bluuebunny/crossref_metadata_2025_split huggingface dataset:
11.45: Cyclic testing on hybrid buckling‐restrained Braces (HBRBs)
Authors: Pandikkadavath Muhmaed Safeer , Sahoo Dipti Ranjan 
Published: September 2017

ABSTRACTBuckling‐restrained braced frames (BRBFs) are dependable lateral load‐resisting systems to safeguard buildings against seismic actions. Nearly‐symmetric and stable hysteretic response of buckling‐restrained braces (BRBs) stimulated the wide spread incorporation of BRBFs in various structural systems. However, BRBFs suffer from increased drift demands as compared to other braced frame systems, mainly due to the low post‐yield strength/stiffness of BRBs. This study proposes a hybrid buckling‐restrained brace (HBRB) combining the short yielding core BRB (SBRB) and a heavy elastic hollow steel section (HSS) in series. SBRB is allowed to undergo desired level of plastic deformation, whereas the elastic HSS segment can provide the improved stiffness to the HBRBs. Such HBRBs have similar, stable and balanced hysteresis and enhanced elastic and post elastic stiffness as compared to conventional BRBs. In this study, three reduced‐scale models of proposed HBRBs with varying yielding lengths are fabricated and sub‐assemblage tests are carried out under modified non‐linear reversed cyclic loading conditions. For the buckling‐restraining of SBRB segments, concrete filled detachable casings with all‐around end cover plate arrangement is used, whereas a rigid connection between the SBRB and HSS is considered. Results showed that HBRBs were capable of withstanding an axial core strain of more than 6% without any instabilities. Further, HBRBs exhibited excellent hysteric response, load‐resisting capacity, deformation ductility, and hysteretic energy dissipation potential. Strength‐adjustment factors of HBRBs are also found to be little larger than those of conventional BRBs.
11.51: Numerical investigation of short seismic links in shear
Authors: Bulic Mladen , Causevic Mehmed 
Published: September 2017

ABSTRACTIt is well known that seismic links are usually designed to remain in elastic region during ordinary loading but withstand nonlinear deformation during seismic event having capability to dissipate seismic energy. The use of short seismic links is recommended because they are capable of dissipating seismic energy in larger quantity by shear, while the webs in these links are expected to yield in shear during large seismic events, i.e. dissipation of seismic energy by bending in links is negligible. Shear deformations are basically plane deformations of the cross section web of the link, without any significant tendency towards lateral torsional buckling. To achieve the required plastic rotation, local instabilities such as flange or web buckling should be delayed. The flange local buckling is delayed by specifying width to thickness ratio, while the web local buckling will be prevented by adding number of transverse stiffeners along the web of the link. The main purpose of the stiffeners is to preserve buckling of the seismic link web, i.e. to achieve plastification of the cross section by shear. Dissipation of energy in the stiffened link will occur sooner through inelastic shear deformations than through inelastic web buckling. The seismic links were chosen having the same cross section and the same length, but with different number of stiffeners, i.e. with three couples of stiffeners, two, one and without any stiffener respectively. A finite element modelling approach in investigating the structural behaviour of short links is presented. Both the material and geometric nonlinearities are considered in the FE modelling using the software ABAQUS and the Shear force – Displacement relationships was obtained. The FEA results are validated against the test results and the comparisons indicated that the FE analysis procedures agree well with the test results.
11.55: Development of a 2‐dof model simulating the dynamic response of special truss moment frames with shape memory alloy bars as dissipation devices in the special segment
Authors: Ntina Maria , Sophianopoulos Dimitrios , Tsopelas Panos 
Published: September 2017

ABSTRACTThe Special Truss Moment Frame (STMF) is a seismic load‐resisting system that consists of trusses as horizontal members and specially designed segments that are expected to withstand large cyclic deformation during seismic events. The initial concept [1–3] was based on designing a special segment inside the truss as a fuse to dissipate the input energy in a ductile manner, while the other members outside the special segment stay in the elastic range. Later on, special dissipation devices in the aforementioned segment were incorporated [4], and the results obtained showed an adequate performance of the STMF. In view of the above, the present work aims to develop a simplified structural model of a STMF, with shape memory alloy bars as dissipation devices in the special segment. After developing a more sophisticated constitutive model of these bars, a 2‐degrees‐of‐freedom simulation is proposed, in order to initially capture the dynamics of the STMF in a satisfactory manner. This model has two degrees of freedom, one translational and one rotational, accounting for simplified assumptions regarding the elastic response of the STMF columns and truss outside the special segment. After fully exploring the deformation features of the model, the equations of motion are formulated. Results obtained under various simple as well as complex excitation patterns showed that the model at hand may be used as basis for on‐going research.
I.11.39: Behaviour factor evaluation of moment resisting frames having dissipative elements
Authors: Alavi Amin , Castiglioni Carlo Andrea , Brambilla Giovanni 
Published: September 2017

