High-strength Cables Research Articles

Product Development to Improve and Automate Orchard Fruit Handling

In transporting field fruits to the packing house, physical damage to the product can occur, especially if the facility is far from the orchard and needs proper traffic conditions. This study aimed to develop a solution to enhance the transportation of fruits from orchards to packing houses in the São Francisco Valley, Bahia properties. The method comprised the following steps: (1) System Definition; (2) Translation of Needs into Requirements; and (3) Generation and Detailing of Concepts. The proposed solution involves an innovative aerial transportationsystem utilizing high-strength cables and containers for moving fruits, eliminating the necessity for roads or other conventional means of transportation. This solution can potentially advance knowledge in the field and be implemented in similar contexts.

The Anti-Impact Characteristics of Cables under Impact Load

The cable plays a vital role in roadway support. As the last barrier to prevent roof collapse and impact disaster accidents, it is of great significance to study stress characteristics of cables under impact dynamic load to guide the rock burst roadway support. With high-strength cables of Φ21.6 and Φ21.8 mm and low-resistance high-extension cables of Φ21.5 mm as examples, this paper studied the instantaneous mechanical state and energy dissipation characteristics of different types of cables under impact loads by using impact testing machines and high-frequency data acquisition system. The results show that the impact process can strengthen the strength of the cable. The strength and elongation of anchor cables are a pair of characteristic indexes with an inverse relationship. Simply increasing one index cannot improve the overall impact resistance of the cable. To quantitatively characterize the impact resistance and energy absorption effect of cables, the impact resistance index k was introduced. The smaller the index, the better the energy absorption effect of cables. In the process of dynamic load impact of high-strength cable, about 43.7% of the total energy is dissipated disordered in the form of mechanical energy. The dynamic load impact process of low-resistance and high-extension cables is similar to the viscoelastic impact. In the collision compaction stage, the force of the cable is basically constant. Most of the impact energy is absorbed or transformed by the cable, about 17.7% of which is mostly dissipated in the form of mechanical energy. The disordered dissipated mechanical energy is less, so the impact resistance and energy absorption effect of this cable are better. The cable plays an important role in the process of bearing the dynamic load of surrounding rock. The anti-impact performance index of cables should be considered in dynamic load impact roadway support design.

Resiliency and post‐earthquake realignment

SummaryAlthough the mechanics of free‐standing rocking cores have been amply investigated and that numerous replaceable energy dissipating devices with recentring capabilities have been proposed, the literature on complete sustainable earthquake resistant structures has not been fully developed. Seismic sustainability (SS) can be achieved if and only if the structure is capable of collapse prevention (CP) and/or post‐earthquake realignment and repairs (PERR). Rigid rocking core moment frame (RRC‐MF) combinations are special earthquake resistant structures that are capable of damage control, elimination of residual effects, CP, and PERR. High strength cables are commonly utilized as rocking core stabilizers, gap opening and closing regulators as well as energy absorbing devices. RRCs are articulated shear walls developed to reduce relative drift and seismic demand on earthquake‐resistant structures (ERSs), prevent plastic collapse, and help realign the system as needed. After discussing sustainable seismic design (SSD), the mechanics of hybrid rocking–stepping cores and self‐centering steel beams are briefly examined. The following innovations are introduced as part of the current article: (1) introduction to global stiffness reduction (GSR), (2) introduction to restoring force adjustment (RFA), (3) the hybrid rigid rocking–stepping core (RRC), (4) tendon‐enhanced replaceable energy dissipating moment connections (REDMCs), and (5) the heat‐generated realignment system.

Performance of prestressed T-type self-centering energy-dissipation brace

In this study, high-strength cables were used to create a prestressed T-type self-centering energy-dissipation brace (PTSEB), which can be used for multi-story and high-rise frame structures. The brace can dissipate energy through friction, provide lateral stiffness through prestressed cables, and automatically return to its original position under the action of cable tension after the external load disappears. Lever action is used to significantly amplify the deformation ability of the brace. Moreover, the energy-dissipation ability of the brace is considerably better than that of a traditional self-centering brace. A test and a finite element analysis were performed on the PTSEB, and the results indicated that the brace had a strong energy-dissipation ability, as well as a high deformation capacity and self-centering capacity. ABAQUS was used to analyze and compare the performance of braces with different sizes. The results showed that in a certain range, as the shell height increased, the seismic performance of the PTSEB was improved significantly; however, an increase in the shell width did not improve the seismic performance of the PTSEB significantly. Reasonable sizes for the PTSEB were proposed based on a finite element parameter analysis to ensure that the brace would have improved energy-dissipation and self-centering abilities. A restoring force model of the PTSEB was constructed, and the key points of the restoring force model were obtained using some proposed formulas. The design parameters of the PTSEB could be determined based on these formulas.

Mathematical modeling of deformation of pre-stressed steel trusses taking into consideration the possibility of emergencies

An algorithm of finite-element modeling has been developed in a geometrically non-linear setting of steel plane trusses which are pre-stressed using high strength cables, in the event of emergency in the form of single cable breakage. The application of framework gravity forces, consecutive introduction of tie bars and their pre-stressing, application of running load and emergency impact have all been monitored. Herewith, the condition of static loading using the dynamic relaxation method has been simulated. A factor taken into consideration is non-linearity associated with the inclusion of new cables into the framework, analysing the possibility of their behaviour strictly under tension, and removal of a cable from the loading system in the event of its breakage. The problem has been solved using numerical integration based on the development of the Newmark method via deriving equations of equilibrium of a discretised structure in the deformation state during each step of integration. The operability of the suggested algorithm is illustrated by the example of a steel truss with a span of 60 m, including two cables. The dynamic behaviour of an object is considered at a sudden breakage of the pre-stressed cable.

