bluuebunny/crossref_metadata_2025 huggingface dataset:
I.11.20: Design recommendations for dual moment – eccentric braced frames with replaceable links
Authors: Dubina Dan , Stratan Aurel , Chesoan Adriana
Published: September 2017

Modern seismic codes allow for inelastic deformation in dissipative zones during design earthquakes, accepting damage to the relevant structural parts to a certain extent. Experience has shown that repair work is needed after moderate to strong earthquakes. To obtain a seismic resilient structural system means to be easily repairable. For a given structure, to be repairable, after an earthquake, it must be calibrated by design to concentrate the inelastic deformations into the removable dissipative members, only, and after their removal, avoid permanent (residual) drift. To obtain re‐centring capability in a structure with eccentrically braced frames (EBFs) and removable dissipative members, a dual structural configuration is used, which combines EBFs and moment‐resisting frames (MRFs). If the more flexible MRFs are kept elastic – high strength steel might be used on this purpose, they would provide the restoring force necessary to re‐centre the structure upon the removal of the damaged removable links (the dissipative members). First, this paper summarises the experimental validation of technical solution and re‐centring capability of a dual EBFs with replaceable links, based on a full‐scale experimental testing programme performed at the European Laboratory for Structural Assessment (ELSA) at the Joint Research Centre (JRC) in Ispra, Italy. Secondly, with a numerical model, calibrated on these test results, parametric studies have been performed with the aim to offer a base for drafting specific design recommendations. These recommendations include prequalification procedures for the links.
I.11.47: A risk‐consistent approach to determine behavior factors for innovative steel lateral load resisting systems
Authors: Vamvatsikos Dimitrios , Castiglioni Carlo , Bakalis Konstantinos , Calado Luis , D'Aniello Mario , Degee Hervé , Hoffmeister Benno , Pinkawa Marius , Proenca Jorge Miguel , Kanyilmaz Alper , Morelli Francesco , Stratan Aurel , Vayas Ioannis
Published: September 2017

A risk‐consistent approach is proposed for the evaluation of behaviour factors that are compatible with Eurocode 8 using nonlinear static and dynamic analysis. The proposed process comprises seven discrete steps, involving hazard assessment and record selection at multiple sites, designing and modelling multiple archetype buildings and assessing their performance vis‐à‐vis target safety objectives. In all cases, uncertainty is incorporated and propagated to the final results whereby a flexible verification procedure is offered to account for the confidence of the investigator on the data available. The value added goes beyond the current state of art, offering a consistent risk basis for the seismic design of different systems that is compatible with current uniform hazard design spectra and future risk‐targeted hazard maps.
12.02: High strength steel I‐section arches: Inelastic lateral buckling and moment capacity
Authors: Pi Yong‐Lin , Bradford Mark Andrew , Liu Airong
Published: September 2017

Little research has been reported about high strength steel (HSS) arches and no adequate code provisions are available for their strength design although HSS structures are increasingly used in engineering construction. This paper presents an investigation of global inelastic lateral‐torsional buckling and strength of HSS I‐section arches using a validated finite element model. HSS arches in uniform bending are considered and the yield strength of the HSS used in the investigation is 460MPa, 690MPa, and 960MPa. Initial out‐of‐plane bow and twist imperfections and residual stresses are included in the investigation. It is demonstrated that the HSS influences inelastic lateral‐torsional buckling and strength of HSS arches significantly. The high yield strength of the HSS increases the moment capacity of HSS arches and reduces the difference between their inelastic and elastic lateral‐torsional buckling moments. Formulas for the dimensionless capacity of HSS arches in uniform bending, which is consistent with those in AS4100‐1998 and in Eurocode 3 for mild steel members, are developed. It is shown that the predictions of the new formulas for the dimensionless moment capacities of HSS arches in uniform bending agree with the finite element results very well.
12.08: Cross‐section stability of stainless steel channel sections subjected to combined loading
Authors: Liang Yating , Zhao Ou , Long Yue‐ling , Gardner Leroy
Published: September 2017

This paper presents a comprehensive experimental and numerical study of the cross‐section stability of stainless steel channel sections under combined axial compressive load and major axis bending moment. The experimental investigation included material coupon tests, initial geometric imperfection measurements and eight eccentrically loaded stub column (combined loading) tests, while the numerical modelling programme comprised a valiadtion study and a parametric study to generate further structural performance data. Both the experimental and numerical results were carefully analysed and then used to assess the accuracy of the current Eurocode design provisions for stainless steel channel sections subjected to combined loading. Generally, the Eurocode was found to result in unduly conservative and scattered strength predictions. Improved design rules have been proposed through extension of the deformation‐based continuous strength method (CSM) to the case of channel sections under combined loading. Comparisons between the proposal and the test and numerical results indicate a high level of design accuracy and consistency in the predictions. The reliability of the new proposal has also been confirmed by means of statistical analyses according to EN 1990.
12.13: On recent characterisations of the post‐yield properties of structural carbon steels
Authors: Sadowski Adam J. , Rotter J. Michael , Ummenhofer Thomas
Published: September 2017

