Internal Force Distribution in Steel-Concrete Composite Structure for Pylon of Cable-Stayed Bridge

Adopting a steel-anchor beam and steel corbel composite structure in the anchor zone on pylon is one of the key techniques for the design of Jintang bridge, a cable-stayed bridge in Zhoushan, China. In order to ensure the safety of the steel-concrete composite structure, a stud connector model for the joint section was put forward. Experiments were conducted to obtain the relation between load and slip of specimen, the failure pattern of stud connector, the yield bearing capacity and ultimate bearing capacity of a single stud, etc. The whole process of the structural behavior of the specimen was comprehensively analyzed. The features of the internal force distribution in the steel-concrete composite structure and the strain distribution of stud connector under different loads were emphatically studied. The test results show that the stud connector is applicable for the steel-concrete composite structure for pylon of Jintang bridge. The stud has a good ductility performance and a obvious yield process before its destruction. The stud connector basically works in a state of elasticity under a load less than the yield load.

Internal Force Analysis Due to the Supporting Translation in Statically (Indeterminate) Structures for Different Elastic Modulus

For statically indeterminate structure, the internal force will be changed with the translation of the supports, because the internal force is related to the absolute value of the stiffness EI. When the tension is different with the compression modulus, EI is the function of internal force and is not constant any more that is different from classic mechanics. In the other words, it is a nonlinear problem to calculate the internal force. The expression for neutral axis of the statically indeterminate structure was derived in the paper. The iterative program for nonlinear internal force was compiled. One case study was presented to illustrate the difference between the results using the different modulus theory and the single modulus theory as in classical mechanics. Finally, some reasonable suggestions were made for the different modulus structures.

New Insights on the Deflection and Internal Forces of a Bending Nanobeam

Nanowires, nanofibers and nanotubes have been widely used as the building blocks in micro/nano-electromechanical systems, energy harvesting or storage devices, and small-scaled measurement equipment. We report that the sur- face effects of these nanobeams have a great impact on their deflection and internal forces. A simply supported nanobeam is taken as an example. For the displacement and shear force of the nanobeam, its dangerous sections are different from those predicted by the conventional beam theory, but for the bending moment, the dangerous section is the same. Moreover, the values of these three quantities for the nanobeam are all distinct from those calculated from the conventional beam model. These analyses shed new light on the stiffness and strength check of nanobeams, which are beneficial to engineer new-types of nano-materials and nano-devices.

AN ANALYTICAL METHOD FOR SOLVING INTERNAL FORCES AND DEFORMATIONS OF BAR-SYSTEM STRUCTURE IN SPACE

In this paper, based on the idea of finite element method, the initial parametric method in bending, problem of a beam is extended to analyse the bar-system structure by employing Dirac function and llcavisidc step function.Then a new method for analysing the internal forces and deformations of bar-system structure in space is suggested by improving the mixed method in statically indeterminate structure.The inferred process and obtained answer will be more succinct and accurate when the problem of internal forces and deformations of bar-system structure is analysed by using the new method provided in this paper.

Electro-elastic Fields of Piezoelectric Materials with An Elliptic Hole under Uniform Internal Shearing Forces

The existing investigations on piezoelectric materials containing an elliptic hole mainly focus on remote uniform tensile loads. In order to have a better understanding of the fracture behavior of piezoelectric materials under different loading conditions, theoretical and numerical solutions are presented for an elliptic hole in transversely isotropic piezoelectric materials subjected to uniform internal shearing forces based on the complex potential approach. By solving ten variable linear equations, the analytical solutions inside and outside the hole satisfying the permeable electric boundary conditions are obtained. Taking PZT-4 ceramic into consideration, numerical results of electro-elastic fields along the edge of the hole and axes, and the electric displacements in the hole are presented. Comparison with stresses in transverse isotropic elastic materials shows that the hoop stress at the ends of major axis in two kinds of material equals zero for the various ratios of major to minor axis lengths; If the ratio is greater than 1, the hoop stress in piezoelectric materials is smaller than that in elastic materials, and if the ratio is smaller than 1, the hoop stress in piezoelectric materials is greater than that in elastic materials; When it is a circle hole, the shearing stress in two materials along axes is the same. The distribution of electric displacement components shows that the vertical electric displacement in the hole and along axes in the material is always zero though under the permeable electric boundary condition; The horizontal and vertical electric displacement components along the edge of the hole are symmetrical and antisymmetrical about horizontal axis, respectively. The stress and electric displacement distribution tends to zero at distances far from the elliptical hole, which conforms to the conclusion usually made on the basis of Saint-Venant’s principle. Unlike the existing work, uniform shearing forces acting on the edge of the hole, and the distribution of electro-elastic fields inside and outside the elliptic hole are considered.

