Connection Configurations Research Articles

Исследование структурно-функциональной надежности системы управления движением и навигации малого космического аппарата в условиях многорежимности ее функционирования

In the course of the design, creation and application of complex multi-mode systems, which undoubtedly include the motion control system of small spacecraft for remote sensing of the Earth, when choosing the configuration of elements and connections between them, as well as the parameters of the system, it is advisable to explore the possibilities of using dynamic operation modes significantly affecting the structural and functional reliability of the system. Based on the new original concept of the parametric genome of the complex multi-mode object structure, introduced by the authors, the article describes the results of the studies of the influence of various options for activating the modes of operation on the structural and functional reliability of the motion control and navigation system of the small spacecraft “Aist-2D”. To assess the structural and functional reliability of the system under study integral indicators have been introduced. At the same time, the possibility of involving joint activation of the modes of operation, the equivalence of the intensities of utilizing the activation of the modes of operation and the homogeneity of the traffic control system were taken into account.

Dynamic response of monolithic and precast concrete joint with wet connections under impact loads

Precast concrete (PC) structures have been popularly used in construction practice and PC beam-column joints are critical for structural integrity and safety. In this study, dynamic responses of one monolithic reinforced concrete (RC) joint and three PC joints with different wet connection configurations were investigated by using a pendulum impact test system. The impact behaviours of monolithic RC and PC joints were examined and compared in terms of failure modes, dynamic responses, and energy dissipation. The effects of various wet connection configurations on the dynamic response of PC joints were discussed and analysed. It is found that the interface damage between PC beam and joint led to the reduced integrity of the PC joints. In addition, numerical models of beam-column joints were developed by using software LS-DYNA and calibrated by the test data. The calibrated numerical model was used to investigate the influences of various wet joint configurations on its performance subjected to impact at different locations. Numerical results showed that the shear key and interface rebar employed for wet connections were beneficial to resist shear-governed damage but less effective in resisting flexural-governed damage induced by impact loads. Therefore, the wet connections should be properly designed for PC joint to resist the designated impact loading scenarios.

Tools for Describing the Communicative Space of Scientific Schools

To manage research activities, it is necessary to develop up-to-date tools that allow to quickly and efficiently assess the effectiveness of the scientific space functioning. Contradictions between the new industry of scientific communication and traditional forms of preserving and multiplying intellectual capital have become more acute, new points of interaction between the institutional structures of science (scientific schools, “invisible colleges”, expert and experimental (real and virtual) laboratories, etc.) have appeared. The concepts of the cultural codes of representation and translation of the subjects (individual and collective) of scientific communication have changed, and there is a need to update the requirements for the culture of their identification and positioning in the age of digital technologies. A scientific school is a multi-purpose collective that simultaneously implements the functions of production, dissemination, protection of scientific knowledge and reproduction of scientists. The cultural traditions of its functioning, as well as the cultural norms of institutionalization, are being transformed.On the material of bibliographic description of the genesis and development of the cultural studies school of the Southern Urals (centered in the Chelyabinsk State Institute of Culture), the article shows opportunities for scientometric and informational analyses. The author offers to discuss and use two bibliographic publications (the catalog of the scientific school and the bibliographic navigator, which include information about research topics, successful scholars, scientific leaders, postgraduate students and applicants, opponents, leading organizations of the communicative field of cultural studies of the Southern Urals), as well as cultural researchers’ landmark publications, innovatively identified by the method of introspection. The publications are reviewed as tools in the system of cultural studies of the scientific school positioning.The article draws conclusions based on the study and comparison of the configurations of connections between persons (academic advisor, postgraduate student, opponent), leading organizations and scientific leaders and their geolocation, subject headings: “applicant — academic advisor — opponent”, “subject heading/topic — leading organization — opponent, specialty number”, etc. These connections are individual for the related concepts: “management — coordination”, “interpretation of a communicative challenge — adequacy of a communicative response”, “practical meaning — purpose of communication”. These areas of analysis of the scientific school functioning provide a vision of the scientific interaction communicative fields’ intersection, the increment and examination of scientific knowledge, the basis for making managerial decisions to organize science.