New design methodologies are being developed that permit the full plastic condition and strain hardening properties of steel members and structures to be exploited. However, it has long been recognised that even the full plastic moment of a cross‐section cannot be attained assuming only an ideal elastic‐plastic material law, since infinite curvatures would be required to do so. Further, tests on structural members routinely show that, due to strain hardening, the full plastic condition is exceeded at finite slendernesses where one might expect stability to affect the result. This indicates that strain hardening should be a key consideration in design. Unfortunately, the strain hardening properties of carbon steels are not guaranteed by any standard or steel manufacturer, and no reliable depository of information is known to exist. Similarly, the proliferation of powerful modern finite element software that can handle significant geometric and material complexities is at odds with the paucity of information available to the analyst on the reliable choice of post‐yield material properties for carbon steels.

This paper presents a brief overview of the results presented in recent publications by the authors that attempt to tackle this problem. The intention is to alert the structural engineering community to the wealth of information contained in a typical tensile stress‐strain curve relationship beyond that which is commonly reported, and to show the tentative progress that has been made in characterising the post‐yield properties of some of the most common structural steels. A specialised algebraic formulation is used to process a database of 225 stress‐strain curves of various grades, allowing an accurate assessment of their post‐yield material properties. These include the length and gradient of the yield plateau, the initial tangent strain hardening modulus of the post‐plateau region, and preliminary statistical bounds for these for the most common grades. The paper additionally flags the novel notion that the yield plateau itself exhibits a small but finite and statistically significant positive gradient, which is potentially important in structural resistance calculations.
12.14: Ultimate response and design of stainless steel continuous beams
Authors: Kokosis Georgios , Gkantou Michaela , Theofanous Marios , Dirar Samir
Published: September 2017

Due to lack of available experimental data, plastic design of stainless steel (SS) indeterminate structures is currently not permitted by Eurocode 3: Part 1.4, despite the excellent material ductility and the existence of a Class 1 slenderness limit, thereby compromising design efficiency. The high initial material cost warrants the development of novel design procedures, in line with the observed structural response, which fully utilise its merits, improve cost‐effectiveness and minimise material consumption. This paper focuses on the response and design of stainless steel continuous beams. FE models of austenitic and lean duplex stainless steel SHS and RHS were developed and validated against published test data. The validated FE models were used to conduct parametric studies, in order to obtain structural performance data over a range of cross‐sectional slendernesses, cross section aspect ratios, moment gradients and loading arrangements. Based on obtained results, it was concluded that the current Eurocode 3: Part 1.4 approach significantly underestimates the strength of continuous beams. This is because the formation of successive plastic hinges and moment redistribution in indeterminate structures with adequate deformation capacity, as well as the effect of strain‐hardening at cross‐sectional level, are not accounted for. It is shown that accounting for both strain‐hardening and moment redistribution is of paramount importance for design. To this end, the application of the Continuous Strength Method (CSM), which rationally accounts for local buckling at cross‐section level, is extended to the design of stainless steel indeterminate structures. Further research is underway to quantify the effect of high shear stresses on the design procedure and to extend the method to the design of pinned based and fixed based stainless steel frames.
12.15: Structural performance of stainless lap bolted joints
Authors: Freire Raphael , da Silva Vellasco Pedro Colmar Gonçalves , da Silva André Tenchini , de Lima Luciano Rodrigues Ornelas
Published: September 2017

The stainless steel employed in the structural elements present high corrosion resistance, durability, fire resistance and high aesthetic value compared to those constructed using carbon steel. In contrast, the stainless steel structures design is made following the requirements based on the carbon steel analogies. In fact, the structural performance of stainless steel is complex and dissimilar where some stainless grades presenting nonlinear tension versus strain curves without a defined yield plateau and large strain hardening. These properties influence on structural performance of the lap bolted joints. The Eurocode 3 pt. 1.4, one of the most adopted design codes, recommends two structural design criteria for the stainless steel elements under tension: ultimate resistance of the net cross‐section at holes or plastic resistance of the gross cross‐section. The present work aimed to investigate the structural response of lap bolted joints made of three stainless steel grades: austenitic, ferritic and duplex. Nonlinear numerical analyses has been carried out using ABAQUS 6.14 program where the response have shown a good agreement in terms of the maximum loads and failure modes when compared to the performed experiments. The results indicated a conservative level of safety from Eurocode 3 pt. 1.4 code provisions in comparison to the experimental results.
12.17: Economical design of high strength steel trusses using multi‐criteria optimization
Authors: Mela Kristo , Tiainen Teemu , Heinisuo Markku
Published: September 2017

