bluuebunny/crossref_metadata_2025_split huggingface dataset:
11.42: Cyclic behaviour of European carbon steels
Authors: Both Ioan , Zub Ciprian , Stratan Aurel , Dubina Dan 
Published: September 2017

ABSTRACTThe deformation capacity of steel structures subjected to seismic or other repetitive loadings depends on structural configuration, member and connection characteristics, as well as on the cyclic response of material. While monotonic response of steel is generally available from standard tensile tests, information on response of steel under low cycle and extremely low cycle loading is limited. For numerical analysis, a basic option to determine the steel structures response is to use the tensile properties affected by a calibrated damage of the material. The literature offers several models for more rigorous analysis but these models are more reliable if their calibration is based on experimental results. Experimental results are found in the literature but mostly for low strain cycles. In the case of higher strains, the testing procedure, including the testing machine, requires supplementary support to avoid lateral displacement of the machine cross‐head which makes these tests more difficult to be performed. A dedicated device for the cyclic loading was designed against lateral displacement of the machine cross‐head. In comparison to the tensile test specimen, the cyclic test specimens have a shorter calibrated length. The paper presents the results of an experimental research on four European steel grades (S275, S355, S460 and S690) subjected to cyclic loading with constant and variable amplitudes. The specimens were tested with a universal testing machine of 250 kN under quasi‐static strain rate. The results emphasize the stress‐strain curve, number of maximum cycles for constant amplitude, maximum strain for variable amplitude and hardening or softening for the steel response to cyclic loading. Based on experimental data, parameters for modelling cyclic response of steel in Abaqus were determined.
11.49: Lifetime seismic performance assessment of steel frame structures
Authors: Hickey John , Broderick Brian 
Published: September 2017

ABSTRACTSteel Concentrically Braced Frames (CBFs) are stiff, lightweight, potentially low‐cost structures that efficiently resist lateral load through diagonal bracing members. Under dissipative seismic design principles, these bracing members are allowed to behave inelastically during infrequent high‐intensity earthquakes. In Eurocode 8 based design the extent of this inelasticity is effectively controlled by the behaviour factor, q. Increasing the behaviour factor results in a greater degree of nonlinear behaviour, however doing so allows for reduced member sizes and consequently reduced initial costs.The conventional aim of seismic resistant CBF design has been solely to ensure life safety given the occurrence of an appropriate maximum earthquake event. However, like most structures, when designed in accordance with modern codes, CBFs are unlikely to suffer collapse. Yet, significant losses can still be incurred as a consequence of seismic action, primarily due to non‐structural damage caused by smaller, more frequent events. Hence, the overall suitability of a particular CBF design, compared to either other structural forms such as moment resisting frames or alternative CBF solutions, cannot be adequately assessed by examining life safety requirements alone. This paper therefore considers damage to both structural and non‐structural elements caused by seismic events across the entire hazard range. The expected damage, and the resulting losses, over the expected lifetime of the facility are calculated probabilistically, by applying a lifetime seismic performance assessment procedure. Thus, comprehensive comparisons are made between alternate frame designs.Using the OpenSees computational platform to perform non‐linear time‐history analysis and the PACT performance assessment tool to estimate expected losses, this work investigates the impact of the behaviour factor on the lifetime seismic performance of low rise CBFs designed to Eurocode 8. Alternative Moment Resisting Frame (MRF) designs are also examined. On a general level, the study demonstrates how performance assessment can be employed to improve and optimise design. More specifically to CBFs, it is demonstrated that the ideal behaviour factor is not necessarily the largest value recommended by the code. The work also highlights the significance of losses suffered by acceleration‐sensitive non‐structural components and the consequent importance of limiting floor accelerations as well as storey drifts in order to fully exploit the damage limiting potential of CBFs.
11.50: Modelling hysteretic behaviour of U‐shaped steel dampers
Authors: Atasever Kurtulus , Celik Oguz C. , Yuksel Ercan 
Published: September 2017

