Prestressed Structures Research Articles

Structure Design and Comparison Analysis of Frame System with Angle-Steel Column and Prestressed Beam

In combination with structure design of the JuLang farm activity center, a new frame structure which consists of angle-steel concrete composite column and prestressed concrete beam is adopted. Three kinds of schemes and the concrete design process are given, those are the well beam-shape structure, prestressed girder floor structure and prestressed beam and slab structure. Clear height indoor, material costs and time limit of three kinds of schemes are analyzed comparatively, the reason selecting prestressed girder structure system is given, these can provide reference for scheme selection and design of similar engineering.

Whole-Span and Whole Length Pre-Stress Loss Monitoring Technique Study in Bonded Pre-Stressed System

The load of pre-stress structure comes from stretching of steel strand, but the stress built on the steel strand would be lost. The lost causes many problems on the structure, such as pre-stress uneven and margin of safety reduced. Monitoring stress lever on the steel strand can provide information of the structure, and then expert can estimate the behavior under load of structure. It is hardly to monitor the whole-span and whole length of steel strand by traditional senses and method, because of measure range, protection and interference of electromagnetic environment. A novel method based on Optic Fiber Bragg Grating (OFBG), which mentioned in the article, provides a successful experience on the monitoring of pre-stress loss in whole-span and whole length.

Viscoelastic behaviour of non-homogeneous variable-section beams with post-poned restraints

The aim of this paper is to develop a procedure able to calculate the long-term stress and strain patterns in modern prestressed composite structures which are largely influenced by creep and shrinkage and whose final static configuration is the result of many phases of loading and restraints conditions. The introduction of equivalent moduli, depending on the viscous and elastic features of materials, can guarantee a significant simplification of the problem presented above. The proposed calculation model has been used to design the "Quattroquercie Viaduct" located on the highway "A3" Salerno-Reggio Calabria, Italy.

Experimental Study on the Interface Properties of Geotechnical Anchorage Bolt under Cyclic Loading

Geotechnical prestressed anchorage structures are widely used in high slope, deep foundation pit, dam and other geotechnical reinforcement engineerings. Under the influence of the outside environment, its pretensioned force is not fixed, but presents a kind of approximate closed cyclic loading mode, under which the development and evolution regularity of the interface shear stress for the inner bond section of geotechnical prestressed anchorage structure is directly related to the ultimate bearing capacity and its long-term durability. In the experiment, the means of indoor model test was adopted, in which the different loading scheme and loading amplitude were taken into account and the interfaces mechanical properties of inner bond section for geotechnical prestressed anchorage structures under cyclic loading were studied. According to the test results, the development and evolution regularity of the interface shear strain for the inner bond section is revealed, and the long-term durability of the geotechnical anchorage bolt under cycle loading is put forward.

Study and Application on Structural Floor’s Comfort of Stadium with Long-Span Floor

The structural comfort of long-span floor structure which setup stadium is studied in this paper. The measured spectrum is used to simulate human movement loads. All possible loads are considered and key parameters about structural comfort of the long-span floor structure are analyzed, and then, the comfort of athletes in match and audiences on the stadium stand are analyzed. The results show the vertical acceleration and natural frequency of structure are decreased approximate linearly with increasing of the slab thickness; take one engineering project for example, according to the method proposed in this paper, the different structural comfort control index should be adopted in sports field and audience stand, respectively. Comprehensive and system design references of load simulation, pre-stressed structure dynamic analysis, comfort performance index and control standards are offered in this paper for long-span pre-stressed steel floor structure project that used for stadium.

Externally Prestressed Steel Box Girder Bridge

With a small cross section, a light deadweight and a convenient replaceable tendon, externally prestressed bridges have many special traits compared with other bridges. With a practical case, this paper analyzes the design of externally prestressed steel box girder bridges, which contains the bridge span, beam construction, externally prestressed layout, substructure and construction programs. Through economic, social analysis, discusses the prospects for the application of external prestressing structure .

Research on the Process of Pre-Stressing Construction of Suspen-Dome considering Temperature Effect

Suspen-dome is a highly efficient pre-stressing spatial structure. The pre-stressing force in cable has a significant effect on its structural performance. During pre-stressing construction, the temperature variation due to solar radiation and seasonal change might affect the pre-stressing force in cables. However, the construction tensile method which is widely adopted in engineering project does not cope with the effect of temperature change on the cable force. As a result, it is expected that the actual cable force differs from the designed cable force. In this study, the effect of temperature change during pre-stressing construction on pre-stressing force in cable is firstly studied. A significant difference of cable force, up to 212%, is observed between cases considering temperature change and cases not considering temperature change. It is therefore necessary to take the effect of temperature changing on pre-stressing force into account in design of suspen-dome. In this purpose, a new construction pre-stressing control method and a simplified calculation formula are proposed and verified.

