Rigid Connection Research Articles

Multi-Story Volumetric Blocks Buildings with Lower Frame Floors

This article presents the results of experimental studies of the stress–strain state of volumetric blocks based on the underlying frame structures. The aim of the research is to evaluate the stress–strain state and the nature of damage development as a result of an increase in the load up to a critical level. Based on the analysis of the nature of the damage, recommendations have been developed to strengthen the destruction zone. Data were collected on the redistribution of stresses and deformations, the formation of cracks and joint openings, the magnitude of horizontal displacements, and the failure mode of volumetric blocks and floor frames. Five full-scale volumetric blocks were tested under the loading of hydraulic jacks, differing in concrete type, reinforcement, presence of doors, and dimensions of the stylobate beams. When the volumetric modules were supported by a frame floor the results revealed that the maximum destructive load of 10,462 kN was observed in the first specimen; the horizontal displacements of the walls decreased by 13–18 mm, and there was a decrease in the crack opening width to 0.5 mm. The cracks decreased the strength of the walls, leading to a redistribution of the compressive stresses and their increase in the support zone. The most significant compressive strains in concrete in the corner parts of longitudinal walls were in the range of (600–620) × 10−6, and in the middle part of the walls, 370 × 10−6 were observed. Furthermore, the largest cracks caused significant horizontal displacements (deplanation) of the walls, which decreased the stiffness of the conjunction of longitudinal walls with the floor slab and created an additional eccentricity of the vertical force. Based on the findings, the correlation between the measured parameters of each specimen at all stages of vertical load increase is demonstrated and illustrated in graphs of the measured parameters. The importance of quantity compliance with the initial rigid connection between the longitudinal wall and ceiling plate has been estimated.

A Vision-Based Bolt Looseness Detection Method for a Multi-Bolt Connection

Many vision-based bolt looseness detection methods that directly observe the bolts have been developed. However, these methods have many limitations in terms of the conditions and processes of their implementation. To address these problems, this paper proposed a fully automated vision-based bolt looseness detection method for a rigid multi-bolt connection. The proposed method combines digital shearing speckle pattern interferometry (DSSPI) and recurrent neural network (RNN) and involves capturing speckle fringe patterns under various looseness cases using the DSSPI system and classifying these patterns with an RNN model to detect the loose bolts. The proposed method can detect all the bolts within the measured surface at one time, which is efficient. On the other hand, it eliminates the need for prior information such as the initial angle and position of each bolt. It can even detect unseen bolts in multi-bolt connections, making it applicable for connections in complex structures in which occlusion often occurs. Additionally, the method eliminates the complex process of distortion rectification. These features make the method achieve a single-judgment time (four bolts at one detection) of only 4.70 millisecond with a detection accuracy over 99%, which has potential for the real-time detection of loose bolts in multi-bolt connections.

Shaking Table Tests and Numerical Analysis Conducted on an Aluminum Alloy Single-Layer Spherical Reticulated Shell with Fully Welded Connections

Aluminum alloy offers the advantages of being lightweight, high in strength, corrosion-resistant, and easy to process. It has a promising application prospect in large-span space structures, with its primary application form being single-layer reticulated shells. In this study, shaking table tests were conducted on a 1/25 scale aluminum alloy single-layer spherical reticulated shell structure. A finite element (FE) model of the reticulated shell structure was established in Ansys. Compared with the experimental results, the deviation in natural frequency, acceleration amplitude, and displacement amplitude was less than 20%, confirming the validity of the model. An extensive analysis of the various rise–span ratios and connection constraints of a single-layer spherical reticulated shell structure was carried out using the proposed FE model. The experimental and simulation results showed that as the rise–span ratio of the aluminum alloy reticulated shell increases, the natural frequency of the reticulated shell structure also increases while the dynamic performance decreases. The connection of the circumferential members changes from a rigid connection to a hinged connection. The natural frequency of the reticulated shell structure is reduced by about 40% while the acceleration and displacement response values are decreased by approximately 15%.