Analysis and Calibration of Internal Flow Force of EjectorPowered Engine Simulator System in Wind Tunnels

The ejector-powered engine simulator(EPES)system is an important piece of equipment in conducting an influence test of the intake and jet flow in low-speed wind tunnels.In this work,through the analysis of the structure and principle of EPES,three parts of the internal flow force were obtained,namely,the additional resistance before the inlet,the internal flow force in the inlet and the thrust produced by the ejector.On the assumption of one-dimensional isentropic adiabatic flow,the theoretical formulae for calculating the forces were derived according to the measured total pressure,static pressure and total temperature of the internal flow section.Subsequently,a calibration tank was used to calibrate the EPES system.On the basis of the characteristics of the EPES system,the process and method of its calibration were designed in detail,and the model installation interface of the calibration tank was reformed.By applying this method,the repeatability accuracy of the inlet flow rate calibration coefficient was less than0.05%,whereas that of the exhaust flow rate and velocity was less than 0.1%.Upon the application of the calibration coefficients to the correction of the wind tunnel experiment data,the results showed good agreement with the numerical simulation results in terms of regularity and magnitude before stall,which validates the reasonableness and feasibility of the calibration method.Analysis of the calibration data also demonstrated the consistency in the variation law and trend between the theoretical calculation and actual measurement of internal flow force,further reflecting the rationality and feasibility of the theoretical calculation.Nevertheless,the numerical difference was large and further widened with a higher ejection flow rate mainly because of the accuracy of flow measurement and the inhomogeneity of internal flow.The thrust deflection angle of EPES is an important factor in correcting this issue.In particular,the thrust deflection angle becomes larger with small ejection flow and becomes smaller with an increase in flow rate,essentially exhibiting a general change of less than 10°.

Study on the Distribution Law of Horizontal Seismic Forces between Slab-Column and Shear Wall

In slab column-shear wall structures,both the whole structure′s seismic behavior and failure mode are greatly influenced by the distribution of horizontal seismic forces between slab-column and shear wall.In this paper,a pushover analysis of topical slab column-shear wall structure was carried out,the seismic shear force that the slab-column and shear wall should undertake was worked out,the influences of plastic internal force redistribution and structure stiffness characteristic value on horizontal seismic distribution were studied and the calculation formula was given.The analysis results showed that with the yield of the shear walls,the story shear force was undertaken by slab-columns correspondingly increased while with the decrease of characteristic value of stiffness of a structure,and the horizontal seismic force was undertaken by slab-columns correspondingly decreased.According to the code,the design of horizontal force distribution may be cause insecurity problems,so it is necessary to give the distribution law of horizontal seismic forces in slab-column shear wall structures as the supplement to the corresponding regulation of the Code.

Effects of connection types and elevated temperature on the impact behaviour of restrained beam in portal steel frame

Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experimental measurement and numerical simulation techniques. Comprehensive parametric studies are carried out to discuss the influence of end connection types, temperature, impact velocity,impact mass and span-to-depth ratio(SDR) on the dynamic response of the beams. The characteristics of deformation, internal force and energy distribution about the restrained beams and its joints are investigated. A temperature dependent criterion for evaluating the frame joint performance is proposed to measure the degree of performance degradation and impact resistance of the joint. The dynamic displacement amplification factor in different temperature environments are proposed for the different beam end constraint types and SDRs. Results of the experimental and numerical analysis show that the welded connection(WC) of three typical joint types is the strongest, and the extended endplate connection(EEC) is the weakest in terms of the impact resistance performance. With regard to the failure mode of the joint, the failure positions of the WC and the welded-bolted connection are located in the inner web of the column. Meanwhile, the EEC is located in the connection position between the beam and the endplate. Three different internal force stages and two obvious critical temperature boundaries of the restrained beams emerge with the increase in temperature, and they have significant characteristics in terms of deformation trend, internal force transfer and energy distribution. During the impact, a phenomenon known as “compression arch action” develops into “catenary action” with the increase in deflection in the frame beam mechanism.

Driving Force to Socialize the International Norms of Human Rights

Human rights, as a great term and lofty goal, have unquestionably become a topic of mainstream talk in the present-day world.2 Such mainstream talk has been internal- ized into part of the social structure. The current international society is experiencing a profound reorganization and transition in values. All kinds of new interactions under the context of globalization have resulted in the development of the current norms of international human rights, which are constructed on the basis of law and ethics. Therefore, analyzing the dynamic factors of socialization that support the operation of human rights norms in international society has become increasingly important in today＇s mutually dependent society.

