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Network-based hiring is a common form of recruitment in businesses across the world. We administered a unique survey of Egyptian retail establishments to study the use of these hiring methods. We document important differences in establishments' use of ties to the owner ("connections") and to employees ("referrals") and their relationships with hiring outcomes. While all types of establishments use referrals at similar rates, use of owner connections varies widely and is most common among small informal establishments. Armed with these facts, we construct a simple model of hiring which clearly predicts that connections and referrals should have heterogeneous effects on hiring outcomes depending on establishment type. Our empirical results are consistent with the model's predictions. When high-productivity establishments use connections, the practice is associated with lower-quality hires (nepotism), yet when low-productivity establishments use connections, they find more productive workers. By contrast, referrals benefit high-productivity establishments more due to network homophily. These findings indicate that policies designed to either limit or expand network-based hiring could benefit one type of organization while having negative effects on others. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) has become popular as a construction material and the design of CLT connections is typically based on empirical equations with an average embedment strength of the wood-based product. The experimental study presented herein aims at enhancing the understanding of the relationship between the CLT embedment behaviour and the single layers it is composed of. Non-linear embedment stress–displacement relationships were measured in 244 full-hole and half-hole embedment tests on structural timber boards as well as on CLT produced of parts of the same boards. Three different fasteners, namely a steel dowel with a diameter of 12 mm and the threaded part of screws with a nominal diameter of 6.5 mm and 10 mm, were studied. The design of the experiments allowed to validate a simple mechanical model with parallel springs for the CLT, which showed good agreement with experiments. In addition to a validation of the non-linear spring model, this unique experimental data-set is further exploited in a comparison with empirical equations and for the derivation of a non-linear embedment ratio, between parallel and perpendicular to the grain embedment stresses, over the displacement. Knowledge of the relationship between the non-linear embedment behaviour of the single layers and the CLT element can be further exploited in the engineering design and numerical modelling of CLT connections with dowel-type fasteners. • Validated spring model for the prediction of the non-linear CLT embedment behaviour. • Consistent experimental dataset of CLT and structural timber embedment properties. • Prediction of CLT embedment strength and foundation modulus for different fasteners. • Derivation of a non-linear embedment ratio of stresses parallel to perpendicular to the grain. [ABSTRACT FROM AUTHOR]

What patterns of economic relations arise when people are altruistic rather than strategically self-interested? What are the welfare implications of altruistically-motivated choices of business partners? This paper introduces an altruism network into a simple model of choice among partners for economic activity. With concave utility, agents effectively become inequality averse towards their friends and family. Rich agents preferentially choose to work with poor friends despite productivity losses. These preferential contracts can also align with welfare since the poor benefit the most from income gains and these gains can outweigh the loss in output. Hence, network inequality—the divergence in incomes within sets of friends and family—is key to how altruism shapes economic activity, output, and welfare. When skill homophily —the tendency for friends to have the skills needed for high production—is high, preferential contracts and productivity losses disappear since rich agents have poor friends with the requisite qualifications. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study aimed at characterizing the lateral cyclic behaviour of Glulam (GL), Laminated Veneer Lumber (LVL), and Glued Laminated Veneer Lumber (GLVL) shear walls anchored to the foundation by means of conventional hold downs and angle brackets, which are fastened to the timber walls with annular ring nails. Monotonic and cyclic tests are conducted on these mechanical anchors, with hold down connections tested under tensile loads and angle bracket connections under shear loads. Withdrawal tests on annular ring nails embedded in GL, LVL, and GLVL elements are also conducted, to investigate the withdrawal response of the fasteners. The experimental tests reveal that the lateral behaviour of GL, LVL, and GLVL shear walls is similar to that of Cross-Laminated Timber (CLT) shear walls, primarily governed by the wall base connections and by the wall geometry. Hold down and angle bracket connections exhibited a mechanical behaviour governed by the steel-to-timber joints, to large extent comparable with that of typical hold downs and angle brackets fastened to CLT elements. Generally, higher ductility and lower load carrying capacity were reached by hold downs and angle brackets fastened to GL elements compared to those reached by hold downs and angle brackets fastened to LVL and GLVL elements. All quantities relevant for the seismic design, such as stiffness, load carrying capacity, ductility, and overstrength factors are calculated and discussed through the paper. These quantities are then compared with results from different experimental investigations on hold downs and angle brackets fastened to CLT elements available in the literature. Finally, an analytical model for the calculation of the lateral load carrying capacity of the shear walls is presented and used to verify that the same calculation models used for CLT shear walls can be adopted for GL, LVL, and GLVL shear walls. • The lateral behaviour of Glulam, LVL and GLVL shear walls is investigated. • The cyclic behaviour of hold downs and angle brackets fastened to Glulam, LVL and GLVL elements is investigated. • Mechanical properties and overstrength factors of the wall base connections are presented. [ABSTRACT FROM AUTHOR]

Although there are several steel-to-timber joint types, there is still a lack of studies that more precisely characterize the components in the interaction between steel and timber in compression. Thus, this work aims to characterize the steel T-stub compressing the glued laminated timber (GLT) parallel to the grain component, focusing on formulating analytical expressions for design resistance, stiffness coefficient and deformation capacity. In order to validate the analytical models and increase the reliability of the component method, an experimental campaign was conducted through compression tests on 90 specimens composed of steel T-stubs with five different flange thicknesses under full and partial compression. It was identified that although GLT has lower compressive strength and lower stiffness than steel, the main failure mode in specimens studied was T-stub flange yielding. The proposed formulations were consistent with the experimental results and it can be used to predict the structural behavior of this component. The application of the component analytical variable elastic approach to a semi-rigid connection showed an increase in the accuracy for predicting its moment resistance. • The main failure mode observed was the T-stub flange yielding, due to small stiffness of the flange and to the concentration of stresses in the central region of the timber. • The component is characterized by proposing equations for resistance, stiffness coefficient, and deformation capacity. The precision of these parameters has been improved compared to experimental results and to equations proposed by other authors for joints with similar geometry. • Experimental evaluation of the steel T-stub compressing timber parallel to the grain component carried out with five different T-stub thicknesses and timber subjected to full and partial compression. [ABSTRACT FROM AUTHOR]

Direct reuse and recycling of materials can significantly reduce the net environmental impact of the global construction sector. The feasibility of reuse and recyclability of building systems is affected by the materials used and the interfaces between constituent components. Yet there is a lack of quantitative methods for assessing the environmental benefits of alternative recovery strategies for multi-component and multi-material systems over the building lifetime. In this work, a novel assessment method was developed to enable a systematic and quantitative evaluation of the transient environmental reclamation potential (RP). The reclamation potential is a measure of the ability to disassemble and reuse recovered building systems at their end-of-life and is influenced by the constituent components and the interfaces between components. The proposed method accounts for the technical service lifetimes of components, including performance degradation over time, and can thus inform decisions on the most suitable recovery route for new and existing designs. The graphical outputs from the RP assessment are a network diagram which highlights the system components and connections between components, and an RP-graph which illustrates the embodied environmental impact and reclamation potential over time of alternative reuse/recycling strategies. The methodology is demonstrated on a glazed double-skin façade where the influence of component service lifetimes and replacements over time is quantified in terms of embodied energy and embodied carbon. The outcomes of the assessment can guide decision-making in design for disassembly (DfD) strategies and/or aid in the identification of high-value material recovery strategies at the end-of-life stage. • Implications of material selection and construction techniques on reuse are over-looked. • A novel method to assess the reclamation potential of multi-material designs is developed. • The reclamation potential metric measures the ability for components to be re-deployed. • New and existing designs can be compared based on their transient reclamation potential. • Component replacements have a significant impact on life-cycle environmental impact. [ABSTRACT FROM AUTHOR]

