirements, the feasibility of using the most common linear methods of analysis, the adequacy of the code deformation capacity limits for steel members, the treatment of uncertainty and the influence of modelling approaches, are herein discussed. In brief, this work intends to present to the scientific and structural engineering community the current limitations of EC8‐3, to identify topics in need of future research and to disseminate new findings achieved by the authors.
14.04: Temporary steel structures: for strengthening of a large excavation for new metro in Sofia
Authors: Partov Doncho , Petkov Milen , Matuski Vladimir , Zhelev Dimo
Published: September 2017

The topic of this paper relates to the projects, forming the conception design and technology of construction of the temporary steel structures used for strengthening of deep excavations for Sofia metro Line – 1 Extension Project from Sveta Nedelya Square to Vassil Levski Stadium. The excavation is supported by R.C. wall and pilot, which are additionally supported to keep vertical position by steel frames. The temporary steel construction is analysed as a frame structure using FEM in the light of robustness structures theory. The steel frames is from hot‐rolled section in the range from HEB 300 to HEB1000, doubled and situated along the whole perimeter of the frame.
14.06: Beam‐to‐column joints, column bases and joint components under impact loading
Authors: Demonceau Jean‐François , Vanvinckenroye Hélène , D'Antimo Marina , Denoel Vincent , Jaspart Jean‐Pierre
Published: September 2017

Recent events such as natural catastrophes or terrorist attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. For more than 10 years, the University of Liege is strongly involved in researches on the response of structures further to such exceptional events through participations to national or European research projects.

In particular, the University of Liege has contributed very recently to a European research project entitled ROBUSTIMPACT investigating the behaviour of steel or steel‐concrete composite building structures subjected to impact loading and proposing simplified procedures to predict the response of such structures under the considered scenario.

As a contribution to this research project, an experimental test campaign was realised in Liège; the objective was to study the behaviour of beam‐to‐column joints, of column bases and of most of their constitutive components under impact loading and, in particular, to highlight the influence of the strain rate effects on the response of the studied joints and components.

The proposed paper first describes the conducted test campaign with all the required details about the tested specimens and the testing setup; then the analysis of the so‐obtained experimental results is presented. Finally authors’ views on how to account for the strain rate effects in analytical approaches for joint design is briefly expressed.
15.04: Parametric study on steel beams with fin‐plate joints under falling floor impact
Authors: WANG Hao , TAN Kang Hai , YANG Bo , PENG Jing
Published: September 2017

During the past decade, many quasi‐static tests were conducted on structures against progressive collapse. As a typical testing method, middle‐column‐removal scenario was used in most studies. It should be noted that another important scenario, i.e. falling floor impact, may also cause progressive collapse. In this paper, a series of numerical analyses was carried out to study the dynamic behaviour of steel beams subjected to falling floor impact. Fin plate connections were used to connect the beam and the columns. 3‐D finite element models (FEM) were established by ANSYS/LS‐DYNA and validated against experimental data. Good consistency was shown between experimental tests and numerical analyses. By using the validated finite element models, four parameters including strength of material, impact load, impact location and inertia effect were studied. High strength materials were beneficial to enhance the impact resistance in the falling floor impact scenario. Higher impact velocity can slightly improve the capacity of energy dissipation. For location of falling impact, it was more critical if the hammer dropped onto the joint region compared to the mid‐span region. The inertial effect should be considered in the impact analyses because it significantly decreased the maximum vertical displacement of specimens.
00.06: Advances and development needs in the structural design of steel box girders for major bridges
Authors: Polk Henrik , Walker Chris
Published: September 2017

Major cable‐supported bridges with a span exceeding 600m would not normally be feasible without a steel box girder to carry the traffic load. These box girders generally comprise a structural steel deck plate stiffened longitudinally by open or closed ribs and transversely by diaphragms. The stiffened deck plate supports the local wheel load and distributes it to the diaphragms from where it is transferred into the box girder. The stiffening ribs also increase the total cross‐sectional steel area and thereby contribute to the overall bending capacity of the box girder and finally, the stiffeners increase the resistance of the plate to buckling.

This type of deck structure is generally called an “orthotropic bridge deck” due to the orthogonal nature of the stiffened deck plate and was first developed and utilised in 1950. The orthotropic steel deck is considerably lighter than a concrete slab in a composite girder and therefore makes longer span bridges possible, by reducing the self‐weight forces that would otherwise dominate. The self‐weight of the girder is a key driver in major bridge designs since it must be carried by all other bridge components, such as cables, towers, anchorages and foundations. The orthotropic steel girder is usually a fully closed box girder with all stiffening ribs placed inside the girder giving a smooth outer surface that is easy to paint and maintain. The interior of the closed box is often dehumidified without being painted giving an environmentally‐friendly fabrication that is safe to operate and maintain.

