Vertical Connectors Research Articles

Development of Double Frame Method to improve the seismic performance of low-rise reinforced concrete buildings

ABSTRACT The current paper proposes a seismic reinforcement method that uses a double frame and is called the Double Frame Method (DFM). Performance tests are conducted to assess the material suitability of a post-installed anchor that directly connects the existing frame to the double frame, while a shear performance test is conducted to examine the vertical connector. The performance of column members with and without DFM reinforcement was compared and evaluated. Ultimately, we have fabricated a two-story, one-span reinforced concrete existing frame test specimen and a DFM reinforced frame test specimen that we can use to examine the effect of improving seismic performance through repeated loading tests. The result of the anchor’s pull-out test show that the average tensile strength is 27.9 kN, exceeding the average design strength of 21.7 kN suggested by the manufacturer. The shear strength test results of the anchor show an average value of 28.7 kN. Meanwhile, the vertical connector test show that the internal force per anchor is 46.83 kN, which is approximately 163% more than the single anchor design shear strength of 28.7 kN. As a result of the DFM-reinforced column test, in the actuator direction, the yield strength is improved by about 120%, while the maximum strength is improved by about 150–180%. As a result of the two-story frame experiment, the double frame reinforced specimen shows a maximum strength of about 4.0 to 4.5 times that of the non-seismic specimen.

Vertical Connectors in Ancient Monuments: Documentation and Experimental Study of the Behaviour of Iron and Titanium Connectors

ABSTRACT Ancient monuments are constructed following the dry construction system. Large dimensional structural members, with perfectly plane interfaces, are placed without mortar. Two types of iron connectors, vertical and horizontal, used to connect individual stone blocks, are activated in case of relative displacements, e.g. earthquakes. The paper focuses on, iron or titanium, vertical connectors, crossing the interfaces between successive stone courses, and investigates their seismic behaviour. In situ and bibliographical documentation of vertical connections in ancient Greek monuments, including their topology, dimensions, and typical pathology attributed to them, served as a basis for the design of an experimental program. First, specimens simulating the original connections are tested under monotonic and cyclic actions. The behaviour of those connections, effectuated using iron vertical connectors, having confirmed the pathology observed in situ, i.e. fracture of the substrate, an alternative connection was tested aiming at avoiding or significantly delaying the failure of the substrate (marble). An unbonded length was provided to the connector, close to the interface, to postpone the contact between the connector and the marble. The test results confirmed the anticipated change of behaviour, associated though with smaller shear resistance and larger displacements at its attainment than for the original connections.

Interconnect for Dense Electronically Scanned Antenna Array Using High-Speed Vertical Connector.

We present the design and the performance evaluation of a new interconnect for large-scale densely packed electronically scanned antenna arrays that utilize a high-speed digital board-to-board vertical connector. The application targets microwave tissue, imaging in the frequency range from 3 GHz to 8 GHz. The tissue-imaging arrays consist of hundreds of active antenna elements, which require low-reflection, low-loss, and low-crosstalk connections to their respective receiving and transmitting circuits. The small antenna size and the high array density preclude the use of coaxial connectors, which are also expensive and mechanically unreliable. Modern board-to-board high-speed connectors promise bandwidths as high as 12 GHz, along with high pin density, mechanical robustness, and low cost. However, their compatibility with the various transmission lines leading to/from the miniature printed antenna elements and microwave circuitry is not well studied. Here, we focus on the design of the transitions from coplanar waveguide transmission lines to/from a high-speed vertical connector. The performance of the interconnect is examined through electromagnetic simulations and measurements. Comparison is carried out with the expensive sub-miniature push-on sub-micro coaxial connectors commonly used in miniature radio-frequency electronics. The results demonstrate that high-speed vertical connectors can provide comparable performance in the UWB frequency range.

Development and Seismic Performance of Precast Concrete Shear Wall with Vertical Connectors Subjected to Cyclic Loading

ABSTRACT A precast shear wall with vertical connectors (PSWVC) is proposed, in which the wall panels are assembled through dampers at the vertical seams. Cyclic loading tests were conducted on two full-scale specimens with X-shaped metal dampers and lead viscoelastic dampers. Based on the test results, the better seismic performance of the wall panels with dampers was observed. In addition, a finite element analysis model of shear walls was proposed, and a parameter study was performed to investigate the seismic performance of the PSWVC. Simplified calculation methods were also proposed to predict the strength of shear walls.