ABSTRACTConventional approach to earthquake resistant building design relies upon strength, stiffness, and inelastic deformation capacity, which are great enough to withstand a given level of design earthquake effects. However, modern approach in today's designs aims to mitigate seismic energy before the input energy reaches the structural elements. Dissipating seismic energy through the inelastic deformation of metallic dampers is one of the cost effective solutions. After appearing concept of dissipating energy through the inelastic deformation (mainly yielding and post yielding) of metallic dampers, numerous types of metallic dampers, such as X‐shaped, J‐shaped, U‐shaped, shear panel, triangular plate dampers have been developed and their effectivenesses have been proved both theoretically and experimentally. Inelastic hysteretic behaviour of U‐shaped devices is somewhat complex and varies with geometry of the damper. To address this issue and possibly attain some practical results, this present paper focuses on modelling hysteretic behaviour of U‐shaped dampers. ABAQUS has been used as the computational tool in which a finite element model made of the C3DR8 solid element is adopted. Nonlinear kinematic and isotropic hardening material assumptions are considered to determine cyclic behaviour at 0º, 45º and 90º loading directions. For each analysis, effective stiffness, effective damping ratio, and maximum reaction forces (i.e. horizontal strengths) of the damper are calculated to evaluate performance. As an additional parameter, two different loading protocols are taken into consideration. Hysteretic curves and deformed shapes of a selected damper type taken from an existing experimental work and this numerical study show very good agreement proving that the modelling assumptions made during the analyses are appropriate and sufficient for a better prediction of behaviour. Additional numerical analyses on several dampers under various loading protocols reveal that effective damping ratio of the damper is more than ξeff =40% at the maximum displacement level due to significant energy dissipation through plastic deformation of the damper. A numerical example of mixed use of U‐shaped steel dampers and rubber isolation bearings on a selected two story steel framed building is also discussed.
11.52: Local buckling behavior and plastic deformation capacity of H‐shaped beams under reversed axial forces
Authors: Suzuki Atsushi , Kimura Yoshihiro , Kasai Kazuhiko 
Published: September 2017

ABSTRACTIn general, beams with concrete slabs in the moment resisting steel frames are assumed to be rigid axially when pushover or dynamic analyses are conducted. Consequently, axial forces acting on the beams are not considered in a design procedure. However, steel beams are subject to axial forces when a frame has buckling restrained braces during the earthquake. Ultimate strength, plastic deformation capacity, and cumulative plastic deformation capacity of beams with axial forces decrease and severe damage may occur to compare with beams with no axial force.The purpose of this research is to elucidate the characteristics of H‐shaped beams under alternating axial force, which models the reversed axial forces from the dampers. Firstly, this paper conducts monotonic and cyclic loading tests on beams to understand local buckling behaviors under different loading protocols of axial force (no axial force, constant compressive axial force, and alternating axial force). Secondly, influences of the loading protocol of axial force on the ultimate strength, plastic deformation capacity, and cumulative plastic deformation capacity are investigated. Thirdly, the differences of capacity due to the magnitude of axial force and the number of cycles are examined. Finally, the effects of the width‐thickness ratio of beams on the buckling behaviors and performances under the alternating axial force are summarized.As a result, beams under the alternating axial force show local buckling under the compressive axial force and the pinching effect under the tensile axial force. Although the performances of beam under alternating axial force degrade to compare with those under no axial force, larger ultimate strength, plastic deformation capacity, and cumulative plastic deformation capacity than those under the constant compressive axial force are obtained. This enhancement of performances under alternating axial force is originated by the stretch of residual deformation due to local buckling under the compressive axial force when tensile axial force is applied to the beam.
11.53: Reduced cross‐sections in seismic resistant steel structures
Authors: Köber Helmuth , Stoian Marina 
Published: September 2017

