Research on Mechanical Properties and Parameter Identification of Beam-Column Joint with Gusset Plate Angle Using Experiment and Stochastic Sensitivity Analysis

Based on stochastic sensitivity analysis, a new style of joint structure with greater ductility and higher strength—the beam-column joint with gusset plate angle (JGA) steel—was proposed. Research on the static and hysteretic behavior of the JGA was performed using finite element analysis and experimental methods. The research results indicated that adding a seat angle could increase the positive and negative initial rotational stiffness and strength and provide a better energy consumption performance of the joint. An improved chaotic particle swarm optimization (ICPSO) neural network algorithm was used to study the stochastic sensitivity. Seven important parameters that influence the bending stiffness and strength of the JGA, namely, the beam height, beam flange width, beam web thickness, gusset plate thickness, connection angle steel thickness, connection angle steel width, and seat angle steel thickness, were investigated by stochastic sensitivity analysis. Moreover, the beam height, connection angle steel, and seat angle steel thickness, which had significant influences on the mechanical properties of the joints, were studied in depth by finite element analysis. Within the range of the parameters of the joint, the higher the beam height was, the larger the connection angle thickness was; the smaller the connection angle width was, the better the joint performance was. A reasonable design of the JGA is proposed: a beam with the SH2 section (250 × 125 × 6 × 9 mm) and a 10 mm thick and 75 mm long angle steel connection.

A simple method for mitigating error in the fixed-offset of a double-crystal monochromator

In order to maintain a constant monochromatic synchrotron X-ray beam height for all energies, the separation between the crystals of a double-crystal monochromator is typically adjusted, via translation of the second crystal, while X-ray energy is varied, via rotation of the crystal pair. The ability to accurately translate the second crystal requires precise knowledge of the separation between the two crystals and, when present, crystal miscuts. Here, a simple method for calibrating the crystal gap from measured variation in the X-ray beam height that eliminates error in the fixed beam offset is provided.

Holes' Parameters Analysis of a Perforated Thin-Walled Lipped Beam Buckled Under a Bending Load

This work studied the effects of holes on the buckling characteristic of an open thin-walled lipped channel beam under a bending load. A nonlinear finite element method was utilised to examine the buckling behaviour of the beam. Experimental works were carried out to verify the finite element simulation. Three factors were chosen to examine their influence on the buckling of the beam. These factors namely, the holes’ shape, perforated ratio (hole length to beam height) and spacing ratio (centre to centre distance between holes to beam height). The finite elements output was analysed by implementing the Taguchi method to distinguish the best group of three parameters collections for optimal strength of buckling. Whereas the analysis of variance technique (ANOVA) method was applied to specify the impact of each parameter on critical buckling load. Outcomes showed that the combination of parameters that gives the best buckling strength is the hole with a hexagonal shape, perforated ratio =1.7 and spacing ratio =1.3, and the holes’ shape is the most effective factor. In addition, the study demonstrated that the hole's shape factor has the greatest influence on the buckling capacity. While the perforated ratio factor is the least influential.

Seismic Behavior of Top-weld Bottom-bolt Joints between CFST Columns and H-beams

In recent decades, connections between concrete-filled steel tubular columns (CFST) and H-steel beams have been well designed and implemented. However, owing to poor construction quality, brittle failure often occurs at weld seams. In this study, an innovative joint was developed to connect CFST columns and H-steel beams using a top-weld bottom-bolt (TWBB) connection to minimize the effect of welding quality on the seismic resistance of joints. Six specimens were designed for cycle-reversed loading tests to discuss the seismic performance of this joint. Four configurations, including different connection methods, beam heights, column forms, and stiffener thicknesses, were considered in the test. The impacts of different configuration forms on the failure mode, strength, stiffness, ductility, and energy dissipation of the specimens were evaluated. The test results demonstrated that the columns with or without concrete had a significant effect on the deformation capacity. However, a smaller effect was observed on other indicators. The replacement of the through-diaphragm and an increase in the beam height adversely influenced the ductility of the joint. Moreover, changing the stiffener thickness and using a full-bolted connection affected the failure mode. The joint type analyzed in this study satisfies the strong column–weak beam design criterion and the related seismic provisions.

Modeling size-dependent thermal-mechanical behaviors of shape memory polymer Timoshenko micro-beam

PurposeIn this paper, a three-dimensional size-dependent constitutive model of SMP Timoshenko micro-beam is developed to describe the micromechanical properties.Design/methodology/approachAccording to the Hamilton's principle, the equilibrium equations and boundary conditions of the model are established and according to the modified couple stress theory, the model is available to capturing the size effect because of the material length scale parameter. Based on the model, the simply supported beam was taken for example to be solved and simulated.FindingsResults show that the size effect of SMP micro-beam is more obvious when the dimensionless beam height is similar or the larger of the value of loading time. The rigidity and strength of the SMP beam decrease with the increasing of the dimensionless beam height or the loading time. The viscous property of SMP micro-beam plays a more important role with the larger dimensionless beam height. And the smaller the dimensionless beam height is, the more obvious the shape memory effect of the SMP micro-beam is.Originality/valueThis work implies prediction of size-dependent thermo-mechanical behaviors of the SMP micro-beam and will provide a theoretical basis for design SMP microstructures in the field of micro/nanomechanics.