Gating systems in the casting grinding balls technology

The article presents a number of experimental and research works on the development of parameters of the casting technology of grinding balls by casting in a lined coquille (chill mould) with a vertical connector. The influence of a multi-level gating system on the efficiency of filling the mold cavity of lined coquilles with melt, on the quality of crystallization of large grinding balls, as well as on increasing the output of suitable casting was revealed. The influence of the thickness of the facing layer on the crystallization of large grinding balls is studied. The effect of modifiers containing barium, magnesium and cerium on the physical and mechanical characteristics of grinding balls and separately cast samples is investigated. Technology has been developed to eliminate contraction cavity in cast grinding balls by enhancing direct crystallization by partially replacing the facing layer with a heat-resistant water coating. The equipment for large-lot production of high-quality large grinding balls developed by OJSC “BELNIILIT” and competitive to world analogs is proposed.

Investigation of the technological parameters of cored castings when in a lined coquille

The article presents a number of experimental and research works on the development of the parameters of the casting technology for castings with internal cavities formed by a sand rod, by casting in a lined coquille (chill mould) with a vertical connector. The influence of gating systems with a central riser and side risers on the thickness of the casting wall shedding and on the mechanical characteristics of the cast iron alloy, including ligatures, is revealed.

Refinement and testing of the mathematical model of heat and moisture transfer in envelope structures of profiled insulated timber with connectors

The account of dependence of moisture conductivity coefficient, thermal conductivity coefficient and heat capacity on temperature and moisture is the main peculiarity of the new physico-mathematical model of combined heat and moisture transfer in walls of low-rise wooden insulated timber buildings. This study is aimed at refining and testing such model, including preliminary evaluation of influence of moisture transfer processes on moisture accumulation in insulated timber structures with connectors at low outside temperatures. The study provides approximation dependences that illustrate variation in thermal characteristics of wooden structures made of timber, plywood and insulation. The results of numerical simulation of heat and mass transfer processes occurring in a representative wall fragment made of high-strength profiled timber are given. Temperature and moisture fields are calculated in a selected inhomogeneous fragment. Maximum humidification in insulated profiled timber walls is located on the external surface of the wall. It is found that the use of additional internal longitudinal lamellae in timber with vertical connectors leads to significantly uneven moisture distribution. Based on the calculation results one may conclude that the wall fragment under study has no areas where free moisture can be possibly accumulated.

Development of a novel friction damped joint for damage-plasticity control of precast concrete walls

The development of a novel friction damped joint (FDJ), which can be installed between two precast concrete walls as a type of vertical connector, is presented in this paper. The specially designed internal mechanism of the proposed FDJ can amplify the vertical slip displacement between precast concrete walls whilst dissipating energy at the same time. Meanwhile, the FDJ can provide enough lateral strength and stiffness to resist vertical slips induced by wind loads and earthquakes. After experimental and analytical studies on the FDJ parameters, the energy dissipated by the proposed FDJ is found to be independent of the excitation frequency. Subsequently, to study the effectiveness of the FDJ conveniently, a simplified numerical model is proposed. The simulation results indicate that, the main features of the FDJ can be captured by the simplified numerical model. To further illustrate the advantage of the FDJ when considering damage-plasticity control, simulated precast walls with different joints are analyzed under the lateral loading. The results show that the FDJ can consume a significant amount of energy, thus protecting the precast walls from damage. The FDJ plays a great role in reducing the plastic damage that may be sustained by the main structure.

A mechanical design model for steel and concrete composite members with web openings

In web opening regions, a significant share of the global shear force is redistributed from the perforated web of the steel beam to the reinforced concrete (RC) slab. This redistribution leads to vertical forces in the shear connectors close to both edges of the opening and influences the internal forces in the steel beam and the RC slab over a length of approximately three times the opening length a0. The global shear failure in the web opening region is affected by the rather brittle behavior of the concrete and is either characterized by a diagonal shear cracking failure of the RC slab, or a local bending failure at the opening edges, or vertical connector failure (concrete break-out) at the ends of the opening. This paper is intended to clarify the structural behavior of web opening regions and proposes easy-to-use models that make it possible to analyze the local internal forces of each partial beam in a mechanically consistent manner. Based on these models, a novel design procedure is presented, that allows efficient design and dimensioning of web openings as well as prediction of shear resistance and failure mode.

Evaluation of cyclic behaviour of special concentrically braced frames with built-up diagonal braces

ABSTRACT The built-up special concentrically braced frames (BSCBFs) containing double-angle and double-channel braces are among the common steel structural systems resisting lateral loads. In this paper, the parameters influencing the BSCBF seismic behaviours are investigated under cyclic loading. For this purpose, nonlinear finite element analyses of a single-bay single-story frame are employed, and the results show that increasing the number of stitches or decreasing their distances along the length of the built-up members may not necessarily improve the behaviour of the braced systems. That is, inelastic deformation concentration probably occurs in individual elements between stitches, resulting in earlier failure of braces. Moreover, the failure results of the built-up brace members display that the usage of vertical stitch connectors (parallel to the webs) should be avoided in all BSCBF systems in comparison with lateral-stitch braces (parallel to the flanges). In addition, the failure results of double-channel back-to-back BSCBFs are much better than those of similar face-to-face ones. The results of the double-angle diagonal braces also reveal that the failures of the back-to-back brace sections occur earlier in comparison with similar face-to-face or toe-to-toe braces.