Geometric forming and mechanical performance of reciprocal frame structures assembled using fibre reinforced composites

Reciprocal frame (RF) structures were developed in this work using pultruded glass fibre reinforced polymer (GFRP) members and the formulation of mathematical model for geometric forming and capacity design of such structures were presented. Firstly, governing geometric relationships are identified for the height, span and slope of the RF structure and its overall geometry can be formed accordingly. Once the geometry is determined, the structure can be analysed to calculate the internal forces of each component and connections under given loads. GFRP pultruded members were used to assemble the RF structure due to their high strength and lightweight. Considering the closed shape of the tubular section and the anisotropy of the materials, an innovative connection configuration was developed to facilitate the assembly and minimise the requirement of tools in the construction. Both the conceptual design and modelling analysis are supported with experimental results at connection and structural levels. The load-drift relationships of the connections were experimentally examined. Subsequently, A GFRP reciprocal frame structure was then assembled with a span of 4.5 m and subjected to multi-point bending to verify the proposed evaluation method and to study its mechanical performance. Verified by experimental results, a two-dimensional numerical model of the RF structure was developed and analysed using the finite element (FE) approach where different structural boundary conditions and connection stiffnesses were discussed. Finally, the geometrical nonlinear analysis was also studied for the structure through FE modelling.

New Technique to Improve the Ductility of Steel Beam to Column Bolted Connections: A Numerical Investigation

A novel method to improve the robustness of steel end plate connections is presented in this paper. Existing commonly adopted techniques alter the stiffness of the beam or the end plate to improve the connection’s robustness. In this study, the robustness is enhanced by improving the contribution of the bolts to the rotational capacity of connections; the higher the bolts’ elongation, the higher the rotational capacity that can be achieved. However, the brittleness of the bolt material, combined with its small length, results in negligible elongation. Alternatively, the load path between the end plate and the bolts can be interrupted with a ductile element to achieve the required elongation. This can be achieved by inserting a steel sleeve with a designated length, thickness, and wall curvature between the end plate and the washer. The proposed sleeve should be designed so that its ultimate capacity is less than the force in the bolt at failure; accordingly, the sleeve develops a severe bending deformation before the failure of any connection components. Using a validated finite element model, end plate connections with various parameters are numerically investigated to understand the performance of the sleeve device. The proposed system substantially enhances the rotational capacity of the connections, ranging between 1.37 and 2.46 times that of the standard connection. It is also concluded that the sleeved connections exhibit a consistent elastic response with the standard connections, indicating the proposed system is compatible with codified elastic design approaches without modification. Furthermore, for a specific connection, various ductile responses can be achieved without altering the connection capacity nor configuration.

Dynamic connectivity predicts acute motor impairment and recovery post-stroke.

Thorough assessment of cerebral dysfunction after acute lesions is paramount to optimize predicting clinical outcomes. We here built random forest classifier-based prediction models of acute motor impairment and recovery post-stroke. Predictions relied on structural and resting-state fMRI data from 54 stroke patients scanned within the first days of symptom onset. Functional connectivity was estimated via static and dynamic approaches. Motor performance was phenotyped in the acute phase and 6 months later. A model based on the time spent in specific dynamic connectivity configurations achieved the best discrimination between patients with and without motor impairments (out-of-sample area under the curve, 95% confidence interval: 0.67 ± 0.01). In contrast, patients with moderate-to-severe impairments could be differentiated from patients with mild deficits using a model based on the variability of dynamic connectivity (0.83 ± 0.01). Here, the variability of the connectivity between ipsilesional sensorimotor cortex and putamen discriminated the most between patients. Finally, motor recovery was best predicted by the time spent in specific connectivity configurations (0.89 ± 0.01) in combination with the initial impairment. Here, better recovery was linked to a shorter time spent in a functionally integrated configuration. Dynamic connectivity-derived parameters constitute potent predictors of acute impairment and recovery, which, in the future, might inform personalized therapy regimens to promote stroke recovery.