ABSTRACTCivil structures subjected to strong earthquakes need to dissipate large amounts of energy. Hence, the conventional systems suffer significant inelastic deformations (costly damages) in main structural elements (steel beams, columns and concrete slabs) and residual interstorey drifts after a strong seismic event. Repair work, however, in these cases is most of the time not feasible, or too expensive. FUSEIS Bolted Beam splices, therefore, can be installed in buildings in order to protect the structural elements during the seismic events. On the other hand, behaviour factor in EC8 is provided only for conventional frames such as MRFs, CBFs, EBFs and so on without any clear specification for other types of structures i.e. innovative dissipative structures. This paper investigates the seismic performance of buildings having FUSEIS bolted beam splices by means of non‐linear static analysis, results also compared with conventional frames. Behaviour factor of these buildings are then evaluated based on single degree of freedom systems. This paper investigates one of the several possibility of the calculation of the behaviour factor based on SDFS. The other possible methods will be deeply study in the upcoming paper. In order to do so, three buildings regular in and elevation has been deeply investigated as case studies. Numerical results highlight that plastic deformation concentrates mainly in the beam splices, hence, remaining the main elements in elastic region and hence protecting them from any sort of damages.
12.04: Experimental and numerical investigation on the Q690 high strength steel slender columns of welded H‐sections under compression
Authors: Ma Tian‐Yu , Li Guo‐Qiang , Chung Kwok‐Fai 
Published: September 2017

ABSTRACTThis paper presents the experimental and numerical findings on Q690‐QT high strength steel welded H‐sections. A total of seven slender columns under axial compression were successfully carried out. Four sections of different sectional dimensions were involved. Before testing, the initial out‐of‐straightness of all the specimens were measured. All the tests were conducted in a 1,000 tons universal servo‐controlled testing machine. During the test, displacement transducers were used to record lateral deflections at the mid‐height section and axial deformations at the top ends of all the specimens. Strain gauges were mounted onto the outer surface of the flanges at three sections of each specimen. The strain gauge readings were used to calculate the loading eccentricities at both ends of the columns. All the columns were failed by overall buckling about the minor axes of their cross‐sections and neither weld nor material fracture was found. Separate specimens were fabricated for the measurement of residual stresses of all the sections. The numerical simulation on these tests are also reported. The numerical models were based on the measured geometrical dimensions and material properties of all the specimens. The measured out‐of‐straightness, loading eccentricities, and residual stress patterns were also introduced in the models. These numerical models were proved able to simulate the behaviour for all the test specimen except one, in which the end rotational restraints were significant. Both the test result and the numerical result with normalized initial out‐of‐straightness were compared with the current design codes. It is preliminarily proposed that column buckling curve a in the current design codes may be appropriate for the design of Q690 high strength steel welded H‐sections. And this proposal is need to be confirmed by complementary parametric study in the future.
13.18: Advanced analysis of braced steel frames: Modelling accounting for the post‐limit behaviour of compressed angle braces
Authors: Giżejowski Marian Antoni , Barszcz Anna Maria 
Published: September 2017

ABSTRACTThis paper presents a method of advanced analysis applied to steel plane load bearing systems like trusses as well as unbraced and braced frames. The effects of both material and geometrical nonlinearities on the structural behaviour are studied together with tracing the whole range of truss member behaviour. In the braced frameworks, the truss bracing model accounts for the effect of post‐limit behaviour on the inelastic redistribution of forces in frame members. Details of finite element incremental stiffness matrices for frame members and truss bracing members are briefly presented and followed by the discussion how the effects of gradual yielding, buckling and semi‐rigid joints are included. The implementation into engineering computer software is summarized and followed by certain aspects of truss and frame structural systems design according to Eurocode 3. A simple two‐bar arch truss sensitive to the elastic snap‐through buckling for which the closed form solution exists is considered as an example. Simulations of the behaviour of this truss show how the nonlinear behaviour of a single member affects the global instability of the truss. Conclusions are formulated with reference to the application of advanced analysis in direct design of steel braced frameworks.
14.01: Influence of beam‐to‐column joints on the robustness of earthquake‐resistant moment‐resistant frames
Authors: Francavilla Antonella B. , Latour Massimo , Rizzano Gianvittorio , Demonceau Jean‐François , Jaspart Jean‐Pierre 
Published: September 2017