Study on the strength of glued laminated timber beams with round holes: difference in structural performance between homogeneous-grade and heterogeneous-grade timber

Various design codes and design proposals have been proposed for glued laminated timber beams with round holes, assuming that the entire beam is composed of homogeneous-grade timber. However, in Japan, glued laminated timber composed of homogeneous-grade timber is rarely used for beams. In this study, the difference in the load-bearing capacity of glued laminated beams composed of homogeneous-grade timber and heterogeneous-grade timber with round holes when fractured by cracking was investigated experimentally and analytically. The materials used in the tests were glued laminated beams composed of homogeneous-grade Scots pine timber with a strength grade of E105-F345 and heterogeneous-grade Scots pine timber with a strength grade of E105-F300. Experiments confirmed that although the glued laminated beams composed of heterogeneous-grade timber have a lower material strength in the lamina with holes, its resistance to fracturing due to cracks associated with the holes is almost the same as that of the glued laminated beams composed of homogeneous-grade timber. The stresses acting on the holes in the laminated timber with holes of less than half the beam height were lower in the glued laminated beams composed of heterogeneous-grade timber than in the glued laminated beams composed of homogeneous-grade timber. The ratio of the stresses was found to be approximately equal to the ratio of the maximum bending stress or the maximum shear stress acting on the inner layer lamina, as determined by Bernoulli–Euler theory.

OPTIMAL HEIGHT OF STEEL PLATE GIRDERS WITH CORRUGATED WEBS

This work is carried out in order to study the classical problem of determining the optimal height of a plate girder with given moment of resistance in relation to the features of the real operation of a beam with a corrugated web. A bi-symmetric plate girder with a wavy web is considered. The structural model parameters of the girder correspond to the Zenam technology, which determines the structural limitations of the task. The physical model is the 1st class double-tee girder according to the stress-strain state (in accordance with the current design standards of Ukraine SCS (State Construction Standards of Ukraine) В.2.6-198). The mathematical model is considered as a task of minimizing the objective function (beam mass) taking into account design factors. The height is a project variable. The objective function is formulated as one-parameter taking into account the bending strength of the beam. The structural coefficients and their influence on the objective function are considered. Both the shear strength constrain and overall wall shape stability constrain are taken into account. Deflections are determined taking into account the shear deformations of the thin web. The minimum values of the beam height are considered when the permissible deflection is not exceeded. It is shown that the introduction of the conditions of shear strength and wall stability into the resolving equation indicates the lower limit of the calculated variable value. The constraint is inactive in the area of feasible solutions. Areas of rational decisions are shown. Numerical studies have been conducted for corrugated beam structures. Design requirements in accordance with design standards are used as method constraints. The optimal values of the beam height are obtained according to the minimum mass criterion in the range of applied spans and loads. The effective values of spans and loads for beams with corrugated walls in the range of optimal parameters and technological limitations have been determined. Further research is needed to explore constructive solutions that would minimize the values of constructive coefficients, taking into account specific effects such as local tensions and real-world operating conditions.

Numerical Investigation of the Dynamic Performance and Riding Comfort of a Straddle-Type Monorail Subjected to Moving Trains

The driving comfort of a straddle-type monorail, while considering the influence of the bridge structure, was studied on the basis of multibody dynamics and the finite element method. In this study, the coupled vehicle-bridge model was established through SIMPACK and ANSYS; the 3D model of the bridge was established in ANSYS, and the vehicle model with 35 degrees of freedom (DOFs) was established in SIMPACK. The influence of the vehicle speed, pier height, track irregularity, and vehicle load on riding comfort was studied. Overall, straddle-type monorails had a good running stability, and the lateral comfort of the vehicle was better than the vertical comfort, due to symmetrical horizontal wheels. As the vehicle speed increased, the acceleration of the bridge and vehicle increased accordingly. Track irregularity had a substantial influence on riding comfort. Three types of track irregularity were simulated, and this factor should be strictly controlled to be smoother than the Chinese national A-level road roughness. The bridge pier height had a notable influence on the lateral riding comfort. In addition, this study attempted to improve riding comfort from the perspective of increasing the bridge stiffness, which could be achieved by increasing the cross-beam thickness or the track beam height.