Reliability-based optimization of structural systems by adaptive target safety – Application to RC frames

Reliability-based design optimization (RBDO) aims to find the best compromise between cost reduction and safety assurance. Traditionally, component optimization is defined by minimizing the structural cost under a prescribed reliability target for a single limit state. However, as structural failure is rarely devoted to only one component, the system approach becomes necessary to deal with realistic applications. In this paper, a methodology for system reliability-based design optimization (SRBDO) is proposed. Instead of specifying identical predefined component targets, the method is based on adaptive target reliabilities for structural components. An updating procedure is included in the optimization process to ensure the required system reliability. The proposed method aims to find the best compromise between satisfying the target system reliability and optimizing the component performance. The application to reinforced concrete structures shows the interest of the adaptive target reliabilities as well as the efficiency of the updating procedure.     

Preparation of a Novel Nano-scale Lead (II) Zig-Zag Metal–Organic Coordination Polymer with Ultrasonic Assistance: Synthesis,Crystal Structure,Thermal Properties,and NBO Analysis of [Pb(μ-2-pinh)N<Subscript>3</Subscript> H<Subscript>2</Subscript>O]<Subscript>n</Subscript>

A novel nano-cauliflower-shaped lead(II) metal–organic coordination polymer, [Pb(μ-2-pinh)N₃ H₂O]_n (1), was synthesized using an ultrasonic method. The nanostructure was characterized by scanning electron microscopy (SEM), X-ray powder diffraction, IR spectroscopy, elemental analysis, and thermal analysis. The compound was structurally characterized by single-crystal X-ray diffraction. The coordination compound takes the form of a zig-zag one-dimensional polymer in solid state. The coordination number of the lead(II) ions is six (PbN₄O₂) with three nitrogen atoms and one oxygen atom from two linker organic ligands, as well as one oxygen from coordinated water and one nitrogen atom from terminal coordinated azide anion. It has a stereo-chemically active lone electron pair, and the coordination sphere is hemidirected. The zig-zag 1D chains interact with neighbouring chains through weak interactions, creating a 3D supramolecular metal–organic framework. Lead oxide nanoparticles were obtained by thermolysis of the new nano coordination compound at 180 °C with oleic acid as a surfactant. The morphology and size were further studied using SEM. Natural bond orbital analyses demonstrate the electronic properties of the lead centre and other atoms.     

Sonochemical Synthesis and Characterization of the New Micro-Hexagonal-Rod Lead (II)-Azido Coordination Compound

The preparation of micro hexagonal-rods of a new 1D polymeric lead(II) complex containing the Pb₂-(μ-N₃)₂ motif, [Pb(dmp)(N₃)₂] _n (dmp is the abbreviation of 2,9-dimethyl-1,10-phenanthroline) by the sonochemical method is described. The new microcrystal is characterized by scanning electron microscopy, X-ray diffraction (XRD), elemental analyses and infrared spectroscopy. A single crystalline material is obtained by applying a heat gradient applied to a solution of the reagents. The single-crystal XRD analyses show that the coordination number for the Pb(II) ions is six, PbN6, with “stereo-chemically active” electron lone pairs and the coordination sphere being hemidirected. The single-crystal X-ray data show the chains of [Pb(dmp)(N₃)₂] _n interact with each other through the π–π stacking interactions, which create a 3D framework.     

Textile applications of commercial photochromic dyes: part 7. A statistical investigation of the influence of photochromic dyes on the mechanical properties of thermoplastic fibres

The influence of the concentration of a commercial photochromic dye, incorporated into as-spun and drawn fibres produced from polyethylene and polypropylene, on their mechanical properties was investigated. As-spun fibres were produced by incorporating a commercial photochromic dye at different concentrations at the extrusion stage of the production process of polypropylene, polyethylene and polyester. The fibres from polypropylene and polyethylene, which showed photochromism when exposed to UV light, were then drawn, and their mechanical properties evaluated and analysed using a factorial experimental design, applying appropriate statistical methods. No further investigation was carried out on the polyester as the dye appeared to degrade at the higher temperatures required for its extrusion, leading to a brown fibre, which was not photochromic. According to the analyses, the most significant parameter influencing the mechanical properties of the as-spun fibres was the polymer type; the effect of the dye concentration was dominated by the significance of the polymer type. The effects of the multi-stage hot-drawing process used to produce the fibres on the mechanical properties of the drawn polypropylene and polyethylene fibres were characterised and statistically modelled. It was found that the dyeing concentration had a negative effect on the tenacity and the modulus of the drawn polypropylene fibres but a positive effect on the tenacity and the modulus of the drawn polyethylene fibres. A dye concentration of 0.2% on mass of polymer had a positive effect on the elongation of the drawn polypropylene and polyethylene fibres, whereas the higher dye concentration of 0.4% had a negative effect on the elongation of both drawn fibres. A new forecasting data source was obtained to optimise the selection of the polymer and the dye concentration and to specify the direction of modification, either increasing or decreasing, the significant process parameters.     