This paper deals with the face plate component in steel joints and addresses the full characterization of the nonlinear behaviour of the face plate component. An equivalent beam strip model is proposed that tackles the connection of a beam to the column web of open I-sections in a minor axis joint or the face of tubular columns, covering endplate or fin plate joint typologies. Closed-form analytical solutions are obtained for the elastic large displacement and the elastic-plastic large displacement behaviour of the equivalent beam strip. Criteria for the establishment of the design resistance using the continuous strength method are also proposed. It was concluded that the model is easy to apply, was validated against a large parametric study using finite element beam models, leads to accurate solutions and demonstrates the need to consider membrane effects in design. • Elastic large displacement exact solution for beam strip subject to patch load. • Elastic-plastic large displacement solution for beam strip subject to patch load. • Application of CSM (Continuous Strength Method) to establish design resistance. • Model applicable to component face plate not yet covered by design standards. [ABSTRACT FROM AUTHOR]

This paper presents a study that evaluates effective section moduli for the design of welds in circular hollow section (CHS)-to-CHS moment T-connections under in-plane bending. Experimental data from previous full-sized connection tests is used to verify a finite element (FE) modelling approach for weld-critical connections. A subsequent FE parametric study including 137 fillet and partial-joint-penetration groove welded CHS-to-CHS connection models is performed to cover wide ranges of non-dimensional design parameters: i.e., branch-to-chord diameter ratio (0.4 to 1.0), branch-to-chord thickness ratio (τ) (0.2 to 1.0), and chord slenderness ratio (2 γ) (10 to 50). The analysis reveals that as τ and 2 γ increase, more chord deformation, less uniform weld stress, and hence a lower unit weld strength, should be expected. New formulae for the weld effective elastic section modulus for in-plane bending, which build on recommendations from the previous work, are developed to consider this phenomenon and verified for use in conjunction with AISC 360. • An FE parametric study is performed on welds in CHS-to-CHS moment T-connections. • 137 new FE models, with weld fracture, are developed to supplement existing data. • New weld design formulae are proposed for the loading case considered. • The formulae provide a reliability index commensurate with AISC 360's target. [ABSTRACT FROM AUTHOR]

Holistic retrofit solutions for RC buildings carried out from the outside through structural exoskeletons, have been widely proposed in recent years. Based on the need to further investigate this type of intervention, the interaction between the existing building and the external exoskeleton was studied and discussed using a simplified 2DOF model. Both elastic and nonlinear retrofit solutions were considered. In the nonlinear case, the nonlinearity of the retrofit was lumped into the connection between the elements representing the existing building and the exoskeleton, yet the simplified model could be slightly adjusted to account for the nonlinearity in all its elements. The main contribution of the paper is the definition of design spectra aimed at the preliminary proportioning of elastic and nonlinear seismic retrofit solutions. Based on existing building characteristics, the developed design spectra provide the minimum retrofit stiffness required to achieve a given target displacement and, in the case of a nonlinear retrofit, the connection stiffness and yielding force that minimizes such displacement. The proposed design spectra allow for a direct comparison of the response of different retrofit solutions thus defining the optimal parameters for the retrofit system; the advantages and disadvantages of introducing elastic and nonlinear retrofit solutions may be discussed. A simplified design method was proposed and validated through nonlinear analyses applied to a 3D case study resembling an existing RC building that requires seismic retrofit. The case study validates the design spectra findings highlighting how the use of nonlinear connection could minimize the displacement. Furthermore, it highlights the beneficial effects of nonlinear connections in reducing the burden on the foundation of the new retrofit system and in reducing the seismic actions in the existing floors. • Interaction between the existing building and the retrofit solution. • Method and the processes of deriving design spectra for elastic and nonlinear retrofit solutions. • Design spectra for the preliminary proportioning of strengthening solutions for existing buildings. • Influence of the connections between existing building and retrofit in the structural behavior of the system. • Validation through nonlinear analyses applied to a 3D case study. [ABSTRACT FROM AUTHOR]

We shall analyze the intrinsic geometric structure of Yang-Mills theory from the standpoint provided by (what we shall call) the homotopic paradigm. This mathematical paradigm was mainly developed in the framework of (higher) category theory and homotopy type theory and relies on a groupoid-theoretical understanding of equality statements of the form a ​= ​ b. From a philosophical perspective, we shall argue that the homotopic paradigm relies a) on a rejection of Leibniz's Principle of the Identity of Indiscernibles and b) on a constructivist understanding of propositions as types of proofs. We shall apply the homotopic reconceptualization of equalities to the equalities between the base points and the fibers of the fiber bundle associated to a Yang-Mills theory. We shall revisit in this framework the articulation (heuristically established in the framework of the so-called gauge argument) between gauge symmetries and the mathematical notion of connection. We shall argue that this homotopic-theoretic understanding of Yang-Mills theories paves the way toward an ontological interpretation of gauge symmetries, that is an interpretation according to which gauge symmetries—far from being nothing but a " surplus structure " resulting from a descriptive redundancy—rely on the intrinsic geometric structures of Yang-Mills theories. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interfaces in composite metastructures are treated as delaminating cracks • Upon extension, connection failure is influenced by laminate thickness rather shape • Aside numerical tools, moment or force-driven delamination is dealt analytically • Variable thickness and/or filler material reduce crack driving force on connections • Connection or ligament failure is treated by first-ply failure & toughness limit Metastructures hold significant potential for applications such as adaptive structures and soft robotics. Architectures of fiber-reinforced polymer metastructures may relate to modular arrangement of straight and curved laminates, with their connections to resemble perfect cracks, thus susceptible to delamination. This study investigated geometrical effects on the load-carrying capabilities of these connections upon a global tensile deformation, as well as lean modeling tools to facilitate the development of architected composite metastructures. Numerical fracture mechanics approach on different connection geometries and thicknesses showed that connection delamination is a critical failure mode, but crack-driving-force has low dependence on connection shape for given ligament thickness (and stiffness). Adopted analytical models could capture either moment or force-driven delamination failure, while the intermediate regime necessitates numerical tools. First-ply failure may precede depending on shape and ligament stiffness. These trends were also verified on an exemplary rotating chiral composite geometry. Furthermore, interface load-carrying capability improvements were studied via design considerations including connection filler material and element variable thickness. Indicatively, the latter showed a 157 % increase in bending deflection (and global deformations), while reducing crack driving force by 38 % for a given load case. The conducted analysis offers valuable insights into the design of lightweight, load-carrying composite metastructures. [ABSTRACT FROM AUTHOR]

