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This paper investigated the potential applicability of the specification equation for the shear pull-out strength of a power-actuated fastener (PAF) connection to nail connections between steel sheets thinner than 2.9 mm. The tested G300, G450, and G550 specimens had thicknesses ranging from 0.6 to 2.4 mm, connected with 2.5- or 3.6-mm helically knurled nails. The pull-out strength is a function not only of the thickness of the member not in contact with the fastener head, but also of the other member's thickness. The member thicknesses have greater influence than the nail diameter on the pull-out strength, contrary to the design equation. Based on the test results of 93 shear nailed connections failing in pull-out, the paper proposes a design equation that is applicable to connections using helically knurled nails of steel sheets thinner than 2.9 mm. A group effect factor of 0.75 is suggested for serial nail connections based on the test results of 19 multiple nail connections. A resistance factor of 0.55 is recommended for use with the proposed equation for determining the pull-out strength of shear nailed connections in thin steel sheets. An additional finding is that the current design equation for the bearing and tilting strength of a PAF connection is applicable to connections in which the member not in contact with the fastener head is much thinner than the specification minimum of 3.2 mm, and in which the fastener diameter is smaller than the specification minimum of 3.7 mm. [ABSTRACT FROM AUTHOR]

Fastening systems play a significant role in railroad track dynamics. In this paper, three approaches are investigated for rail fastenings modeling using FEM: (1) spring–damper pairs covering the areas representing the fastening connections; (2) a solid-load approach that explicitly models the solid baseplates and includes toe loads by applying external loads; and (3) a solid-spring approach that takes into account the coupling of rail with the ties by using prestressed springs. Experimental tests were carried out to evaluate the performance of the FEM models. The mode shapes obtained from the FEM models and the experiments were used for the evaluation. A measurement quantifying the similarity of the mode shapes was proposed, which considers both shape similarity and distance similarity. The results showed that the rail foot's mode shapes obtained from the model using the spring–damper approach demonstrated the most similarity with the ones obtained from the experiments. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) panels, when used as shear walls or diaphragms, are commonly connected with multiple (n) doweltype fasteners in a row. For such connections, it is frequently observed that the load-carrying capacity of multiple fasteners is less than the sum of the individual fastener capacities, a phenomenon referred to as the group effect. The research presented in this paper investigated the group effect in self-tapping screw (STS) shear connections between CLT panels. Different joint types (surface splines with STS in shear, and half-lap and butt joints with STS in either shear or withdrawal) were evaluated in a total of 175 quasi-static monotonic and reversed cyclic tests, with the number of STS in one row varied between 2 and 32. The results showed that the group effect for the joint capacity (strength) can be expressed as neff = 0.9n for all joints under static loading, where neff is the effective number of fasteners. In case of cyclic loading, a more pronounced group effect was observed that can be expressed as neff = n0.9. These reductions are significantly less conservative than the current Canadian design provisions for lag screws. For the reduction in stiffness and ductility, neff = n0.8 and neff = n0.9 can be used for all joints under static and cyclic loading, respectively. Finally, the capacity, ductility, and stiffness for joints under cyclic loading where the STS acted in withdrawal were on average 10% lower compared with the static values. [ABSTRACT FROM AUTHOR]

The research presented in this paper examines the shear resistance performance of self-tapping screws (STS) in three-ply crosslaminated timber (CLT) panels. Specifically, the feasibility of using innovative STS assemblies with double inclination of fasteners was investigated for the shear connection of CLT panels. The specimens (1.5 × 1.5 m) were subjected to quasi-static and reversed-cyclic loading. The tests were set up to approximate pure shear loading, with three-panel CLT assemblies connected with STS. The resulting loaddisplacement and hysteretic curves were used to determine an equivalent energy elastic-plastic curve to estimate assembly capacity, yield load, yield displacement, ductility ratio, stiffness, and damping. Excellent structural performance in terms of capacity and stiffness was obtained while still providing the required ductility for the system to be used in seismic applications. The average static and cyclic yield loads were 6.0 kN=screw and 5.9 kN=screw, respectively. Average static and cyclic and ductility ratios were 7.7 and 4.1, respectively, allowing the connection to be classified as highly ductile under quasi-static loading and moderately ductile under reversed cyclic loading. The data obtained allow engineers to specify an innovative connection assembly with double inclination of fasteners for lateral load-resisting systems of CLT structures. [ABSTRACT FROM AUTHOR]