ABSTRACTRobustness of Moment Resistant Frames (MRFs) designed according to current seismic codes and subjected to a loss‐of‐column scenario is strictly linked to the deformation capacity of beam‐to‐column connections, which are usually subjected to combined axial and bending loads. In the seismic design of steel frames, once avoided the yielding of columns, a global dissipative collapse mechanism has to be ensured by imposing the formation of plastic hinges at the ends of the beams or in the connections and guarantying, provided that the elements involved in plastic range have an adequate energy dissipation capacity. Within this framework, the aim of this paper is to analyse the influence of the response of the connections designed for seismic application on the global behaviour of MRFs under a loss‐of‐column scenario providing an accurate modelling of connections subjected to combined axial and bending loads. To this scope four different beam‐to‐column joints designed for seismic actions, previously tested under cyclic load history at the STRENGTH laboratory of Salerno University, have been modelled and introduced in a case‐study structure, whose response has been assessed by means of push‐down analyses. The performances of the analysed frames have been analysed and is compared using the Residual Reserve Strength Ratio (RRSR) index combined with the energy balance method.
15.02: Direct analysis of steel frames with non‐prismatic sections via tapered beam‐column elements
Authors: BAI Rui , LIU Si‐Wei , CHAN Siu‐Lai 
Published: September 2017

ABSTRACTMembers with tapered sections are popularly used in contemporary structures for architectonic appearance, besides that, this is in the most optimal, economic and effective manner to use material to the actual requirement according to the section strength along the member length. This paper proposes a new design approach based on direct analysis method for steel frames with tapered sections, where the structural behaviours of members are accurately simulated via sophisticated non‐prismatic beam‐column elements with analytical formulations. Conventional method uses approximated assumptions for section properties along the member length, causing unreliable estimations on member stiffness and strength and usually bringing over‐conservative design results. To this, this research analytically expresses the flexural rigidity and sectional area for the stiffness and mass matrixes of an element, respectively. In order to directly reflect column buckling effects on the proposed element, a generalized imperfection shape‐function for tapered section is developed, where the imperfection shape function is expressed highly fitting the 1st Eigen‐buckling mode shape. Examples are employed to validate and verify the reliability, efficiency and accuracy of the proposed elements. The current research is believed to be a great contribution to the modern design of non‐prismatic members.
16.20: Influence of bearing length on the patch loading resistance of multiple longitudinally stiffened webs
Authors: Loaiza Nelson , Graciano Carlos , Chacón Rolando , Casanova Euro 
Published: September 2017

ABSTRACTIncremental launching is one of the common steel bridge assembly methods used nowadays, its practical application consists in passing the bridge assembly through the launching shoes as well as over each support pile. In some cases, when plate girders are used, it is usual to find longitudinal stiffeners reinforcement in order to prevent web local buckling produced by the vertical reaction acting in the support pile. A considerable number of studies have focused on evaluating the impact of a single stiffener on the resistance of plate girder subjected to patch loading. However, the effect of multiple longitudinal stiffened plate girders subjected to lengthy compressive load has received little attention.Therefore, this paper aims at studying the influence of load bearing length on the ultimate strength of multiple longitudinally stiffened webs subjected to compressive loads. Patch loading resistance is numerically calculated using a previously validated nonlinear finite element analysis. Subsequently, a parametrical study is conducted to investigate the effect of the aforementioned load length and the relative position and size of the stiffeners on the ultimate strength.
16.25: Hot‐dip galvanized composite dowel strips in bridge construction: The combination of two advantageous developments
Authors: Ungermann Dieter , Holtkamp Svenja , Feldmann Markus , Kühne Ronny , Rademacher Dennis 
Published: September 2017

ABSTRACTComprehensive research during the last years showed that hot‐dip galvanizing of steel members in bridge structures allows significant economic and ecological advantages. It could be demonstrated that the first corrosion protection can last over a bridge's lifetime of 100 years, even in an environment with a high corrosivity, so that no major maintenance measures of the corrosion protection are necessary.Parallel to this research, another innovative solution to increase the efficiency of composite bridges has been developed. Starting with several research projects and a first application in 2003, composite dowel strips offer a very economical solution for shear connections between steel girder and concrete slab in composite bridge constructions. Continuous improvement and further development finally led to a general technical approval by DIBt in Germany. Many bridges containing this new technology are built since then, not only in Germany. However hot‐dip galvanizing may not be applied to bridges with composite dowel strips as the effects of the hot‐dip galvanizing on the fatigue resistance of flame cut composite dowel strips are unknown. Therefore, the necessary fatigue check according to EC 3‐1‐9 [2] can currently not be carried out properly.A new research project was launched by the Institutes of Steel Construction of RWTH Aachen University and TU Dortmund University [4], with the aim to analyse the fatigue behaviour of hot‐dip galvanized composite dowel strips. Furthermore a simplified evidence of absence of cracks according to DASt‐Guideline 022 [5] shall be performable by defining a detail class for composite dowel strips. The research work includes extensive experimental and numerical studies on the influences during hot‐dip galvanizing and on the fatigue behaviour of galvanized dowel strips. First results of these studies will be presented in this paper as well as the experiences of a first bridge project with hot‐dip galvanized composite dowel strips in Germany.
18.02: Optimisation of masts and towers
Authors: Støttrup‐Andersen Ulrik , Nielsen Mogens Gunhard , Laursen Thomas Brink 
Published: September 2017