The effect of the pitch of the boards in the transverse layer on the deformability and stress distribution in a threelayer CLT panel rigidly clamped on both sides

CLT panels are made by gluing several layers of boards crosswise, which provides them with high load-bearing capacity and bending resistance. In addition to the number of layers in the panel, the deformability and bearing capacity are influenced by the geometric parameters of the plate, the way the layers are attached to each other, the way the structure is supported, etc. Due to the fact that the material has recently been used in construction, many issues remain poorly understood, and therefore there is an opportunity and need to optimize some aspects both in the CLT panels themselves and in the way they interact with other building structures.In this article, the influence of the pitch of boards in the transverse layer on the deformability and stress distribution in a three-layer CLT panel rigidly pinched on both sides was studied. Numerical studies of the finite element method (FEM) were carried out using the computing complex SCAD+. The computational model of the plate in this study is a composite orthotropic plate with rigid connections between the layers. The result of the study is numerical data reflecting the dependence of the distribution of normal stresses OX and OY and the transverse deformation of the plate on the pitch of the lamellae (boards) in the bottom layer. Projections of the computational model with normal stress isofields on the stretched and compressed plate layer are also obtained. This makes it possible to identify general patterns of stress distribution and deformation changes with variations in geometric parameters for this type of support for their use in the design of building structures using CLT panels as well as in the optimization of the structure in order to increase the cost efficiency of resources.

Design and architecture of a slender and flexible underwater robot

This paper presents the design and analysis of a biomimetic underwater snake-like robot, addressing the main limitations of current underwater robotic systems in terms of maneuverability and adaptability in complex environments. The innovative design incorporates flexible joint modules that significantly enhance the robot’s ability to navigate through narrow and irregular terrains, which is a notable limitation in traditional rigidly connected underwater robots. These flexible joints provide increased degrees of freedom and enable the robot to absorb and release energy, ensuring stability even under external impacts, thus extending the operational lifespan of the robot. Finite element analysis demonstrates the flexible joints’ superior performance in various underwater conditions, offering a greater range of motion and workspace compared to rigid connections. The results indicate that the robot’s modular design, combined with the flexible joint module, leads to improved agility and maneuverability, allowing for precise and intentional operation. The control module, equipped with advanced sensors and a CPU, manages the complex dynamics introduced by the flexible joints, ensuring effective navigation and operation. The specific advantages of this design include the robot’s enhanced structural integrity, its ability to conform to irregular surfaces, and its adaptability to environmental variations. The paper concludes with a discussion on the implications of these findings for the future design and operation of underwater serpentine robots, emphasizing the need for a balance between the effects of elastic modulus and workspace to maximize the benefits of flexible joints.

Evolution characteristics and performance evaluation of extended end-plate joints with single and double side connections under cyclic loading

Experimental studies were conducted on four extended end-plate joints subjected to cyclic loading at the column top, investigating the evolving patterns of the joints' mechanical performance. The paper provides a detailed analysis and discussion of the test joints' failure modes, ductility, stiffness degradation, and energy dissipation capacity. The Mann-Kendall (M − K) trend analysis tool was applied to the mechanical response curves, identifying key performance evolution points (evolution initiation point P and overall yield point Q). The trends in bolt forces, deformations, and strains at critical joints were effectively validated, revealing the transition of the energy system from quantitative to qualitative changes and the component's failure process from stability to instability. Additionally, based on the experimental joints' hysteresis curves and energy dissipation capacity, a theoretical hysteresis model was established to predict the joint's hysteresis curve and cumulative dissipated energy accurately. According to EC3 requirements, joints were classified as partially rigid connections. The experimental results of the initial rotational stiffness and plastic moment were further used to evaluate the calculated values in existing standards EN 1993-1-8, ANSI/AISC 358-16, and GB 51017-2017. The results indicate that extended end-plate connections possess sufficient strength, joint rotational stiffness, ductility, and energy dissipation capacity, making them suitable for seismic moment frames.

Taut cables with hanging masses: A metamaterial-like dynamic behavior

We inspect the dynamic behavior of suspended cables presenting a periodic array of scatter elements, consisting of a discrete set of masses that are hanging by means of elastic or rigid connections. By introducing some approximations, we show that the problem in the continuous domain can be brought back to an equivalent discrete problem, whose solutions depend on the variation of an effective mass. We find that the essential spectrum of the problem presents band gaps. By considering boundary conditions, eigenmodes can only be found at frequencies belonging to pass bands for the propagation problem of the unbounded system. This is no more true when a defect of periodicity is inserted, leading to the formation of localized modes. We provide a quantitative validation of these theoretical results by means of comparison with experimental tests.

Apico-aortic conduit: a readily available technical modification.

When neither surgical valve replacement nor transcatheter aortic valve implantation is possible, performing an apico-aortic conduit remains a therapeutic option. This procedure has become rare and the rigid angled apical connectors usually used to facilitate ventricular anastomosis are no longer commercially available. We described the technique that we performed on a 60-year-old patient with readily available material.