ABSTRACTIn case of flexural dissipative members in eccentrically braced frames, a detail with reduced beam flanges sections at the link ends leads to a better control of the inelastic deformations along the dissipative member, together with a reduction of the plastic hinge rotation demand and with significant lateral stiffness of the braced frame.Configurations resembling the “dog‐bone” near the ends of the upper stories diagonals in concentrically braced frames ensure on one hand, the abidance of the slenderness demand for the braces and on the other hand, small values of the amplification ratio Ωi(N)=NplRd,i/NEd,i. The reduced cross‐section of the diagonal in the “dog‐bone” detail zones ensures an adequate tensile capacity of the braces and small Ωi(N) values. At the same time the buckling behaviour and slenderness of the braces is not significantly affected by the reduced cross‐sections near the member ends and the slenderness demand of the braces will be fulfilled.A favourable global plastic hinge mechanism can be sized by design for concentrically braced frames by providing configurations with reduced cross‐sections for potentially plastic zones located in the frame girders in the neighbourhood of the beam/column connections. So plastic deformations can develop in the braces, at the bottom of first‐story columns and in potentially plastic zones located near the ends of frame girders, and a favourable global plastic failure mechanism can be achieved. The same design concept can be used for sizing a favourable global plastic mechanism for frames with rigid beam/columns connections equipped with buckling restrained braces.Configurations with “dog‐bone” details near the base of bottom‐story columns appear to be safer from the point of view of assuring the general stability of the first‐story column in the situation when plastic deformations occur in the potentially plastic zone at the bottom of the column. Further, a better control of the plastic deformations along the first story columns is ensured.
11.56: Test rig for seismic experiments of drive‐in racks
Authors: Shaheen Mahmoud S.A. , Rasmussen Kim J.R. 
Published: September 2017

ABSTRACTThis paper describes the construction and commissioning of an experimental facility for testing heavily loaded full‐scale steel storage racks under seismic excitation. A one‐degree‐of‐freedom rig was built to test drive‐in racks with pay load up to 60tons. The rig was supported on rollers moving along girders attached to the ground. Different sets of non‐destructive tests took place during the commissioning process. The first set of tests was for commissioning the hydraulic actuator. The test results showed that the test rig setup was able to reproduce feedback signals that are very close to earthquake demand waveforms based on actual recordings of seismic events at various locations around the world. The second set of non‐destructive tests was for determining the dynamic friction coefficient in the rig. Force versus displacement test results under different loading conditions showed that the average friction coefficient was not sensitive to the speed of the jack or the weight, and was found to be in the order of 1% which is negligible. Hence, the test rig was found to operate as intended and met the design objectives.
11.59: Study on highly elastic seismic structural system based on very‐high strength steel and damage‐control fuses
Authors: Lin Xuchuan , Hu Yangyang , Okazaki Taichiro 
Published: September 2017

ABSTRACTA highly elastic seismic structural system that enables continuous use after major earthquakes is proposed, by making full use of the benefits of high‐strength steel, damage‐control fuses and energy dissipators. The high‐strength steel has a minimum specified yield stress of over 690 MPa. An experiment study is carried out to examine the performance of welds between high‐strength steel components and the effects of fuses on protecting the welded beam‐to‐column connections. Full penetration weld applied to the high‐strength steel worked well, and the beam using high‐strength steel achieved an elastic deformation rotation of about 0.018 rad and a maximum bending moment larger than its estimated plastic bending moment. The damage‐control fuses are effective to prevent the high‐strength steel components from yielding. The replacement of fuses is confirmed to be feasible, and the visible buckling deformation can be used as an indicator of replacement.
11.62: A numerical study on the seismic performance of experimentally‐tested steel single‐storey concentrically braced frames
Authors: Penelov Chavdar , Hadzhiyaneva Irena , Belev Borislav 
Published: September 2017

ABSTRACTThe paper presents an overview on nonlinear modeling and numerical evaluation of the seismic response of two steel single‐storey concentrically braced frames with X‐brace configuration previously tested by other researchers.The numerical simulations included series of nonlinear time history analyses using OpenSees computational framework. The brace members were modeled with fiber frame finite elements with distributed plasticity taking into account their initial imperfections. The material model accounted for the low‐cycle fatigue effects based on the approach proposed by several other research works on the topic.The maximum response displacements of the investigated specimens were also evaluated following the procedure given in Annex B of EN 1998–1 (Eurocode 8). However, the previously conducted shake table testing and the herein presented numerical results indicated that this procedure may significantly underestimate the displacements of single‐storey dissipative short‐period CBFs designed with high values of the behaviour factor.It was also found that the numerical estimation of the maximum and residual lateral response displacements of the analyzed CBFs based on nonlinear time history analysis is very sensitive to small variations of the material properties and assumed damping model (damping matrix definition). Therefore the experimentally‐obtained response displacements can be realistically predicted only if the parameter variations are taken into account in the numerical analyses.The authors believe that the use of high values for the behaviour factor in the design of low‐rise CBFs may result in excessive residual displacements and low‐cycle failure of the brace members. It is suggested the further revisions of Eurocode 8 impose lower reference values of the behaviour factor for the short‐period steel CBFs with slender braces in order to reduce their ductility demand and related damage in strong earthquakes.
11.63: Seismic protection of gas tanks
Authors: Henriques Jose , Morelli Francesco , Salvatore Walter , Degée Hervé 
Published: September 2017