A series of 6 shear and bending tests was carried out on end-posts to cellular beams using nominally simply supported end-plate and fin–plate connections in order to determine the shear resistance of the end-posts in comparison with design predictions to EN 1993-1-13. The tests also included end-posts without and with notches to the beam flanges and openings with half infill plates. The cellular beams were 560 mm deep with 400 mm diameter openings. The test with a narrow end-post connected to a bolted fin-plate failed by in-plane bending of the end-post whereas the same test with an end-plate failed by Vierendeel bending at the first opening at 2% higher load. The tests with a narrow end-post and notches to the flanges failed at 86% and 90% of the equivalent test without notches. The test with a half infill plate failed by buckling of the plate at 22 to 26% higher load than the narrow end-post. In all cases, the failure loads were significantly higher than the design predictions using measured properties. • A series of 6 shear and bending tests was carried out on end-posts to cellular beams • Nominally simply supported end-plate and fin–plate connections were studied • Tests included end-posts without and with notches to the beam flanges and openings with half infill plates • Narrow end-post connected to a bolted fin-plate failed by in-plane bending of the end-post • Test with an end-plate failed by Vierendeel bending at the first opening • EN 1993-1-13 does not present a definitive design method for the end-posts with half infill plates or for notched beams • When test failure loads compared to the end-post buckling resistances given in the draft EN 1993-1-13, exceeded the predicted resistances by 35 to 83% [ABSTRACT FROM AUTHOR]

Extensive numerical studies and analysis are presented to gain insights into the mechanism of load transfer in T- and K-type concrete-filled steel tube (CFST) connections. The new mechanism of load transfer investigated in this paper manifests that the shear load is transferred non-uniformly in the CFST column. Using validated finite element (FE) models, contact pressure stresses of the concrete-tube and angle-concrete interfaces are investigated to examine the interfacial interaction between each component. It indicates that the friction resistances between three components occur almost throughout the loading process, which is non-uniformly distributed along the column length. In addition, stress in each component is evaluated to determine the region of non-uniform load transfer in the column. For T-type connection, non-uniform load transfer shall only be considered for concrete-tube interface. For K-type connection, non-uniform load transfer should be considered for both concrete-tube and angle-concrete interfaces. Non-uniform load transfer mainly occurs in the connecting region and one time diameter of column above the connecting region for theses connections. Finally, the uneven transferred load of each component for the connections is analysed, whilst different force allocation schemes are compared. Based on the shear stresses at the tube-concrete and concrete-angle interfaces, non-uniform load transfer factor of each interface is calculated to quantitatively evaluate the non-uniformity of load transfer for the T- and K-type CFST connections. • Numerically assesses the mechanism of non-uniform load transfer in K- and T-type connections. • Investigate region of non-uniform load transfer of tube-concrete and concrete-angle interfaces. • Analyses non-uniform load transfer of tube, concrete and encased angles. • Compare strength and stiffness allocation schemes of load transfer in connections. • Propose using non-uniform load transfer factors to evaluate new load transfer mechanism. [ABSTRACT FROM AUTHOR]

One-shot instruction in academic libraries is a librarian-controlled bibliographic instruction that responds to the point of information need for subject-related courses. The assessment of teaching effectiveness tends to take a summative approach, which provides an answer to what students learned but does not address how they learned. This column theoretically explores the framework of Ideas-Connections-Extensions (ICE) in library instruction and the classroom setting, which demonstrates learning outcomes and explores the learning journey, and integrates assessment, learning, and teaching through collaborative efforts by academic librarians and classroom faculty. [ABSTRACT FROM AUTHOR]

• A timber system is proposed for the seismic retrofit of URM buildings. • Analytical equations are derived for design against different failure modes. • Wall in-plane and out-of-plane responses, diaphragms and connections are addressed. • The proposed equations are applied to case-study buildings and structural members. • Good agreement between analytical calculations and experimental data is shown. An innovative timber retrofit was investigated at the EUCENTRE and at the University of Pavia, Italy, as part of a comprehensive research campaign on the seismic vulnerability of existing unreinforced masonry buildings subjected to induced seismicity in The Netherlands. The retrofit system consists of timber frames, connected to the masonry piers and to the floor diaphragms, and oriented-strand board sheathing nailed to the frames and to flexible timber diaphragms. Starting from the main critical aspects observed in experimental tests, the proposed solution was conceived to enhance the in-plane and out-of-plane capacities of masonry piers, improve the overall wall-to-diaphragm connections, increase the floor diaphragm stiffness and strength, and allow possible integration with energy efficiency upgrades. This paper, the first of a series of two, focuses on the conceptual bases of the seismic retrofit system and on the analytical equations that can be used for the design of its components. Moreover, a step-by-step design procedure is presented to guide the reader through the application of these equations. A companion paper [1] will discuss the validation of the analytical formulation with the experimental data from quasi-static cyclic and dynamic shake-table tests on building components and complete specimens. [ABSTRACT FROM AUTHOR]

As construction moves towards modularization and prefabrication, adhered joints have become increasingly prevalent across civil infrastructure, particularly in automotive, naval, aerospace, engineered wood, and concrete industries. Adhered joints offer the benefits of easier application and continuity of the connection without inducing additional residual stress in the connections in the ways that traditional bolted and welded connections do. However, these benefits are largely ignored in the steel industry. This paper discusses the success of structural adhesives in heavy structural settings, highlighting the opportunities for adhered joints in heavy structural connections. A review of test standards and research on steel-to-steel connections was performed and revealed that the performance assessment of structural adhesives should be standardized. A database of available adhesives appropriate for steel-to-steel connections was compiled and analyzed herein and indicates that for increased use of structural adhesives by the steel industry, uniformity in reporting of physical and mechanical properties of adhesives by adhesive manufacturers is necessary. From this database, preliminary statistical-analysis based design objectives for adhesive steel-to-steel connections were established. • Relevant research and standards on adhered steel-to-steel joints is reviewed. • Limit states for adhered steel connection design are discussed. • A database of commercially available structural adhesives is compiled and analyzed. • There is currently no uniformity in adhesive property reporting by manufacturers. • Performance based objectives are developed based on available adhesive data. [ABSTRACT FROM AUTHOR]