The roof-to-wall connection in a house is designed to transfer the uplift and lateral loads during strong winds by providing a continuous load path from the roof to the foundation. The uplift capacity and failure mode of the connection depends on the number and type of fasteners (nails), timber species, type of framing anchor, and constructions defects. This paper presents experimental results that were used to assess the uplift capacity variation of typical roof-to-wall connections. Based on tests with two types of connections (triple grip and truss grip) assembled with two types of timber (radiata pine and spruce pine), nails (hand and gun), and framing anchors (triple grip and universal triple grip), the results show that the variation in timber species, nail, and triple grip type changes the strength and the failure modes of the connection. The strength of the connection was reduced by about 24% when the timber species was changed from radiata pine to spruce pine and the hand nail to gun nail on the triple grip connection. This study also showed that construction defects in roof-to-wall connections influence the design uplift capacity. If there are two missing nails in the hand-nailed triple grip connection (i.e., one nail on the truss and another one on the top plate) the design uplift capacity reduces by about 40% of the ideal hand-nailed triple grip connection. This study identified the critical nails and their locations required to mitigate failure of the roof-to-wall triple grip connection subject to wind loading. [ABSTRACT FROM AUTHOR]

This paper assesses the performance of a newly developed blind bolt, intended for use in constructing bolted moment-resisting connections to concrete-filled tubular steel profiles. A total of ten connection tests are reported, with each configuration having been subjected to a predominantly tensile force in a representation of the tension region of a typical moment connection. The test variables included type of fastener, addition of concrete to the tube, strength of the concrete, spacing among bolts, and bolt class. On the basis of deformability response, the benefits of filling the tubular member with concrete are highlighted. The favorable performance that results from using a relatively, high-grade concrete infill is also highlighted. The addition of a concrete infill to the tube stiffens and strengthens the otherwise relatively flexible tube walls, enhancing overall connection behavior in terms of stiffness, strength, and ductility. The performance of connections to concrete-filled tubular steel profiles using blind bolts with headed anchors is shown to be suitable for moment-resisting construction. [ABSTRACT FROM AUTHOR]

Vibration energy harvesters (VEHs) can utilize the vibration of the track to generate electricity and provide power for other devices within the harvester. To analyze whether energy harvesters arranged in an array harm track operation, we conducted a simulation analysis. Based on the vehicle–track coupling model, the influence of inductive electromotive force on track vibration was analyzed and compared with the simulation results obtained from the classical vehicle–track coupling model. The rail vibration displacement was reduced from 0.5 to 0.0692 mm, and the maximum vibration acceleration of the rail was reduced from 2.3759 to 0.4534 m/s2. The energy harvester can attenuate the vibration of the track significantly, and has a minor influence on the regular operation of the track. The vibration of a railway can be transformed to electric energy and used to power sensors at the railway side and train sides, such as velocity sensors, temperature sensors, accelerometers, wireless transmission modules, and other wireless sensor network (WSN) devices. It also can be used as backup power for the auxiliary load on the railway side, such as traffic lights and speed measuring radar. A vibration energy harvester installed at the fastener has a simple structure and can provide enough power for WSN sensors. It provides a good energy supply for line-side monitors and auxiliary devices. Because safety is the most critical issue for track devices, the effect of the installation of VEHs on the operation of the track should be analyzed. The vibration of a track with a fastener VEH is less than that without a VEH, which will reduce the impact of vibration on the environment and ensure the safe running of trains. This method also applies to the safety analysis of other track energy harvesting devices. [ABSTRACT FROM AUTHOR]