Seismic response analysis of single‐degree‐of‐freedom structure coupled with tuned self‐centering wall

AbstractThis paper investigates the possibility of using self‐centering walls (SCWs) as tuned mass dampers (TMDs) to control the seismic response of structures. The basic characteristics of this system are investigated using a two‐degree‐of‐freedom (2‐DOF) model, representing the main structure as a single‐degree‐of‐freedom (SDOF) oscillator interconnected with an SCW through viscous and elastic devices. The nonlinear equations of motion for the proposed coupled system are derived and then utilized to determine the displacement amplification response. The coupling parameters are optimized to minimize the dynamic response of the oscillator using a numerical method. A simulation study is conducted to investigate the response of the proposed system by considering six recorded earthquakes. Several parameters are studied, including the mass ratio, the influence of prestressing, and the slenderness angle of the wall. The displacement spectra are generated using the optimized parameters and compared to those of the uncoupled system and the traditional coupled system, which features a rigid connection between the structure and the wall. The results reveal that the proposed system effectively suppresses both maximum and root mean square responses of structures, outperforming the traditional coupled system in most cases. Improved performance for the proposed system can be achieved by increasing the wall's mass ratio and decreasing the slenderness angle. Moreover, prestressing has an adverse impact on the system's displacement response. Finally, the influence of wall flexibility is examined using a finite element model, revealing a minimal effect on the system's response.

Experimental investigation of the mechanical performance of novel rigid connections in prestressed circular composite precast concrete columns under cyclic lateral loading

The present study introduces an advanced design of Prestressed Circular Composite Precast Concrete Columns (PCCPCCs), which have been applied in real-world structures, equipped with two novel rigid connection types (i.e., the reinforcing-cage connection and the welded-plate connection) to address existing challenges in the design, construction, and quality control of traditional precast concrete (PC) columns. Five full-scale specimens were experimented individually to assess the mechanical performance of PCCPCCs subjected to cyclic lateral loading and constant axial loading. The results indicate that the specimens exhibited no signs of collapse or loss in axial load capacity during the tests. Furthermore, all specimens met or exceeded the performance criteria set by relevant standards, such as GB50011-2010 and ACI 374.1-05, regarding drift ratio, moment capacity, energy dissipation, and ductility. It demonstrates that the novel design of PCCPCCs proposed in this study can be integrated into practical construction projects designed as lateral-force-resisting systems, such as moment-resisting frames and bridges, to accommodate diverse construction project requirements.

Simplified Model Study of Autoclaved Aerated Concrete Masonry Flexible Connection Infilled Frames with Basalt Fiber Grating Strips

Infilled walls and frames typically employ closely spaced rigid connection, which, under seismic actions, can lead to adverse effects such as amplified seismic responses, overall torsion, and the formation of weak layers in the structure. Flexible connection isolating the infilled walls from the frames can effectively mitigate the adverse effects of rigid connections. In order to reduce the structural mass and seismic impacts, Autoclaved Aerated Concrete (AAC) masonry flexible connection infilled walls have been widely researched. However, most AAC masonry flexible connection infilled walls require complex process operations for AAC blocks, which is not conducive to practical applications in engineering. Therefore, an AAC flexible connection infilled wall with Basalt Fiber Grating (BFG) strips instead of steel bars, with simplified process operations, has been proposed. Existing finite element models for BFG strip-reinforced AAC masonry flexible connection infilled walls employ solid elements, which are difficult to apply to large-scale structural simulations; moreover, existing simplified models for flexible connection infilled walls cannot simulate out-of-plane loading. In this paper, based on homogenization methods, using simplified elements to simulate components, a simplified model for the BFG strip-reinforced AAC masonry flexible connection infilled frame is proposed. Utilizing this model, stress analyses under both in-plane and out-of-plane loading are conducted and compared with corresponding experimental results. The results indicate that the in-plane simplified model (ISM) fits well with the experimental results in terms of hysteresis curves, with similar relationships between stiffness degradation and strength attenuation. The displacement force curve of the out-of-plane simplified model (OSM) before reaching the peak load is in good agreement with the experimental results. The maximum plastic range of OSM is 5% smaller than the test results, and it can be considered that the plastic ranges of the two are comparable, manifesting the models’ capability to adequately manifest arching behavior. The simplified model enables simulation of out-of-plane loading and provides a new approach for modeling large-scale frame structures with flexible connection infilled wall.