Evaluating the economy of high strength steel in structural applications is typically difficult since accurate cost data is not available. In this study, multi‐criteria optimization approach is employed to provide the designer with a decision‐making tool for finding compromise solutions between material and fabrication costs without the need for cost data. Structural weight, painted area and volume of welds are the three conflicting and non‐commensurable criteria considered. These quantities represent the main sources of costs in tubular trusses, namely material, surface treatment and welding. By examining the Pareto optimal solutions, the trade‐off between weight savings and fabrication costs can be assessed. The proposed approach is especially suitable when applying topology optimization, as the number of braces can be varied during optimization, which has clear impact on the fabrication costs.
12.20: Mechanical properties of cold‐formed stainless steel
Authors: Mařík Jan , Jandera Michal
Published: September 2017

Stainless steel is a material of many specific properties, which significantly differs from carbon steel ones. One of the main attributes of all stainless steel grades that haven't been satisfactorily investigated is the significant change of stress‐strain behaviour due to cold‐forming in fabrication process of structural elements. In the last decades some proposals for the most basic material properties have been developed. However they don't predict the whole stress strain diagram. In the paper presented research involves testing programme focused on virgin and cold‐worked elements of four stainless steel grades: austenitic (1.4404), ferritic (1.4003), duplex (1.4462) and lean duplex (1.4162). Selected grades represent the most used families of stainless steel specified for structural purposes and used for section fabricating via cold‐forming. Gathered data together with other available experimental results serve as a base for analytical part of the research. The main output was establishment of an analytical solution for a stress‐strain diagram of a whole structural cross‐section represented by square and rectangular hollow sections. Further objective was to establish relationships for mechanical properties such as ductility or ultimate strength as these issues have not been sufficiently investigated before. Conclusions contribute to the common design of stainless steel structures and help to precise finite element analyses using enhanced properties of cold‐worked stainless steel.
12.23: Research on low‐yield‐point steels in Tsinghua University
Authors: Shi Gang , Wang Xun , Zhang Yong
Published: September 2017

For the advantages of low yield strength, high tensile‐to‐yield strength ratio and excellent ductility, low‐yield‐point steels are extremely applicable for energy dissipation in seismic design of steel structures, so they are more and more used in steel structures in seismic areas. To get comprehensive understanding on material properties of low‐yield‐point steels and give support to the design and engineering application, the research group in Tsinghua University has conducted the study on the LY100, LY160 and LY255 three grades of low‐yield‐point steels in China. The data of mechanical properties such as tensile strength, yield strength, percentage elongation and impact work from the steel manufacturer have been collected and analyzed by the mathematical statistics method based on the reliability theory, and the partial factors for resistance of low‐yield‐point steels have been proposed. Also low‐yield‐point steel coupon specimens were tested by different cyclic loading programs, and the constitutive models under cyclic loading were proposed and calibrated. Furthermore, the low‐cycle fatigue behavior of low‐yield‐point steels were studied by tests, and the test results can be used to predict the cyclic loading safety and life of low‐yield‐point steel components in steel structures under earthquakes.
13.01: Net cross‐section failure of steel plates at bolt holes: Numerical work and statistical assessment of design rules
Authors: Snijder H.H. , Dekker R.W.A. , Teeuwen P.A.
Published: September 2017

This paper concentrates on the design rule for net cross‐section resistance as one of the design rules relevant for bolted connections. In a previous paper twelve experimental test results were presented of a test program containing 28 specimens in total, with different bolt hole configurations, ranging from one bolt hole to multiple staggered and non‐staggered holes. The specimens contain bolts or not, meaning that plates with only bolt holes are tested as well as plates connected by bolts. This paper now summarizes all experimental test results.

Subsequently, these experimental test results were used to validate a finite element model. Strain hardening needs to be taken into account in the numerical model. The paper discusses the result for different strain hardening models available in codes.

The validated finite element model was then used to create a database of numerical test results. In the database, configurations of plates with and without bolts are included. Bolts M16, M20 and M24 are considered. Both staggered and non‐staggered bolt configurations are included with different end and edge distances and pitches. Plate thicknesses range from 8 to 26 mm. Most configurations use steel grade S235 but S460 was also considered.

The database was used to perform a statistical assessment of the current design rule for net‐section resistance, using the procedure of Annex D of EN 1990 as further developed in the RFCS project Safebrictile together with the statistical distributions for steel properties of Safebrictile.