• Energy-absorbing connections (EAC) are investigated to improve energy-dissipation in timber assemblies under blast loading. • Typical load-displacement relationships are described and obtained from dynamic testing in a shock tube and static testing. • Configurations with well-defined plateau were capable of dissipating a significant amount of energy. • Single-degree-of-freedom (SDOF) and finite element analysis (FEA) were validated for predicting the performance of EACs. • An example of the application of EACs in a mass timber assembly is demonstrated. This study presents the results of an experimental program investigating the use of steel energy-absorbing connections (EAC) for the purpose of improving the energy dissipation capabilities of timber assemblies. The performance of the EACs is investigated both experimentally and numerically. A total of thirty-six specimens, representing nine configurations, including angle and circular hollow-steel sections, were tested under quasi-static and dynamic loading. The results of the study showed that connection configurations with well-defined plateaus were capable of dissipating a significant amount of energy and as such can be used in design for blast mitigation. Scalability of resistance based on the connection's depth was shown to be achievable experimentally. The welding configurations were shown to impact the behaviour significantly, and thus the details used in manufacturing must be identical to those assumed in design. The resistance curves of the EAC configurations investigated were reasonably predicted using Finite Element models. Analysis with single degree of freedom utilizing resistance curves obtained experimentally or from the finite element model mimicked the observed behaviour of the EACs. An example of the application of EACs in a mass timber assembly is demonstrated. This example showed that a 247 % increase in the energy absorption of the system might be obtained when compared to glulam members with idealized simply-supported boundary conditions. [ABSTRACT FROM AUTHOR]

• Evaluated effects of two brown rot fungi (Gloeophyllum trabeum and Rhodonia placenta) on performance of laterally loaded connections. • T-shaped connection assemblies modelling floor-to-wall connections in buildings were inoculated with fungi for up to 40 weeks. • Evaluated capacity, stiffness, energy dissipation, and ductility of connection assemblies through quasi-static cyclic connection tests. • Load carrying capacity and energy dissipating capacity were the most adversely affected of all the parameters evaluated. The effects of brown rot decay fungi on mechanical properties of CLT connection assemblies were investigated. CLT connections evaluated were assembled with code approved angle bracket connectors and modelled as floor-to-wall systems in mass timber buildings. Physical changes, mass loss and quasi-static cyclic tests were used to assess the performance of connection assemblies up to 40 weeks after fungal inoculation. Peak load, stiffness, energy dissipation and ductility of connections were characterized based on force–displacement data generated from the destructive test of connections. Assemblies experienced up to 57 % loss in load carrying capacity and 90 % loss in energy dissipating capacity of the connections after 40 weeks of fungal exposure. Connection stiffness was only slightly impacted over this period but wetting and redrying caused significant degradation of connection ductility. [ABSTRACT FROM AUTHOR]

Post-Tensioned Timber (PTT) frames combine high-strength tendons with heavy timber elements to create seismic low-damage or longer span timber structures. Although many aspects of structural performance, including seismic and long-term performance, have been investigated the behaviour of beam-column connections in fire has not been studied. Since it is the ductile rocking beam-column connections that give this system its advantageous response, the behaviour of these connections is key to evaluating the full-structural performance in fire. This paper presents the results of an experiment of a simple PTT beam-column subassembly under an applied load and exposed to an ISO 834 Standard Fire. The connection decompressed after 3 min and the beam rotation increased exponentially until it the applied moment was unable to be resisted at 20 min. Temperatures in the timber connection away from and at the connection are presented. Although the tendon force decreased from the effects of heating, the primary reduction in tendon force was due to crushing of timber under the anchorage. • A simple PTT beam-column subassembly was loaded and exposed to fire. • Measured temperatures show the development of the thermal field at the connection. • Moment resistance primarily decreased due to crushing under anchorage. [ABSTRACT FROM AUTHOR]

We prove that for a Lie group SO n (R) ⊂ G ⊂ GL n (R) , any G -structure on a smooth manifold can be endowed with a torsion free connection which is locally the Levi-Civita connection of a Riemannian metric in a given conformal class. In this process, we classify the admissible groups. [ABSTRACT FROM AUTHOR]

Circular hollow sections (CHS) are widely used in construction, particularly in space structures. This paper aims at investigating the feasibility of employing a machine leaning approach to predict the axial strength of longitudinal branch plate-to-CHS connections subjected to branch loadings. Using nonlinear finite element analysis, numerical models are developed for the connections subjected to tensile or compressive branch loading. The difference between the load–displacement responses for the connections under compressive and under tensile loading is established. Furthermore, the influence of various geometric and material parameters on the strength is investigated in depth. Using the results, two different strength models for the prediction of both tensile and compressive strength of longitudinal branch plate-to-CHS T-connections are developed. One prediction model is attained using traditional nonlinear regression analysis, and the other model is attained through symbolic regression. Finally, theoretical predictions are compared with numerical results, and strengths predicted with current design methodologies. [ABSTRACT FROM AUTHOR]

Nowadays, longitudinal branch plates are used as structural members in several engineering applications to connect brace members to Circular Hollow Section (CHS) chord members, which are widely employed due to their aesthetical appeal and efficiency. At ultimate limit state, the failure mechanism of T-type branch plate-to-CHS connections is characterized mainly by the formation of yield lines in the chord. This paper presents an analytical methodology developed using the yield line approach to predict the compressive strength of the longitudinal T-type branch connections. A numerical finite element parametric model was developed and calibrated with experimental work from literature to accurately assess the joint capacity in different configurations. Results obtained from the proposed analytical model show very good agreement with the calibrated FE model. Moreover, a comparison between the results of the parametric FE analysis with both previous studies and current design guidelines is presented. The proposed analytical model takes into consideration the most influential geometrical parameters and the effect of membrane stresses, which was found to be significant in slender chord members. The newly proposed equation also considers the slenderness of chord members which is not considered in the current design equations. • A failure mechanism model for longitudinal T-type branch plate-to-CHS connections under compression is developed. • The proposed model is developed using limit analysis theory. • Various geometrical configurations are investigated through nonlinear finite element analyses. • A plastic collapse mechanism resembling experimental pattern is developed. • Theoretical predictions show good agreement results from previous studies. [ABSTRACT FROM AUTHOR]

A framework to model timber connections at normal temperature and in fire, based on combined finite-element (FE) heat-transfer analyses and temperature-dependent Johansen-type load-carrying models, was developed and applied in a parametric study of previously tested beam-to-column steel-to-timber dowelled connections. Comparison with experimental results shows that the FE heat transfer models provide good estimates of measured temperatures and the load-carrying model gives good approximations of the load-carrying capacity at normal temperature (for dowel and embedment failures) and under standard fire exposure. For the degrees of utilisation expected in fire E fi / R 20 ≈ 0.3 , the developed models are able to predict the failure mode of each dowel and the expected load-carrying capacity. Simulation results showed a clear influence of the thickness of the side members on the fire resistance of the analysed connections. The influence of dowel spacing is not so clear, as it also depends on the dowel diameter. A smaller dowel diameter seems to slightly improve the fire resistance, namely for smaller degrees of utilisation or thinner side members, but compromises the load carrying capacity at normal temperature. • Framework to model timber connections in fire applied in parametric study of previously tested beam-to-column connections. • Models provide good estimates of temperatures, load-carrying capacities, and failure modes. • Results show a clear influence of the thickness of the side members on the fire resistance of the analysed connections. • Influence of dowel spacing is not so clear, as it also depends on dowel diameter. • Smaller dowel diameter slightly improves fire resistance, but compromises load carrying capacity at normal temperature. [ABSTRACT FROM AUTHOR]

