• Steel and Composite Structures
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• v.42 no.3
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• pp.315-323
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• 2022

Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self-tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

• Structural Engineering and Mechanics
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• v.84 no.3
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• pp.311-321
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• 2022

In the buildings with long spans and high floors, such as logistics warehouses and semiconductor factories, it is difficult to install supporting posts under beams during construction. Therefore, the size of structural members becomes larger inevitably, resulting in a significant increase in construction costs. Accordingly, a prestressed hybrid wide flange (PHWF) beam with hollowed steel webs was developed, which can reduce construction costs by making multiple openings in the web of the steel member embedded in concrete. However, since multiple openings exist and prestress is introduced only into the bottom flange concrete, it is necessary to identify the shear resistance mechanism of the PHWF beam. This study presents experimental shear tests of PHWF beams with hollowed steel webs. Four PHWF beams with cast-in-place (CIP) concrete were fabricated, with key variables being the width and spacing of the steel webs embedded in the concrete and the presence of shear reinforcing bars, and web-shear tests were conducted. The shear behavior of the PHWF beam, including crack patterns, strain behavior of steel webs, and composite action between the prestressed bottom flange and CIP concrete, were measured and analyzed comprehensively. The test results showed that the steel web resists external shear forces through shear deformation when its width is sufficiently large, but as its width decreased, it exerted its shear contribution through normal deformation in a manner similar to that of shear reinforcing bars. In addition, it was found that stirrups placed on the cross section where the steel web does not exist contribute to improving the shear strength and deformation capacity of the member. Based on the shear behavior of the specimens, a straightforward calculation method was proposed to estimate the web-shear strength of PHWF beams with CIP concrete, and it provided a good estimation of the shear strength of PHWF beams, more accurate than the existing code equations.

• Computers and Concrete
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• v.16 no.6
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• pp.825-846
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• 2015

In this study, shear tests on steel fiber reinforced-prestressed concrete (SFR-PSC) members were conducted with test parameters of the concrete compressive strength, the volume fraction of steel fibers, and the level of effective prestress. The SFR-PSC members showed higher shear strengths and stiffness after diagonal cracking compared to the conventional prestressed concrete (PSC) members without steel fibers. In addition, their shear deformational behavior was measured using the image-based non-contact displacement measurement system, which was then compared to the results of nonlinear finite element analyses (NLFEA). In the NLFEA proposed in this study, a bi-axial tensile behavior model, which can reflect the tensile behavior of the steel fiber-reinforced concrete (SFRC) in a simple manner, was introduced into the smeared crack truss model. The NLFEA model proposed in this study provided a good estimation of shear behavior of the SFRPSC members, such as the stiffness, strengths, and failure modes, reflecting the effect of the key influential factors.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.95-104
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• 2004

The horizontally curved bridges have been used to connect bridges and roads. Until 1960s, they had been constructed with straight girders, called 'kinked girder bridges', which requires much cost and time-consuming construction of substructure. In case of using curved girders, practiced later, they would have many advantages such as reduction in the total construction cost and time, and ability to make aesthetic bridges. In designing plate girder bridges, it is necessary to determine the spacings between vertical stiffeners and the allowable shear stresses based on shear buckling capacity because it plays a key role in preventing the premature local shear buckling. Compared with the straight web, the critical shear buckling stresses of curved web panels vary with both aspect ratio and curvature coefficient. For designing curved web panels, a simplified formula and shear buckling coefficients were proposed by parametric models with F.E.M in this study.

• Earthquakes and Structures
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• v.9 no.1
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• pp.127-143
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• 2015

In conventional seismic design, structures are assumed to be fixed at the base. To reduce the impact of earthquake loading, while at the same time providing an economically feasible structure, minor damage is tolerated in the form of controlled plastic hinging at predefined locations in the structure. Uplift is traditionally not permitted because of concerns that it would lead to collapse. However, observations of damage to structures that have been through major earthquakes reveal that partial and temporary uplift of structures can be beneficial in many cases. Allowing a structure to move as a rigid body is in fact one way to limit activated seismic forces that could lead to severe inelastic deformations. To further reduce the induced seismic energy, slip-friction connectors could be installed to act both as hold-downs resisting overturning and as contributors to structural damping. This paper reviews recent research on the concept, with a focus on timber shear walls. A novel approach used to achieve the desired sliding threshold in the slip-friction connectors is described. The wall uplifts when this threshold is reached, thereby imparting ductility to the structure. To resist base shear an innovative shear key was developed. Recent research confirms that the proposed system of timber wall, shear key, and slip-friction connectors, are feasible as a ductile and low-damage structural solution. Additional numerical studies explore the interaction between vertical load and slip-friction connector strength, and how this influences both the energy dissipation and self-centring capabilities of the rocking structure.