ABSTRACTWithin the last decades the need for tall structures has accelerated with the requirements for effective communication especially the advent of radio, radar and television. Latest the exponential growth in the use of cellular phones has meant a new era for towers and masts.There are many challenges for the engineers associated with these tall and slender structures especially when it concerns guyed masts. Many experts have stated that “a guyed mast is one of the most complicated structures an engineer may be faced with”. This statement is unfortunately underlined by the fact that the number of collapses of masts is relatively far greater than for other types of structures.The overall layout of telecommunication masts and towers is governed by the requirements to the transmission and receiving conditions. Added hereto the access and working conditions for installation and service are important issues for the design.A total optimising of towers and masts to the functional, economical and environmental requirements is a job for specialists, and it should normally take into account the total lifetime of the structure. However the optimising is often only focused on minimising the direct costs for the establishment of the structure, neglecting the many other factors influencing the “correct” optimisation.The extensive increase in the number of new masts and towers in the last few years, especially due to the expansion in the cellular telephones, has resulted in increased concern of the aesthetic appearance of these structures and this is an additional challenge to the designers.This paper gives an introduction to the optimisation of these structures and examples of designs are presented.
18.04: Experimental investigations of members from angle sections
Authors: Spiliopoulos Andreas , Dasiou Maria‐Eleni , Vayas Ioannis 
Published: September 2017

ABSTRACTAngle sections are commonly used in many Civil Engineering applications and especially in lattice towers for telecommunication purposes. Nevertheless, due to their geometrical characteristics, design expressions, as for example those included in EN1993‐1‐1 or EN 1993‐3‐1, do not apply for cross sections or members composed of angle sections. Although a number of numerical investigations for cross section strength and member stability and proposals for relevant design expressions exist, only limited experimental investigations on members from angle sections, mostly on cold‐formed ones, can be found in literature.In the current paper a test campaign on members from equal leg hot rolled angle sections that has been carried out at the Institute of Steel Structures of the National Technical University of Athens (NTUA) is presented. Tests included eight 3‐point bending tests and thirty‐one buckling tests on columns subjected to concentric and eccentric compression. The aim of the research is to use the experimental data for calibration of numerical models, the investigation of possible inelastic reserves for angles that were detected in analytical models and as reference for the development of new design expressions oriented towards angle sections only.
01.04: Joints between open section beams and tubular columns: New configuration for semi‐rigid and moment resistant bolted joints
Authors: Vicente Guiomar , Simões Rui , Rebelo Carlos 
Published: September 2017

ABSTRACTThe appealing shape and the mechanical properties of the tubular members are the main responsible for their growing popularity amongst architects and engineers. However, their potential hasn't been properly explored due difficulties encountered in the joints conception and design, with special emphasis on the bolted joints if rigid and/or full strength behaviour is required for the joint.Currently, in the European regulation scenario, the guidance for the joints design is given in the EN 1993‐1‐8. The recommendations for joints with tubular members are given in its seventh chapter, where only welded solutions are considered. Bolted solutions aren't referred, and no guidance is given to predict the joints rotational stiffness and rotation capacity. However, a window is left open in the standard sixth chapter with the given method to predict the joints structural properties (component method). The method is applicable to joints in frames of any type, independently of its configuration and of the joined members’ sections. Once known the nonlinear response of each joint basic component, commonly represented by force‐displacement curves, the component method can be used to predict the joint structural properties.Regarding the current lack of information in this subject, the authors propose a new configuration for joints connecting open section beams to rectangular or square hollow section columns. The configuration was conceived with the double purpose of getting a joint with bending moment resistance capacity and with high initial rotational stiffness. Furthermore, looking on the current regulation scenario, it would be desirable that joints with the proposed configuration could be designed by the component method. Thus, the authors identified the joint active basic components, and are developing experimental work in the sense of establish the force‐displacement curves which represent the nonlinear response of the new basic components. The experimental work, already developed, on the basic components structural response is here summarily presented.