Seismic Behavior of One-Storey Gabion-Box Walls Buildings

Gabion-boxes, made with steel wire mesh and filled with stones of appropriated size, are normally stacked up one into another to form a retaining wall. Given their reduced costs and the easy availability of their constituting materials, gabion-box walls have been extensively used in developing countries (such as Nepal) also to realize simple one-storey residential buildings. In recent years, many of these structures have been subjected to several strong earthquakes and have shown a good seismic behaviour, even if they have never been the object of a proper structural design. In the scientific literature, research studies have been developed on gabion-box walls used as retaining systems, but no investigations have been conducted on the performances of gabion-box walls buildings. In this respect, the general objective of this research work is to give a first insight into the static and seismic behaviour of such gabion-box walls buildings through analytical considerations and numerical models. In detail, with reference to a typical 5 m x 5 m plan model, this paper investigates the in-plane and out-of-plane seismic responses of its constituting walls, by means of simple analytical interpretations and Discrete Element Method (DEM) numerical simulations. Even if this study should be considered as a starting point and even if the fundamental cellular behaviour of the 3-dimensional structure has not been fully taken into account, some criticalities have been disclosed and the order of magnitude of the seismic activation load multipliers has been estimated. The out-of-plane collapse mechanism is characterised by multiplier around 0.15, whilst the in-plane mechanism multiplier depends on the position of the door in the single wall (0.10 – 0.20), but can be easily increased with lintel beams placement. The results are based on the assumptions taken by several authors and have not been verified with experimental tests. Nevertheless, some practical suggestions (basically in terms of spacing and construction details, such as vertical connectors and reinforcing steel knots) can be derived to improve the construction in order to ensure a better seismic behaviour.

Expansion of Parents' Undetermined Experience in Socioeducational Programs: Extending the Dialogical Self Theory.

The Dialogic Self Theory (DST-Hermans et al. Integrative Psychology and Behavioral Sciences, 51(4), 1-31, 2017) is extended here in its dynamic aspects through focusing on the notions of indeterminacy, emptiness and movement. Linking with Husserl, I propose moving the dialogical self (DS) from a clear position in the "repertory of the Self" to an undetermined horizon. This makes it possible to introduce "holes" (emptiness) into the schematic representation of the "repertory of the Self". Yet Husserl's concept of horizon seems to focus too much on making the indeterminable determinate. To overcome this limit, I incorporate Bergson's concept of empty form into the DST. This enables conceptualising the extension and emergence of horizon. Extending Bergson's concept of organisation, it is possible to see how the expansion of the horizon in a movement of globalisation does not necessarily entail the disorganisation of the DS but rather to its further organisation. Extending the system of DS by Hermans et al. Integrative Psychology and Behavioral Sciences, 51(4), 1-31, (2017), I open by suggesting that movements are both horizontal (between people) and vertical (between the person, the institutions and the norms) connectors. My conceptual propositions are illustrated by parents' and educators' discourses in two Canadian socio-educational programs.

Corrigendum: A novel mutation in EED associated with overgrowth.

Correction to: Journal of Human Genetics (2015) 60, 339–342; doi:10.1038/jhg.2015.26; published online 19 March 2015 Since the publication of the above article, the authors of the above paper have noticed an error in Figure 1. In the pedigree presented (Figure 1i), vertical connectors to individualsII-1 and II-2 were incorrectly omitted.

온도하중과 인양하중에 영향을 받는 모듈러 도로 슬래브 수직연결부의 상세해석

교량의 슬래브에 파손이 발생할 경우 슬래브의 보수보강을 위한 공사로 인해 차량 통행이 제한된다. 모듈러 교량의 경우 이러한 시간적 비용을 줄일 수 있는 방법으로서 많은 연구가 진행되고 있다. 본 연구에서는 연결부에 높은 응력이 발생하는 모듈러 도로 슬래브를 온도하중과 차량하중을 적용하여 구조해석을 실시하였으며 수직연결부 부근에 나선철근을 매입하여 그 성능을 확인하였다. 또한 인양 시의 모듈러 도로 슬래브의 거동 및 취약부분을 확인하기 위하여 인양하중을 적용한 구조해석을 실시하여 유리한 조건의 인양방법을 살펴보았다. 그 결과 온도하중에 의해 수직연결부가 항복하는 것이 확인되었으며, 나선 철근을 수직연결부 부분에 매립할 경우 인양 시에 구조물의 손상이 감소하는 것을 확인할 수 있었다. 또한 6개 수직연결부를 이용하여 인양할 시 3개 수직연결부 사용대비 50%의 응력을 감소시킬 수 있는 것으로 확인되었다.

