LOCALIZED ANALYSIS OF THIN-WALLED STRUCTURE’S BUCKLING/INITIAL POST-BUCKLING AND ITS ACCURACY

A method of localization is proposed to lower the high order of equations in FEM calcula- tion for the stability of a complex thin-walled structure.The localized analysis enables us to obtain both the upper and lower limits for the bifurcating point in a whole linear elastic structural system,as well as an ap- proximate solution to asymptotic post-buckling problem.Some numerical examples are included.

Elastoplastic analysis of thin-walled structures in reservoir area

In the structural design of the high pier,in order to analyze the strength and structure stability,the pier was often considered a thin-walled structure.Elastoplastic incremental theory was used to establish the model of elastoplastic stability of high pier.By considering the combined action of pile,soil and pier together,the destabilization bearing capacity was calculated by using 3-D finite element method(3-D FEM) for piers with different pile and section height.Meanwhile,the equivalent stress in different sections of pier was computed and the processor of destabilization was discussed.When the pier is lower,the bearing capacity under mutual effect of pile,soil and pier is less than the situation when mutual effect is not considered;when the pier is higher,their differences are not conspicuous.Along with the increase of the cross-sectional height,the direction of destabilization bearing capacity is varied and the ultimate capacity is buildup.The results of a stability analysis example are almost identical with the practice.

Transformation Matrix for Combined Loads Applied to Thin-Walled Structures

This paper transforms combined loads, applied at an arbitrary point of a thin-walled open section beam, to the shear centre of the cross-section of the beam. Therein, a generalized transformation matrix for loads with respect to the shear centre is derived, this accounting for the bimoments that develop due to the way the combined loads are applied. This and the authors’ earlier paper (World Journal of Mechanics 2021, 11, 205-236) provide a full solution to the theory of thin-walled, open-section structures bearing combined loading. The earlier work identified arbitrary loading with the section’s area properties that are necessary to axial and shear stress calculations within the structure’s thin walls. In the previous paper attention is paid to the relevant axes of loading and to the transformations of loading required between axes for stress calculations arising from tension/compression, bending, torsion and shear. The derivation of the general transformation matrix applies to all types of loadings including, axial tensile and compression forces, transverse shear, longitudinal bending. One application, representing all these load cases, is given of a simple channel cantilever with an eccentrically located end load.

Study on local topology model of low/high streak structures in wall-bounded turbulence by tomographic time-resolved particle image velocimetry

The relationship between the in the logarithmic law （log-law） region of bursting event and the low/high-speed streak a turbulent boundary layer is investigated. A tomographic time-resolved particle image velocimetry （TRPIV） system is used to measure the instantaneous three-dimensional-three-component （3D-3C） velocity field. The momentum thickness based Reynolds number is about 2 460. The topological information in the log-law region is obtained experimentally. It is found that the existence of the quadrupole topological structure implies a three-pair hairpin-like vortex packet, which is in connection with the low/high-speed streak. An idealized 3D topological model is then proposed to characterize the observed hairpin vortex packet and low/high-speed streak.

Interaction of Oblique Waves and A Rectangular Structure with An Opening Near A Vertical Wall

With the method of separation of variables and the eigenfunction expansion employed, an analytical solution is presented for the radiation and diffraction of a rectangular structure with an opening near a vertical wall in oblique seas, in which the unknown coefficients are determined by the boundary conditions and matching requirement on the interface. The effects of the width of the opening and the angle of incidence on the hydrodynamic characteristics of a rectangular structure with an opening near a vertical wall are mainly studied. The comparisons of the calculation results with wall-present and with wall-absent are also made. The results indicate that the variation trends of the heave added mass and excitation force with wall-present are almost the same as those with wall-absent, and that the peak values in the former case are obviously larger than those in the latter due to the reflection of the vertical wall.

Progressive collapse resisting capacity of reinforced concrete load bearing wall structures

Reinforced concrete(RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the "load factor" parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure.

Optimal Design for Thin-Walled Box Beam Based on Material Strength Reliability

According to the reliability of material strength,the optimal design for the cross sectional size of thin walled box beam was studied.Firstly the cross sectional size as design random variable was determined,then its stochastic nature was researched,with which the objective function is to seek the maximum reliability of the beam under given constraint conditions.This way is not the same as the conventional optimal design for the minimum weight of the material.With establishing the optimal objective,the reliability of the material under conditions of static and fatigue was considered.The corresponding calculated expressions are given.Normally the cross section sizes are fitted to the normal distribution,for the simplification of the design variable,the variation of the section size is assumed as a dependent variable proportional to the mean of the size.The way is different not only with the conventional optimal design but also with the common reliability design.The maximum reliability of material is obtained,meanwhile the area of the cross section is reduced,i.e.,the weight of the material is decreased.