Comparative performance evaluation of the mechanical and adsorption hybrid cooling systems for the cascaded and the serial connected evaporators configurations

The goal of this study is to investigate comparatively the performance of an integrated cooling system comprised of an adsorption cooling cycle (ADC) and a vapor cooling cycle (VCC) with two different configurations, namely (cascaded and serial connected evaporators). The ADC chiller relies on the thermal compressor with two adsorption beds, which use three different adsorbents (RD silica gel, RD silica gel 2060, and silica gel- LiCl) and water (adsorbate) as a working pair separately. The thermal compressor operates by outside waste or solar-based thermal sources that have low-level temperatures below 100 °C. R152A was selected for the VCC chiller. This article pays particular attention to evaluating the ADC adsorbents and (ADC-VCC) connection configurations based on the first and second law of thermodynamics. The investigations have been implemented at different ADC evaporator temperatures. The effect of adsorption cycle time and ambient temperature on the overall coefficient of performance were also investigated and discussed for both configurations. Furthermore, the ADC and VCC coefficient of performances and the performance ratio (PR) were investigated at different ADC evaporator temperatures. The relation between the adsorbent mass and the cooling load was also discussed in this paper.

Qalification assessment practices: new possibilities and constraints

Introduction. The transformation of the educational system and the labour market determines the need for objective procedures for independent assessment of qualifications that meet the needs of all stakeholders. The need to overcome the qualification gap is becoming more acute, and it is necessary to change the configuration of connections and relationships in the process of qualifications assessment, which determines the relevance of the current research.Aim. The present publication is aimed to analyse social processes related to the development of practices for evaluating qualifications obtained in both formal and non-formal education in Russia.Methodology and research methods. The methodological framework of the research is based on the principles of the activity approach and the concept of structuration, in which the practice of qualifications assessment is viewed as a combination of social relations between individual and collective actors in the space of social and labour relations. Data collection and analysis was carried out using a qualitative methodology of the sociological approach. A semi-formal interview was selected as the method of expert survey. Twenty-four experts from various sectors of the economy (Moscow, Ekaterinburg and Tyumen) took part in the interviews.Results and scientific novelty. The possibilities and constraints of existing practices for qualifications assessment were identified: assessment centres, qualification assessment centres, internal certification, professional evaluation of working professions within the framework of the “WorldSkills” programme in Russia. The analysis of international experience is presented. Based on expert assessments, it was established that practices specific to the industrial model of the economy prevail in Russia. Thus, the infrastructure and regulatory field were established for the development of new practices of independent qualification assessment. However, the main participants of the process are not involved enough in mutual interaction. The primary sector of the economy hinders the development of the high-technology manufacturing industry and the employers who are interested in creating a competency framework. According to experts, the importance of non-formal education in the development of relevant competencies is increasing, and new mechanisms for qualifications assessment obtained in both formal and informal training are required. The authors presented the cases, which illustrate new configurations of participants’ relationships, when independent assessment of qualifications is integrated with the formal educational system at the stage of state final certification, ensuring the interrelated procedures. The article reveals the contradictions, which are manifested in the interaction between applicants/employees, employers and the state. It is concluded that such contradictions affect the institutional mechanisms for the formation of a national system of independent qualification assessment.Practical significance. The analysis of alternative models for qualifications assessment revealed the interests of different stakeholders involved in this process, the possibility of using “hybrid” forms of qualifications assessment, as well as a number of contradictions related to regulatory, functional and institutional features. The results of the study can be useful for managers of educational institutions and employers to synchronise the processes for mutual assessment of qualifications. As a result, recommendations for the development of an independent qualification assessment system in Russia are proposed, and the prospects for further research are outlined.

