Daniel Grecea

Evaluation on static and dynamic structural coefficient of steel frames with semi-rigid joints via numerical simulations

Publisher Summary This chapter summarizes the results of some numerical simulations concerning the response of steel frames with semi-rigid joints and different moment-rotation models, under static and seismic loads. It focuses on the influence of EC3 Annex J and JJ M-Φ curve on the stability and dynamic behavior of steel structures. A simplified computation model dedicated to analyze steel frames with semi-rigid joints via a bi-linear M-Φ curve is also discussed in this chapter.

Seismic Response of Composite Eccentrically Braced Frames with Short Dissipative Element

Eccentrically braced frames (EBF) in steel and composite solution are very well suited structural assemblies for buildings in areas with high seismicity. Due to their good energy dissipation capacity, they can undergo important lateral deformations by plastic hinge formation in the dissipative element (link element) without impacting the structural integrity of the system. The dissipative link elements can be short, medium or long (according to modern design norms, such as Eurocode 8), based on the ratio between shear force and bending moment. If the dissipative element length is smaller than 1.6(Mpl/Vpl) [mm], it is considered to be a short element and is predominantly subjected to shear. The links can be realized on steel solutions or composite with the concrete slab. However, the steel behavior is assumed for composite link. The current article presents the results of extensive numerical testing based on experimental results on the behavior of composite EBF with short link elements subjected to seismic-like lateral loads. The results will present the main differences in strength, stiffness and ductility between the responses of steel and composite EBFs. Finally, a parametrical study will show the influence of link length, influence of number of stiffeners and of the web slenderness.

Conversion of a Temporary Tent with Steel Frame into a Permanent Warehouse

The paper is dealing with the problem of a functional conversion (involving both architectural and structural issues) applied to the case of an industrial building. As well known, temporary tents, designed according to the European Code EN13782, represent a remarkable stake on the building market and a fast and practical solution for some situations. It is exactly the case approached by the paper, where the investor has initially decided to erect on his platform a provisional shelter for agricultural machines and subsequent staff, built of a light steel structure covered by PVC roofing and cladding. This temporary tent has been acquired from a specialized supplier in form of a series product. After using the tent for a number of years, the investor has decided to convert the existing structure from architectural and structural point of view by switching to a permanent structure designed accordingly. Important changes were thus imposed both to the architectural part (technological flows, openings, facades) and especially to the structural part where this switch imposed a re-design to the codes of permanent structures (especially as far as climatic loadings are concerned). The required architectural change implied the building of a 70 cm high concrete plinth and replacing the PVC membrane temporary roofing and cladding by permanent 60 mm thick PUR sandwich panels. Together with a new system of openings this has led to renewed facades of the buildings. As for the structural change, the required conversion has imposed a thorough checking of the existing steel structure (very slender and typical to a tent) in view of transforming it into a permanent structure. The consolidation measures of the existing galvanized steel structure are described, together with the measures applied at infrastructure level in order to implement the required conversion.

Numerical analysis of short link steel eccentrically braced frames under seismic action

Eccentrically braced frames are well known for their capacity of dissipating seismic energy by plastic hinge formation in the so called ‘link elements’, which represent the dissipative devices of the eccentrically braced frame. The link element can be short, which means it will be mainly subjected to shear forces; long being mainly subjected to bending moment or intermediate in length subjected to a combined action of shear force-bending moment. The current study is focused on the calibration of existing experimental results with numerical finite element models of steel eccentrically braced frames with short link elements and a subsequent parametrical study considering different link lengths and multiple stiffeners along the link web panel.