bluuebunny/crossref_metadata_2025_split huggingface dataset:
11.27: Elastic buckling load and load resistance of core‐separated assembled BRB confined by two concrete‐infilled tubes
Authors: Zhu Bo‐li , Guo Yan‐Lin 
Published: September 2017

ABSTRACTThis paper presents a novel type of the core‐separated assembled BRB (CSA‐BRB). It consists of two single BRBs confined by concrete‐infilled tubes that are connected longitudinally by two continuous webs. This directly results in a sectional cavity of the CSA‐BRB by spacing two independent BRBs, and significantly enhances its cross‐sectional flexural stiffness and load‐carrying capacity. The two independent steel cores of the CSA‐BRB are strengthened and connected at its end with a core stiffener to form a robust H‐shaped sectional core, as a whole. The core stiffener is inserted into the restraining member by a distance, further remarkably improving the core strength and stiffness at un‐restrained core projections of the CSA‐BRB. The CSA‐BRB is simulated approximately by “an equivalent framed model” and accordingly its elastic buckling load was obtained by using an equilibrium method. A number of numerical examples of CSA‐BRBs were designed and investigated by using a large deflection elastic‐plastic beam element model to predict the influence of the restraining ratios on their load‐carrying capacities. An overall geometric imperfection with the amplitude of l/1000 at mid‐span of the CSA‐BRB is also involved in the analysis. The results obtained reveal that the CSA‐BRBs could achieve required load‐carrying capacity without overall failure, considering the strain hardening (for example 0.02E) of the core after its initial yielding, as well as the ultimate axial compressive strain of 2% applied to the core if the restraining ratio of CSA‐BRBs is greater than around 3.0.
11.28: Seismic response of built‐up steel columns with semi‐continuous base‐plate connections: Experimental results vs. theoretical predictions
Authors: Della Corte Gaetano , Cantisani Gaetano , Landolfo Raffaele 
Published: September 2017

ABSTRACTThe paper describes a comparison of experimental results and theoretical predictions regarding the lateral force‐displacement response of built‐up steel columns with semi‐continuous (semi‐rigid and partial‐strength) base‐plate connections.Two specimens, representing samples from real columns of an existing industrial building, were fabricated and tested. The columns were both made of two I‐shaped profiles connected by means of battens, but with significant differences in the scheme of battening from one specimen to the other. The base plate connections were also significantly different in the two cases, in terms of local detailing. Preliminary tests were carried out in the elastic range of response, under varying levels of applied axial force. Such elastic tests were used to measure variations of the initial stiffness and corresponding yield displacements with the applied axial force. Subsequently, a cyclic loading test was carried out, per each specimen, to investigate the inelastic response.Initially, the paper describes and comments on the relative performance of the two tested specimens, in terms of stiffness, resistance and ductility, as resulting from the experimental tests.Subsequently, the paper provides theoretical predictions along with a comparison to the experimental results. Firstly, results from finite‐element (FE) models – developed using the Abaqus software – are described. Secondly, results from the application of simplified mechanical models are illustrated. The adopted mechanical models essentially followed the component‐method stipulated by Eurocode 3, but with some adaptations and modifications. The paper finally provides a comparison of experimental results with both numerical and analytical models.
11.35: Numerical study on steel braces under reversed cyclic loads
Authors: Faggiano Beatrice , Formisano Antonio , Vaiano Generoso , Landolfo Raffaele , Mazzolani Federico Massimo 
Published: September 2017