It was found that the current partial factor is over‐conservative and can be substantially lowered. Alternatively, the design rule can be modified. The paper concludes with a proposal for a new design rule.
13.03: Bending‐shear interaction of steel I‐shaped cross‐sections: Statistical investigation
Authors: Dekker R.W.A. (Rianne) , Snijder H.H. (Bert) , Maljaars J. (Johan)
Published: September 2017

Clause 6.2 of EN 1993‐1‐1 covers the cross‐sectional resistance of steel sections. The bending‐shear interaction design rules for I‐shaped cross‐sections make use of a reduced yield stress for the web area. On this basis, a reduced design plastic resistance moment allowing for the shear force is presented. The effect of shear on the bending resistance may be neglected if the shear force is less than half of the plastic shear resistance of the cross‐section. Plasticity in the Eurocode is described by the well‐known Von‐Mises yield criterion, however, the formula used for the reduced yield stress deviates from this criterion, resulting in sometimes greater and sometimes smaller values. The background of the Eurocode formula for reduced yield stress can be found in a publication by Drucker. The purpose of the present research is to investigate the influence of shear on the bending resistance of I‐shaped steel cross‐sections with as result a possible reconsideration of the Eurocode design rules.

At Eindhoven University of Technology an experimental investigation on bending‐shear interaction in rolled steel I‐shaped sections was performed. A numerical model was developed in Abaqus Finite Element software to simulate the experiments. With the validated numerical model a larger database of numerical ‘test’ results was generated, which was subsequently used in a statistical analysis following Annex D of EN 1990 as further developed in the RFCS project Safebrictile. The statistical distributions of the steel properties recommended by Safebrictile were adopted.

This paper presents the results of the statistical analysis and safety assessment of the strong axis bending‐shear interaction design rule currently present in Eurocode 3. The parametric test group consists of HEA, HEM and IPE sections in the steel grades S235, S355 and S460: in total 180 numerical simulations with increasing amount of shear. A stress‐strain model including strain hardening was used in the numerical simulations, since the influence of strain hardening is also largely present in the experimental test program. Based on strain hardening material behavior it is show in this paper that the current partial factor is un‐conservative for shear dominated beams and should be increased. Alternatively, the design rule should be modified.
13.06: Calibration of Eurocode design models of thin‐walled cylinder under bending with full scale tests
Authors: Peters Dirk Jan , Sadowski Adam , Rotter J. Michael , Taras Andreas
Published: September 2017

Design formulas for thin‐walled cylinders in bending show remarkable differences in various codes, including versions of the Eurocodes. Thin‐walled, high grade steel cylinders are used in piles, e.g. in combined walls for quay wall construction or in large mono‐piles for mooring structures or offshore foundations. These piles experience a dominant loading in bending, and may be designed with Eurocode formulas for shell buckling of prismatic cylinders.

In recent years, a relatively large number of new results of full scale experiments has become available. These results can be combined with test results from the literature and can be used for calibration of the design model formulas for thin‐walled tubes, in particular in the range that has a high susceptibility to elastic or plastic local buckling. The diameter range of the tests is 400 to 900 mm. The d/t ratios range from 40 to 110 and the steel grades from S235 to S460.

New capacity‐based formulas for Reference Resistance Design (RRD) of cylinders in bending have been developed from extensive GMNIA calculations (geometrically and materially nonlinear analyses with imperfections included) that included many variations of the relevant parameters and buckling pre‐conditions. A calibration against the tests forms a potentially valuable confirmation of those design rules. The methodology of the calibration is based on statistical procedures that prove sufficient reliability according to the Eurocode requirements.

Similar to other calibration exercises, it appears that the difference between the nominal and real material strength is, amongst other aspects, an important input parameter for the calibration result.

The evaluation performed here shows that the published Eurocode EN 1993–1–6 2007 strength‐based formulas produce conservative results and that the new RRD amendment which produces less‐conservative design values can still be safe.
00.03: European research on steel structures in seismic areas
Authors: Mazzolani Federico M.
Published: September 2017

In Europe the research activities on steel structures in seismic areas is very intense and productive since the ‘80s of the last century. Many research projects have been developed. In particular, the activity started within the Technical Committee 13 (seismic design) of ECCS deeply contributed to the scientific debate and to the genesis of current Eurocode 8, which is currently under maintenance. This paper summarizes the main topics already consolidated and the related research activities currently ongoing, together with the ones needing further developments, in order to highlight the research perspectives of the European community of experts working on the field of steel structures in seismic areas. In particular, the discussion focuses on material properties, local ductility, full strength and dissipative joints, innovative types of links in eccentrically braced frames, capacity design rules, cold‐formed applications, new structural types and devices, the use of steel in structural consolidation.
13.07: Extension of EN 1993‐1‐10 and EN 1993‐1‐12: To higher strengths and thinner sections
Authors: Wallin Kim , Karjalainen‐Roikonen Päivi , Suikkanen Pasi
Published: September 2017

The Eurocode 3 sections EN 1993‐1‐10 and EN 1993‐1‐12 contain tables for the maximum permissible values of element thickness as a function of steel grade, quality and reference temperature. The tables cover steel strengths from S235 to S700 and section thicknesses above 10 mm. The tables have been constructed based on a fracture mechanical brittle fracture analysis using a Charpy‐V impact energy criterion as reference.