• Structural Engineering and Mechanics
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• v.47 no.4
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• pp.531-544
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• 2013

Compared with pavement structures of ordinary road sections, pavement structures in the intersection are exposed to more complex traffic characteristics which may exacerbates pavement distresses such as fatigue-cracking, shoving, shear deformation and rutting. Based on a field survey about traffic characteristics in the intersection conducted in Shanghai China, a three dimensional dynamic finite-element model was developed for evaluating the mechanistic responses in the pavement structures under different traffic characteristics, namely uniform speed, acceleration and deceleration. The results from this study indicated that : (1) traffic characteristics have significant effects on the distributions of the maximum principal strain (MPS) and the maximum shear stress (MSS) at the pavement surface; (2) vehicle acceleration or deceleration substantially impact the MPS and MSS at pavement surface and could increase the magnitude of them by 20 percent to 260 percent; (3) in the vertical direction, with the increase of vehicle deceleration rate, the location of the MPS peak value and the MSS peak value changes from the sub-surface layer to the pavement surface.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.233-240
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• 2018

Pullout tests are usually employed to determine the ultimate bearing capacity of reinforced soil, and the load-displacement curve can be obtained easily. This paper presents an analytical solution for predicting the full-range mechanical behavior of a buried planar reinforcement subjected to pullout based on a bi-linear bond-slip model. The full-range behavior consists of three consecutive stages: elastic stage, elastic-plastic stage and debonding stage. For each stage, closed-form solutions for the load-displacement relationship, the interfacial slip distribution, the interfacial shear stress distribution and the axial stress distribution along the planar reinforcement were derived. The ultimate load and the effective bond length were also obtained. Then the analytical model was calibrated and validated against three pullout experimental tests. The predicted load-displacement curves as well as the internal displacement distribution are in closed agreement with test results. Moreover, a parametric study on the effect of anchorage length, reinforcement axial stiffness, interfacial shear stiffness and interfacial shear strength is also presented, providing insights into the pullout behaviour of planar reinforcements of MSE structures.

• Geomechanics and Engineering
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• v.6 no.3
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• pp.277-292
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• 2014

Soil nailing, as an effective stabilizing method for slopes and excavations, has been widely used worldwide. However, the interaction mechanism of a soil nail and the surrounding soil and its influential factors are not well understood. A pullout model using a hyperbolic shear stress-shear strain relationship is proposed to describe the load-deformation behavior of a cement grouted soil nail. Numerical analysis has been conducted to solve the governing equation and the distribution of tensile force along the nail length is investigated through a parametric study. The simulation results are highly consistent with laboratory soil nail pullout test results in the literature, indicating that the proposed model is efficient and accurate. Furthermore, the effects of key parameters, including normal stress, degree of saturation of soil, and surface roughness of soil nail, on the model parameters are studied in detail.

• Steel and Composite Structures
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• v.30 no.4
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• pp.383-392
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• 2019

Passive steel dampers have shown favorable performance in last earthquakes, numerical and experimental studies. Although steel dampers are more affordable than other types of damper, they are not economically justified for ordinary buildings. Therefore, in this paper, an innovative steel damper with shear yielding mechanism is introduced, which is easy to fabricate also can be easily replaced after sever earthquakes. The main goal of implementing such a mechanism is to control the possible damage in the damper and to ensure the elastic behavior of other structural components. The numerical results indicate an enhancement of the hysteretic behavior of the concentrically braced frames utilizing the proposed damper. The proposed damper change brittle behavior of brace due to buckling to ductile behavior due to shear yielding in proposed damper. The necessary relations for the design of this damper have been presented. In addition, a model has been presented to estimate load-displacement of the damper without needing to finite element modeling.

• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.205-219
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• 2019

This paper analyzes nonlinear free vibration of the circular nano-tubes made of functionally graded materials in the framework of nonlocal strain gradient theory in conjunction with a refined higher order shear deformation beam model. The effective material properties of the tube related to the change of temperature are assumed to vary along the radius of tube based on the power law. The refined beam model is introduced which not only contains transverse shear deformation but also satisfies the stress boundary conditions where shear stress cancels each other out on the inner and outer surfaces. Moreover, it can degenerate the Euler beam model, the Timoshenko beam model and the Reddy beam model. By incorporating this model with Hamilton's principle, the nonlinear vibration equations are established. The equations, including a material length scale parameter as well as a nonlocal parameter, can describe the size-dependent in linear and nonlinear vibration of FGM nanotubes. Analytical solution is obtained by using a two-steps perturbation method. Several comparisons are performed to validate the present analysis. Eventually, the effects of various physical parameters on nonlinear and linear natural frequencies of FGM nanotubes are analyzed, such as inner radius, temperature, nonlocal parameter, strain gradient parameter, scale parameter ratio, slenderness ratio, volume indexes, different beam models.