ABSTRACTDiagonals are typically assumed as dissipative elements in seismic‐resistant steel braced structures. However there are still some uncertainties on the behaviour of steel braces subjected to reversed cyclic loadings. The paper deepens such key issue, focusing on the numerical simulation of the experimental tests conducted by Black et al. (1980) on single steel members. FEM analyses are performed by means of the software ABAQUS v6.13‐1 on three struts having either H‐shaped, or circular, or square hollow cross‐sections. A refined model, calibrated by varying boundary conditions, cross sections and slenderness ratios is set up, allowing for a suitable approximation of the hysteretic behaviour in terms of strength, stiffness and ductility. It is a powerful tool for parametric analyses, necessary for acquiring the main aspects of the cyclic behaviour, thus leading to the definition of appropriate design criteria.
11.44: An integrated experimental and numerical assessment of force‐based design for concentrically braced steel frames
Authors: Ryan Terence , Broderick Brian , Salawdeh Suhaib , Hickey John 
Published: September 2017

ABSTRACTThis study uses an integrated experimental and numerical approach to assess the use of the force‐based design (FBD) methodology presented in Eurocode 8 (EC8) for multi‐storey steel concentrically‐braced frames (CBFs).In the EC8 approach, the design seismic action is defined by first generating an elastic response spectrum. This spectrum is reduced to create the design spectrum by applying an appropriate behavioural factor (q) to account for energy dissipation. The value of q chosen depends on the form of the lateral‐load resisting structure, the structural material(s) to be used, the ductility class and the degree of irregularity in the structural layout. The design base shear force calculated from the design spectrum is used to estimate the seismic forces on the structure and hence determine the final member cross‐section sizes.In this study, the FBD approach to the design of structures presented in Eurocode 8 is described and applied to 4‐ and 8‐storey CBF structures. Both dissipative (Ductility Class High – DCH) and non‐dissipative (Ductility Class Low – DCL) design is considered for each structure.A numerical modelling approach developed using the OpenSees seismic analysis software and validated from a series of full‐scale experimental tests of single‐storey CBFs is outlined. The two‐dimensional reference model assigns appropriate out‐of‐plane rotational stiffnesses to the ends of the bracing members based on the strength and geometry of gusset plates specified.The experimental work used to validate the model, carried out as part of the BRACED transnational research project funded by the European Commission's Seventh Framework Programme (FP7) is briefly described. The experimental observations support model validation at different levels of earthquake ground motion including elastic, inelastic and ultimate response conditions.The validated numerical modelling approach is used to perform a series of non‐linear time history analyses (NLTHA) of the designed 4‐ and 8‐storey frames by subjecting them to appropriately scaled simulated ground motion accelerations. The key recorded responses of the NLTHA of the modelled frames (displacements, drift, brace forces and ductility demands) are compared, and the implications of the assumed energy dissipations are discussed.
11.48: An experimental study on welded overlap core: Steel encased buckling‐restrained braces
Authors: Bozkurt Mehmet Bakır , Topkaya Cem 
Published: September 2017

ABSTRACTBuckling restrained braced frames (BRBFs) can be used as a lateral load resisting system in seismic regions. A typical buckling restrained brace (BRB) is composed of a core segment, debonding material and a buckling restraining mechanism (BRM). The cross‐section of the core segment can be changed along the length to constrain yielding in a limited domain. Most of the BRBs utilize a rectangular core segment which is reduced in width throughout yielding length. The gradual reduction in the width of the core segment produces stress concentrations and employs costly CNC cutting. A novel type of BRB named the welded overlap core steel encased BRB was developed to provide an alternative that does not require CNC cutting of the core plate. This type of a BRB is formed by welding flat bars with different widths to each other. The yielding and non‐yielding segment lengths and areas can be easily tailored to meet the stiffness and strength requirements. An experimental program has been undertaken to study the performance of welded overlap core steel encased BRBs. Pursuant to this goal four BRBs were manufactured and subjected to sub‐assemblage testing. All specimens were tested using the loading protocol recommended in the AISC Seismic Provisions for Structural Steel Buildings (AISC341‐10). Welding detail used to connect the built‐up BRM members was considered as the primary test variable. The experimental results indicated that the proposed core segment concept can be an alternative to more traditional core segment designs. The weld configurations used to connect the buckling restraining mechanisms affected the response significantly. According to the results, properly detailed and inspected welded overlap core BRBs can provide acceptable performance by sustaining cumulative strains in excess of 400 times the yield strain.
11.57: Assessment of the ductile behaviour of CBF structures considering energy dissipation in bolted joints
Authors: Martin Pierre‐Olivier , Rodier Anthony , Couchaux Maël , Kanyilmaz Alper , Degée Hervé 
Published: September 2017