In previous works the group inverse of a network obtained by some perturbations, as the deletion of a vertex, the addition of a new vertex, contraction of an edge, etc. is obtained in terms of the group inverse of the original network. In this work, two given networks are connected with some edges and the group inverse of the new network is obtained from the group inverse of the two original networks. In particular, the formula for the connection of two networks by just one edge is obtained, and besides the formula for the Kirchhoff index of this kind of networks is given. [ABSTRACT FROM AUTHOR]

In fire conditions the provision of connection ductility is key to the prevention of brittle failure and progressive collapse of steel and steel-concrete composite framed structures. This paper describes the development and testing of a novel connection concept intended to provide appropriate ductility enhancement compared to that of conventional connection types. The connection consists of two connection pieces, each of which takes the form of a web cleat which includes a semi-cylindrical section. This section allows the beam-end to move towards or away from the column-face by deforming plastically. A simplified analytical model has been developed to simulate the mechanical behaviour of the proposed connection, and this model will eventually enable the incorporation of this new connection type into global frame analysis to be used in performance-based structural fire engineering design. The model has been tested against FEA simulations and against model-scale experiment results, indicating that it can predict the behaviour of the connection with satisfactory accuracy. Preliminary sub-frame analysis results indicate that the proposed connection behaves similarly to an idealized pinned connection under ambient-temperature conditions, but provide significantly larger ductility, and resistance to disproportionate collapse, compared to conventional connection types. • A novel connection which allows large deformation of connected beam is proposed. • Analytical models have been developed to simulate mechanical behaviour of connection. • Analytical models have been validated against FEA simulations and experiment results. • Simple sub-frame model has been created to study the performance of novel connection. • The novel connection can provide larger ductility compared to conventional types. [ABSTRACT FROM AUTHOR]

Highlights • The paper deals with an experimental investigation of cross-laminated timber (CLT) elements subjected to simulated blast loading. The focus of the work was on the connections between the wall and the floor since such connections can deform inelastically and provide some of the critical energy dissipation needed. Current analysis and design methods assume the connections to be simply supported and while this assumption simplifies the analysis significantly, it ignores the important contribution of the connection. • Connection types and associated failure modes are established and suitability of such connections for blast design are discussed. Also, current analysis methods and design provisions are evaluated and where appropriate suggestion are made to possible improvement in approaches. • The study showed that the detailing of the connections appears to significantly affect the behaviour of the CLT slab. Typical detailing for platform construction where long screws connect the floor slab to the wall in end-grain performed poorly and experienced brittle failure. Bearing type connections generally behaved well. Yielding in the fasteners and/or angles brackets significantly reduced the energy imparted on the CLT slab and caused less displacement and thereby less damage in the slab. • The study showed that using simplified tools such as single-degree-of-freedom (SDOF) models together with current available material models for CLT is not sufficient to adequately describe the behaviour and estimate the damage. The study also demonstrated that current blast design codes do not adequately address the design of connections in timber structures subjected to dynamic loads. Abstract Recent research efforts have established key dynamic characteristics of cross-laminated timber (CLT) panels and developed parameters that are suitable for analysis and design. Despite such effort, no information is available on the critical role connections play in the behaviour of CLT when subjected to blast loads. The current study investigates a total of thirteen full-scale CLT wall panels with varying connection detailing by simulating the blast loading through a shock tube apparatus. The study found that typical connections with end grain screws into wall elements as well as angled double-threaded screws performed poorly and failed prematurely in tension perpendicular to grain. Reinforcing the connection with screws applied on the panel face did not mitigate the brittle failure. It was found that connection types where the wood is bearing on steel angles or directly on other wood members performed well even when under-designed according to the blast design standard. Whereas thin steel angles provided significant energy dissipation in bending of the angle resulting in reduced panel deflection and damage, thicker steel angles provided the energy dissipation through yielding in the screws as well rotational restraint of the panel ends. Using balloon type assemblies provided significant rotational restraint at the panel ends. The study also found that simplified models developed for idealized simply-supported conditions were not adequate to describe the behaviour of the system. [ABSTRACT FROM AUTHOR]

Abstract Fibre reinforced polymer (FRP) composites have become known for their specific advantages for civil infrastructure construction. High corrosion resistance in particular is one such strength, which has led to successful applications worldwide. This paper focuses on the structural applications of FRP composites as major load-carrying members (therefore strengthening of existing structures is not included) in aggressive environments. It is review and comparatively studied for environmental effects on FRP composites at the structural level mainly about joints and connections, including elevated environmental temperatures, humidity and water immersion, and ultraviolet (UV) exposure. The quantifications of such environmental effects on structural responses further assist development of large scale civil structures made from FRP composites. We therefore also present a few implementations of FRP composites in civil infrastructure construction including i) FRP truss and frame structures in high humility areas, ii) FRP composite bumper systems for bridge piers, iii) floating FRP structures for solar panels, iv) FRP steel composite piles for foundation applications, and v) FRP sheets, planks and piles for modular assembly of a retaining wall. These results are introduced as initiatives from own experiences, with the aim of demonstrating their applicability and providing examples for others with similar needs. [ABSTRACT FROM AUTHOR]

Abstract The work herein presented proposes an innovative approach to the use of friction dampers in seismic resistant steel structures. In fact, reference is made to dual systems where dissipative devices are located at beam ends, column bases and intersections of chevron braces. Friction devices are those investigated in the framework of the European Research Project "FREEDAM" (FREE from DAMage steel connections), supported by Research Found for Coal and Steel (RFCS). The aim of this project is the development of beam-to-column connections equipped with friction dampers showing low damage. Investigations concerning the prototype structure herein presented have been carried out to gain relevant information in the framework of the research project. Incremental Dynamic Analyses (IDA) are developed with reference to the maximum interstorey drift ratio, the maximum slippage velocity and the cumulative displacement, i.e. the travelled distance of the friction dampers. Moreover, the influence of the seismic intensity measure on the required friction damper stroke is investigated. Highlights • The work is developed within the RFCS Project "FREEDAM" to study beam-to-column connections equipped with low damage friction dampers. • MRF-CBF dual systems with low damage connections are designed by the Theory of Plastic Mechanism Control (TPMC) • The seismic performance is investigated by IDA analyses [ABSTRACT FROM AUTHOR]