Ultra high strength steels above 700 MPa are not covered by the tables. Such steels are generally used in thinner sections than 10 mm, when the tables in EN 1993‐1‐10 and EN 1993‐1‐12 are limited to section thicknesses above 10 mm. Here, the same basic procedure as used for the tables in EN 1993‐1‐10 and EN 1993‐1‐12 is used to extend them to higher strength steels and thinner sections. The procedure is modified slightly to account for special characteristics of ultra high strength steels and thin sections. These modifications do not affect the present tables, but they provide a smooth transition to higher strength steels and thinner sections. The strong inherent conservatism in the EN 1993‐1‐10 procedure is not affected either.
13.09: Yield stress independent column buckling curves
Authors: Stan Tudor‐Cristian , Jönsson Jeppe
Published: September 2017

Using GMNIA and shell finite element modelling of steel columns it is ascertained that the buckling curves for given imperfections and residual stresses are not only dependent on the relative slenderness ratio and the cross section shape but also on the magnitude of the yield stress. The influence of the yield stress is to some inadequate degree taken into account in the Eurocode by specifying that steel grades of S460 and higher all belong to a common set of “raised” buckling curves. This is not satisfying as it can be shown theoretically that the current Eurocode formulation misses an epsilon factor in the definition of the normalised imperfection magnitudes. By introducing this factor it seems that the GMNIA analysis and knowledge of the independency of residual stress levels on the yield stress can be brought together and give results showing consistency between numerical modelling and a simple modified Ayrton‐Perry formulation. In this paper magnitudes of imperfections and residual stresses in relation to the Eurocode will be discussed. It will be shown that the use of equivalent imperfections may be very conservative if considered by finite element analysis as described in the current Eurocode code. A suggestion is given for a slight modification of the Eurocode formulations of imperfections leading to adequate inclusion of modern high grade steels within the four bucking curves.
13.11: DSM design approach for hot‐rolled steel angle columns
Authors: Dinis Pedro Borges , Camotim Dinar , Vieira Luís
Published: September 2017

This work reports the latest results of an ongoing investigation on the Direct Strength Method (DSM) design of hot‐rolled steel equal‐leg angle columns with fixed and pinned (cylindrical or spherical hinges) supports and short‐to‐intermediate lengths, i.e., buckling in flexural‐torsional modes. It extends the scope of similar studies carried out by the authors for cold‐formed (higher leg width‐to‐thickness ratios) steel angles with the same characteristics. After reviewing (i) the most relevant findings unveiled in the studies concerning hot‐rolled steel angles, including the role played by residual stresses in eroding their ultimate strength, and (ii) the available experimental and numerical failure load data, comprising fixed‐ended and pin‐ended columns with several geometries (cross‐section dimensions and length) and reported by various researchers, the paper briefly addresses the mechanical reasoning behind an efficient DSM‐based design approach proposed by the authors in the context of cold‐formed steel (slender legs) short‐to‐intermediate angle columns. Then, the available failure load data is used to assess the quality of their estimates provided by this DSM design approach, including the determination of the corresponding Load and Resistance Factor Design (LRFD) resistance factors. It is shown that the proposed design approach can be also successfully applied to predict hot‐rolled steel angle column failure loads, leading to LRFD resistance factors above the value currently prescribed, for compression member design, by the North American Specification (ϕc=0.85).
13.13: Earthquake loss assessment of steel moment‐resisting frames designed according to EC8
Authors: Macedo Luís , Castro José Miguel
Published: September 2017

The development of damage in buildings is implicit in the seismic design process. However, stakeholders and building owners generally have the perception that code design provisions ensure safe and minor damaged buildings for any seismic intensity level. It is therefore crucial to provide support decision information, which can help stakeholders and building owners taking informed selection of design opinions. Most recent design and assessment standards/guidelines define several performance levels seeking to ensure that structures exhibit appropriate behaviour and protection at different seismic intensity levels. Moreover, for steel moment‐resisting frames (MRFs), EC8‐3 defines the building performance acceptance criteria at different performance levels by ensuring that local deformation demands are lower than pre‐defined local deformation capacities. The main objective of the research presented in this paper is to evaluate the expected direct economic seismic losses of steel moment‐resisting framed structures designed according to Eurocode 8. To this end, the PEER PBEE methodology with the improvements proposed by [1] was implemented and used. A set of 30 archetype buildings, representative of the current building stock, were designed according to Part 1 of Eurocode 8 (EC8‐1) using three different behaviour factors (q). The EC8 proposed upper limits for the behaviour factor (q) and the behaviour factor obtained from an Improved Force‐Based Design (IFBD) procedure have been used [2]. The expected economic losses and its disaggregation were evaluated for the EC8‐1 and EC8‐3 seismic intensity levels, allowing in this way to characterize the performance with improved seismic performance metrics which can help stakeholders and building owners to take their decisions.
13.16: Design of tension components: Revision and further development of EN 1993‐1‐11
Authors: Annan Rachid , Bechtold Martin , Friedrich Heinz , Kemmler Roman , Misiek Thomas , Numminen Veikko , Ruff Daniel C.
Published: September 2017