Exploring the synergy between structural engineering design solutions and life cycle carbon footprint of cross-laminated timber in multi-storey buildings

ABSTRACT Low-carbon buildings and construction products can play a key role in creating a low-carbon society. Cross-laminated timber (CLT) is proposed as a prime example of innovative building products, revolutionising the use of timber in multi-storey construction. Therefore, an understanding of the synergy between structural engineering design solutions and climate impact of CLT is essential. In this study, the carbon footprint of a CLT multi-storey building is analysed in a life cycle perspective and strategies to optimise this are explored through a synergy approach, which integrates knowledge from optimised CLT utilisation, connections in CLT assemblies, risk management in building service-life and life cycle analysis. The study is based on emerging results in a multi-disciplinary research project to improve the competitiveness of CLT-based building systems through optimised structural engineering design and reduced climate impact. The impacts associated with material production, construction, service-life and end-of-life stages are analysed using a process-based life cycle analysis approach. The consequences of CLT panels and connection configurations are explored in the production and construction stages, the implications of plausible replacement scenarios are analysed during the service-life stage, and in the end-of-life stage the impacts of connection configuration for post-use material recovery and carbon footprint are analysed. The analyses show that a reduction of up to 43% in the life cycle carbon footprint can be achieved when employing the synergy approach. This study demonstrates the significance of the synergy between structural engineering design solutions and carbon footprint in CLT buildings.

Bearing capacity of bolted-mortar infill connections in bamboo and yield model formulation

Bolted-mortar infill connections in bamboo structures are one of the most challenging aspects of the design and construction of these structures, due to the uncertainty in the evaluation of the connection strength. The shape of bamboo cross-sections (round, hollow and tapered) and the interaction between bamboo, mortar infill, and steel bolts or dowels are not clearly understood. Therefore, the main objective of this research was to develop an analytical method to estimate the strength of Bolted mortar infill (BMI) bamboo connections, based on the modified yield model theory (EYM). The proposed model consists of 5 controlling yield modes used to predict a BMI bamboo connection behaviour under load applied parallel and perpendicular to the fiber direction, based on the strength and geometry of materials. To validate the proposed model, a comprehensive experimental program that consisted of 112 tests for evaluating dowel-bearing strength on the Guadua bamboo, 126 test for determining bearing strength of the mortar filling, 61 test for evaluating bolt bending yield strength and 70 BMI connections were performed for 10 different configurations of dowel diameter and load angle direction. After calibration procedures, the model adequately predicted the connection strength for the different connection configurations with an average difference between the predicted and tested and Colombian National Code (NSR-10) values of 15.7% and 11.6%, respectively. In general, the predicted values of the proposed model, underestimate the connections capacity. This research aims to improve the design procedures and national regulations for BMI connections of Guadua Angustifolia Kunth and other bamboo species.

Optimization of electric spring operational strategy to minimize electricity bill

This paper aims at using electric spring to reduce the monthly electricity bill by developing its optimal operational strategy to capitalize on the variable energy cost over a day. An hourly-sampled optimization algorithm is presented to devise an optimum daily strategy for electric spring as a tool to smartly manage energy among the loads, utility, and storage devices, provided that load and solar power forecasts are available. Uncertainty in forecasts is dealt with by embedding certain stochastic processes with the proposed optimization algorithm to identify an envelope of probable operational strategies. The development and deployment of the proposed optimization algorithm are presented on a realistic load profile of a typical net-zero energy house in South Australia. The obtained results are analyzed under different connection configurations. Consequently, a significant reduction in the monthly electricity bill is realized.