ABSTRACTRecent earthquakes demonstrated the susceptibility of industrial plants to such events. In extreme situations, as the earthquake in Fukoshima (Japan), the impact of the seismic action on these infrastructures leads to catastrophic results with consequences for the environment, neighbour population and economy. The impact of an earthquake on an industrial plant may result in a local failure, leading to an interruption on the operation, or a total collapse. In any of these cases, it is imperative the improvement of such facilities with high importance class. It is to this end that the European project PROINDUSTRY is ongoing. The objective is the development of innovative seismic protection systems for industrial buildings or infrastructures made of steel. In the present paper the numerical study of a gas tank is presented. For this type of infrastructures, amongst the different devices under development, the base isolation system was selected as it is seen as the most suitable. The proposed device is the Curved Surface Slider (CSS). In order to evaluate the performance of such device, numerical studies, namely Incremental Dynamic Analysis, were conducted. The results of these analyses lead to a calibration of the main properties of this device, static friction and vibration period, and allowed to verify the effective protection of the gas tank upon an earthquake event.
I.11.03: Influence of splitting beam and column stiffness on CBFS ductile behaviour
Authors: Georgiev Tzvetan , Raycheva Lora 
Published: September 2017

ABSTRACTConcentrically braced frames with X‐bracing configuration (X‐CBFs) are one of the most popular systems for seismic resistant design. Their ductile behaviour is provided primarily by yielding of braces in tension and to a small extent by plastic rotation in buckled braces. An improved CBF configuration by introducing bracings with modified sections was developed in research program. In order to facilitate joint detailing, it is efficient that braces intersect into a horizontal member named ”splitting beam”. Experimental study has shown that braces, being above and below the splitting beam, often do not buckle simultaneously. This leads to concentration of inelastic deformations within one of the brace and causes unbalanced horizontal and vertical force. Finally, it might result in reduced storey ductility and premature brace fracture.It was assessed through extensive parametric non‐linear analysis that splitting beams in cooperation with columns have crucial impact on the brace buckling sequence and on the type of the global plastic mechanism. An analytical model and design procedure for determining the stiffness and strength demand of splitting beams and braced frame columns are proposed. The procedure ensures achievement of buckling of both halves of compression braces and formation of anticipated plastic mechanism. Some case studies based on static nonlinear analysis are presented.
I.11.05: Parametric finite element analyses of detachable short links
Authors: Zimbru Mariana , D'Aniello Mario , Stratan Aurel , Landolfo Raffaele , Dubina Dan 
Published: September 2017

ABSTRACTDetachable short links are an effective system to guarantee both large dissipative capacity and the possibility to repair easily the structure by replacing the damaged links after an earthquake. Therefore, the detailing of links and the design of their connections are of paramount importance given their role in the overall structural performance of eccentrically braced frames (EBFs). Recent analytical and experimental studies highlighted that shear links under large deformations and with axial restraints may develop shear overstrength larger than EC8 recommended value (i.e. 1.5) and significant tensile axial forces, which are not accounted for in EC8. This feature is crucial for detachable links, because the link end connections should be designed to resist also these forces in order to prevent undesirable and premature failure. In light of these considerations, this paper presents the results of a comprehensive parametric finite element study devoted to investigate the behaviour of end‐connections of replaceable links. The finite element models are validated against the results of full‐scale experimental tests carried out on a three‐storey EBF. The obtained results allows evaluating both the level of axial force in the link, varying the boundary conditions, the link length and the shape of the profile.
I.11.20: Design recommendations for dual moment – eccentric braced frames with replaceable links
Authors: Dubina Dan , Stratan Aurel , Chesoan Adriana 
Published: September 2017

ABSTRACTModern 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

ABSTRACTA 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.