The paper gives an introduction as well as background information on proposed changes and amendments in EN 1993‐1‐11 “Design of structures with tension components”, implemented during the ongoing revision. Due to some deficits in the currently applicable standard this revision is not only limited to some restructuring and editorial changes, but includes also major technical changes in the following fields: safety concept and structural analysis, actions and loads, robustness and reparability, design of tension components and design of clamps and saddles.
14.05: A mehcanical model of composite floor systems under internal column‐removal scenarios
Authors: FU Qiu Ni , TAN Kang Hai , YANG Bo
Published: September 2017

Slabs play a vital role in enhancing structural capacity to resist progressive collapse. However, there are only some qualitative suggestions rather than quantitative provisions in the current codes and design guides concerning the beneficial effect of slabs to mitigate under progressive collapse. Therefore, a mechanical model for calculating load‐carrying capacities of floor systems against progressive collapse is timely and necessary. In this paper, a new mechanical model is proposed to quantify load‐carrying capacities of 3D composite floor systems for internal column removal scenarios. The assumptions, simplifications and failure criteria of the model, which are based on the results of validated numerical analyses and other researchers’ tests, are introduced first. After that, the derivations of the proposed model are discussed. Then, the static load‐displacement responses obtained from this model are compared with the test results. Good agreement is obtained between the model and the test results.
15.05: The experiment of H‐shaped beams with continuous restraint on upper flange
Authors: Sano Tatsuhiko , Ikarashi Kikuo , Ohnishi Yuki , Shirai Daigo
Published: September 2017

This study aims to investigate the elastic–plastic behavior of H‐shaped beams with continuous, complete restraints on the upper flange through a static loading test, and to understand the effect of restraint and the influence of raising the neutral axis. In the loading test, the upper flange is restrained using a restraint device with four hinges. The shifting of the neutral axis position is simulated by increasing the shape of the upper flange. The following conclusions are drawn from the results: (1) The continuous, complete restraint on the upper flange significantly increases the maximum strength and the plastic deformation capacity of the beam with respect to the lateral buckling. The buckling waves are observed close to the fixed end. (2) The continuous, complete restraint on the upper flange slightly increases the maximum strength and plastic deformation capacity of the beam in the local buckling of the web, and has no effect on the beam considering the local buckling of the flange. (3) The elastic web local buckling of the H‐shaped beams with a continuous, complete restraint on the upper flange occurs easily because the neutral axis shifts its position. The plastic deformation capacity of the beam may have been reduced.
15.10: Probabilistic analysis of steel columns under blast induced loads
Authors: Karlos Vasilis , Solomos George , Larcher Martin
Published: September 2017

A growing interest for the design of structures to sustain blast induced loads has been observed in recent years due to the worldwide rise of terrorist bombing attacks. The blast parameters that are essential for design can be located in various publically available blast design manuals, where the proposed graphs and equations are based on a large experimental database established several decades ago. The degree of uncertainty in the determination of these parameters is significant, as a result of the unstable nature of explosives, the efficiency of the measuring equipment and the large pressure and impulse values involved in the blast phenomena.

These uncertainties have been identified in the current study which focuses on the response of steel open sections under blast induced loads and addresses the influence of such uncertainties on the flexural response of axially loaded structural members. The variation of structural and load parameters was considered in the design procedure by utilizing a reliability‐based assessment methodology. A probabilistic approach was followed and the reliability of the column was defined with respect to limit states proposed in various blast design manuals. Probability curves are constructed, by using single‐degree‐of‐freedom models, showing the cumulative probability distribution of reaching a certain capacity with respect to a selected limit state. This way instead of a deterministic safe‐unsafe criterion in design, the probability of damage is introduced in relation to the applied axial load, which provides a valuable insight to the behaviour of structural members subjected to an explosion.
15.11: Lab testing and modelling of thermal break assemblies: Mitigating structural penetrations in building envelopes
Authors: Hamel Scott , Peterman Kara
Published: September 2017

The large temperature differentials between inside and outside spaces in Alaska (>100°F) has triggered the use of thermal‐break details for envelope point protrusions for decades, mostly to prevent condensation on interior structural members. This has been done, however, using engineering judgment, and, prior to this study, no experimental or computational analysis has been conducted on the effectiveness of these details.

