bluuebunny/crossref_metadata_2025_split huggingface dataset:
11.08: Reliable calibration of cyclic models for steel members
Authors: Chisari Corrado , Francavilla Antonella B. , Latour Massimo , Piluso Vincenzo , Rizzano Gianvittorio , Amadio Claudio 
Published: September 2017

ABSTRACTAccurate response predictions of steel structures subjected to earthquake loading involve the use of models able to simulate properly the cyclic behaviour of the regions where nonlinear phenomena take place. These include hardening, softening, strength and stiffness degradation, pinching and gap closure. In case of full‐strength joints, all nonlinear effects appear in the members connected, and particular relevance is assumed by softening and strength degradation. Even though a number of phenomenological models have been developed in the last decades, their calibration seems to have received less attention. Usually, calibration is based on matching the experimental and numerical cyclic responses under loading protocols proposed by standards. These protocols have been developed to give a reliable estimate of the cyclic deformation demand of the considered structural system, since demand strongly depends on the loading history and the hysteretic behaviour when dealing with structural elements characterised by nonlinear behaviour. In general, the accuracy of a numerical model calibrated minimising the discrepancy between experimental and computed response is controlled by the sensitivity of the considered response on the parameters, and since the original aim of loading protocols is not the calibration of numerical models, investigation is needed to assess the predictive capability of so calibrated models.In this work, a calibration procedure based on the minimisation of response discrepancy is presented and critically discussed, with reference to an experimental programme carried out at the University of Salerno. In particular, cyclic, monotonic and pseudo‐dynamic tests were carried out on a hollow square member, with the aim of calibrating an advanced phenomenological model. It is shown that a calibration based on cyclic response under ordinary loading protocols only is not robust, since its accuracy under different loading conditions may deteriorate. In particular, loading histories characterised by sudden strong impulses after small‐amplitude cycles may involve parameters which are not well represented by ordinary cyclic loading protocols. The introduction of the monotonic test in a multi‐objective framework may be effective, and its accuracy is confirmed by the results of pseudo‐dynamic tests.
11.09: Validation of probabilistic theory of plastic mechanism control by means of Monte Carlo simulations
Authors: Castaldo Paolo , Nastri Elide , Piluso Vincenzo , Pisapia Alessandro 
Published: September 2017

ABSTRACTThis work aims at the validation of the Probabilistic Theory of Plastic Mechanism Control (P‐TPMC), reported in a companion paper, by means of Monte Carlo simulations. P‐TPMC is devoted to stochastic frames with the aim to assure a collapse mechanism of global type despite of the influence of random material variability. A mechanism of global type develops when all the beams are yielded at their ends while the columns remain in elastic range with the only exception of the base sections of the first storey columns.A parametric analysis is performed considering steel moment resisting frames having different number of bays and different number of storeys. Moreover, in order to achieve a predefined level of reliability in the attainment of the design goal, the parametric analysis is also repeated for increasing values of an overstrength factor of the dissipative zones aiming to its calibration. Finally, a quadratic regression has been derived to provide a simple relationship to compute the value of the overstrength factor needed to include the influence of random material variability in the application of deterministic Theory of Plastic Mechanism Control.
11.15: Seismic behaviour of single layer cylindrical lattice steel shells
Authors: Cedrón Francisco , Elghazouli Ahmed Y. 
Published: September 2017

ABSTRACTCylindrical lattice shell structures are commonly used in many applications such as in train stations, gymnasia, and sports halls. In comparison with their behaviour and design under gravity loading, their behaviour under seismic loading has received less attention, particularly in terms of the development of practical design procedures. Current European codes of practice lack specific guidance on the seismic design of these shells. In this paper, the salient considerations influencing the seismic response of single layer cylindrical lattice shells are examined. The effect of key geometric parameters such as the rise to span ratio, length to span ratio, inter‐element angles, as well as the structural mass, on the characteristic natural periods and corresponding vibration modes are investigated using the finite element program OpenSees for two typical situations of boundary conditions. The influence of these parameters on the axial forces and bending moments in the members when subjected to the horizontal and vertical components of an earthquake is also assessed. The response is evaluated in the linear and nonlinear ranges, including representative time history analyses, with due consideration of both material and geometric nonlinearities. The results provide an insight into the main factors that govern the seismic behaviour of single layer cylindrical lattice shells, with a view to supporting the development of practical design and assessment procedures for this structural form.
11.17: Seismic retrofitting of concentrically braced frames by rocking walls and viscous dampers
Authors: Barbagallo Francesca , Bosco Melina , Marino Edoardo M. , Rossi Pier Paolo 
Published: September 2017

