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The growth of industrialization and the rapid expansion of densely populated urban areas have increased the risk caused by technological and man-made hazards. In particular, the accidental or intentional detonation of high explosives (e.g., improvised explosive devices IEDs), can cause damages to buildings and infrastructures and severe harm people. These risks can be minimized by a better planning, design, and construction, e.g., avoiding brittle construction materials, especially within the building envelope, and adopting more robust construction techniques. The study presented in the paper investigates the capacity of light steel-based wall panels to resist the effects of external explosions. The experimental results showed the ultimate capacity of the wall panels is strongly dependant on the initial design conditions and panel-to-structure fastening solution. A numerical model has been also calibrated using Etabs program.

The performance of structures under severe seismic action is ensured by properly calibrated ductility, stiffness, and strength. The "plastic" members of ductile mild carbon steel (S235 to S355) dissipate the seismic energy, acting as "structural fuses", while the "elastic" members must be provided with adequate overstrength, to have the capacity to carry the stresses corresponding to yielded and strain hardened plastic hinges. High strength steels, such as S460 to S690, might be used for these elastic members, providing them with the necessary overstrength, without enhancing the stiffness, as that could unbalance the structural system. Dual structural systems, as moment resisting frames (MRFs) combined with eccentrically braced frames (EBFs), can be equipped with replaceable mild carbon steel dissipative links acting as seismic fuses. The MRFs, possibly fabricated from high strength steel, remain elastic, being able to recover the initial position. The key problem in such systems is the design and calibration of the fuses, i.e. the replaceable bolted links, which should be carefully qualified by tests. The present paper reviews past research on bolted replaceable links and discusses the experimental qualification requirements. [ABSTRACT FROM AUTHOR]

During the European research project entitled EQUALJOINTS (European pre-Qualified steel JOINTS) [1], which recently concluded, the matter of providing a set of pre-qualification procedures for moment resisting beam-to-column connections which are currently used in Europe has been addressed. During the experimental campaign 24 specimens with bolted extended end-plate connections with haunches were tested. The current paper presents the numerical model which has been developed such that numerical testing may be performed to further investigate specific details. In what concerns the material, an isotropic material model has been calibrated and used based on tensile tests of coupons extracted from the specimens to model the actual plastic behaviour. Moreover, the imperfections of the beam have been taken into account using a bucking analysis to model as accurate as possible the specimens tested. The interaction between parts has been modelled using contacts with different interaction laws. The model used for the bolt has been calibrated such that the preloading and failure replicate the behaviour of the actual bolts used in the experiments.

Modelling the cyclic response of structural steel plays an important role in the design and performance assessment of steel structures. Up to date, several mathematical models were developed to simulate metal plasticity, but only some of them were implemented in Finite Element Method (FEM) based software packages such as Abaqus, by using incremental plasticity procedures. Within this article, the “built-in” combined isotropic/kinematic hardening model is used to model metal plasticity under cyclic loading regime. A brief description of the constitutive model together with the calibration procedure of the material parameters based on experimental data are presented. Finite element analyseswere carried out on simplified FEM models to provide numerical predictions using the calibrated material parameters. Since the “built-in” combined model has several limitations (especially related to the isotropic component), adjustments of the material parameters were made to accommodate to different loading histories. The chosen material model and the calibrated input parameters are validated byanalysing the FEM predictions to be in good agreement with the experimental results with respect to cyclic behaviour and failure mode.

The study summarised in the present paper has investigated the post-earthquake robustness of multistorey steel framed structure prone to fire action. Building Frames, i.e., homogeneous system with moment resisting frames (MRFs) on one direction and centrically braced frames (CBFs) with inverted V braces on the other direction, of 4 and 8 stories, as case study structures, are numerically analysed. The structures were designed according to the relevant codes for persistent and seismic design situations in 2 locations with different seismicity. The structures were assessed and optimized for seismic loading using a push-over analysis. Afterwards, the robustness capacity was checked against thermal action, through a nonlinear dynamic analysis, using Extreme Loading for Structures (ELS) software [8]. [ABSTRACT FROM AUTHOR]

Building constructions are susceptible to significant risks from numerous low probability hazards during their design lifetime. Typical examples include fire, impact, explosion, earthquake, and severe weather hazards (wind, snow). The probable risks also include a special category pertaining to unidentifiable events, such as human errors in design and construction. As such exposures and hazards are difficult to quantify, the consequences can be severe, ranging from injuries or loss of life to serious economic costs. The paper presents the results of investigations conducted in the aftermath of a partial collapse during the construction of an intermediate roof built from hybrid steel-timber trusses in an existing market. The experimental tests and numerical simulations allowed the investigators to reconstruct the chain of events and identify the local damage that triggered the progressive collapse. [ABSTRACT FROM AUTHOR]