Research on Plasticity Shaped Technology of Gear for New Type Agricultural Vehicles

With the development of modern agriculture, agricultural vehicles have broad prospects for development, for existing problems of the agricultural vehicles spur gear original forging die , designed new precision forging new technology of gear and new type precision forging die to use for production , in order to enhance radial intensity of concave model and reduce the cost of updating die, using fluctuating concave model level bisection ，three-player pre-stressed composite concave model structure ，lock-oriented , top concave model and model core are floating . Forgings parts formed in a closed ring mold cavity ，forging parts without fly side , significantly reduce turning remaining of semi-finished product,the material utilization, production efficiency and quality of forgings significantly improved , gained good economy benefit.

Research on Plasticity Shaped Technology of Rear Axle Gear of Motorcar

Rear axle spiral bevel gear of motorcar, as its special shape structure , alveolar much deeper than straight bevel gear , and has spiral angle effect , therefore, extrusion of rear axle gear than extrusion of straight bevel gear is much more difficult , deal with the problems, have made closed extrusion new technology of rear axle gear , designed new type die structure, die adopt fluctuateing concave model level bisection ， pre-stressed composite concave model structure , concave model and model core floating , parts have no fly side , tooth surface can reach the level of rough milling ,higher production efficiency and life of die , satisfied production requirements. Process test showed that compared with the open die , required extrusion distortion force reduced 50% , increase material utilization 15%, debase electric power consumption 50%, with significant economic benefits .

Impact Analysis of Different Cable Types on Saddle-Shaped Cable-Net in Construction Process

Cable is widely used in the actual project of prestressed steel structure for its mechanical properties can be fully used. Saddle-shaped cable net is a new type of large-span prestressed structure, but there is little study on the impact of different cable types on the mechanical properties of saddle-shaped cable net during the construction. In order to meet the thought of integration of design and construction, a finite element model of saddle-shaped cable net has been established. The four types of cables such as semi-parallel steel tendon cable, steel wire rope cable, steel strand cable and full-locked coil rope are chosen. The impact on mechanical properties of the structure was analyzed by different cable types.

Finite Element Analysis of Composite Flywheel with Two-Layer Pre-Stressed Rotor Structure

In this paper, considering the material properties of the composite flywheel and the characteristics of the pre-stressed structure, stresses and strains induced by rotor rotation and interference fit were calculated by finite element (FE) method based on the plane stress hypothesis, in the commercial software ANSYS. Based on the given material properties and the main dimension with a certain speed of rotation, three 2D FE-models of hybrid composite flywheel rotors with two-layer rotor structure were built with the unit property of plane stress, axisymmetric and plane strain respectively. Followed, the radial stress, circumferential stress and radial displacement of the rotor were obtained. The three simulation results are almost accordant with the present theoretical results. It shows that the numerical analyses are reliable. It can be shown that is advisable to design and optimize the flywheel rotor.

Strength Test of Parallel Carbon Fiber Bundle for Prestressed Bridge

Because of good mechanical properties of the fiber composites, the fiber bundles without the resin curing process and with the features of high modulus, high strength and good performance of creasing resistance etc, can be used in prestressed structures. According to the strength properties of the fiber, the tensile characteristic function of the fiber bundles is derived. The tensile test is designed and the parameters of the weibull distribution are estimated based on the result of the test. The ultimate strength of fiber is inversely proportional to the length of fiber. The calculating strength should be reduced in design, because the discreteness of the strength of the fiber bundle in test is much larger than the calculated values.

A Novel GFRP-FBG Smart Steel Strand and its Properties Research

Prestress strands are the key parts of the prestressed structure, and the stress of the prestressed strands is one of the important indicators to assess prestress component security. Unfortunately, up to date, there are no qualified techniques to handle this issue due to that it is too hard for sensors to survive the harsh construction environments and the time-dependent service life of prestressed structures. In this paper, a novel smart steel strand based on the technique of GFRP-FBG rebar was introduced, and its sensing principle has also been given in details. The novel smart steel strand has been tested by serious experiments to research its mechanical and sensing properties. The monitoring results show that the mechanical properties of the smart strands are similar to ordinary strands, and its sensing properties include that distinguish-ability is less than 0.466% F•S, hysteresis less than 2.15% F•S, repeatability less than 1.32% F•S, linearity less than 0.86% F•S, and overall accuracy less than 2.67% F•S. Such kind of GFRP-FBG smart steel strand can be used for both structural and functional materials and applied in practical prestressed structure.