ABSTRACTIn dissipative seismic concept according to Eurocode 8, capacity design leads to additional cost for brace connections. In this concept, connections, either bolted or welded, remain elastic during seismic events whereas the braces dissipate energy by yielding and buckling. However the bolted gusset plate connections of braces are able to dissipate energy by sliding, bearing and block shear when minimal requirements are fulfilled. Within the RFCS project Meakado, both experimental tests and numerical simulations have been performed on bolted connections under cyclic actions to assess this potential dissipative mechanisms. An equivalent non‐linear spring model has been calibrated from these results to represent the ductile behaviour of concentrically braced frames (CBF) bolted joints when the non‐ductile mechanisms are prevented. Taking into account this equivalent spring model, the seismic global behaviour of CBF structures in the context of moderate seismicity have been studied both by time history and by push‐over analyses. Finally this paper proposes a calibration of the behaviour factor q of CBF structures when energy dissipation is considered in the bolted connections of braces together with the braces dissipation. The scope of application of these results is discussed.
11.60: Experimental investigation under cyclic loadings of an innovative passive mitigation device
Authors: Titirla Magdalini D. , Katakalos Konstantinos V. , Papadopoulos Panikos K. 
Published: September 2017

ABSTRACTThe present study focuses on the experimental investigation of an innovative passive mitigation steel device, mentioned as CAR1. It consists of three distinguished parts; the external cylindrical ring, the internal prismatic holder and several superimposed blades that are responsible for the transfer of forces between the aforementioned 2 parts. CAR1 is utilized for strengthening either existing or new steel and R/C structures. The behaviour of the innovative device is changing according to the developed levels of displacement. It is designed so that it can be locked at a preselected level of displacement, thus, offering an extra safety reserve against strong earthquakes. By using CAR1, the beam–column frames can be easily and safely strengthened at many predefined levels according to the desire of the designer. The mechanism of the energy absorption is developed on the superimposed blades through both yielding of steel and friction. The number and dimensions of the superimposed blades, their elastoplastic properties as well as the friction coefficient at their interface, define the equivalent nonlinear constitutive law of CAR1. A full‐scale device was fabricated and experimentally investigated under cyclic loading. The experimental sequences were conducted at the premises of Laboratory for Strength of Materials and Structures of Aristotle University of Thessaloniki. The investigated variables are the geometry of the blades, the rate and number of the cycles of the loading sequence. The obtained results depicted the overall behaviour of CAR1 with respect to the absorbed seismic energy, and whether or not it will break during the cycle loading. Each experimental sequence imposed more than 50 cycles on the investigated specimen, with a different target load and rate each and every time. The results showed that CAR1 is an alternative device for mitigating the energy developed to a structure during an earthquake.
I.11.00: Innovative systems for seismic resistance: The INNOSEIS Project
Authors: Vayas Ioannis , Vamvatsikos Dimitrios , Thanopoulos Pavlos 
Published: September 2017