Effect of passive structure and toroidal rotation on resistive wall mode stability in the EAST tokamak

If βN exceeds βNno-wall, the plasma will be unstable because of external kink and resistive wall mode （RWM）. In this article, the effect of the passive structure and the toroidal rotation on the RWM stability in the experimental advanced superconducting tokamak （EAST） are simulated with CHEASE and MARS codes. A model using a one-dimensional （1D） surface to present the effect of the passive plate is proved to be credible. The no wall fiN limit is about 3li, and the ideal wall βN limit is about 4.5li on EAST. It is found that the rotation near the q = 2 surface and the plasma edge affects the RWM more.

Synthesis,Crystal Structure and Thermal Property of a 2D Brick Wall Framework Constructed from a New Mononuclear Complex

One new coordination polymer with the chemical formula [CoCu2L2·K2·1.5C2H5OH]n（H4L = 2-hydroxy-3-[（E）-（{3-[（2-hydroxybenzoyl）amino]propyl}imino）methyl] benzoic acid） has been synthesized based on the slow diffusion method,and characterized by IR spectroscopy,thermalgravimetric and X-ray diffraction analysis.It crystallizes in the monoclinic system,space group P21/n with a = 11.98860（10）,b = 24.4279（3）,c = 14.9008（2） ,β = 104.7490（10）°,V = 4220.01（8） 3,Z = 2,Mr = 1009.94,Dc = 1.590 g/cm3,F（000） = 2056,μ（MoKα） = 1.649 mm-1,the final R = 0.0411 and wR = 0.1178 for 5920 observed reflections with I 2σ（I）.The compound possesses a 2D brick wall structure constructed from trinuclear units.

AN EFFICIENT ASSESSMENT METHOD FOR INTELLIGENT DESIGN RESULTS OF SHEAR WALL STRUCTURE BASED ON MECHANICAL PERFORMANCE,MATERIAL CONSUMPTION,AND EMPIRICAL RULES

Efficient methods for incorporating engineering experience into the intelligent generation and optimization of shear wall structures are lacking,hindering intelligent design performance assessment and enhancement.This study introduces an assessment method used in the intelligent design and optimization of shear wall structures that effectively combines mechanical analysis and formulaic encoding of empirical rules.First,the critical information about the structure was extracted through data structuring.Second,an empirical rule assessment method was developed based on the engineer's experience and design standards to complete a preliminary assessment and screening of the structure.Subsequently,an assessment method based on mechanical performance and material consumption was used to compare different structural schemes comprehensively.Finally,the assessment effectiveness was demonstrated using a typical case.Compared to traditional assessment methods,the proposed method is more comprehensive and significantly more efficient,promoting the intelligent transformation of structural design.

Experimental Study and Numerical Simulation of Hypervelocity Projectile Impact on Double-Wall Structure

Tests of hypervelocity projectile impact on double-wall structure were performed with the front wall ranging from 0.5 mm to 2.0 mm thick and different impact velocities. Smooth particle hydrodynamics (SPH) code in LS-DYNA was employed for the simulation of hypervelocity impact on the double-wall structure. By using elementary shock wave theory, the experimental results above are analyzed. The analysis can provide an explanation for the penetration mechanism of hypervelocity projectile impact on double-wall structure about the effect of front wall thickness and impact velocity..

Welding sequences optimization of box structure based on genetic algorithm method

In this article, The genetic algorithm method was proposed, that is, to establish the box structure＇s nonlinear three-dimension optimization numerical model based on thermo-mechanical coupling algorithm, and the objective function of welding distortion has been utilized to determine an optimum welding sequence by optimization simulation. The validity of genetic algorithm method combining with the thermo-mechanical nonlinear finite element model is verified by comparison with the experimental data where available. By choosing the appropriate objective function for the considered case, an optimum weldiing.sequence is determined by a genetic algorithm. All done in this study indicates that the new method presented in this article will have important practical application for designing the welding technical parameters in the future.

Discussion on Structure Design and Optimization of Building Curtain Wall

To discuss the structure design and optimization of building curtain wall, the dynamic characteristics of point supported glass curtain wall system are analyzed by the finite element method. The various technologies are made use of, and according to the characteristics of the structure system, the finite element analysis model with steel structure glass plate beam element and shell element as the basic elements is established. Then, the dynamic characteristics are analyzed, and the modal parameters such as inherent frequency and vibration type are identified. The research results show that the node displacement response power spectrum under the load of wind is obtained, which provides the basis for rationally optimizing the structure. Based on the above findings, it is concluded that the optimization design based on finite element model has a wide significance, which is a useful attempt to reduce the blindness of design and has great engineering significance and application value.