Neural network control for earthquake structural vibration reduction using MRD

Structural safety of building particularly that are intended for exposure to strong earthquake loads are designed and equipped with high technologies of control to ensure as possible as its protection against this brutal load. One of these technologies used in the protection of structures is the semi-active control using a Magneto Rheological Damper device. But this device need an adequate controller with a robust algorithm of current or tension adjustment to operate which is further discussed in the following of this paper. In this study, a neural network controller is proposed to control the MR damper to eliminate vibrations of 3-story scaled structure exposed to Tōhoku 2011 and Boumerdès 2003 earthquakes. The proposed controller is derived from a linear quadratic controller designed to control an MR damper installed in the first floor of the structure. Equipped with a feedback law the proposed control is coupled to a clipped optimal algorithm to adapt the current tension required to the MR damper adjustment. To evaluate the performance control of the proposed design controller, two numerical simulations of the controlled structure and uncontrolled structure are illustrated and compared.     

Multi-level enhancement of structural behavior of bracing systems with coupling beams at floor level

Despite good rigidity, braced frames have weak nonlinear behavior and inadequate distribution of ductility in stories, which cause significant structural damage. In this research, a seismic resistant system called coupled concentrically braced frame (CCBF) is developed to enhance the performance of braced frames by coupling them with a beam. In this case, the coupling beams are the primary source for ductility of the system, and after their yielding in more severe earthquakes, the structure continues to benefit from the ductility of the braces as the secondary source; therefore, the system has two-level behavior caused by different probable seismic excitations. In this case, in addition to maintaining the stiffness of the two concentrically braced frames, the coupling beams resist against the movement of the braced frames, and as a result, the stiffness of the system is increased. Therefore, lighter elements can be used to resist lateral loads. Linear and nonlinear analyses of CCBF, and its comparison with other braced frames, indicate that participation of the coupling beams provides an adequate stiffness and ductility. These frames have more stable nonlinear behavior than conventional ones and continue their nonlinear behavior even after fracture of coupling beams in severe earthquakes.     

Action of grignard reagents and amines on some N-(Arylmethyleneamino)phthalimides

N-(Arylmethyleneamino)phthalimides ( 2a–c ) carrying an o-substituent in the aryl group were prepared by the reaction of N-aminophthalimide with o-substituted benzaldehydes. The reaction of these compounds with Grignard reagents proceeded either by normal addition to one of the carbonyl groups to give 3a–c or by addition and cleavage to give 4-arylphthalaz-1-ones 5a–c . The steric effect exhibited by either the Grignard reagent or the N-arylmethylene compound was studied. The reaction of N-furfurylideneaminophthalimide ( 2d ) with Grignard reagents was also investigated. N-(Arylmethyleneamino)phthalimides reacted with primary amines to give N,N′-dialkylphthalamides ( 7a and b ) while the reaction with secondary amines gave ( 8a and b ).     

A comparison of different algorithms for phasing haplotypes using Holstein cattle genotypes and pedigree data

Phasing genotypes to haplotypes is becoming increasingly important due to its applications in the study of diseases, population and evolutionary genetics, imputation, and so on. Several studies have focused on the development of computational methods that infer haplotype phase from population genotype data. The aim of this study was to compare phasing algorithms implemented in Beagle, Findhap, FImpute, Impute2, and ShapeIt2 software using 50k and 777k (HD) genotyping data. Six scenarios were considered: no-parents, sire-progeny pairs, sire-dam-progeny trios, each with and without pedigree information in Holstein cattle. Algorithms were compared with respect to their phasing accuracy and computational efficiency. In the studied population, Beagle and FImpute were more accurate than other phasing algorithms. Across scenarios, phasing accuracies for Beagle and FImpute were 99.49–99.90% and 99.44–99.99% for 50k, respectively, and 99.90–99.99% and 99.87–99.99% for HD, respectively. Generally, FImpute resulted in higher accuracy when genotypic information of at least one parent was available. In the absence of parental genotypes and pedigree information, Beagle and Impute2 (with double the default number of states) were slightly more accurate than FImpute. Findhap gave high phasing accuracy when parents’ genotypes and pedigree information were available. In terms of computing time, Findhap was the fastest algorithm followed by FImpute. FImpute was 30 to 131, 87 to 786, and 353 to 1,400 times faster across scenarios than Beagle, ShapeIt2, and Impute2, respectively. In summary, FImpute and Beagle were the most accurate phasing algorithms. Moreover, the low computational requirement of FImpute makes it an attractive algorithm for phasing genotypes of large livestock populations.     

Silica-modified magnetite Fe3O4 nanoparticles grafted with sulfamic acid functional groups: an efficient heterogeneous catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-one and tetrahydrobenzo[b]pyran derivatives

Silica-modified magnetite-polyoxometalates functionalized with sulfamic acid groups as hybrid nanoparticles were prepared by sulfonation of diamine-functionalized propyl group grafted on the magnetic silica-coated Fe₃O₄ nanoparticles. This heterogeneous nanocatalyst was explored to present high catalytic performance for the synthesis of 3,4-dihydropyrimidinones and tetrahydrobenzo[b]pyrans under mild reaction conditions. The properties of this nanocatalyst were characterized by FT- infrared, energy-dispersive X-ray spectrum, scanning electron microscope, X-ray diffraction, X-ray fluorescence and elemental analysis. Easy separation of the nanocatalyst by using an external magnet, recyclability, non-toxicity, versatility and high stability of the catalyst combined with low reaction times and excellent yields make the present protocol very useful and attractive for the synthesis of the titled products.