ABSTRACTIn this paper, a design procedure for seismic retrofitting of concentrically braced frames is proposed and validated. The reasons leading to the need of an enhancement of the seismic performance of these frames may be multiple. As an example, the expected response of concentrically braced buildings may not match the desired performance objectives because (1) the initial design of the structures was deficient or (2) the design performance objectives have changed in time due to an update of the seismic hazard map or to more demanding requirements of the owners of the building. In this paper, rocking walls are proposed to ensure an almost uniform distribution of the storey drifts along the height of the building. To achieve a direct and efficient control of the ultimate peak ground acceleration, the design procedure is founded on the displacement‐based approach. The equivalent viscous damping ratio capacity of the concentrically braced structure with rocking walls is calculated based on semi‐empirical relationships specifically calibrated for concentrically braced frames. Viscous dampers are added and arranged between the existing structure and the rocking walls. The design internal forces of the rocking walls are evaluated considering also the contributions of the higher modes of vibration. The proposed design procedure is applied to an eight‐storey chevron braced frame and its effectiveness verified by incremental dynamic analysis.
11.18: Seismic analysis of innovative hybrid steel concrete coupled walls
Authors: Zona Alessandro , Leoni Graziano , Dall'Asta Andrea 
Published: September 2017

ABSTRACTAn innovative hybrid steel concrete coupled wall made by a single reinforced concrete wall connected to two steel side columns by means of dissipative steel links is considered in this study. Such a hybrid system is conceived to take advantage of the stiffness of the reinforced concrete wall and of the dissipation capacity of the steel links acting as dissipative fuses that can be replaced if damaged. The performance of the studied structural system under seismic conditions is assessed by means of multi‐record nonlinear incremental dynamic analysis. To this end a set of buildings is designed following a recently proposed ductile design approach and varying two parameters: the building height and the degree of coupling between the steel columns and the reinforced concrete wall. A material and geometric nonlinear finite element model developed within an open source software is introduced and the main results of the numerical analyses are presented to provide insight into the expected seismic response. Overall, the outcomes of the numerically simulated response results indicate that the proposed hybrid steel concrete coupled wall has interesting potentialities as seismic resisting system being able to effectively exploit the lateral stiffness of the RC wall as well as the dissipation capacity of the steel links.
11.19: Seismic fragility assessment of steel frames: Application of advanced reliability analysis
Authors: Hazay Máté , Vigh László Gergely 
Published: September 2017

ABSTRACTDuring the application of advanced design procedures (e.g. performance based design) engineers may need to compute the actual risk of the structures. The fragility of structures exposed to seismic effects is often characterized by the fragility curves that show the failure (or collapse) probability under an earthquake characterized by a given intensity measure. Since the accurate calculation of such curves can be computationally demanding and extremely complicated due to the high nonlinearity of the problem and the difficulties in describing the seismic effect, common methodologies often invoke significant simplifications: neglecting certain types of uncertainties, assuming certain distribution model, using simplified analysis procedures to calculate the mechanical response of the structure, etc. It is emphasized that uncertainties in the resistance are often handled in a vague manner in the calculations, since their relevance is thought to be secondary in comparison to the uncertainties in the seismic effect.Current paper illustrates a comprehensive methodology bridging over the above gaps. In order to accomplish this goal, fragility curves are determined on the basis of the full probabilistic approach. The stochastic model properly incorporates all the relevant random variables with proper distribution types and parameters. The mechanical response of the structure is computed by nonlinear dynamic (time‐history) analysis in OpenSees finite element software. Reliability analysis is completed using First Order Reliability Method in FERUM. In order to perform the iterative calculations, the coupling of the stochastic and the mechanical model had to be performed, which required the synchronization of the above mentioned software.The main steps and results of the current framework are illustrated through an example of a) low‐rise and b) three‐storey steel portal frames. According to the results, the uncertainties in the resistance may have a significant effect on the probability of failure. Considering, that the results of the approximate methods found in the literature may significantly differ from the results obtained by reliability analysis, there is an understandable need for the more frequent usage of the full probabilistic approach as a background for practical applications, hence all types of uncertainties can be handled elaborately.
11.21: Experimental evaluation and explicit fracture simulations of stainless steel seismic dampers
Authors: Baiguera Marco , Vasdravellis George , Karavasilis Theodore L. 
Published: September 2017

