• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.1-8
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• 2014

The present study proposes a simple equation to straightforwardly determine the potential plastic hinge length in boundary element of reinforced concrete shear walls. From the idealized curvature distribution along the shear wall length, a basic formula was derived as a function of yielding moment, maximum moment, and additional moment owing to diagonal tensile crack. Yielding moment and maximum moment capacities of shear wall were calculated on the basis of compatability of strain and equilibrium equation of internal forces. The development of a diagonal tensile crack at web was examined from the shear transfer capacity of concrete specified in ACI 318-11 provision and then the additional moment was calculated using the truss mechanism along the crack proposed by Park and Paulay. The moment capacities were simplified from an extensive parametric study; as a result, the equivalent plastic hinge length of shear walls could be formulated using indices of longitudinal tensile reinforcement at the boundary element, vertical reinforcement at web, and applied axial load. The proposed equation predicted accurately the measured plastic hinge length, providing that the mean and standard deviation of ratios between predictions and experiments are 1.019 and 0.102, respectively.

• Journal of the Korean GEO-environmental Society
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• v.5 no.1
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• pp.55-64
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• 2004

Stone column is a soil improvement method and can be applicable for loose sand or weak cohesive soil. Since the lack of sand in korea, stone column seems one of the most adaptable approach for poor ground as a soil improvement technique. However, this method was not studied for practical application. In this paper, the most affective design parameters for the bearing capacity of stone column were studied. The parametric study of major design factors for single stone column was carried out under the bulging and general shear failure condition, respectively. Especially, a test result of single stone column by static load was compared with the bearing capacity values of suggested formulas. The analysis result showed that the ultimate bearing capacity by the formula was much less than the measured value by the static load test. Especially, the result of the parametric study under general shear failure condition showed that the bearing capacity has big difference between each suggested formulas with the variation of the major design parameters. Therefore, the result of this study can be appliable for the future stone column project.

• Earthquakes and Structures
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• v.9 no.6
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• pp.1233-1250
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• 2015

The behavior of reinforced concrete (RC) columns made from high strength materials was investigated experimentally. Six high-strength concrete specimen columns (1:4 scale), which included three with high-strength transverse reinforcing bars and three with normal-strength transverse reinforcement, were tested under double curvature bending load. The effects of yielding strength and ratio of transverse reinforcement on the cracking patterns, hysteretic response, shear strength, ductility, strength reduction, energy dissipation and strain of reinforcement were studied. The test results indicated that all specimens failed in splitting failure, and specimens with high-strength transverse reinforcement exhibited better seismic performance than those with normal-strength transverse reinforcement. It also demonstrated that the strength of high-strength lateral reinforcing bars was fully utilized at the ultimate displacements. Shear strength formula of short concrete columns, which experienced a splitting failure, was proposed based on the Chinese concrete code. To enhance the applicability of the model, it was corroborated with 47 short concrete columns selected from the literature available. The results indicated that, the proposed method can give better predictions of shear strength for short columns that experienced a splitting failure than other shear strength models of ACI 318 and Chinese concrete codes.

• Earthquakes and Structures
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• v.27 no.1
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• pp.31-39
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• 2024

The reliability-based seismic design of steel frames is a complex process that incorporates seismic demand with a structural capacity to attain safe buildings aligned with specified constraints. This paper introduces an efficient base shear force formulation to support the reliability-based design process of steel frames. The introduced base shear force equation combines the seismic demand statistics with the reliability objective to calculate a fictitious base shear force for linear static analysis. By concentrating on the seismic demand and promising to meet a certain level of reliability, the equation converts the reliability-based seismic design problem to a deterministic one. Two code-compliant real-size steel moment frames are developed according to different reliability objectives to demonstrate the competency of the proposed formula. The nonlinear dynamic analysis method is used to assess the seismic reliability of the constructed frames, and the numerical results validate the credibility of the suggested formulation. The base shear force calculation method regarding seismic reliability is the main finding of this study. The ease of use makes this approach a potent tool for design professionals and stakeholders to make rapid risk-informed decisions regarding steel moment frame design.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.83-90
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• 2007

The present study reports a simple unbonded-type shear strengthening technique for reinforced concrete beams using wire rope units. Fifteen beams failed in shear were repaired and strengthened with wire rope units, and then retested to failure. Influence of the prestressing force, orientation and spacing of wire rope units on the shear behavior of strengthened beams having shear span-to-depth ratios of 1.5, 2.5, or 3.25 were investigated. Test results showed that beams strengthened with wire rope units exhibited a higher shear strength and a larger post-failure deformation than the corresponding original beams. Inclined wire rope units was more effective for shear strength enhancement than vertical wire rope units. The increase of the prestressing force in wire rope units causes the decrease of the principal tensile stress in concrete, as a result, the diagonal tensile cracking strength of strengthened beams was higher than that of the corresponding original beams. Shear capacity of strengthened beams is compared with predictions obtained from ACI 318-05 and EC 2. Shear capacity of strengthened beams having shear span-to-depth ratio below 2.5 is reasonably predicted using ACI 318-05 formula. On the other hand, EC 2 overestimates the shear transfer capacity of wire rope units for beams having shear span-to-depth ratio above 2.5.