Study on Structure of Arched Longitudinal Beams of Deep-Water Wharf

High-pile and beam-slab quays have been widely used after several years development. They are mature enough to be one of the most important structural types of wharves in China coastal areas. In order to accommodate large tonnage vessels, wharves should be eorrstructed in deep water gradually. However, conventional high-pile and beam-slab structares are hard to meet the requirements of large deep-water wharf. According to arch＇ s stress characteristics, a new type of wharf with catenary arched longitudinal beams is presented in this paper. The new wharf structure can make full use of arch＇s overhead crossing and reinforced concrete compression resistance, improve the interval between transverse bents greatly, and decrease underwater construction quantity. Thus, the construction cost cab be reduced. Take the third phase project of the Yangshan Deep-water Port for example, comparative analysis on catenary arched longitudinal beams and conventional longitudinal beams has been made. The result shows that with the same wharf length and width, the same loads and same longitudinal beam moment, catenary arch structure can improve the interval between bents up to 28 m, decrease the nmnber of piles and underwater construction quantity.

Self-contained Capsubot Propulsion Mechanism

In this paper, a self contained capsubot （capsule robot） propulsion mechanism is investigated. The proposed capsubot works on the principle of internal force-static friction. A modified linear DC motor is used to drive the capsubot. A novel acceleration profile is proposed for the moving part （linear cylinder） based on the principle. A significant feature of the proposed capsubot is that it is legless, wheelless, and trackless. The developed capsubot with a proposed propulsion mechanism demonstrates a very good average velocity. The propulsion mechanism has the potential to be used for the propulsion of a wireless-controlled self-propelling capsule endoscope. Simulation and experimental results demonstrate the performance of the self-contained capsubot with the proposed acceleration profile.

Seismic response of the long-span steel truss arch bridge with the thrust under multidimensional excitation

Purpose–Under different ground motion excitation modes,the spatial coupling effect of seismic response for the arch bridge with thrust,seismic weak parts and the internal force components of the control section of main arch ribs are analyzed.Design/methodology/approach–Taking a 490 m deck type railway steel truss arch bridge as the background,the dynamic calculation model of the whole bridge was established by SAP2000 software.The seismic response analyses under one-,two-and three-dimension(1D,2D and 3D)uniform ground motion excitations were carried out.Findings–For the steel truss arch bridge composed of multiple arch ribs,any single direction ground motion excitation will cause large axial force in the chord of arch rib.The axial force caused by transverse and vertical ground motion excitation in the chord of arch crown area is 1.4–3.6 times of the corresponding axial force under longitudinal seismic excitation.The in-plane bending moment caused by the lower chord at the vault is 4.2–5.5 times of the corresponding bending moment under the longitudinal seismic excitation.For the bottom chord of arch rib,the arch foot is the weak part of earthquake resistance,but for the upper chord of arch rib,the arch foot,arch crown and the intersection of column and upper chord can all be the potential earthquake-resistant weak parts.The normal stress of the bottom chord of the arch rib under multidimensional excitation is mainly caused by the axial force,but the normal stress of the upper chord of the arch rib is caused by the axial force,in-plane and out of plane bending moment.Originality/value–The research provides specific suggestions for ground motion excitation mode and also provides reference information for the earthquake-resistant weak part and seismic design of long-span deck type railway steel truss arch bridges.

Quantifying the contribution of natural variability to September Arctic sea ice decline

Arctic sea ice extent has been declining in recent decades. There is ongoing debate on the contribution of natural internal variability to recent and future Arctic sea ice changes. In this study, we contrast the trends in the forced and unforced simulations of carefully selected global climate models with the extended observed Arctic sea ice records. The results suggest that the natural variability explains no more than 42.3% of the observed September sea ice extent trend during 35 a（1979–2013） satellite observations, which is comparable to the results of the observed sea ice record extended back to 1953（61 a, less than 48.5% natural variability）. This reinforces the evidence that anthropogenic forcing plays a substantial role in the observed decline of September Arctic sea ice in recent decades. The magnitude of both positive and negative trends induced by the natural variability in the unforced simulations is slightly enlarged in the context of increasing greenhouse gases in the 21st century.However, the ratio between the realizations of positive and negative trends change has remained steady, which enforces the standpoint that external forcing will remain the principal determiner of the decreasing Arctic sea ice extent trend in the future.

Measuring Internal Velocity of Debris Flows by Temporally Correlated Shear Forces

Debris flow is a kind of geological hazard occurring in mountain areas.Its velocity is very important for debris flow dynamics research and designing debris flow control works.However,most of past researches focused on surface velocity and mean velocity of debris flow,while few researches involve its internal velocity because there is no available method for measuring the internal velocity for its destructive power.In this paper,a method of temporally correlated shear forces（TCSF） for meas-uring the internal velocity of debris flows is proposed.The principle of this method is to calculate the internal velocity of a debris flow using the distance between two detecting sections and the time differ-ence between the two waveforms of shear forces measured at both sections.This measuring method has been tested in 14 lab-based flume experiments.