Vertical Connector Performance of Modular Roadway Slab

This study investigated vertical connector performance of modular roadway slab. A modular roadway utilizes precast members of slabs and crossbeams under the slabs, and the connection between them is critical. The vertical connector has to resist horizontal loads and allow the thermal movements. In the preliminary study, two boundary conditions were investigated to identify the better vertical joint functionality. Based on the results, detailed analysis models were developed and displacements and internal forces of the vertical connector were investigated. The analysis results showed that for the given modular slab and developed vertical connector, the vertical connector provides better stability and functionality but required 80 kN of horizontal shear forces.

浮遊式海流発電装置の電力ケーブル荷重に関する研究

This paper discusses power cable loads for a floating ocean current turbine. The floating ocean current turbine is supposed to have unique motion characteristics, which causes unknown loads to the power cable. In this study, two severe situations and three candidates of cable configuration have been considered. In one of these situations, the cable shows unique motion due to bend & torsion moment. To confirm the accuracy of numerical calculation in this situation, calculation by two methods and an experiment are performed. In addition, theoretical analysis is performed to interpret the reason of the motion. The results show that the FEM analysis agrees well with the experiment, and that the cable motion is interpreted as energy shift from bending to torsion energy. Therefore, full scale calculation is performed using the FEM program. The results show that floater style with vertical connector is the most suitable cable configuration for the floating ocean current turbine and the maximum loads do not exceed 15% of allowable loads of the power cable even in the severe situations.

Shear tests on stone masonry walls with metal connectors

Many strengthening techniques for masonry structures have been thoroughly investigated in various studies. Nevertheless, there is still a lack of information on the shear effects of metal connectors used in historical masonry structures. This paper presents the investigation of the effectiveness of metal connectors in relation to the shear collapse mechanism of stone masonry walls. A series of 12 stone masonry walls with metal connectors and an unreinforced masonry reference wall were subjected to shear forces. The test parameters were the length and number of clamps (horizontal metal connectors), and number of dowels (vertical metal connectors). The performance of the different metal connector configurations was compared in terms of strength and mechanism of failure. The results clearly show the effectiveness of metal connectors on shear behaviour of stone masonry walls.

Installation Technology of Deepwater Vertical Collet Connector

Installation is the key technology of the deepwater vertical collet connectors. Based on thorough analysis of the existing installation technology and construction resources, combined with the technical features of installation used to connect different types of jumpers, new designs of vertical collet connectors installation for rigid jumpers and flexible jumpers are proposed in detail in this paper.

Development of wooden block shear wall – Improvement of stiffness by utilizing elements of densified wood

Abstract The objective of this research was to study the performance of a wooden block shear wall which utilizes compressed wood as a connecting element in place of the traditional metal connectors. The compressed wood was made by compressing Japanese cedar (Cryptomeria japonica) to a compression ratio of 63% without fixation treatment. The connecting elements, namely diamond keys (DKs), recover their radial compressed dimension when absorbing moisture. The expansion of the wood causes a tighter fit of the wood blocks, thereby improving the system stiffness. DKs work as fuses by absorbing most of the stress and damage. This allows the structure to be readjusted and reused after earthquakes. The wooden blocks are made of glued-laminated timber based on European red pine (Pinus sylvestris). The behavior of the wall was studied by means of a finite element method (FEM) and full-scale shear tests. The material properties were found by performing mechanical tests, using digital image analysis, and strain gauges to measure the strain. The stiffness of the wall and how it is affected by the DKs are described. The FEM provided predictions which are in agreement with experimental results of wood block wall systems. The addition of DKs increased the stiffness by up to 2.5-fold. Future improvement of FEM will include accounting for the contribution of vertical connectors and out-of-plane forces.

Reinforcement of Brick Walls Spanning Vertically

A vertical shear connector suitable for manufacture by automated sheet metal processes from steel coil is developed in an experimental program involving 90 small area bearing tests, 18 shear tests, and 6 tension tests. A comparison of three full‐scale wall panel tests (standard cavity wall, cavity wall with an unbonded steel mullion, and cavity wall with a vertical shear connector) demonstrate that the connector significantly increases both the post‐ and pre‐cracking strength and stiffness of a vertically spanning brick masonry cavity wall under out‐of‐plane loads.