Laser Cut passing‐through Open‐to‐CHS Beam‐to‐Column Connections

AbstractAlthough Circular Hollow Sections (CHS) have always demonstrated their excellent properties in resisting high compression, tension as well as bending in all directions, thanks to their inherent shape and geometry, the existing open ‐to‐CHS connections used in the current industry (conventional connections) generally require a substantial amount of stiffeners or gusset plates due to their construction method i.e. direct welding or diaphragm connections. As a result, huge welding quantities are required which further complicates the fabrication procedure. Furthermore, due to a direct connection, the CHS column becomes prone to localized distortions. In order to minimize the aforementioned drawbacks, a “passing‐through” approach was proposed and investigated in the EU‐RFCS research project LASTEICON where connecting elements (i.e. one or more steel plates or a piece of I‐profile) pass through the CHS column through Laser Cut slots made in the column and the primary beams (namely the “main” I‐beams) are connected to both ends of the passing through elements (named as “through‐members”). The applied shear force, and if relevant the applied moment, is effectively transferred by the “through‐member” to the CHS column, whereas, the CHS column contributes significantly in resisting it through its large flexural and shear capacity. The present article summarizes the most interesting results obtained based on the experimentally validated numerical simulations for the different types of LASTEICON connections. Thanks to the superior fabrication quality and versatility offered by the laser cutting technology, different types of connection configurations were developed within the project. This article introduces a few of these possibilities: (1) Two‐way steel moment resisting connections, (2) Asymmetric steel connections, (3) Four‐way steel connections, and (4) Composite connections.

Behaviour of Smart Steel Column‐Beam Connection Under Blast Loading

AbstractThe generated damages in steel structures due to terrorist attack explosion has attracted structural engineering communities, because the effect of blast loading is extremely sever and destructive. The behavior of Superelastic Nickle Titanium Shape Memory Alloy (NiTi SMA) beam‐column connection was infrequently studied under the effect of blast loading. The present study develops smart steel beam‐column connection under the effect of blast loading. The performance of the proposed connection configuration is evaluated numerically to make better understanding of the conceptual design of NiTi SMA‐based smart bolted connections. NiTi SMA‐based smart connection stiffness and strength is determined based on Eurocode steel joint design procedures. Analytically, Simplified Kingery Airblast Calculations approach is used to generate time history blast reflected overpressure parameters. The austenite effect of NiTi‐SMA is introduced to the global 2D frame model by moment rotation capacity curves. The structural components are verified in Ultimate Limit State (ULS) by using the results of global 2D model. The outputs from the 2D global model is introduced in sub‐numerical models. The sub‐models examined by finite element software code. The result shows that the hysteresis flag‐shaped loop of NiTi‐SMA is well expressed by the sub‐models' numerical solutions. As a result, the proposed connection configuration can highlight the efficiency of NiTi‐SMA in terms of energy dissipation capacity under blast loading successfully.

Insights into the electro-hybrid ozonation-coagulation process–Significance of connection configurations and electrode types

The electro-hybrid ozonation-coagulation process (E-HOC) integrates electrocoagulation (EC) and ozonation simultaneously in a single unit. Nevertheless, the performance of the EC process is highly dependent on the polar connection configuration (monopolar vs. bipolar connection) and the type of generated coagulants (single-coagulant vs. dual-coagulants). In this study, the removal efficiency of the E-HOC process with different connection configurations and types of coagulants was assessed. The E-HOC process with bipolar connection (BE-HOC) exhibited higher removal efficiency for wastewater treatment plant (WWTP) effluent organic matter and ibuprofen (IBP) compared with the E-HOC process with monopolar connection (ME-HOC). Furthermore, dual-coagulant generation (released from both Al and Fe electrodes) in the BE-HOC process greatly improved the WWTP effluent organic matter and IBP removal efficiency. Lower energy consumption was observed for the BE-HOC process compared with the ME-HOC process. It was found that ozonation promoted the polymerization reactions during coagulant hydrolyzis in the E-HOC process. Compared with the ME-HOC process, the BE-HOC configuration and dual-coagulant mode further facilitated polymeric hydrolyzed coagulant species formation, thereby improving ozone catalytic and coagulation performance. According to trapping experiments and EPR analysis, •OH formation was enhanced in the BE-HOC process and dual-coagulant mode. In addition, more active reaction sites of generated hydrolyzed coagulant species were observed with bipolar connection and in the dual-coagulant generation mode based on X-ray photoelectron spectroscopy (XPS) analysis.