International Cooperation for China's Labor Force

At present, the keystone for integration of the world’s economy is the liberalization of commodities, services, investment and finance. While it reinforces the global mobility of high-technology staff, it does not actually lead to the cross border flow of general labor, especially low-skill labor in the developing countries. This may create a problem for the developing countries, that is, how to combine international capital, which is expanding incessantly and has strong mobility, with the international labor, which is great in quantity and weak in mobility. China’s accession to WTO in 2001 is an important milestone of China’s reform and opening up. This means that China

Variable stiffness design of redundantly actuated planar rotational parallel mechanisms

Redundantly actuated planar rotational parallel mechanisms（RAPRPMs） adapt to the requirements of robots under different working conditions by changing the antagonistic internal force to tune their stiffness.The geometrical parameters of the mechanism impact the performances of modulating stiffness.Analytical expressions relating stiffness and geometrical parameters of the mechanism were formulated to obtain the necessary conditions of variable stiffness.A novel method of variable stiffness design was presented to optimize the geometrical parameters of the mechanism.The stiffness variation with the internal force was maximized.The dynamic change of stiffness with the dynamic location of the mechanism was minimized,and the robustness of stiffness during the motion of the mechanism was ensured.This new approach to variable stiffness design can enable off-line planning of the internal force to avoid the difficulties of on-line control of the internal force.

Structural form-finding of bending components in buildings by using parametric tools and principal stress lines

This paper aims to provide an efficient and straightforward structural form-finding method for designers to extrapolate component forms during the conceptual stage.The core idea is to optimize the classical method of structural form-finding based on principal stress lines by using parametric tools.The traditional operating process of this method relies excessively on the designer’s engineering experience and lacks precision.Meanwhile,the current optimization work for this method is overly complicated for architects,and limitations in component type and final result exist.Therefore,to facilitate an architect’s conceptual work,the optimization metrics of the method in this paper are set as simplicity,practicality,freedom,and rapid feedback.For that reason,this paper optimizes the method from three aspects:modeling strategy for continuum structures,classification processing of data by using the k-nearest neighbor algorithm,and topological form-finding process based on stress lines.Eventually,it allows architects to create structural texture with formal aesthetics and modify it in real time on the basis of structural analysis results.This paper also explores a comprehensive application strategy with internal force analysis diagramming to form-finding.The finite element analysis tool Karamba3D verifies the structural performance of the form-finding method.The performance is compared with that of the conventional form,and the comparison results show the practicality and potential of the strategy in this paper.

Application of Strut-and-Tie Model for Design of Interior Anchorage Zone in Post-tensioned Concrete Structure

This paper presents an application of strut-and-tie model(STM) to design the interior anchorage zone(IAZ) in the post-tensioned concrete structure.The STM theory and range of IAZ are introduced.Then,based on the finite element analysis,a series of simplified equations to calculate internal forces in IAZ are presented.Finally,the STM model for IAZ is given.In the proposed STM model,internal forces in ties vary with the dimension ratio and the eccentricity of load.The U-turn of internal forces is suggested to allocate rebar to resist bearing flexural tensile force.Compared with the FIP(International Federation for Prestressing) model,the proposed STM model is more reasonable and applicable.

The relative contributions of soil hydrophilicity and raindrop impact to soil aggregate breakdown for a series of textured soils

Soil aggregate breakdown is the first key factor that causes soil erosion.At present,research on the mechanisms of soil aggregate breakdown during rainfall is common.However,the research to on quantifying the relative contributions of internal and external forces to aggregate breakdown remains limited.This paper was conducted to analyse the relative contribution of internal and external forces to aggregate disintegration and the factors affecting aggregate stability during rainfall.Soil aggregates with a series of textures were selected as test soil samples;deionized water was employed as the soaking solution and rainfall material in static disintegration experiments and rainfall simulation tests.The effect of internal force(soil hydrophilicity)on aggregate disintegration was analysed by the static disintegration method,and the combined effects of internal force(soil hydrophilicity)and external force(raindrop impact)on soil aggregate breakdown were analysed by rainfall simulation experiments.The results indicated that external force caused more severe soil aggregate breakdown than internal force,and the crushed aggregate was mainly distributed in the range of 2–0.25 mm.With increasing rainfall kinetic energy,the degree of aggregate breakdown increased gradually,and the degree of aggregation of the soil particles decreased gradually.Furthermore,soil aggregates with a high clay content(>30%)were more stable than medium-clay(20–30%)and low-clay(<20%)soil aggregates,and the correlation coefficient provided a good representation of the relationship between the clay content and soil aggregate stability index(ASI).Therefore,external force contributed more to soil aggregate breakdown than internal force during rainfall,and clay plays an important role in aggregate stability.The results of this study are of great significance for elaborating the mechanism and factors affecting aggregate breakdown.