• Computers and Concrete
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• v.30 no.5
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• pp.311-321
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• 2022

The interfacial bond strength of partially encased composite (PEC) structure tends to 0, therefore, the cast-in-place concrete theoretically cannot embody better composite effect than the fabricated structure. A total of 12 specimens were designed and experimented to investigate the energy dissipation and damage of fabricated PEC beam through unidirectional cyclic loading test. Because the concrete on both sides of the web was relatively independent, some specimens showed obvious asymmetric concrete damage, which led to specimens bearing torsion effect at the later stage of loading. Based on the concept of the ideal elastoplastic model of uniaxial tensile steel and the principle of equivalent energy dissipation, the energy dissipation ductility coefficient is proposed, which can simultaneously reflect the deformability and bearing capacity. In view of the whole deformation of the beam, the calculation formula of energy dissipation is put forward, and the energy dissipation and its proportion of shear-bending region and pure bending region are calculated respectively. The energy dissipation efficiency of the pure bending region is significantly higher than that of the shear-bending region. The setting of the screw arbors is conducive to improving the energy dissipation capacity of the specimens. Under the condition of setting the screw arbors and meeting the reasonable shear span ratio, reducing the concrete pouring thickness can lighten the deadweight of the component and improve the comprehensive benefit, and will not have an adverse impact on the energy dissipation capacity of the beam. A damage model is proposed to quantify the damage changes of PEC beams under cyclic load, which can accurately reflect the load damage and deformation damage.

• Steel and Composite Structures
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• v.32 no.6
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• pp.743-752
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• 2019

Steel and concrete composite structures are commonly applied in multi-story buildings as they maximise the material strength through composite action. Despite the popularity of employing a trapezoidal deck slab, limited experimental data are available under elevated temperatures. The behaviour of the headed shear stud embedded in a transverse trapezoidal deck and solid slab was investigated at both ambient and fire conditions. Twelve push-out tests were conducted according to the ISO 834 standard fire utilising a customised electric furnace. A stud shearing failure was observed in the solid slab specimen, whereas the failure mode was changed from a concrete-dominated failure to the stud shearing in the transverse deck specimen with an increase in temperature. Comparisons between the experimental observations and design requirements are presented. The Eurocode design guidance on the transverse deck slab gives a highly conservative estimate for shear resistance. A new design formula was proposed to determine the capacity of the shear connection regardless of the slab type when the stud shearing occurs at high temperatures.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.611-620
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• 2006

In the shear failure mechanism of a beam, beam and arch actions always exist simultaneously. According to the shear span to depth ratio, the proportion between these two actions is varied and the contribution of these actions to shear capacity is changed. Moreover, the current codes provide recommendations based on experimental results of normal strength concrete, so the application range of concrete strength must be extended. Based on this mechanism and new requirement, a simplified analytical equation for shear capacity prediction of reinforced high strength concrete beams without stirrups is proposed. To reflect the change in the contribution between these actions, stress variation in the longitudinal reinforcement along the span is considered by use of the Jenq and Shah Model. Dowel action with horizontal splitting failure and shear friction between cracks are also taken into account. ize effect is included to derive a more precise equation. Regression analysis is performed to determine each variable and simplify the equation. And, the formula derived from theoretical approaches is evaluated by comparison with numerous experimental data, which are in broad range of concrete strength(especially in high strength concrete), shear span to depth ratio, geometrical size and longitudinal steel ratio. It is shown that the proposed equation is more accurate and simpler than other empirical equations, so a wide range of a/d can be considered in one equation.

• Steel and Composite Structures
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• v.27 no.5
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• pp.537-543
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• 2018

Mechanical shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface in composite beams. Steel pipe as a new shear connector is proposed in this research and its performance to achieve composite strength is investigated. Experimental monotonic push-out tests were carried out for this connector. Then, a nonlinear finite element model of the push-out specimens is developed and verified against test results. Further, the finite element model is used to investigate the effects of pipe thickness, length and diameter on the shear strength of the connectors. The ultimate strengths of these connectors are reported and their respective failure modes are discussed. This paper comprises of the push-out tests of ten specimens on this shear connector in both the vertical and horizontal positions in different reinforced concretes. The results of experimental tests are given as load-deformation plots. It is concluded that the use of these connectors is very effective and economical in the medium shear demand range of 150-350 KN. The dominant failure modes observed were either failure of concrete block (crushing and splitting) or shear failure of pipe connector. It is shown that the horizontal pipe is not as effective as vertical pipe shear connector and is not recommended for practical use. It is shown that pipe connectors are more effective in transferring shear forces than channel and stud connectors. Moreover, based on the parametric study, a formula is presented to predict the pipe shear connectors' capacity.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.69-76
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• 2005

The pull-out capacity of expansion anchor(heavy duty anchor and wedge anchor) was studied experimentally in this paper. Loading conditions included tension, shear, and combined tension and shear. The heavy duty anchor and wedge anchor were manufactured in domestic and installed In plain concrete. The failure mode of steel and concrete were studied carefully for the analytical formula of the anchorage design and the experimental data were compared with different models for the interaction of tension and shear capacities. Based on the research, the following conclusion may be drawn : The interaction of forces is well-described by an elliptical interaction relationship.