Highlights • A new type of encased CFT column base connections was proposed. • Eight large-scale encased column base connections were tested. • The proposed connection type achieved desirable seismic behavior. • The steel wraps effectively prevent the shear failure of outer components. • A model was proposed to predict the flexural strength of encased column base connections. Abstract The vulnerability of traditional encased column base connections, which consist of inner base-plate column bases partially encased by reinforced concrete outer components, has been demonstrated by previous earthquakes. This paper presents a new type of encased column base connections using steel wraps to confine reinforced concrete outer components, and the seismic behavior of both the traditional and the proposed encased concrete filled steel tube (CFT) column base connections was experimentally studied by testing of eight large-scale specimens under simulated seismic loads. The test parameters mainly included thickness, height and flexural reinforcement ratios of outer components, with or without steel wraps and shear studs. The effects of the test parameters on the failure modes, load-deformation response curves, stiffness, strength, ductility, energy dissipation ability and strain distribution of the encased column base connections were comprehensively evaluated. The test results indicate that encased column base connections with properly design can achieve desirable seismic behavior and the use of steel wraps can effectively prevent the shear cracking of reinforced concrete outer components. Finally, the methods of predicting the flexural strength of encased CFT column base connections were also discussed. [ABSTRACT FROM AUTHOR]

Highlights • SPSW in RCF with proposed connections improves load carrying capacity of RCF. • Initial stiffness and ductility is significantly influenced by connection types. • Three of proposed connections can be used for rehabilitation of RC structures. • One connection (type 4) proposed for new structures. Abstract In the reinforced concrete (RC) structures with steel plate shear walls (SPSWs) as a lateral resisting system, to obtain maximum capacity of SPSW, implementing proper connections play an important role to transfer force from wall to the frame. In this paper, four connection types are proposed and numerically investigated to transfer the tension field forces between SPSW and RC frame (RCF). Three types of connections are applicable for rehabilitating of existing RC structures and one type can be used for new construction. The behavior of connections has been evaluated using non-linear finite element analysis (NLFEA). Results of the specimens with different types of connections demonstrated that the use of SPSW in RCF with appropriate connections could provide excellent ductility as well as high load carrying capacity and initial stiffness by distributing the yielding zone in SPSW along the wall height. [ABSTRACT FROM AUTHOR]

Abstract Beam-to-column joints equipped with friction dampers are promising solutions to improve the performance of steel moment resisting frames due to the possibility to guarantee large dissipation capacity limiting the structural damage under severe seismic conditions. In this paper, the experimental tests and the numerical simulations of two types of joints are shown and discussed with the aim of developing pre-qualified configurations. The friction dampers are designed to be easily removable from both the lower beam flange and the column face by means of bolted connections. The devices are composed of a stack of steel plates conceived to assure symmetrical friction. The friction surface is set in vertical direction in first case and in horizontal direction in the second type. The experimental tests confirmed the effectiveness of both examined joints and the finite element analyses allowed characterizing their local response, thus providing additional insights to improve the design requirements. Highlights • The behavior of steel beam-to-column joints equipped with friction dampers is investigated. • Dampers with both horizontal and vertical friction surface are investigated. • Experimental tests on joints equipped with friction dampers show satisfactory response with negligible damage. • The tested joints show non-symmetric response under hogging and sagging moment. • Finite element simulations show that the vertical friction damper exhibit plastic deformations lower than the horizontal friction damper. [ABSTRACT FROM AUTHOR]

• Initial stiffness of steel connection component face plate. • Validation of the initial stiffness of the component with experimental and numerical results. • Derivation of design-oriented analytical methodology. The component method for joint analysis relies on the formulation of stiffness and strength of individual parts to derive the global properties of the joint. One of these components is the web of an open I-section, or the face of a rectangular hollow section, hereby referred to as face plate. It is currently not codified despite its frequent occurrence in the engineering practice. Hereby, a new mechanical model is proposed to estimate the initial stiffness of the face plate component under out-of-plane loading, leading to closed-form analytical expressions. The model is validated against experimental test results and an extensive numerical parametric study, showing excellent agreement. [ABSTRACT FROM AUTHOR]

Design provisions for the shear resistance of double shear (3-ply) cold-formed steel screw connections are not provided by the existing CSA S136 and AISI S100 Standards. The resistance of the mid-ply layer of screwed double shear connections was investigated to determine whether the use of the bolt bearing provisions was a reasonable substitute. Forty-eight individual normal ductility steel connections with fastener diameters between 4.17 mm and 5.49 mm and inner sheet thicknesses between 0.36 mm and 1.09 mm, as used for previously constructed centre-sheathed shear walls, were tested. Bearing damage and a combination of bearing and tearing failure were observed. The strengths of the connections tended to increase as displacement progressed due to expansion of the bearing area. When a displacement limit of 6.35 mm was enforced, the tested strengths of the screw connections were a reasonable match to the bolt bearing provisions. The resistance factor ϕ for the double shear screwed connections was identified to be 0.54 (LRFD) and 0.43 (LSD). [ABSTRACT FROM AUTHOR]

Let M be a manifold endowed with a flat torsionless connection ∇. A symmetric bivector field h on (M , ∇) is said to be a Koszul-Vinberg (K-V for short) bivector field if it satisfies: (∇ α # h) (β , γ) = (∇ β # h) (α , γ) , where α # : = h # (α) and h # : T ⁎ M → T M is the contraction of h. The pair (∇ , h) is called a K-V structure and the triple (M , ∇ , h) is called a K-V manifold. When h is non-degenerate, (M , ∇ , h − 1) is a pseudo-Hessian manifold, otherwise, we have a singular foliation defined by I m h # called the associated affine foliation whose leaves are pseudo-Hessian manifolds. In this paper, we study invariant K-V structures on homogeneous spaces. More precisely, we give an algebraic characterization of these structures in the same spirit of Nomizu's theorem on invariant connections on homogeneous spaces, and we give many classes of examples mainly for reductive or symmetric pairs (G , H). We establish many properties of pseudo-Hessian homogeneous manifolds, in particular, we show that when G is a semi-simple Lie group then G / H does not admit any non trivial G -invariant pseudo-Hessian structure. Finally, we show that the leaves of the affine foliation associated to an invariant K-V structure are homogeneous pseudo-Hessian manifolds. [ABSTRACT FROM AUTHOR]

• CLT screw reinforcement greatly increased the shear capacity. • The addition of concrete topping compositely connected to the CLT panel significantly improves out-of-plane shear capacity. • TCC system with kerf plates provided a very stiff and strong and was the most economical option. • The results from this research guided the project-specific design decisions for a 10-storey tall timber building. This paper presents full-scale experimental investigations on cross-laminated timber concrete composite (TCC) systems. The primary objective was to determine the stiffness, ultimate load-carrying capacity, and failure modes of TCC systems using three different shear connectors: self-tapping screws, steel kerf plates, and proprietary glued-in perforated steel plates. The secondary objective was to determine the effectiveness of shear reinforcement in the CLT panels. The TCC system was comprised of 245 mm thick, 7-ply CLT panels with a 150 mm concrete topping. A total of 24 half-span (4.6 m long) and 9 full-span (9.2 m long) CLT and TCC floor segments were tested under symmetric four-point bending as well as torsional bending. For all test series, the CLT panels were either unreinforced, or reinforced using self-tapping screws. The shear reinforcement increased rolling shear capacity which helped to avoid CLT shear failure. Adding the concrete topping increased the shear capacity by up to 167%. The tests showed that the floors with steel kerf plates exhibited the highest capacity and stiffness, while also being the most easy-to-install solution. The results from this research guided project-specific design decisions for "Limberlost Place", a mass timber building for George Brown College, in Toronto, Canada. [ABSTRACT FROM AUTHOR]