Study on Mechanics Performance of Suspension Bridge with 1960 MPa Cable Wire

In suspension bridge, the main cable is the major bearing member, instead of the 1770MPa cable wire normally adopted in current design, the application of cable wire strengths up to 1960MPa can lighten the dead weight, reduce the size of tower and anchorage, and shorten the construction period, obtain economical design. In this paper, a under-construction suspension bridge with span of 1688m is taken as a case-study, Comparative analyses are performed mainly focusing on basic parameters, carrying efficiency of main cable, static behavior and dynamic properties as different high strength cable are adopted in this suspension bridge. The results show that compared with 1770MPa main cable, using 1960MPa main cable in suspension bridge is benefit for improving the carrying efficiency of main cable, the steel consumption is also saved by 13%, but the vertical stiffness of the structure is reduced partly; the changes of main cable slightly affect the natural vibration frequency of girder, but have greater influences on vibration of main cable.

Study on the Effect of Prestress to the Dynamic Characteristics of Truss String Structure

Truss string structure (TSS) is a new type of large-span space structure which is composed of upper spatial truss and bottom high-strength cables with vertical supports. For certain upper truss, the main affect factor of dynamic characteristics of a TSS are prestress of the cables, pole number, rise-span ratio and vertical span ratio. In modal parameters, modal frequencies is the most direct and easily observed parameter, which largely reflects the stiffness of the structure and plays an important role in the dynamic response of the structure. In this paper, the mode testing experiment and finite element analysis is executed, to study the changes of the lower modal frequencies in different prestressed cables and to study the influence of the prestress to the dynamic properties of TSS.

Self-assembly of carbon nanotubes and boron nitride nanotubes into coaxial structures

Coaxial carbon nanotube/boron nitride nanotube (CNT/BNNT) multi-walled structures are ideal components in nanoelectronic systems. Our molecular dynamics simulations show that separate CNTs and BNNTs can self-assemble into stable coaxial structures in water under appropriate conditions. In case study three types of representative coaxial structures: (5, 5) CNT/(10, 10) BNNT, (5, 5) BNNT/(10, 10) CNT and (5, 5) BNNT/(10, 10) BNNT are obtained. Simulation results also reveal that the self-assembly time between two separate BNNTs is increased remarkably due to the polarization of BNNTs in water. The mechanism of self-assembly among these tubes is demonstrated in detail. Further, coaxial (10, 10) BNNT/(10, 10) CNT/(15, 15) BNNT nanoheterojunctions are achieved for potential application in nanoelectronic systems. The present work shows the feasibility to fabricate the coaxial nanodevices such as insulating high-strength cables, high frequency oscillators and nanojunctions using self-assembly approach.

Parametric study of truss bridges by the post-tensioning method

The post-tensioning method has been successfully used to improve the performance of existing concrete structures. Applications of the method are rare in steel structures, however. Post-tensioning using high-strength cables or bars can be effectively used to increase the working load carrying capacity of steel structures. In this paper, the elastic behavior of post-tensioned trusses with straight and draped tendon profiles for truss strengthening is examined. The effects of design parameters such as the tendon profile, truss type, prestressing force, and tendon eccentricity on working load and deflection of trusses are studied. The results show that the allowable load of a truss increases proportionally with the increase in prestressing force and eccentricity. Post-tensioning enlarges the elastic range, increases the redundancy, and reduces the deflection and member stresses, eventually increasing the load-carrying capacity of truss bridges.Key words: post-tensioning method, steel structures, post-tensioned trusses, truss strengthening, design parameters, load-carrying capacity.

Quality of high-strength cables of steel U10A made by different processes

To study the effect of the purity of the charge materials and refining processes on the properties of high-strength wires and cables made of steel UIOA, the Zlatoust ~letallurgical Plant made this steel by the following methods: I) In an open-hearth furnace on a normal charge by the scrap process; 2) by the scrap process, with treatment of the steel in the ladle with synthetic slag (SS); 3) on a semifinished product (100% pig), with ladle treatment of the steel with SS; 4) on a semifinished product treated with SS, with treatment of the steel in the ladle with SS as well; 5) by the electroslag remelting method (ESR); 6) by double ESR; 7) by the vacuum-arc-remelting method (VAR); 8) by combination refining (ESR + VAR).

A Prestressed Composite Girder for Short Span Bridges

During the last two decades, a great deal of research has been done on various types of girders for bridges—namely, prestressed steel girders, composite steel girders, prestressed concrete composite girders, and prestressed steel composite girders. The prestressing of a steel girder (plate or lattice girder) can be achieved by using prestressed high strength steel cables anchored at the bottom flange of the girder. Composite construction has successfully been substituted for noncomposite construction in bridges and buildings since the 1950s. Prestressed composite design is similar to conventional composite design except that the composite girders are prestressed by means of high strength cables after the concrete has reached its required strength. The analysis of composite steel girders prestressed by using high strength cables before the concrete slab is cast has been discussed by Hoadley9 and by Reagan and Krahl. These studies show that the use of high strength cables for prestressing is not as effective as the addition of a cover plate in conventional composite design for working stress. However, prestressed composite beams of this type have been used both for bridge and for building construction.