On the physical rigidity of Frenkel-Gross connection

On the physical rigidity of Frenkel-Gross connection

How to Obtain High Load-Bearing Al-Cu Joints by Nanoscale Sculpturing

The electrochemical formation of high-mechanical-load-bearing Al-Cu joints and their characterization is presented in this paper. These Al-Cu joints rely on the mechanical interlocking between the Al and Cu layer obtained by nanoscale sculpturing of the Al joint partner, resulting in a hierarchical surface structure. The structure consists of cubes of various sizes acting like hooks. When enclosed by Cu the cubic Al hooks establish a rigid connection between the Al and Cu joint partners. In addition, the hierarchical cubic Al structures allow for a gradual transition from Al to Cu in the Al-Cu joint. Therefore, such Al-Cu joints exhibit an extraordinary load carrying ability compared to other Al-Cu joints.

Fluid inerter-based vibration control of multi-modal structures subjected to vertical vibration

The so-called inerter is an attracting device that offers a solution to the goal of realizing or improving structural control devices with high mass ratios while avoiding the undesirable increase in dead load. The research presented here focuses on evaluating the performance of a fluid inerter in mitigating vertical vibrations of structures that exhibit multi-modal behavior, such as plates. First, a numerical study based on previous experimental data investigates the properties of the connection between the inerter and the structure to be controlled. Considering that a flexible connection has been shown to introduce a linearization effect, while a rigid connection of the inerter to the controlled structure can achieve significant displacement reductions, the influence of these two connection types over different inertance ratios is analyzed. To evaluate the practical suitability of the flexible connection to reduce the inherent nonlinear effects associated with the device, a novel application of the fluid inerter for vibration control in multi-modal structures is presented, exemplified by a cross-laminated timber panel, and compares its control performance with that of a conventional Tuned Mass Damper (TMD). This provides insight into the effectiveness of the inerter in controlling vertical vibrations. In addition, optimization procedures are employed to determine connection parameters that enhance the effectiveness of both the TMD and the inerter in mitigating vertical vibrations.

Influence of unsupported sleepers on flange climb derailment of two freight wagons

Abstract Two freight platform wagons connected together conventionally or in the form of so-called rigid connection were taken into account to investigate the influence of unsupported sleepers on climb flange derailment on transition curve. Presented results are related to the freight wagons equipped with two-axle Y25 standard bogies, entering at an acceptable speed in the transition curve of the track with the radius of 150 or 1,000 m. Three cases have been analyzed: only the inner rail, only the outer rail, or both rails had unsupported sleepers. Simulation models were prepared using the VI-Rail software and nonlinear wheel–rail contact model. The dynamic calculations showed that wheel flange climb derailment caused by unsupported sleepers will only occur if deflection of the rail or track on transition curve is deep enough. These tests allowed us to determine the relationship between the radius of curvature and the depth of the trough causing derailment of the wagons. Calculation results allowed us to answer also the questions whether the method of connection and the weight of freight wagons have a significant impact on the wheel flange climb derailment.

Pretended antinomy of historical experience: To the G.-G. Gadamer and F.R. Ankersmit interpretations of the historical experience concept

The article is devoted to the analysis of the phenomenon of historical experience in Gadamer's hermeneutics and Ankersmit's philosophical-historical concept. The interest of the philosophy of history in experience was actualized against the background of exhaustion of the heuristic potential of historical narrativism and constructivism, closely related to the so-called "linguistic turn". At first glance, Gadamer and Ankersmit are representing antinomic interpretations of historical experience: as mediated by the effects of involvement in a tradition or heritage and direct, extracontextual encounter with the past. However, the investigation proves that, despite the apparent antinomy of these approaches, the Gadamerian hermeneutic experience as an experience of the prevailing historical reality is not so far from the sublime historical experience of Ankersmit. And, on the contrary, the sublime historical experience, despite its claims to immediacy, turns out to be an experience of the finitude of human existence, that is, it is close to what Gadamer considered the essence of hermeneutic experience. In both cases, historical experience is considered as a condition for the possibility of understanding the past, and therefore, the question of the universal structure of such experience and understanding necessarily arises. The differences in the positions of the two authors stem from fundamentally different ontological prejudices that they share. For Gadamer, this is the reduction of history to a linguistically structured heritage, as a result of which most of the past falls out of hermeneutic experience. For Ankersmit, this is an uncritical understanding of time, as a result of which his concept of the sublime does not receive a reliable methodological foundation. Clarification of the temporality of the sublime historical, as well as rejection of the rigid connection between historical experience and language, open the prospect of removing the abstract antinomy of contextuality and immediacy of historical experience. The temporality of human existence turns out to be a universal prerequisite of historical experience, the two opposite forms of which are heredity and discontinuity. Contrary to the widespread criticism of Ankersmit's theory as far from historiographical practice, the development of the potential of the concept of sublime historical experience reveals its relevance to the dynamic and tragic modern history that Ukraine is currently experiencing.

