Massimo Latour

Experimental Analysis of Bolted Steel Beam-to-Column Connections: Component Identification

In this paper, the results of an experimental program dealing with the ultimate behavior of bolted beam-to-column connections under cyclic actions are presented. The design criteria adopted for tested specimens are discussed in detail, aiming to point out how the ultimate behavior can be governed by properly strengthening the components for which yielding has to be prevented. To this scope, the component approach is adopted as a design tool for component hierarchy criteria. The aim of the paper is the investigation of the actual possibility of extending the component approach to the prediction of the cyclic response of beam-to-column joints. To this scope, the attention has been focused on the possibility to evaluate the overall energy dissipation capacity starting from the energy dissipation of the single joint components, provided that they are properly identified and their cyclic behavior is properly measured.

Cyclic Modeling of Bolted Beam-to-Column Connections: Component Approach

The work is aimed at the prediction of the cyclic response of bolted beam-to-column joints starting from the knowledge of their geometrical and mechanical properties. To this scope a mechanical model is developed within the framework of the component approach already codified by Eurocode 3 for monotonic loadings. Accuracy of the developed mechanical model is investigated by means of the comparison between numerical and experimental results with reference to an experimental program carried out at Salerno University. The obtained results are encouraging about the possibility of extending the component approach to the prediction of the cyclic response of bolted connections.

Experimental Behavior and Mechanical Modeling of Dissipative T-Stub Connections

This work aims to enhance the energy-dissipation capacity of classical rectangular T-stubs by proposing an hourglass shape for the T-stub flange according to the approach usually adopted for added damping and stiffness (ADAS) devices. A new type of axial damper is developed. First, a mechanical model of the device is set up and a finite-element model is carried out in ABAQUS code. The accuracy of both models is verified through comparison with experimental results. Next, on the basis of cyclic tests, the improvement of the energy-dissipation capacity of classical T-stubs provided by the proposed approach is quantified, and the low-cycle fatigue curves are determined with reference to the case of both T-stubs on rigid support and of coupled T-stubs. The results of the work also represent a useful tool for designing a dissipative double split tee connection.

Cyclic Behavior and Modeling of a Dissipative Connector for Cross-Laminated Timber Panel Buildings

This article aims to propose an innovative type of angle to be used in substitution of the hold-down in cross-laminated timber (CLT) panel buildings. The new connection, called XL-stub, applies a concept similar to the classical ADAS (added stiffness and damping) device. In order to characterize the force-displacement response under cyclic loads of the proposed XL-stub, an experimental campaign is presented. Successively, the effectiveness of the proposed angle is proved by analyzing the non-linear response under seismic loads of a single wall alternatively equipped with hold-downs or the XL-stub.

FINITE ELEMENT ANALYSES ON FREE FROM DAMAGE SEISMIC RESISTING BEAM-TO-COLUMN JOINTS

The seismic design strategy implemented in current codes is based on the capacity design principles that allow the formation of plastic hinges into predefined parts of the structure. Therefore, significant damage is expected at ultimate limit state, to which high repair costs are associated. Recently, new design strategies have been proposed in order to avoid the damage of the structure. The most of them are grouped into two categories, namely i) using special damping devices introduced in the structure as additional resisting element; ii) changing the dissipation mechanism of the structure by means of friction-based dissipative joints. The second possibility is promising and really effective because it guarantees no architectural interference if adopted for moment-resisting frames (MRFs), and low forces transferred to the foundations. The novelty of free from damage (FREEDAM) joints lays in the fact that the energy is dissipated by friction at the interface between plates in contact instead of the classical plastic deformation energy dissipation mechanism. In this paper, the seismic behaviour of FREEDAM joints is investigated by means of parametric finite element analyses carried out in order to examine the influence of geometric and mechanical feature of the friction device (e.g. position of friction plane, type of friction interface, bolt clamping, bolt strength). The accuracy of finite element models is also validated on the basis of some experimental tests. 802 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 802-814

Experimental Analysis on the Cyclic Response of Beam to Column Joints:State-of-the-Art at Salerno University

