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See detailPressure-impulse diagram of a beam under explosion - Influence of the indirectly affected part
Hamra, Lotfi ULg; Demonceau, Jean-François ULg; Denoël, Vincent ULg

in Landolfo, Raffaele; Mazzolani, Frederico (Eds.) Proceeding of the 7th European conference on steel and composite structures (Eurosteel 2014) (2014, September 10)

The paper studies the structural response of a beam subjected to a close-field local internal blast loading. In the literature, the pressure-impulse (p-I) diagram is commonly used to design elements or ... [more ▼]

The paper studies the structural response of a beam subjected to a close-field local internal blast loading. In the literature, the pressure-impulse (p-I) diagram is commonly used to design elements or structures for a given blast loading. The p-I diagram is a spectrum representing the level sets of damage or required ductility for a given structural system, nonlinear beam in this paper. This representation is much appreciated because a simple reading for the actual pressure p and impulse I of the considered load indicates the ductility demand of the structural system. Recent works of quasi-static behaviour have indicated the crucial need to account for the membrane effects taking place in the extreme loading of frame beams. This paper will thus extend the state-of-art features, establishing thus the p-I diagram for a beam including the lateral restraints offered by the rest of the structure, the development of non-linear membrane action and also, the M-N interaction that develops in the plastic hinges. [less ▲]

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See detailPrincipal Static Wind Loads on a large roof structure
Blaise, Nicolas ULg; Hamra, Lotfi ULg; Denoël, Vincent ULg

in Proceedings of the 12th ANIV conference of wind engineering In Vento (2012, October 07)

Usually, structural wind design is realized using static wind loads. Such loadings are expected, as a main property, to recover by static analyses, the envelope values that would be obtained by a formal ... [more ▼]

Usually, structural wind design is realized using static wind loads. Such loadings are expected, as a main property, to recover by static analyses, the envelope values that would be obtained by a formal buffeting analysis. For simple structures, equivalent static wind loads might be used but they are established in order to reproduce envelope values of specific structural responses and are thus not suitable to reconstruct efficiently the entire envelope. Recently, more general methods were derived to propose global static loadings that reconstruct the entire envelope but several drawbacks remained as their robust applicability for any structure and accuracy. This paper addresses a new type of static loadings, the principal static wind loads, derived in a strict mathematical way, the singular value decomposition, to make it optimum for the envelope reconstruction problem. The method is illustrated with a large roof and the reconstruction accuracy is analysed by studying the rate of envelope reconstruction, envelope previously obtained by a rigourous stochastic analysis. The way principal loadings are derived makes them suitable for combinations in order to increase the rate of the envelope reconstruction. As a major outcome, the method provides a finite number of design load cases that matches a desired level of accuracy in the envelope reconstruction. [less ▲]

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See detailSimplification du chargement aérodynamique sur une toiture de stade
Hamra, Lotfi ULg

Master's dissertation (2012)

The stochastic analysis of a structure subjected to turbulent wind gives estimation of the extreme (or peak) responses necessary for the structural design. These extreme values are established for each ... [more ▼]

The stochastic analysis of a structure subjected to turbulent wind gives estimation of the extreme (or peak) responses necessary for the structural design. These extreme values are established for each response within the structure (displacements, internal forces, reactions, etc ...). Notwithstanding, engineers from design office are used to design structures under static wind loads. The major challenge is thus to compute equivalent static loads that take into account the dynamic behavior of the structure and by simple static analyses, reconstruct the most accurately the extreme responses obtained from a stochastic dynamic analysis. Equivalent static wind loads are determined by applying various methods and the aim of this work is to extract a reduced basis, the principal static wind loads. These principal static wind loads are well suited for combinations in order to have a minimum number of design cases. Focus is made on the responses of the structure which are composed of mean, quasi-static and resonant contributions and on the number of design static wind loads to provide an accurate reconstruction of all extreme responses. [less ▲]

Detailed reference viewed: 164 (65 ULg)