This study proposes an innovative type of simple connection utilizing power-actuated fasteners to join a cold-formed steel channel to a rectangular hollow section column via a web-side plate or a T-section. An experimental program composed of 26 specimens was carried out to investigate the behavior of the connections under the combination of shear and rotation. The experimental results are discussed in two limit states including bearing and pull-out by shear. An analytical model is proposed to predict the shear strength of the connections based on the provided information of vectorial force at a fastener, displacement, and rotation at the connections. The proposed model yields a conservative prediction for the tested connections with a mean test-to-prediction ratio of 1.05 and the coefficient of variation of 6% or 9%, depending on the limit state. A design example is provided to illustrate the implementation of the proposed model in practice. [ABSTRACT FROM AUTHOR]

A total of 105 cross-tension tests were conducted to investigate the strength and behavior of power-actuated fastener (PAF) connections under quasi-static monotonic tensile loading. Three types of PAF were used to join sheets with thicknesses ranging from 0.75 to 4.00 mm to thicker plates with thicknesses ranging from 3.00 to 20.0 mm. All of the steel materials were high-strength cold-formed steel, except for the 20-mm-thick steel, which was hot-rolled steel. The studied parameters were the type and diameter of the fasteners and the thicknesses of the top and base steel materials. The majority of the specimens failed by pull-out failure, although some thinner sheets failed by transverse fracture of the top sheet. The test results reveal that PAF connections exhibit a high tensile capacity as long as a sufficient embedment length is provided. A model is proposed to evaluate the pull-out strength of PAF connections based on the base material strength and the average embedded diameter and embedment length of the fastener. The proposed model produces a mean of test-to-prediction ratio equal to 1.02 with a coefficient of variation ranging from 0.12 to 0.16. Reliability analyses were carried out and resulted in a resistance factor of 0.56–0.69 for Load and Resistance Factor Design. [ABSTRACT FROM AUTHOR]

The installation of guardrails around a roof perimeter is an efficient way to protect construction workers against falls from heights, provided the guardrails are strong enough to arrest a fall. A guardrail's strength relies heavily on its fastening to the roof parapets, and an improper fastening could lead to unsafe guardrails. This article investigates the in situ strength of temporary steel guardrails installed on the flat roof parapets of two existing buildings, respectively built in 2008 and 2013. Thirty-six strength tests were conducted on three different guardrails and four different parapets, considering different methods of fastening the vertical posts to the parapets and varying the fastening hardware. The results show that some guardrails are not easily installed on smaller roof parapets, which could lead to improper installation on some work sites. Fastening using only one plane of the parapet often resulted in guardrails failing before reaching the regulatory strength requirement. Fastening using two planes of the parapets gave satisfactory results in comparison, and that should be the preferred fastening method to guarantee workers' safety. [ABSTRACT FROM AUTHOR]

Embedment strength is an important parameter that governs the ductile load-carrying capacity of timber joints with dowel-type fasteners. This property is dependent upon several factors, especially on the surface conditions of fasteners. In current design standards, however, the embedment strength depends only on the timber density and the diameter of fastener, though the surface conditions of dowels and fully threaded bolts are different. In this study, embedment tests for dowels, fully threaded bolts and glued-in rods in the direction parallel to the grain were carried out. Comparisons with the existing design equations in Eurocode 5 Design of Timber Structures (EC5) and American National Design Specification (NDS) were performed. It is found that the embedment strength in timber for dowels can be accurately predicted by EC5 and NDS, while the embedment strength for fully threaded bolts is underestimated. In addition, the embedment strength for glued-in rods is not addressed in the current design standards. Based on the presented experimental results, new empirical expressions for the embedment strength parallel to the grain in timber for fully threaded bolts and glued-in rods were proposed. [ABSTRACT FROM AUTHOR]