Highlights • Two-way shear tests on beech LVL-concrete connections with singly inclined screws. • 45° tension and compression screw connections of high strength and ductility. • 90° screws enable similar strength/modulus to 45° tension/compression screws. • Repeat tests show good consistency of failure load, much less so of slip modulus. • Gamma method shows sensitivity to the connection of uncracked depth and deflection. Abstract Double-shear tests are reported on beech LVL-concrete composite connections based on coach screw connectors singly inclined at either 45° or 90°. On different specimens with the same screw orientation the longitudinal shear force was applied either in forward or reverse, because in practice concrete shrinkage, moisture-induced timber expansion and oscillatory (e.g. seismic) or moving loads can induce reversal of the force on the connection. The test data show that relative to the 90° screw connections, sloping the screws to 45° in tension only marginally affected longitudinal shear strength but led to a fivefold increase of slip modulus and to a significant drop in ductility, while sloping the screws the other way to 45° in compression only marginally affected slip modulus but led to an almost fourfold drop in longitudinal shear strength and to a substantial increase in ductility. The specimens tested within each group showed good consistency of shear strength and (except the 45° tension screw specimens, despite their consistent strengths) of failure mode, but high variability of slip modulus. Comparisons with previously tested timber-concrete composite (TCC) connections based on other screw types and layouts suggest good performance of the present connections. The gamma method applied to a given TCC T-section under load shows that the present alternate connections lead to quite different depths of uncracked concrete and so to significant variation of midspan deflection. In closing, it is recommended that both forward and reverse shear testing becomes a protocol for singly inclined coach screw-based TCC connections. [ABSTRACT FROM AUTHOR]

Abstract Design of concrete-filled high strength steel tubular joints subjected to compression is examined. A numerical investigation on concrete-filled high strength steel rectangular hollow section (RHS) joints is presented in this paper. The high strength steel RHS tubes had nominal yield stresses of 700 and 900 MPa. The concrete infills had nominal concrete cylinder strengths of 35 and 100 MPa. Finite element (FE) models were developed and verified against test results, showing the capability of replicating the experimental ultimate strengths, failure modes and load-deformation histories. Upon verification, a parametric study comprised 312 FE analyses was carried out. The ultimate strengths of the concrete-filled high strength steel RHS joints obtained from the parametric study together with available test results in the literature were compared with the nominal strengths calculated from existing design provisions. It is shown that the CIDECT predictions exhibited significant scatter and generally conservative for the concrete-filled high strength steel RHS joints. However, the CIDECT predictions overestimated the strengths of concrete-filled high strength steel RHS joints with chord sidewall slenderness ratio exceeded 50. Therefore, new design rules are proposed in this study for concrete-filled high strength steel RHS joints subjected to compression. Furthermore, reliability analysis was performed to assess the design rules. Highlights • New design rules are proposed for concrete-filled high strength steel tubular joints. • Finite element models of concrete-filled high strength steel tubular joints were developed. • Parametric study of 312 specimens was performed. • Existing concrete-filled tubular joint design provisions are also assessed. [ABSTRACT FROM AUTHOR]

This paper presents an experimental test and finite element (FE) study on the ultimate strength of longitudinal X-type plate-to-circular hollow section (CHS) connections reinforced by external ring stiffeners (abbreviated as PCE connections) under in-plane bending moment. Static tests on four large-scale specimens were performed under both symmetrical and anti-symmetrical loadings. Local axial buckling and transverse plastic deformation failures on PCE connections were observed from the test. Further FE analysis reveals that the external ring stiffener can achieve effective strengthening of the connection and the failure modes are affected by the size of the ring. A total of 541 PCE connections with a various range of geometric configurations and chord stress levels were analyzed and the results obtained were transformed into the ultimate strength of “ring models”. Based on the regression analysis of numerical simulation database, the current design equations by JSTA were re-assessed and a set of novel design model has been proposed utilizing the mathematic design model for transverse X-type plate-to-CHS connections by CIDECT design guide. The proposed design model tends to have practical significance by offering a design guideline for the similar connections. [ABSTRACT FROM AUTHOR]

Connections with metal dowel-type fasteners are important details in timber construction, connecting single members and elements to larger structures. The load-carrying capacity can be described by different failure modes of the fasteners and in the surrounding timber. These failure modes show a dependency on different dimensions and material properties. The failure can be classified into brittle and ductile failure modes based on the deformation capacity. The limited deformation capacity of the brittle failure modes has an impact on the load-carrying capacity of the entire connection with multiple fasteners. The present study takes a critical appraisal of load-carrying capacity and deformation capacity of timber connections and the implementation of their design in the Eurocode 5. By aiming for the ductile failure modes with plastic deformation of the fasteners in the design of the connection, high load-carrying capacities and high reliability can be achieved. For brittle failure modes the reduced resistance and the reduced reliability should be accounted for, especially for connections with multiple fasteners. [ABSTRACT FROM AUTHOR]

Connections in timber beams loaded perpendicular to grain are prone to brittle failure due to fracture induced by tension perpendicular to grain stresses in the surrounding timber. Different approaches can be found in literature and design codes to account for the reduction of load-carrying capacity in the design of the structure. In this study selected design approaches are discussed and their behaviour with regard to different geometrical parameters is analysed. The structural behaviour of connections loaded perpendicular to grain is evaluated on the basis of test results from literature. The impact of different geometrical parameters on the load-carrying capacity is demonstrated and the design approaches are benchmarked against a large number of individual test results. Recommendations for a more reliable design are given. [ABSTRACT FROM AUTHOR]

Within the last 20 years, cross laminated timber (CLT) has become one of the most important building products in contemporary timber engineering. By the end of this decade, its annual worldwide production volume is expected to exceed 1,000,000 m 3 . The industry, engineers, architects and constructors have a strong interest in implementing CLT in European product, design and execution standards. The design of CLT is part of the currently ongoing revision of Eurocode 5. In this context and in addition to the verification of CLT panels in respect of ultimate and serviceability limit states, guidelines on the design of connections in CLT with dowel-type fasteners are of the utmost importance. In this article, we review approaches for calculating characteristic values as provided in literature for single dowel-type fasteners and connections in CLT. We also compare these approaches, with focus on withdrawal and embedment strength of dowels, nails and self-tapping screws, with the current regulations on dowel-type fasteners for solid timber and glulam as formulated in Eurocode 5. These comparisons are made in order to identify the need and potential for revision of current EC 5 equations and state-of-the-art regulations. We summarise regulations on connection design, i.e. minimum spacing, edge and end distances, other additional geometrical conditions, regulations on the effective number of fasteners in a group and minimum penetration depths. Finally, we draw conclusions in respect of the single fastener properties withdrawal and embedment strength and suggest some execution guidelines, which ensure the integrity of CLT structures. Overall, we aim to present a compilation of the current state-of-the-art knowledge on dowel-type fasteners in CLT as a basis for implementing design guidelines for CLT in the new connection chapter of Eurocode 5. [ABSTRACT FROM AUTHOR]