Antisymmetric quadrupole mode of coherent structures in wall-bounded turbulence

Abstract Experiments were conducted in a water tunnel by tomographic time-resolved particle image velocimetry （Tomo-TRPIV）. The Reynolds number Reo is 2 460 on the base of momentum thickness. According to the physical mechanism of the stretch and compression of multi-scale vortex structures in the wall-bounded turbulence, the topological characteristics of turbulence statistics in logarithmic layer were illustrated by local-averaged velocity structure function. During coherent structures bursting, results reveal that the topological structures of velocity gradients, velocity strain rates and vorticities behave as antisymmetric quadrupole modes. A three-layer antisymmetric quadrupole vortex packet confirms that there is a tight relationship between the outer layer and the near-wall layer.

Utilization of IDRIZI Wall System on Building Structures-Characteristic Study Case

Perhaps the best way to demonstrate the gained improvements in seismic performance of buildings, integrated with IDRIZI infill walls, is to analyse typical building structures subjected to real case earthquake scenarios. This paper presents obtained analytical results for a characteristic 2D frame structure which （besides the self-weight, superimposed dead loads and live loads） is subjected to real earthquake ground motions. This study case treats three story planar RC （reinforced concrete） frame opened on the ground story while its upper stories are infilled with classical masonry walls. The purpose of this study case is to demonstrate ＂quantitatively＂ the seismic performance of this frame structure and, more importantly, to estimate the level of seismic response improvements of the frame when at its ground story is utilized IDRIZI infill wall with door opening. The seismic action considered for this study case is a representation of the 1979 Tivari earthquake, Montenegro. Ultimately, this study demonstrates the remarkable benefits the structure gains （in terms of seismic performance and safety） by the use of IDRIZI wall system as a constitutive part of the 2D frame structure.

A study on coherent structures and drag-reduction in the wall turbulence with polymer additives by TRPIV

An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.

Analysis on Construction Quality Control Technology of Reinforced Concrete Shear Wall Structure

In the process of continuous development of construction enterprises, new requirements have been put forward for construction projects. By strengthening the construction quality control of reinforced concrete shear wall structure, the construction level of reinforced concrete can be continuously improved, the construction quality can be guaranteed, and the construction project can be successfully completed, which is worthy of extensive application and promotion in construction enterprises, thus providing a broader development space for construction enterprises.

Research on Occurrence Mechanism of Public Security Emergency from the perspective of the Structure Box

Public security emergency is a public crisis event, and we cannot anticipate the specific time, actual scale, specific situation and influence depth of emergencies. If the emergencies are not under control, the crisis will get worse and its destructive energy will be released quickly.Structure box is an invisible closed system which is constructed by local politics, economy, and culture. Namely, structure box is local social ecological environment. Structure box is a closed area which is full of anger. Therefore, in such environment with too much pressure, we need an outlet to release pressure. Anger is the social and psychological basis of the emotional resonance of onlooker, when the fuse incident occurred, so that the widespread anger in structure box will find the spotlight. The words and actions of the leaders in the informal group will produce a great social infection and circulatory response, and groups’ stirring will cause emotional resonance which is easy to burst. Thus, irrational behavior may caused by people. This processcan use five links to describe： occurrence of fuse events, information diffusion, emotional resonance, situational catalysis, control failure, and occurrence of public security emergency. This is the occurrence mechanism of public security emergency.

The Continuum Analytical Method of Steel Frame- Reinforced Concrete Shear Wall Mixed Structure

The inter-story drift stiffness considered the semirigidity of beam and column joints connection, and P-Delta second order effect of steel frame parts in the mixed structure is presented in the paper. After considering on the influence of semirigidity between steel beams and steel columns, second order effect of beam-column members for steel frame and structural second order effect, the traditional continuum analytial method used in RC shear-frames wall structure is developed to steel frames-reinforced concrete shear wall mixed structure subject to horizontal load in this paper. A continuum approach, which is suitable for analyzing steel frames-reinforced concrete shear wall mixed structure subject to horizontal load, is presented. The method is relatively simple and more practical. It will be referred to structural design for steel frames-reinforced concrete shear wall mixed structure.

A CAD Process for Box Culvert Structure Design

CAD process for structure design of box culvert is introduced. It follows the traditional way of culvert design. All working conditions of culvert are taken into account. It can generate load diagram, bending moment diagram and bending moment envelope diagram for a single-hole, double-hole or triple-hole box culvert .That is to say, the whole CAD process for the box culvert structure design is realized with the self-developed system. It has been used to accomplish several projects in China and the results are satisfactory.