In existing wood strength prediction models for parallel to grain failure in timber connections using dowel-type fasteners, different methods consider the minimum, maximum, or summation of the tensile and shear capacities of the failed wood block planes. It is postulated that these methods are not appropriate since the stiffness of the adjacent wood loading the tensile and shear planes differs, and this leads to uneven load distribution among the resisting planes. A closed-form analytical method to determine the load-carrying capacity of wood under parallel-to-grain loading in small-dowel-type connections in timber products is thus proposed. For the wood strength, the stiffness of the adjacent loading volumes and strength of the failure planes subjected to nonuniform shear and tension stresses are considered. The effective wood thickness for the brittle failure mode is derived and related to the elastic deformation of the fastener. A mixed failure mode is also defined (a mixture of brittle and ductile) and depends on the governing ductile failure mode of the fastener. To help the designer, an algorithm is presented that allows the designer to calculate the resistances associated with predictions of the different possible brittle, ductile, and mixed failure modes. The proposed stiffness-based model has already been verified in brittle and mixed failure modes of timber rivet connections. In the research reported in this paper, an extended application is proposed for other small-dowel-type fasteners such as nails and screws. Results of nailed joint tests on laminated veneer lumber (LVL) and the test data available from the literature on glulam confirm the validity of this new method, and show that it can be used as a design provision for wood load-carrying capacity prediction of small-dowel-type timber connections. [ABSTRACT FROM AUTHOR]

The objective of this work is to investigate the shear capacity of small end distance lap joints in sheet steel fastened with a single bolt. For bolted connections in shear, the current American Iron and Steel Institute (AISI) specification does not differentiate between tilting limit states, in which the fastener rotates and thin sheet curls, and nontilting limit states, such as bearing and tearing. An experimental program consisting of 36 bolted specimens with a small end distance, 18 subject to tilting and 18 not subject to tilting, were conducted to explore this phenomenon. The conducted tests were compared to available predictions in the design specifications and the literature. The comparison indicates that tilting needs to be explicitly considered in the tested condition. Recommendations are provided for design. There is a need for future work to investigate multibolt configurations with small end distance and connections with members. [ABSTRACT FROM AUTHOR]

The simplicity of steel gravity framing systems in their load paths and construction has led to questions regarding their structural integrity or robustness. When considering structural integrity, the problem is often framed around the concept of column-removal scenarios, in which the structure must develop alternate load paths. The sometimes prohibitive space and resource requirements for experimental evaluation of steel gravity framing systems subjected to column-removal scenarios have resulted in the development of computational approaches to the problem. Recent computational research on this topic has highlighted the importance of considering the contribution of the composite slab to system robustness. A shell-based composite layup strip approach is the current state of the art for representing the composite slab in computational models. However, this approach has not been fully validated with experimental data and contains inherent assumptions, such as continuity of the metal deck between bays, that may not reflect construction realities. This study uses the results of experimental component level tests of the composite slab to evaluate those assumptions at the material, component, and system levels of modeling. [ABSTRACT FROM AUTHOR]

Currently, there is no formula for tie and direct fixation fastener (DFF) spacing. Because the rail does not bend between the tie/DFF, it is not possible to calculate spacing by the bending stress formula. Usually, rail-stress analysis confirms a trial spacing. Such analysis may support a longer spacing that might not address issues related to load distribution, pressure on formation, torsional rigidity, noise, and vibration. Thus, tie spacing is formulated from the perspective of wheel-load distribution and load dispersion by ballast, considering the fact that ties under the Benkel beam support the vertical load. The DFF/tie spacing is related to the characteristic length of the track, and this study shows that the desired DFF/tie spacing should be less than the characteristic length. Codes and practical examples validate spacing formulated for DFFs, concrete ties, and wood ties. [ABSTRACT FROM AUTHOR]

The article presents a three-dimensional nonlinear finite-element model that was developed for the study of a top and seat angle bolted steel connection with double web angles. Unilateral contact and friction laws were used to simulate the interaction among the connected parts. Large displacements as well as the von Mises failure criterion were also considered for the steel parts and bolts. Numerical results were compared with the experimental research conducted on the same steel joint. This study finds yielding of the top angle as well as shear failure of the bolts connecting the beam bottom flange with the seat angle to be very important for the overall response of the structure. For this reason, a parametric investigation of the influence of the top angle on the behavior of the structure and the study of the prying forces developed at the top angle were conducted. [ABSTRACT FROM AUTHOR]