Sliding corner gusset connections in concentrically braced frames using BRBs: Numerical analysis and practical design

In braced frames, the frame action, i.e. beam-column joint opening and closing, may cause premature rupture of the welded corner gusset connection and/or its adjacent framing members. To mitigate the detrimental frame action effect, a novel sliding gusset connection, in which the gusset plate is bolt connected to beam and column flanges through slotted end plates and sliding at the gusset-to-frame interfaces is permitted, has been proposed and experimentally studied for buckling-restrained braced frames (BRBFs) in previous research. To extend the findings of the experimental tests and develop a practical design procedure, high-fidelity finite element models for the sliding gusset connections were constructed, and their accuracy was validated against the experimental results. A series of numerical parametric studies were subsequently conducted. Firstly, the effect of different beam-to-column connection configurations was studied. With the strengthened beam end, the beam plastic hinge developed outside the gusset connection region, which reduced the plasticity in the gusset plate and the force demands on the bolts, due to the mitigated normal interaction at the gusset-to-frame interfaces. Secondly, for the design of bolts in the sliding gusset connection, the equivalent tensile force method was proposed. The acting position of the equivalent forces under brace tension action was quantified, considering different bracing angles and frame member sections. Thirdly, the behavior of the sliding gusset connection under the combined brace-frame action was studied. Based on the results, the design method for the gusset plate was validated, and recommended bolt design criterion was proposed. Lastly, based on all the results and discussion, a practical design procedure was proposed for the sliding gusset connection in BRBFs, which can be immediately used by engineers.

Modelling sediment (dis)connectivity across a river network to understand locational‐transmission‐filter sensitivity for identifying hotspots of potential geomorphic adjustment

AbstractRivers act as ‘jerky conveyor belts’ that transmit fluxes of flow and sediment downstream. This transmission of fluxes can be highly variable within a drainage basin resulting in either abrupt or gradational sediment (dis)connectivity patterns and processes. This study assesses sediment (dis)connectivity across a basin as a means to understand the locational, transmission and filter sensitivity properties of a fluvial system. Drawing upon the case study of Richmond River Catchment, New South Wales, Australia we use the concepts of effective catchment area and buffers, along with graph theory and an empirical sediment transport model CASCADE (Catchment Sediment Connectivity and Delivery), to assess (1) the degree to which modelled sediment cascades along the river network are connected or disconnected (2) how the position, pattern and configuration of (dis)connection facilitates or restricts geomorphic adjustment in different parts of a catchment, and (3) use the findings as a basis to explain the locational‐transmission‐filter sensitivity of the catchment. We use this analysis to segregate supply limited and transport limited reaches and identify various controls on sediment dynamics: in‐stream sediment storage units, junctions between different geomorphic river types, tributary confluences and sediment storage units within partly confined floodplain units. Such analysis lays the foundation for network scale identification of potential hotspots of geomorphic adjustment.

The Influence of Friction Blocks Connection Configuration on High-Speed Railway Brake Systems Performance

The influence of friction blocks connection configuration on the interfacial tribology behavior and FIVN (friction-induced vibration and noise) of the high-speed railway braking system is systematically investigated with a scaled brake test bench. The potential relationship among interface contact status, friction, wear, pressure distribution, thermal response, and vibration noise of the system is studied under dragging test conditions. The results indicate that the connection configuration of the friction blocks has a significant impact on systematic interfacial tribology behavior, thermal response, and vibration noise. A floating connection mode can suppress the vibration noise of the brake system. The interfacial thermal response and systematic vibration noise are quite relevant with the contact status, interfacial wear, and pressure distribution. The increase of interfacial wear will lead to an expansion of pressure concentration area and an aggravation of vibration noise. This research is helpful for further design optimization and noise reduction of the railway brake system.