Parametric Drawing Based Optimal Design of Aqueduct Structure

In the optimal design of large prestressed aqueduct structure, the optimal design results need to be automatically drawn. In this paper, the parametric drawing method is proposed by combining high-level programming language FORTRAN and Auto LISP, and developed a designing system of mixed programming using FORTRAN and Auto LISP. The programming system is applied to the optimal design process of large prestressed aqueduct with rectangle and U-shaped cross-section. The optimal design result is automatically transformed into visual graphics (documents), therefore realized the automatic drawing. In this way, designers’ graphics labor intensity and repeated, complicated calculation can be reduced and the design cycle can shorten. Data files (*.DAT) and graphics files (*.LISP) can be generated not only by FORTRAN, but also by other high-level programming languages such as C++, VC etc.

Experiment Study on the Durability of Geotechnical Prestressed Anchorage Structure under Cyclic Loading

Based on the analysis of the pretension force influence factors for geotechnical prestressed anchorage cables that are used in a practical engineering, the cyclic loading characteristics of prestressed force long-term variation is revealed, and the conception of large and small cycles of prestressed force variety are also put forward. Based on these analysis, a device for the fatigue failure test and the corresponding test methods are manufactured and developed to analyze the durability problem of the inner bond section of prestressed anchorage structure under repetitive loading and cyclic loading. In the experiment, the means of indoor similar model test is adopted, in which the different loading scheme and loading amplitude were taken into account. According to the test results, the fatigue failure regularities of inner bond section for geotechnical prestressed anchorage structure are revealed.

Estimation Theory on Cable’s Diameter in Pre-Stressed Mega Brace and Steel Frame Structure

According to the superposition principle of building structure, the lateral deformation mode of pre-stressed mega bracing-steel frame structure was analyzed, then the relation between the structural maximum inter-story drift and cross section area of cable was further established. Based on the area of cable derived by the design target value of inter-story drift, the qualitative estimation theory on cross section area of the cable is finally determined.

Analysis Method of Secondary Moment in Prestressed Plane Structures

In prestressed plane structures, tensioning prestressing tendons in one direction will bring primary moment in another direction, so the method of calculating secondary moment by removing the primary moment from the resultant moment is not applicable for plane structures, in which the primary moment is calculated by prestressing force multiplying the distance from prestressing force to neutral axis of section. The reason for this method can not be used for calculating secondary moment in plane structures is analyzed. The method for calculating secondary moment in plane structures is presented.

Self-Balanced Prestressed Latticed Shell Structure and it's Research Development

Self-balanced prestressed shell structure assembled with elements is a new spatial system composed by prestressed cable and strut elements. The structure can achieve the latticed shell design that the large span without the center column by the rational use of high strength bars and prestressed technology. This paper illustrates the design idea, stress mechanism and structure characteristics of the self-balance prestressed latticed shell. The current research status of self-balanced prestressed shell structure assembled with elements on structure form, shaping method, static and dynamic performances are briefly described in the presented work; It is seen that the research on test of structure mechanical properties, molding technology and structure dynamic performance is an urgent work to be solved in the development of the self-balanced pre-stressed latticed shell structure theory.

Study on the Interface Mechanical Characteristic of Geotechnical Prestressed Anchorage Bolt under Step Loading by Model Test

The development and evolution regularity of the interface shear stress for the inner bond section of geotechnical prestressed anchorage structure is directly related to the ultimate bearing capacity and its long-term durability. By adopting the similar model test and embedding the strain brick at each interfaces of inner bond section, the interface mechanical properties under step loading were systematically studied. Conclusions can be drawn as follows: the interface shear stress along the axial direction of rod is not evenly distributed, and the interface distribution shape at different radial distance from the rod axis also varies. With the gradual increase of external load, the shear stress peak point continues to move into the deep areas, and resulting in the occurrence of gradual damage mode. In the process, the peak value of shear stress also augment gradually. Along radial direction of the rod, the shear stress concentration phenomenon just distributes within a small radius around the rod body. Adopting the two stage linear function to describe the relationship of shear stress and shear displacement at contact surface is suitable.

Study on External Prestressed Concrete-Filled Steel Tubular Flexural Member

According to good property of concrete-filled steel tubes(CFST) when they are subjected to compression load and their disadvantage to bending load. A new type of composite external prestressed concrete-filled steel tubular structure has been presented in this paper, which has the high tension strength of prestressed tendon and good anti-compression capacity of CFST. Based on the analysis of the mechanism, the flexural capacity of the structure can be greatly enhanced. And the criterion and method is given.