Designing a timber connection which is buildable with minimum errors has been considered the most difficult aspect of a timber design. Although many studies have been conducted in the past on various aspects of the usability of Eurocode 5, the authors felt that with the impending revisions to the Eurocodes, it was pertinent to ask the users for their opinions in a more focused manner, with questions aligned with the revision objectives. As part of the activities of the working group 3, “Connection” of the COST Action FP1402, a Europe-wide survey was thus conducted among the practitioners, where a number of questions related to Eurocode 5 in general and the connections chapter in particular was asked. The majority of respondents felt there were improvements to be made both to the technical content, as well as the usability of the standard in terms of clarity and ease of navigation. The results of the survey are summarized in this paper with a proposal for reorganization of the current technical content, which the authors feel answer the majority of the concerns raised by the users. [ABSTRACT FROM AUTHOR]

Normally, the design of steel moment resisting frames in seismic areas encourages the formation of plastic zones in the beams. This paper investigates numerically the performance of moment resisting frames designed to dissipate hysteretic energy in joints and beams together. Joints can be a stable source of hysteresis, provided they are designed with ductility requirements. The commonly used bolted end-plate connection is adopted here. In order to provide spacing between the expected plastic zones in the connection and the beam, a reinforcement scheme with cover plates is employed. Appropriate methodologies are provided for the design of connections and cover plates. The proposed joint and beam dissipative frames are evaluated through parametric push-over and time-history analyses. Comparison is performed with frames designed with rigid joints that dissipate energy mainly in beams. The results show that the proposed frames not only don’t suffer in terms of drifts or capacity, due to the added joint flexibility but they provide superior performance in many aspects, while they can offer economical advantages, due to their reduced bending moment requirements. [ABSTRACT FROM AUTHOR]

Monotonic and cyclic tests were carried out to determine strength and stiffness characteristics of 2.44 m (8 ft) long shear connections with 8 mm and 10 mm diameter self-tapping screws. The goal of this research is to compare test values of cross-laminated timber (CLT) diaphragm connections in seismic force-resisting systems to the design values calculated from formulas in the National Design Specification for Wood Construction (USA) and the Eurocode. Understanding and quantifying the behavior of these shear connections will provide structural engineers with increased confidence in designing these components, especially with regard to the seismic force-resisting systems. Ratios of the experimental yield strength (from the yield point on the load-deflection curve) to factored design strength were in the range of 2.1–6.1. In the ASCE 41-13 acceptance criteria analysis, the m-factors for the Life Safety performance level in cyclic tests ranged from 1.6 to 1.8 for surface spline connections and from 0.9 to 1.7 for cyclic half-lap connections. The half-lap connections with a unique combination of angled and vertical screws performed exceptionally well with both high, linear elastic initial stiffness and ductile, post-peak behavior. [ABSTRACT FROM AUTHOR]

In this paper, the results of an experimental analysis regarding beam-to-column joints equipped with friction dampers are presented. Even though the overall concept is not new, the connection structural detail and the friction pad material are different from previous proposals. In particular, the beam is connected to the column with a classical fixed T-stub fastening the upper flange and a friction damper located at the beam lower flange. The friction damper is composed of a stack of steel plates conceived to assure symmetrical friction. The friction pads are made of steel plates coated with thermally sprayed aluminium. The friction damper is designed in order to slide for a force level equal to or lower than the ratio between the nominal flexural resistance of the connected beam and the lever arm, i.e. the distance between the top T-stub and the friction damper. In this way, it is possible to obtain connections able to dissipate the seismic input energy almost without any damage to the steel elements, provided that all the joint components are designed with sufficient over-strength with respect to the actions corresponding to the friction damper sliding force. In this paper, such approach is validated reporting the results of an experimental campaign. [ABSTRACT FROM AUTHOR]

An extensive set of experimental programme on the behaviour of innovative ring-bar reinforced connections composed of T-shaped concrete-filled steel tubular (CFST) columns and reinforced concrete (RC) beams with slabs are reported in this study. Specifically, for the proposed connection, the T-shaped CFST column is welded with an H-shaped steel corbel, which is embedded into the reinforced concrete beam and slab. Moreover, a few ring-bars are fabricated to improve the seismic resistance capacity of this connection. A total of six specimens are tested: one specimen is tested under monotonic loading to investigate the load-displacement relationship and the development of strains; and the other five specimens are tested under cyclic loading to obtain the seismic behaviour of these specimens. The test results demonstrate that the seismic behaviour of the proposed connections is prominent and that the diameter and number of ring-bar and length of steel corbel are found to be significant factors of the seismic behaviour of the connections. Complementary to the experiments, a finite element (FE) model is developed to further analyse the experimental results by illustrating the failure modes of the specimens and extending the parametric studies which are not studied through the limited experiments. The comparison between the FE analysis and the experimental results demonstrates the accuracy of the proposed model. Numerical results indicate that the ring-bar and slab are able to increase the stiffness and bearing capacity of the specimens; the reinforcement ratio of beam, the concrete strength of the beam and slab play important roles in improving the ultimate strength of the specimens. [ABSTRACT FROM AUTHOR]

Three connection design properties (dowel embedment strength, slip modulus and screw withdrawal capacity) were determined for one species of bamboo ( Guadua angustifolia Kunth) using experimental methods adopted from timber engineering. 151 embedment strength and slip modulus tests were undertaken using smooth dowels with diameters ranging from 3 to 16 mm, whilst 240 screw withdrawal tests were undertaken using 3.5–5 mm diameter self-tapping screws. Using regression analysis, predictive equations for the three connection design properties were derived, based on fastener diameter, density and bamboo wall thickness. Coefficients of determination (R 2 ) ranged from 0.45 to 0.82. The predictive equations for embedment strength and screw withdrawal were adapted to output characteristic values and then compared to similar equations derived for timber contained in Eurocode 5, the latter would seem inappropriate for bamboo. [ABSTRACT FROM AUTHOR]

Glued-in rods have potential for use as moment-resisting connections in timber structures. There has been minimal research to date conducted on the performance of glued-in rods acting under both axial force and moment. The influence of increasing embedded length of the glued-in rod on the strength of the system was assessed using a pull-bending test which subjected the connection to this force combination. The longest length (600 mm) had a pull-out capacity 213% greater than the shortest (80 mm). To reduce instances of splitting in the timber end distance was varied. Optimum end distance of 42 mm (3.5 d r ) was identified with further increase having minimal impact upon overall strength. [ABSTRACT FROM AUTHOR]

In this note, we consider a Lie group G acting on a manifold M . We prove that the category of principal bundles with connection on the differential quotient stack is equivalent to the category of G -equivariant principal bundles on M with G -invariant connection. [ABSTRACT FROM AUTHOR]