Rigid Frame Structure Analysis of Wyndham Hotel Building Palembang

A building that is sturdy, strong, secure, and effective must be designed according to building criteria from all structrural components, starting from columns, beams, floor plates, stairs, foundation, excavations, and basement structures. To build quality that meets the criteria from all aspects. Especially the building under study is a high level building that uses a rigid frame structure where the structure is a rigid connection that connect horizontal beams as well as vertical columns then connected to a plane. And all of this works together so that it is likely that this building meets the criteria for multi-story buildings and guarantees the strength of the building structure to meet its functional aspects.

Парадигмальная соотнесенность методов обучения в современной педагогике высшего образования

The aim of the study is to identify and systematize the paradigmatic correlation of teaching methods for practical use by modern educators in universities. The article identifies and examines the prevailing pedagogical paradigms in the contemporary educational environment, specifically the technocratic, person-centered, and competency-based paradigms. It describes the characteristics of modern teaching methods in relation to pedagogical paradigms and provides recommendations to university teachers on consciously choosing instructional constructs for the educational process. The scientific novelty of the research lies in attempting for the first time to systematize and logically structure the correlation of teaching methods used by i university teachers with modern pedagogical paradigms. As a result of the study, more or less rigid paradigmatic connections of modern instructional constructs have been identified, with some teaching methods being "linked" to one paradigm, while others are associated with two pedagogical paradigms.

Computational Modelling of Intra-Module Connections and Their Influence on the Robustness of a Steel Corner-Supported Volumetric Module

This paper investigates the robustness of a single 3D volumetric corner-supported module made of square hollow-section (SHS) columns. Typically, the moment–rotation (M-θ) behaviour of connections within the module (intra-module) is assumed to be fully rigid rather than semi-rigid, resulting in inaccurate assessment (i.e., overestimated vertical stiffness) during extreme loading events, such as progressive collapse. The intra-module connections are not capable of rigidly transferring the moment from the beams to the SHS columns. In this paper, a computationally intensive shell element model (SEM) of the module frame is created. The M-θ relationship of the intra-module connections in the SEM is firstly validated against test results by others and then replicated in a new simplified phenomenological beam element model (BEM), using nonlinear spring elements to capture the M-θ relationship. Comparing the structural behaviour of the SEM and BEM, under notional support removal, shows that the proposed BEM with semi-rigid connections (SR-BEM) agrees well with the validated SEM and requires substantially lower modelling time (98.7% lower) and computational effort (97.4% less RAM). When compared to a BEM with the typically modelled fully rigid intra-module connections (FR-BEM), the vertical displacement in the SR-BEM is at least 16% higher. The results demonstrate the importance of an accurate assessment of framing rotational stiffness and the benefits of a computationally efficient model.

Optimization of the Mechanical Properties of Bolted Connections between Concrete-Filled Tubular Columns and Steel Beam with Reinforcing Rings

To study the mechanical performance of bolted connections with different structural forms of reinforced rings, based on the results of monotonic loading tests on two bolted connections between a concrete-filled steel tubular column and a steel beam with an outer reinforcing ring, this article uses ABAQUS v.2020 software to establish a three-dimensional refined finite element analysis model of such connections using appropriate constitutive models for concrete and steel. Subsequently, the effect of the dimensions of the steel beam, reinforcing ring, and cover plate on the load-bearing properties and the failure mechanism of the connections is investigated, and the numerical model is consistent with the verification test results. Then, the numerical simulations comparing bolted exterior reinforced rings under seven different construction measures (i.e., number of bolts, stiffeners) based on a conventional welded exterior reinforced rings with rigid connections (i.e., CGJ) are standardized. The research results indicate that when four rows of bolts are introduced on exterior reinforced rings, the web of steel beam is welded with stiffeners, and the top and bottom reinforced rings are also added with stiffeners; this bolted connection with an external reinforcing ring (i.e., GZ-7) can achieve the rigidity and load-bearing capacity of a fully welded external reinforcing ring rigid connection. At the same time, the reinforcing ring plate is bolted to the flange of the steel beam, and the force transmission path at the connection is changed to avoid the brittle fracture easily caused by the welded flange joints. It is also in line with the development trend of sustainable construction of “assembly” and “disassembly”.