ABSTRACTSeismic dampers with high post‐yield stiffness were recently proposed by the authors as the main energy dissipative system in a seismic‐resistant steel frame. The dampers are hourglass‐shaped pins made of duplex stainless steel and their high post‐yield stiffness significantly reduced the residual drifts of the frame after the design earthquake. This work evaluates the cyclic behaviour of the proposed dampers both experimentally and numerically. Two different geometries of full‐scale prototype dampers were tested under various standard and random cyclic loading protocols in a configuration that reproduced the damper‐brace connection in the actual steel frame. The results of fourteen tests showed that the proposed dampers possess excellent hysteresis and fracture capacity. Following the tests, explicit numerical simulations were carried out using the Abaqus software. Geometry‐independent fracture criteria were calibrated using the results of monotonic and cyclic tests on coupon specimens made of duplex stainless steel, and explicitly included in the numerical simulations of the dampers. The finite element models are able to accurately capture the initiation and evolution of fracture in the prototype dampers subjected to both standard and random cyclic loading histories. The results can be used to calibrate reliable macro‐models for seismic collapse simulations of the proposed frame.
11.24: Impact of column flexural stiffness on behaviour of steel plate shear walls
Authors: Curkovic Ivan , Skejic Davor , Dzeba Ivica 
Published: September 2017

ABSTRACTIn the past 40 years steel plate shear walls (SPSW) have seen increased application as vertical stabilization systems of structures. Steel plate shear walls (SPSW) may be considered as vertically installed cantilever composed of boundary frame elements (beams and columns) and very slender steel infill panel. In the past, the loss of stability of the infill plate was prevented by adding vertical and horizontal stiffeners, while the present application relies on post‐critical tension field action of the infill panel. For cost‐effective implementation of steel plate shear wall (SPSW) systems the infill steel panel needs to be completely utilized through ability of tension field formation over the entire steel plate. Due to such load bearing mechanism additional transverse forces are exerted on boundary frame members. Hence, in order to ensure expansion of the tension field throughout the entire infill panel the required minimal flexural stiffness of boundary frame element cross‐section shall be met. This requirement is based on assumptions valid for plate girders, where previous studies, indicate that for steel plate shear walls (SPSW) this requirement could be conservative or even completely unnecessary.This paper presents the results of experimental and numerical research. Laboratory testing included two different specimen groups. In order to determine the influence of the infill panel on the behaviour of moment resisting frame (MRF) three steel moment resisting frame (MRF) specimens were tested in the first group, while experiments of the second group included three steel plate shear wall (SPSW) specimens. In each specimen group flexural stiffness of the boundary columns was varied. Experimental results show that steel plate shear wall (SPSW) specimens whose boundary columns do not meet the required minimal flexural stiffness exhibited small “pull‐in” of their columns. Furthermore, the experimental data was used to calibrate numerical models that have been used for additional parametric numerical analyses. Specifically, the influences of three column flexural stiffness values as well as two steel grades of the infill panel were investigated for five different aspect ratio (L/H) values. Impact of the above parameters was assessed through comparison of residual relative horizontal displacement profiles.
11.30: Experimental behaviour of base plate joints equipped with self‐centering system and friction dampers
Authors: Santiago A. , da Silva L. Simoes , da Silva L.C. Fernandes , Cavallaro G. Ferrante , Francavilla A. , Latour M. , Piluso V. , Rizzano G. 
Published: September 2017

ABSTRACTA FREE from DAMage friction connection is a connection where friction dampers are introduced by adding friction pads, sliding on slotted steel plates, pre‐stressed with high strength bolts. Even though such a technology provides great advantages in terms of removal of damage to the structural elements, it has the main drawback to provide a limited re‐centering capability. In fact, during a seismic loading history, FREEDAM joints rotate concentrating the dissipation in the friction interface but, due to their high stiffness, after the end of the ground motion, they remain in a deformed position, leaving also the structure with residual drifts resulting in out‐of‐plumbs.The goal of the work is to propose an approach to provide FREEDAM structures with a self‐centering capacity by studying particular devices, to be installed in beam‐to‐column joints or column base joints. In this paper, the attention is focused on the problem of re‐centering of base plate joints studying a detail consisting in a connection located at the base of the columns of the first storey equipped with friction dampers and threaded bars. The threaded bars work as elastic springs thanks to sets of Belleville washers used to increase the deformability and to allow the opening of a gap in the connection. The main breakthrough of the proposed technology with respect to the existing literature, aside from the methodology employed for the design of the friction connection, is that the self‐centering capability is obtained with re‐centering elements (threaded bars and Belleville springs) which are not conceived to be extended up to the end of the column at the top storey of the building, but they have a size similar to the column splice's cover plates. The work reports the results of a preliminary experimental investigation on this joint detail which has regarded cyclic and pseudo‐dynamic tests. The experimental results presented seems very encouraging towards the possible development of base plate joints with self‐centering capacity combined with friction dampers.
11.32: Linked columns with friction dampers as a technique for seismic retrofit of steel moment resisting frames
Authors: Bonchev Georgi , Belev Borislav , Mualla Imad 
Published: September 2017