This study outlines a series of thermal and structural tests of thermal bridges and thermal break details for steel sections protruding through the building envelope such as for canopies or rooftop mechanical units. The results of the experimental data will be correlated with thermal finite‐element models to provide insight on the modelling parameters. The results show that some details, while decreasing the potential for condensation, actually increases the overall heat flow through the detail, when compared to the control condition with no thermal break.
15.12: On imperfection‐sensitivity evaluation of BMRF systems: Buckling and post‐buckling responses
Authors: Lotfollahi Mehrdad , Alinia Mohamad Mehdi , Taciroglu Ertugrul
Published: September 2017

Sensitivities of the buckling and post‐buckling responses of braced moment resisting frame (BMRF) systems to initial imperfections in their gusset‐brace sub‐systems are studied. Previously, the effects of imperfection amplitude and type have not been evaluated in requisite detail, and only a general recommendation—which is given as a function of the bracing element's length—has been utilized. Here, highly detailed (centimeter scale) three‐dimensional finite element models are employed in parametric sensitivity analyses to quantify the effects of imperfections on the responses of BMRFs with diagonal and X‐bracing subsystems. The results are discussed and amendments are proposed to the existing empirical equations for evaluating the buckling and post‐buckling capacities of imperfect bracings. The parametric studies showed that while an increase in the imperfection amplitude can dramatically decrease the initial buckling load of BMRFs, this causes only moderate decreases in their post‐buckling strengths, and their ultimate states remain nearly unaltered.
15.13: Discrete sizing optimization of trussed steel portal frames according to Eurocode 3
Authors: Van Mellaert Roxane , Mela Kristo , Tiainen Teemu , Heinisuo Markku , Lombaert Geert , Schevenels Mattias
Published: September 2017

This paper presents a new method to find the global solution of combined truss‐frame sizing optimization problems taking into account all relevant Eurocode constraints. The approach is based on a reformulation of the optimization problem as a Mixed‐Integer Linear Programming problem (MILP) which is solved by means of a branch‐and‐bound method. A portal frame that consists of both beam and truss elements is adopted as a test case. The optimal sections of the portal frame have to be selected from a square hollow sections catalog. The design of the portal frame has to meet the requirements prescribed by the Eurocodes. These requirements are adopted as constraints by reformulating them as or approximating them by a linear equation. Not only the Eurocode constraints related to member strength and stability but also all Eurocode constraints related to the joints of the structure are taken into account during the optimization. As a consequence, a post‐processing step to account for other constraints is avoided, therefore optimality is retained and additional engineering time is reduced. The optimization results are presented and the influence of the different Eurocode constraints on the optimal design is discussed.
15.15: Dynamic Analysis of Steel‐Concrete Composite Building Floors Subjected to Human Rhythmic Activities
Authors: Campista Fernanda Fernandes , da Silva José Guilherme Santos
Published: September 2017

This work aims is to investigate the structural dynamic response of steel‐concrete composite floors, when subjected to rhythmic human activities, based on experimental tests and numerical modelling, from the point of view of human comfort. The main focus of this paper is to study the effect of the dynamic interaction between the occupants and the floors, representing these people by SDOF biodynamic models (mass‐spring‐damper systems), in order to better evaluate the dynamic response and the vibration serviceability states. This way, the investigated structural model is related to a steel‐concrete composite building which is composed of three floors used for aerobics classes, with dimensions of 20m × 20m, a total area of 1200m2 (3 × 400m2) and a ceiling height of 4m. The numerical modelling of the structure was performed by ANSYS program and was based on the finite element method (FEM). In order to evaluate the dynamic response of the investigated steel‐concrete composite building, accelerations associated with 32 individuals practicing rhythmic activities were experimentally obtained to introduce them into the finite element model. Thus, the dynamic response of the building floors was evaluated in terms of the peak accelerations, RMS and VDV values, according to human comfort criteria and considering situations of the design practice.
16.03: Structural analysis of the historical Széchenyi: chain bridge in Budapest
Authors: Kövesdi Balázs , Dunai Péter , Dunai László
Published: September 2017

The superstructure of the historical Széchenyi chain bridge in Budapest was reconstructed several times in the history and currently the renewal of the bridge is under design. The independent static check and expertizing tasks of the renewal process were completed by the Budapest University of Technology and Economics Department of Structural Engineering. During the project numerous specific interesting structural problems and modeling specialties turned out, which comes from the layout of the old historical structure, from the long time traffic and from the corrosion, which required a detailed structural analysis. The current paper presents the typical failure modes observed on similar historical chain bridges all over the word, which gives an impression on their weak‐points to be checked with special attention. To determine the load carrying capacity of the renewed structure and to check the fatigue performance of the old structural details a detailed numerical model is developed. The global model was used to simulate the structural behavior of the whole structure. Local models are used to model the effect of corrosion, the friction between the chains and the pin, and to model all the uncertainties in the design procedure using probabilistic design. The application of advanced analysis methods and design tools on a historical steel structure are discussed in the paper.
16.05: Evaluation of simplified models for short span bridges: Based on a measured train crossing and included substructure
Authors: Brandstetter Georg , Schobesberger Felix , Fink Josef
Published: September 2017

