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We present the design and implementation of a spectral code, called SpectralPlasmaSolver (SPS), for the solution of the multi-dimensional Vlasov-Maxwell equations. The method is based on a Hermite-Fourier decomposition of the particle distribution function. The code is written in Fortran and uses the PETSc library for solving the non-linear equations and preconditioning and the FFTW library for the convolutions. SPS is parallelized for shared- memory machines using OpenMP. As a verification example, we discuss simulations of the two-dimensional Orszag-Tang vortex problem and successfully compare them against a fully kinetic Particle-In-Cell simulation. An assessment of the performance of the code is presented, showing a significant improvement in the code running-time achieved by preconditioning, while strong scaling tests show a factor of 10 speed-up using 16 threads.

Highlights•A state of art approach to evaluate the elliptical tunnel stability of Hoek–Brown rock mass.•Rigorous upper bound and lower bound solutions of elliptical tunnel stability are derived using advanced finite element limit analysis.•Comprehensive design tables and equations are proposed for stability evaluation.

Slot arrays on the narrow wall of rectangular waveguides are designed for the realisation of arbitrarily specified radiation patterns. The derivation of design equations is similar to the procedure introduced by Elliott for the broad wall slots. An error function is constructed having four terms: impedance matching, array pattern synthesis, slot design equations and radiation efficiency. The minimisation of the error function is performed by the combination of genetic algorithm and conjugate gradient method, which determines the geometrical dimensions of slots, such as their slant angles, lengths and spacings. The performance of designs by the proposed method of least squares is verified using full-wave simulation software.

A thorough review was performed to outline the general procedures used for performing drop-weight testing on concrete beam members. Highlights of this review include the problems associated with early tests and the methods used to overcome them, which have now become standard practice. The findings of various types of concrete beams under low-velocity impact have also been examined. These include the impact behavior of conventionally reinforced, fiber-reinforced, and prestressed concrete beams. Next, a database of various concrete beam types has been carefully built for the development and discussion of observed trends. When applicable, comparison of the recorded drop-weight behavior of conventional reinforced concrete (RC) beams was aggregated to its ACI design capacity. Finally, empirical relations for both flexuraland shear-critical members are suggested, with applicability to the ACI design standard. Keywords: ACI design equation; drop-weight testing; fiber-reinforced concrete beams; prestressed concrete beams; reinforced concrete beams.

The paper introduces a step-down converter that exhibits a static conversion ratio of cubic nature, providing an output voltage which is much closer to the input voltage, and at the same duty cycle, compared to a wide class of one-transistor buck-type topologies. Although the proposed topology contains many components, its control is still simple, as it employs only one transistor. A dc analysis is performed, the semiconductor stresses are derived in terms of input and output voltages and output power, revealing that the semiconductor voltage stresses remain acceptable and anyway lower than in other cubic buck topology. All detailed design equations are provided. The state-space approach is used to analyze the converter in the presence of conduction losses and a procedure for calculating the individual power dissipation is provided. The feasibility of the proposed cubic buck topology is first validated by computer simulation and finally confirmed by an experimental 12 V–10 W prototype.

Compression development and lap-splice length provisions in ACI 318-19 [section]25.4.9 and [section]25.5.5 are reexamined after an example was used to show that existing provisions can produce unexpected results in some design conditions, such as compression lap splices longer than tension lap splices. A historical review of ACI Building Codes shows that existing compression bond length provisions are largely based on provisions adopted before test data were available. The provisions in ACI 318-19 are compared with a database of 89 test results and shown to poorly fit the data. Several compression and tension bond equations are also examined and found to fit the data better. It is shown that compression development and lap-splice lengths can be based on several expressions available in the literature for tension development length with minor modification, including the ACI 318-19 equation for tension development length. Using this approach would simplify design by eliminating the use of different expressions to calculate tension and compression development lengths, prevent calculated lengths from being longer in compression than in tension, and provide a better fit to available data. Keywords: bond; database; deformed bars; design equations; development length; end bearing; lap splice.