The effect of implant-abutment connections on peri-implant bone levels around single implants in the aesthetic zone: A systematic review and a meta-analysis.

ObjectiveTo systematically review literature about the effect of different implant‐abutment interface designs on peri‐implant bone level changes, implant loss and mid‐buccal mucosa changes around single implants in the anterior maxilla. Reviewing three connection configurations: Platform switched conical (PS‐conical); Platform switched parallel (PS‐parallel); Platform matched parallel (PM‐parallel).MethodsA detailed search was carried out in Pubmed, EMBASE, Cochrane, Scopus, Open Gray and African journals Online (until December 1, 2020) and was restricted to clinical prospective studies of at least 1 year and with at least 10 human participants. A meta regression analysis was carried out primarily on the pooled peri‐implant bone level changes followed by implant loss and mid‐buccal mucosa level change. Risk of bias was assessed with RoB 2.0 and ROBINS‐I. The manuscript complied with the PRISMA guidelines and was registered in the PROSPERO database (ID: 225092).ResultsA total of 5513 hits gave 44 eligible articles for the analyses. Bone level change did not differ significantly between the two platform switched connections; their bone loss scores were significantly lower than PM‐connection. The PS‐conical connections have significantly lower implant losses than the PM connection. Mid‐buccal mucosa level change was comparable between the three connection configurations. Moderate to high risk of bias was detected in the included studies.ConclusionsThe performance of PS‐conical and PS‐parallel connection configurations both favored bone loss scores compared to the PM‐parallel connection configuration. All three demonstrated mid‐buccal mucosa changes that were small and did not differ significantly amongst the groups.

Cyclic behaviour of a novel steel beam-to-prefabricated CFST column connection with threaded sleeve bolts

As the conventional connection configurations of the steel beam to concrete-filled steel tubular (CFST) column are complex and unfriendly in practice, the application of the blind bolting system in steel beam-to-CFST column connection has been investigated in recent years. However, the blind bolted connections to CFST columns are generally classified as being pinned or semi-rigid and of partial strength due to the susceptibility to outward deformation of the tube wall. This paper developed a novel rigid and full-strength bolted connection of steel beam to prefabricated CFST column embedded with threaded sleeve bolts. Tests on five connection specimens are conducted to experimentally study the cyclic behaviour of the proposed sleeve bolted connections. The experimental parameters include the anchorage details of the sleeve bolt, the thickness of the end plate and level of axial load. To investigate the seismic performance of the proposed connections, the failure modes, hysteretic curves, connection rotation and ductility, stiffness and strength degradation, and energy dissipation capacity are presented and analyzed. The testing results prove that the proposed connection details have a strong influence on the cyclic behaviour and the moment-rotation behaviour of the novel connections. According to EC3, the proposed connection configurations behave as being rigid and of full-strength for non-sway frame. The component-based method is also proposed to predict the initial stiffness of the connections. The experimental and analytical results can provide a reference to promote the application of the novel sleeve bolted connections in engineering practice.

Anti-collapse performance of composite frame with special-shaped MCFST columns

A spatial steel frame with concrete slab and special-shaped multi-partition concrete filled steel tubular columns was tested in a simulated scenario of progressive collapse. The load-deformation relationship of the frame with damaged middle column under vertical load is discussed. Parametric analysis is also conducted by using a validated FE model. The results show that the failure of the specimen resulted from the fracture of the bottom beam flange eventually. The configuration of side plate connection and multi-partition concrete filled steel tubular column both could provide a reliable load-redistribution path for additional loads due to single column loss. The designed frame exerts good robustness to resist the collapse resulting from middle column loss. The simulation shows that single-column removal would cause additional lateral force and moment on the adjacent columns, besides axial force. The length of side plate exhibits more influence on the performance of the frame than the thickness of side plate.