In recent times numerous studies concerning bridges under dynamic loading through train crossing were made. It was found out that there are significant deviations of the measured field results and the results determined by simulations using conventional beam models for bridges with short spans (up to 10m). It was shown that a simply supported beam is not a sufficient model for these structures, since the influence of the subsoil and the substructure cannot be neglected for short bridges.

The main goal of this article is to achieve a better accordance between the measured and the calculated results. Therefore, the model of the simply supported beam is expanded at both supports by: vertical springs and additional nodal masses. Also, different models for the load are examined. To evaluate the quality of this models, an acceleration measurement of a 4m span bridge during a train crossing is used.

It is shown that the measured accelerations can be predicted with acceptable accuracy with an extended beam model by including the load distribution through the rails and the ballast layer (by the method suggested in Eurocode 1).
16.07: Flange buckling resistance of trapezoidal web girders: Experimental and numerical study
Authors: Jáger Bence , Kövesdi Balázs , Dunai László
Published: September 2017

Girders with trapezoidally corrugated web are widely used structural elements in the civil engineering praxis due to their numerous advantages. However, there is a relatively small number of previous investigations focusing on the determination of the flange buckling resistance of the corrugated web girders. Previous experimental and numerical investigations confirmed that the flange buckling resistance model provided by the EN1993‐1‐5 [2] predicts often unsafe results. Therefore, the current paper collects all the previous proposals on the flange buckling resistance and introduces an experimental research program investigating the flange buckling behaviour of trapezoidally corrugated web girders. Based on the test results an advanced FE model is developed, validated and presented. An intensive numerical parametric study is performed on this model to investigate the buckling coefficient and the relationship between the relative slenderness and the reduction factor for corrugated web girders. Based on the experimental and numerical results the current paper introduces an enhanced design method for the determination of the flange buckling resistance. This design method consists of proposal to determine the critical load amplifier of the flange outstand and it also contains a new buckling curve which considers the specialties of the structural behaviour coming from the corrugation profile.
16.14: Operational, ecological and economical assessment of steel railway bridges
Authors: Zinke Tim , Ummenhofer Thomas , Lenz Katrin , Schneider Sarah , Beck Tabea
Published: September 2017

Although for civil engineering structures commercial assessment approaches such as the British CEEQUAL [1] or the American Envision [2] can be found, no sustainability assessment system specialised in railway bridges exists. Here, system specific aspects like construction types, corrosion protection systems and construction processes must be considered. There is a lack of systematic research showing the advantages of prefabrication, and a small number of rehabilitation activities within the operation stage both leading to fewer obstructions of the railway network. Especially interdependencies of building activities and the operation of trains should be analysed and integrated into the assessment.

The paper discusses the approaches and methods essential for a holistic assessment of railway bridges. The special boundary conditions of the rail traffic (compared to road traffic) will be presented. Based on this, economic and ecologic impacts throughout the entire life‐cycle are calculated and operation encumbrance costs caused by the interaction of construction sites and railway operation are shown. This is performed for three types of bridges: a thick plate through bridge, a composite bridge and a tied‐arch bridge.
16.15: Experimental evaluation of a novel demountable shear connector for accelerated repair or replacement of precast steel‐concrete composite bridges
Authors: Suwaed Ahmed S. H. , Karavasilis Theodore L.
Published: September 2017

A novel demountable shear connector for precast steel‐concrete composite bridges is presented. The connector uses high‐strength steel bolts, which are fastened to the top flange of the steel beam with the aid of a special locking nut configuration that prevents slip of bolts within their holes. Moreover, the connector promotes accelerated construction and overcomes typical construction tolerances issues of precast structures. Most importantly, the connector allows bridge disassembly, and therefore, can address different bridge deterioration scenarios with minimum disturbance to traffic flow, i.e. (i) precast deck panels can be rapidly uplifted and replaced; (ii) connectors can be rapidly removed and replaced; and (iii) steel beams can be replaced, while precast decks and shear connectors can be reused. A series of push‐out tests are conducted to assess the behavior of the connector and quantify the effect of important parameters. The experimental results show shear resistance, stiffness, and slip capacity significantly higher than those of welded shear studs along with superior stiffness and strength against slab uplift. Identical tests reveal negligible scatter in the shear load – slip displacement behavior. A design equation is proposed to predict the shear resistance with absolute error less than 8%.