The bond between a steel reinforcement/rod and glulam plays a crucial role in the resistance and deformation capacity of timbers joints. Existing studies provide different bond–slip models for reinforcements and rods with different anchorage lengths, in which the relationship between local bond stress and global bond behaviour cannot not be established. This study presents a unified analytical method for predicting the bond–slip behaviour of ribbed bars and threaded rods along the grain using a local bond–slip model of reinforcement at the elastic and post-yield stages. In the analytical method, equilibrium, compatibility, and constitutive models for reinforcement and rods are considered. The method is verified using test data of rebars and rods with different anchorage lengths. Comparisons between the experimental and calculated results suggest that the analytical method yields reasonably good predictions of the load–slip relationship and failure mode. Furthermore, the embedment lengths required for yield and the ultimate strengths of the reinforcement and rods along the grain are determined by assuming uniform bond stress distributions over the elastic and post-yield steel segment. The average bond stress over the entire anchorage length is calculated and compared with existing equations. Design recommendations for anchorage lengths are proposed for ribbed bars and threaded rods glued in glulam.

A new S600E sorbite stainless steel (SS), which performs outstanding mechanical properties, was introduced in a plate girder to enhance the resistant performance and durability. The resistance from the flange for S600E sorbite SS plate girders developing post-buckling capacity was investigated through numerical analyses, which included the material and geometrical nonlinearity. The value of distance between plastic hinges performed significant effects on resistance from flange. There was a certain distribution range of the flange plastic hinge. Hence, it was difficult to determine the value of distance between plastic hinges accurately based merely on the failure behavior. Considering the theoretical basis of EN 1993-1-4: 2006+A1, the new methods to obtain resistance from the flange and determine the value of distance between the plastic hinges were proposed to avoid the aforementioned error. The parametric study was conducted to investigate the effect of key parameters on the resistance from the flange. To take the above effect into account, a correction factor was proposed for the design equation in EN 1993-1-4: 2006+A1 to predict the distance between flange plastic hinges accurately. The comparison was conducted to validate the accuracy of the proposed equations. The results indicated that the new modified equation could be used to predict the resistance from the flange of the S600E sorbite SS plate girder more accurately.

Through-bolts have demonstrated efficacy as a circular hollow section (CHS) T-joint strengthening method; however, the absence of design guidelines necessitates further investigation. Therefore, using non-linear finite element analysis, numerical research has been conducted to establish robust design equations for predicting the axial capacity of CHS T-joints strengthened using through-bolts under axial brace loading. Focusing on chord face plastification as the primary failure mode, validated finite-elements models were utilized in an extensive parametric study, varying parameters such as the number of through-bolts, spacing between them, chord diameter-to-thickness ratio ( γ  =  d 0 /2 t 0 ), and brace-to-chord diameter ratio ( β  =  d 1 / d 0 ). Subsequently, four equations were formulated to account for different through-bolt arrangements, delivering the through-bolt impact factor ( Q TB ), which can be applied to the design equations for accurate strengthened capacity of the T-joints across a wide validity range. Additionally, empirical ratios were derived to estimate the force in the through-bolts, so that the cross-sectional diameter of the through-bolt can be chosen.

This study assesses improvements in the head and extension sleeve parts for a post-installed anchor. The sleeve and head details were proposed to enhance the structural performance of the post-installed anchor, and the optimal structural shape was determined through finite element analysis. The analysis results revealed that the anchor's performance was most efficiently improved when the sleeve length was 9.0 mm and the head length was 3.0 mm. In the model with these dimensions applied, the performance improved approximately 1.71 times compared to the existing model, validating the effectiveness of the proposed structural details. The improved pull-out strength test of anchor diameter M12 showed an increase of 1.25 times in normal-strength concrete and 1.28 times in high-strength concrete, with an embedded depth of 50 mm. The improved pull-out strength test of anchor diameter M16 showed that the pull-out strength increased by 1.42 times for normal-strength concrete and about 1.33 times for high-strength concrete. This research proposes a modified equation that reflects changes in the effective embedded depth and diameter. A comparison of the proposed equation with that of European Technical Approval Guideline (ETAG) showed that the correlation coefficient changed from 0.908 to 0.962, and the coefficient of variation changed from 18.9 to 10.4%, meaning that the proposed equation reflected the actual experimental values more accurately.