Study of Innovative Built-up Cold-formed Beams

In the present work innovative built-up cold-formed steel beams are presented. These are obtained by combining the pressing and cold-rolling forming techniques of steel sheets, along with the use of suitable connecting systems. Firstly, the beam shape features and the possible application fields, as well as the research project devoted to the assessment of their structural behaviour, are discussed. Then, experimental results concerning the characterization of both sheet material properties and connecting system performances are shown. In particular, the study of the sheet material is carried out by using an appropriate methodology of analysis, aiming at evaluating both mechanical and geometrical imperfections arising from the whole manufacturing process. At the same time, the mechanical behaviour of different connecting systems is investigated by means of several lap shear tests. The obtained results have provided useful design information and will be subsequently used to calibrate the numerical and theoretical models, addressing the prediction of the structural response of these innovative cold-formed beams

Earthquake Response of Cold-Formed Steel-Based Building Systems: An Overview of the Current State of the Art

Building systems fabricated with cold-formed steel (CFS) profiles and members made of wood, gypsum, or other materials allow solving a range of issues arising in common constructional elements thanks to their advantages, such as lightness, strength, durability, physical stability, sustainability, and cost-effectiveness. As a result of this inherent competitiveness of CFS based buildings, their use has been gradually increasing in recent years both in the field of structural systems as non-structural architectural components and, above all, in the area of earthquake resistant buildings, where lightness play a key role. After a general introduction, the paper gives an overview of the current codification and ongoing research on CFS non-structural architectural and structural systems. Finally, the main conclusions are summarised, and possible future developments are outline

On the Origin of I Beams and Quick Analysis on the Structural Efficiency of Hot-rolled Steel Members

In the current paper the origin of steel I beams has been analysed from historical-technological and structural points of view. First, the way leading to discover the most famous structural member of the modern Steel Engineering has been reconstructed. Later on, parameters of structural efficiency, allowing for a quick numerical evaluation of the effects produced by the rolling process on the semi-finished casting products, have been defined as a function of the difference in terms of weight between the solid billet and the member final shape on the basis of the more or less raw material centrifugation. By using the above mentioned structural efficiency parameters, the design criteria used for development of the European list of sections, with particular reference to IPE and HE profiles, have been comprehended. Finally, the proposed method, if applied to members having the same area, allows defining, without considering local buckling phenomena, the best profile for each performance category of steel members

Design Tools for Bolted End-Plate Beam-to-Column Joints

Predicting the response of beam-to-column joints is essential to evaluate the response of moment frames. The well-known component method is based on a mechanical modelling of the joint, through joint subdivision into more elementary components subsequently reassembled together to obtain the whole joint characteristics. Significant advantages of the component method are the following: (i) the mechanics-based modelling approach; (ii) the easier general characteristics of components. However, the method is commonly perceived by practicing engineers as being too laborious for practical applications. Within this context, this paper summarizes the results of a theoretical study aiming to develop simplified analysis tools for bolted end-plate beam-to-column joints, based on the Eurocode 3 component method. The accuracy of the component method was first evaluated, by comparing theoretical predictions of the plastic resistance and initial stiffness with corresponding experimental data collected from the available literature. Subsequently, design/analysis charts were developed through a parametric application of the component method by means of automatic calculation tools. They are easy and quick tools to be used in the first phases of the design process, in order to identify joint configurations and geometrical properties satisfying specified joint structural performances. The parametric analysis allowed also identifying further simplified analytical tools, in the form of nondimensional equations for predicting quickly the joint structural properties. With reference to selected geometries, the approximate equations were verified to provide sufficiently accurate predictions of both the stiffness and the resistance of the examined beam-to-column joints

Experimental ambient vibration tests and numerical investigation on the Sidoni Palace in Castelnuovo of San Pio (L'Aquila, Italy)

In the present paper the experimental and numerical activities related to in-situ Ambient Vibration Tests performed on a monumental masonry building placed in Castelnuovo of San Pio (Italy) are presented. The obtained experimental results, able to identify the dynamic characteristics of the investigated palace, have been successively reproduced by means of a building FEM model through the ABAQUS calculation code. Numerical frequency analysis has been also performed on the original building aiming at evaluating its reduction in stiffness due to earthquake. Finally, appropriate retrofitting interventions have been proposed, their effectiveness being proved by numerical analyses on the improved palace FEM model

State-of-the-art on steel exoskeletons for seismic retrofit of existing RC buildings

Since ‘80s the use of external additive structures, commonly called exoskeletons, is considered one of the possible alternatives for seismic retrofit of existing r.c. structures with low dissipative capacity. The first Japanese and American codes dealing with structural rehabilitation issues, as well as many applications on the use of steel devices at the international level, are testimony of this trend, especially in high seismic hazard areas. Nowadays, the use of this intervention strategy has become of great actuality, not only because it can be implemented in a safe way without interrupting the building use, but also because it can be effectively adopted, in cases of restructuring operations with lateral addition, for the integrated (formal, energetic and functional) retrofit of the entire construction. In the present work, after a thorough state-of-the art of the main researches and applications on steel exoskeletons, their typological classification into families and the definition of the key project parameters, indispensable to both properly conceive and design such systems, have been performed