ABSTRACTFollowing the international trends, extensive research on seismic resistant structures has been carried out in Europe during the last decade, with the introduction of several systems with innovative steel‐based elements, as the result of European and national research projects. However, these systems have not claimed a fair share of the steel construction market, as provisions for their design have not been included in the Eurocodes and only a few designers are confident enough to employ them. The INNOSEIS project, which has received funding from the Research Fund for Coal and Steel (RFCS) with the participation of 11 partners, aims to deal with this shortcoming. In this paper, the valorisation actions for 12 such innovative anti‐seismic devices are presented. Information documents for all dissipative systems have been produced and combined in a single volume, translated in several European languages, for the dissemination to all partners of the construction sector such as architects, structural engineers, construction companies, steel producers and all potential decision makers of the construction sector. Criteria are proposed as to determine which of the systems are characterised as devices and are subject to CE marking in accordance with EN 15129, and which may be considered as innovative systems that require a code approval in EN 1998–1. For the latter, pre‐normative design recommendations are drafted that will allow them to receive the status of code‐approved systems. A reliability‐based methodological procedure to define values of behaviour factors (q‐factors) for building structures is proposed, which will be in turn applied to determine q‐factors for structural systems with the anticipated systems. A number of case studies with application examples of realistic steel buildings, in which the systems are employed, are presented. Dissemination of the project includes seminars and workshops in several European and Mediterranean countries, as well as the development of online, printed and electronic material, which is free for all people involved in the construction sector, in order to achieve the wide application of innovative seismic resistance systems in practical design.
I.11.07: Pre‐test numerical simulations for development of prequalified buckling restrained braces
Authors: Zub Ciprian Ionut , Dogariu Adrian , Stratan Aurel , Dubina Dan 
Published: September 2017

ABSTRACTBuckling Restrained Braces (BRBs) are increasingly used as structural fuse elements due to their stable and quasi‐symmetric cyclic behaviour and capacity to dissipate a large amount of energy. However, a wider adoption of buckling restrained braced frames is often precluded by the proprietary character of most BRBs, need for their experimental qualification and sometimes lack of experience of designers. To overcome these problems, a set of typical BRBs were developed in view of their pre‐qualification. “Conventional” and “dry” devices were considered, with capacities corresponding to typical steel multistorey buildings in Romania. The paper presents the pre‐test numerical simulations program for the “conventional” type of BRBs. The numerical model was developed using the general‐purpose finite element analysis program ABAQUS. The nonlinear cyclic behaviour of the steel core was described by a combined kinematic‐isotropic hardening rule. Calibration of the hardening parameters is also presented. A parametric analysis was performed in order to identify the optimal geometry and mechanical characteristics of brace components. Core aspect ratio, gap size, critical elastic axial load of the buckling‐restraining mechanism were among the investigated geometrical parameters. Also, different values for the friction coefficient were analysed. Outcomes of the finite element investigation were used developing the engineering solution and a design procedure for two conceptually different solutions of “conventional” buckling restrained braces in view of pre‐qualification.
12.01: Global plastic design of stainless steel frames
Authors: Arrayago Itsaso , Real Esther , Mirambell Enrique , Chacón Rolando 
Published: September 2017

ABSTRACTThe use of stainless steel structures has increased during the last decade due to their durability, aesthetics and mechanical properties such as ductility, considerable strain hardening and excellent fire resistance. However, the majority of conducted research works have only focused on single isolated stainless steel members and advances in the analysis of stainless steel frames are limited. EN1993‐1‐4 does not provide global plastic design rules for indeterminate stainless steel structures, such as frames, despite their proved high ductility. On the other hand, the lack of guidance on plastic design is an obstacle for the optimal design of stainless steel structures, leading to uneconomical design. This paper presents a preliminary study on non‐sway stainless steel frames with stocky hollow cross‐sections. The study of the behaviour of stainless steel frames is based on numerical parametric studies, considering the nonlinear material behaviour and different stainless steel types (austenitic and ferritic). The paper deals with the redistribution of internal forces and assesses the existing methods based on global plastic design for frames with stocky cross‐sections, where alternative design approaches accounting for moment redistribution and strain hardening effects are analysed in addition to traditional plastic design method. Preliminary results demonstrate that including bending moment redistribution and strain hardening effects in capacity predictions is essential for an efficient design of stainless steel structures.
12.03: Buckling curves for stainless steel tubular columns
Authors: Afshan Sheida , Zhao Ou , Gardner Leroy 
Published: September 2017