Aiming to provide a contribution to the codification of design rules for dissipative joints to be applied to MRFs, in last five years, a comprehensive experimental and analytical work dealing with the cyclic behaviour of beam-to-column joints has been developed by the research group of the University of Salerno. In particular, the activity has regarded the study of both classical and innovative typologies characterized by the same initial stiffness and resistance but by different hysteretic behaviours due to the different source of energy dissipation supply imposed in the design process. In this paper, the main results of such a study, performed at the laboratory of materials and structures of the University of Salerno, are reported in order to provide an overview on the main mechanisms involved in the energy dissipation of partial-strength connections. A particular attention is given to the design issues by presenting the procedures aimed at providing to the joints adequate characteristics in terms of stiffness, resistance and ductility supply by hierarchically controlling the behaviour of the single joint components. Furthermore, the results of tested joints (classical and innovative) are compared in terms of hysteretic behaviour and energy dissipation supply in order to point out the advantages of the different connecting systems.

Investigation on Friction Features of Dissipative Lap Shear Connections by Means of Experimental and Numerical Tests

RESEARCH ARTICLE Investigation on Friction Features of Dissipative Lap Shear Connections by Means of Experimental and Numerical Tests Mariana Zimbru, Mario D’Aniello, Attilio De Martino, Massimo Latour, Gianvittorio Rizzano and Vincenzo Piluso Department of Structures for Engineering and Architecture, University of Naples Federico II, Napoli, Italy Department of Civil Engineering, University of Salerno, Fisciano, Italy

Finite Element Analysis of Bolted T-Stubs Undergoing Large Displacement: A Preliminary Study

To properly assess the robustness of steel Moment Resisting Frames (MRFs), the non-linear response of structural members and connections would need to be quantified. Under the influence of extreme load cases, structural joints are subjected to both material and geometric nonlinearities, known commonly as second-order effects. These effects cannot be disregarded if catenary actions develop in the connecting beam member. The rotational capacity of bolted joints is directly dependent on the deformation capacity of its components in bending which are typically represented by the equivalent T-stub. A T-stub is composed of a single T-section bolted to a support whose stiffness may be equivalent or greater than that of the T-element. To accurately characterise the response of a T-stub undergoing large displacement, the non-linear behaviour of its flange will need to be thoroughly investigated. In the flange, second order effects are caused by the development of axial (or membrane) forces which can be significant for those T-stubs connected to a rigid support. Hitherto, little information exists on the influence of second-order effects on the response of bolted T-stubs and, consequently, there are no existing guidelines on how to include these effects in design. In this paper, we present the results of a parametric investigation, using finite element (FE) analysis, to assess the influence of second-order effects in T-stubs bolted to a rigid support. Both material and geometrical non-linearities were considered since they are known to have a critical impact upon the performance of T-stubs. A benchmark FE model is first generated and validated against experimental data; it is then used to carry out a parametric investigation, by alternately considering and neglecting geometric non-linearity, to identify the geometric configurations that experience significant second order effects. A method to assess the contributions of membrane forces to the overall deformation response of a T-stub is also proposed

On the Robustness of Earthquake-Resistant Moment-Resistant Frames: Influence of Innovative Beam-to-Column Joints

Received: October 1, 2017 Revised: November 1, 2017 Accepted: December 1, 2017 Abstract: Background: The deformation capacity of beam-to-column connections strongly influences the robustness of earthquake-resistant Moment Resistant Frames (MRFs) when subjected to a loss-of column scenario. As a consequence, with the aim of foresee the structural response up to the failure, an accurate modelling of the ultimate behaviour of the joints is needed.

PRELIMINARY STUDY ON BEAM-TO-COLUMN JOINTS UNDER IMPACT LOADING

Received: October 1, 2017 Revised: November 1, 2017 Accepted: December 1, 2017 Abstract: Background: Recent catastrophic events have pointed out the need to ensure the integrity of structures under “exceptional” events. Since many years, the University of Liège is involved in different activities and projects related to the robustness assessment of structures. The robustness of a structure is the ability of the system to remain globally stable after events not directly accounted for in the design, like impact, fire or consequences of a human error, which should lead to a reasonable damage when compared to the original cause.