ABSTRACTThe existing steel moment‐resisting frames (MRFs) designed to seismic codes of older generation typically have limited local ductility capacity and may not perform to the desired “strong‐column‐weak‐beam” concept due to the lack of capacity design provisions. All these deficiencies require modifications for reducing their seismic vulnerability.The paper proposes a seismic retrofit technique for steel moment frames based on the linked column concept. The linked columns are dual piers connected throughout their height with short horizontal replaceable ductile link elements. Developed in the last decade for new seismic‐resistant steel structures, the linked column frame structural system combines two sub‐systems – a primary lateral force resisting system composed of linked columns and secondary moment resisting frames mainly involved in resisting gravity loads.During a seismic event, the relative deformations of the closely spaced piers activate the links which are designed to yield in shear or bending for seismic energy dissipation, but they also help in controlling interstorey drifts and limiting the forces transferred to the surrounding structural members.The authors present a new innovative design of the linked columns. Instead of short steel beams, rotational friction dampers (RFDs) are used as seismic links in order to avoid the damage expected in conventional link elements. The RFDs are supplied by a Danish company and have been used for seismic protection in many projects for the last decade. They have proven energy‐dissipation capacity and can be delivered in different shapes and slip capacities at relatively low cost.In this study three‐, six‐ and nine‐storey four‐bay steel MRFs have been analyzed using the capacity spectrum method. The added linked columns are arranged symmetrically on both sides of the first interior columns of the MRFs.The results obtained for three different arrangements of the seismic links are presented and summarized. They indicate that the seismic retrofit using linked columns with rotational friction dampers is a promising technique for seismic upgrade of existing steel moment frames.
11.34: Cross‐aisle seismic behaviour of drive‐in rack systems
Authors: Shaheen Mahmoud S.A. , Rasmussen Kim J.R. 
Published: September 2017

ABSTRACTThis paper presents the results obtained from a comprehensive series of earthquake tests carried out on fully loaded drive‐in steel storage racks. The earthquake waveforms used are actual ground motion records obtained from various locations around the world. The ground motions were applied in the cross‐aisle direction, in which the frames are made of a series of couples of uprights interconnected by diagonal braces to form upright frames. The upright frames were fully braced from top to bottom, and presented the most commonly used system configuration in the industry. In the tests, the 3D structural response was recorded to understand the global behaviour of drive‐in rack systems. The paper also presents the sequence of failures of different components that occurred during the tests, and the impact of these on the system behaviour.
11.36: Influence of type of loading protocols and restraining parameters on cyclic response of steel BRB
Authors: Ghowsi Ahmad Fayeq , Sahoo Dipti Ranjan 
Published: September 2017

ABSTRACTBuckling‐restrained braces (BRBs) are the special type of braces capable of yielding in both tension and compression under axial loading. These BRBs provide the nearly symmetrical hysteretic response and the higher energy dissipation potential as compared to the conventional steel braces. However, the use of relatively slender core plates in BRBs results in the smaller elastic and post‐elastic axial stiffness and the possibility of end plate rotation at the transition zone resulting in the unexpected premature damages. One of the possible way to change the stiffness of BRBs is to change the yielding core slenderness ratio to an acceptable limit. The range of reduction of yielding core ratio of BRBs depends on the required magnitude of hysteric energy dissipation as well as maximum and cumulative displacement ductility levels. This research is focused on the influence of core cross‐sections, friction between the core and restrainers, gap between core and restrainers, loading protocols, and core slenderness ratio on the cyclic performance of steel BRBs. A numerical study has been conducted for a series of BRB elements using the finite element software ABAQUS. Numerical models are validated by comparing the predicted results with the findings of a past experimental study on six numbers of steel BRBs subjected to different types of loading protocols. The energy dissipation potential of BRBs did not change significantly with the nature of loading protocols. However, the cyclic response of BRBs was significantly influenced by magnitude of friction and gap between the core and restraining elements. Moreover, the strength adjustment factors are unaffected by the different types of loading and as core cross‐sections.
11.41: Numerical investigation of influence of plate yield point on performance of steel plate shear wall
Authors: Moammer Omid , Deylami Ardeshir. , Jafari Khashayar , Raisszadeh Amir Hossein 
Published: September 2017

ABSTRACTSteel plate shear walls (SPSW) consist of thin infill steel plates attached to beams and columns in steel frames. SPSW are efficient lateral load resisting systems and can act as an alternative to traditional systems. In this study, the nonlinear response of single‐story single‐bay SPSW models having different yield points of infill plates (100, 180, 250 MPa.), were numerically investigated under lateral loading. The other variables in the analysis were the aspect ratio of panels (2 and 2.5), and thickness of the steel plates (3, 5 and 7 mm.). The models were designed according to the “AISC Steel Design Guide 20” and the “AISC 341–10 Provisions”. Finite element models of SPSWs were developed and analysed using ABAQUS nonlinear program. The results show that, using low yield point steel leads to more ductility and with some consideration influence the stiffness of models.