ABSTRACTTowards the development of more resilient and sustainable structures, interest in the use of high performance construction materials, such as stainless steels, has increased in recent years. Recent studies [1] have highlighted a number of deficiencies in the flexural buckling provisions given in Eurocode 3: Part 1.4 for the design of stainless steel compression members. Therefore, this study aims to investigate the effect of production route (cold‐formed and hot‐finished) and material grade (austenitic, duplex and ferritic) on the behaviour and design of stainless steel square and rectangular hollow section columns. Test data from the literature combined with numerical modelling data generated as part of this study are used to derive a series of buckling curves for the design of stainless steel columns. Reliability analysis in accordance with Annex D of EN 1990 has been carried out to show that the proposed buckling curves comply with the Eurocode reliability requirements.
12.10: Structural response of high strength steel hollow sections under combined biaxial bending and compression
Authors: Gkantou Michaela , Theofanous Marios , Baniotopoulos Charalampos 
Published: September 2017

ABSTRACTThe benefits of high strength steel (HSS) as a structural material and its potential to lead to smaller sections and thus lighter structures has increased its use in the construction industry. Current design specifications for HSS are widely based on assumed analogies with normal strength steel, since they are based on a limited number of test data on HSS sections that were available when these specifications were published. Hence, their applicability to HSS requires assessment. Even though research towards this direction has grown, literature on the structural response of HSS under combined biaxial bending and compression is scarce. This paper presents a comprehensive numerical study on the cross‐sectional behaviour of S460 and S690 square and rectangular hollow sections under biaxial bending and compression. Finite element models are developed and validated against experimental results on 12 hot‐finished S460 and S690 stub columns under uniaxial eccentric compression. The numerically generated load‐deformation curves, the ultimate loads and the failure modes accurately replicate the experimental ones. Hence, the FE models are deemed able to predict the behaviour of stub columns subjected to combined compression and bending. Upon successful validation, extensive parametric studies aiming to generate additional structural performance data are executed. Two aspect ratios, eight cross‐sections with different thicknesses, and forty‐three combinations of initial loading eccentricities corresponding to different ratios of axial load to bending moments about both axes, are investigated for both steel grades. The results facilitate the determination of interaction failure surfaces and allow the assessment of relevant design specifications. It is concluded that the capacity of Class 1 and Class 2 cross‐sections is adequately predicted by European design provisions, with some conservative predictions occurring for S460 sections in the stocky slenderness range. For HSS semi‐compact cross‐sections under combined loading, the Eurocode provisions appear rather conservative, whilst the capacity of effective cross‐sections is overall well‐predicted.
12.18: Experimental investigation on cold‐formed high strength steel circular hollow sections under combined compression and bending
Authors: Ma Jia‐Lin , Chan Tak‐Ming , Young Ben 
Published: September 2017

ABSTRACTCold‐formed high strength steel tubular members are gaining increasing attention from engineers due to their high strength‐to‐weight ratio, strong resistance against torsional buckling and aesthetic appearance. This paper presents a test program on cold‐formed high strength carbon steel tubular sections under combined compression and bending. The nominal 0.2% proof stresses of the test specimens were 900 MPa and 1100 MPa. The specimens were loaded through knife edges at both ends to provide pinned boundary conditions. Different loading eccentricities were applied to the test specimens by shifting the position of knife edges from the centroid of the specimens. As a result, a wide range of bending moment‐to‐axial load ratio was achieved. The beam‐column test set‐up and experimental procedures are detailed in the paper. Furthermore, the ultimate strengths, load‐end rotation histories and the failure modes of the test specimens are also reported. The test results were compared with the design strengths predicted from the American, European and Australian codes. The comparison showed that the existing design rules underestimate the ultimate strengths of the cold‐formed high strength steel tubular beam‐columns.