However, the orthotropic steel deck is highly prone to fatigue meaning that the number of passing lorries, their axle/wheel configuration and total vehicle weight have a significant impact on the bridge deck design and fatigue life. The orthotropic deck therefore has higher fabrication costs when compared to conventional steel structures due to the high‐quality steel manufacturing and welding procedures that are necessary to achieve the required fatigue performance.

The overall layout of an orthotropic bridge deck is basically unchanged since the 1960s, however the detailing has been refined considerably to a level where it is now seems difficult to improve it much further. However, the introduction of new materials e.g. sandwich steel deck structures in combination with new welding or gluing techniques could push box girder designs to new heights.
16.02: “La Belle Liégeoise”, the new footbridge in Liège
Authors: Gens Frédéric , Servais Vincent
Published: September 2017

The new footbridge in Liège, known as “La Belle Liégeoise”, was opened on 2 May 2016. Located upstream of the landscape window created by the new Guillemins Esplanade, this bridge provides a connection for soft transport modes from the railway station across the Meuse to La Boverie Park, maintaining clearance for navigation.

The site presents a dissymmetry: an urban bank faces a wooded bank. Reflecting this, the structure of the main section on the left bank develops a suspended typology, while the second section on the right bank is supported by struts.

The main span over the Meuse is 163 metres for a total length of 294 metres. The 5.5 metre wide decking is positioned laterally to the supporting structure.

The footbridge is accessible to “soft” transport modes via the provision of ramps made of variable height steel boxes, supporting the 3.5 metre wide decking of azobé wood. On the right bank, the bridge crosses La Boverie Park through the canopy, offering a new vision of this urban park.

The desire to design a thin and elegant structure integrated into the site, combined with the need to restrict navigation on the Meuse as little as possible, led to the obvious use of steel for the main structure.

Construction involved 740 tonnes of steel. Structural elements 15 metres long were trucked onto a temporary assembly site. These elements were assembled on the ground in six sections, the largest weighing 400 tonnes for a 150 metre length. These six sections were finally transported by barge, lifted and positioned by three floating cranes. The most impressive section, consisting of the suspended part, was transported horizontally before being re‐erected on site.

Finite element analysis was used to determine the reduction elements and check for strength and stability. Funicular geometry tends to maximize the axial forces of elements. For some critical elements (hangers, suspension, pylon, etc.) non‐linear calculations were performed. The same applied for determining the reverse deflection, which reaches 160 cm in the main span.

Adopting a minimalist design for the nodes, the hanger connections are welded, meaning the screed or assembly members do not have to be visible.

This particularly slender type of structure is sensitive with respect to its vibratory dynamic behaviour. Tuned mass dampers were designed to allow the project to meet the required conditions of comfort.

Bureau Greisch, in association with the landscaping architect Corajoud, was responsible for the full architectural and structural design for the footbridge.
Retracted: 01.01: Placement of nut determining failure mode of bolt and nut assemblies
Authors: Grimsmo Erik L. , Aalberg Arne , Langseth Magnus , Clausen Arild H.
Published: September 2017

Bolt and nut assemblies under tension loading can either fail by bolt fracture or thread failure. The latter failure mode is arguably undesired because it leads to failure at a comparatively low deformation level. Moreover, incipient thread failure is challenging to detect in the case of over‐tightening since the bolt remains in the bolt hole after this type of failure occurs. The failure mode of bolt and nut assemblies is determined by several well‐known factors such as the thread engagement length and the relative strength of the bolt and nut. However, one factor that has received limited attention in the literature is the placement of the nut along the threaded portion of the bolt shank. We have performed a series of direct tension tests on various single M16 bolt and nut assemblies, where the placement of the nut was varied. Some of the assemblies experienced that placing the nut close to the thread run‐out, i.e., near the unthreaded portion of the bolt shank, led to thread failure, whereas placing the nut sufficiently far from the thread run‐out led to bolt fracture. We carried out finite element simulations of the tests in order to further investigate the mechanisms occurring during failure. In the case where the nut was located close to the thread run‐out, the simulations revealed that necking of the bolt shank affected the effective overlap of the internal and external threads. This effect seemed to contribute to thread failure in both tests and simulations.
16.12: Winning steel solution for flat arch bridge
Authors: Stroscio Riccardo
Published: September 2017

As part of a new University Campus development in the city of Northampton (UK), a new road access bridge was required to span over the river Nene. The client's aspirations and the planning requirements were set to keep the character of the existing landscape while creating an appropriate landmark structure for the new campus. The client's specimen design included a concrete flat arch bridge spanning 49m with a shallow rise of 3.7m above the navigable channel of the river.

During the tender design competition, closer reviews of the concrete solution were undertaken by the design and build team, concluding that the imposed loads to the foundations and the construction method required to build the concrete deck would not prove to be economical. Thus, an alternative design was developed using a steel‐concrete composite structure. The awarded solution includes 220 tonnes of welded steel plates to form a shallow and flat arch structure with deck cross girders.

This bridge case study paper discusses the design aspects from development at planning phase to tender design and detail design as well as the specific construction stages related to the steelwork erection.