• Structural Monitoring and Maintenance
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• v.7 no.3
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• pp.167-193
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• 2020

In this paper, the behavior of interior steel fiber reinforced concrete beam - column joints (BCJs) under cyclic loading is investigated. An experimental program including tests on twelve reinforced concrete (BCJs) specimens under cyclic loading was carried out. The test specimens are divided into two groups having different geometry: group (G1) (symmetrical BCJs specimens) and group (G2) (nonsymmetrical BCJs specimens). The parameters considered in this study are the steel fibers (SFs) content by volume of concrete (V_f), the spacing of shear reinforcement at the joint region, and the area of longitudinal flexural reinforcement. Test results show that the addition of 0.5% SFs with stirrups spacing S=S_max has effectively enhanced the overall performance of BCJs with respect to energy dissipation, ductility ratio, spreading and width of cracks. The failure of specimens is governed mainly by the formation of a plastic hinge at the face column and outside the beam-column junction. Secondary shear cracks were also observed in the beam-column junctions.

• Structural Engineering and Mechanics
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• v.41 no.1
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• pp.43-65
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• 2012

The primary objective of this study was to identify concrete contribution to the initial shear strength of reinforced concrete (RC) hollow columns under lateral loading. Seven large-scale RC rectangular hollow column specimens were tested under monotonic or cyclic lateral loads. The most important design parameter was column length-to-depth aspect ratio ranging between 1.5 and 3.0, and the other test variables included web area ratio, hollow section ratio, and loading history. The tests showed that the initial shear strength reduced in a linear pattern as the column aspect ratio increased, and one specimen tested under cyclic loading achieved approximately 83% of the shear strength of the companion specimen under monotonic loading. Also, several pioneering shear models proposed around the world, all of which were mainly based on tests for columns with solid sections, were reviewed and compared with the test results of this study, for their possible applications to columns with hollow sections. After all, an empirical equation was proposed for concrete contribution to the initial shear strength of RC hollow columns based on fundamental mechanics and the test results.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1458-1465
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• 2010

A lot of dredging and reclaming projects are recently under way in Korea for the efficient use of limiting land space. Saemanguem area is special case of reclaiming by dredged soil. In case of a confined disposal of dredged soils by a pump dredger, generally coarse grained soils are separated from fines with dropping at the near part of the pump dredger. This kind of seperation of fine contents could be a factor of liquefaction by earthquake. In Korea, recently, earthquakes with magnitude of 3.0 or higher are distinctively increasing in 1990. In this study, cyclic shear characterics of Saemanguem Dredged sand depending on fine content were analyzed. A series of undrained cyclic triaxial test with cyclic stress ratio ($\sigma_d/{2\sigma_{{\upsilon}c}}'$) were performed on both isotropic consolidated specimen and sand with fine contents of 0%, 5%, 15%, 30%, 40% under the effective vertical stress of 100kPa and 50% and 60%, 70% of relative density for fine content of 0%, respectively. In the test results, cyclic shear strength increased by increasing of cyclic stress ratio($\sigma_d/{2\sigma_{{\upsilon}c}}'$) with increasing the relative density at the same number of cyclic under the effective confining pressure of 100kPa. It is almost highest the double amplitude(DA) 1%, 3%, 5%, 7.5% and 10% at fine content of 15% between Cyclic stress ratio($\sigma_d/{2\sigma_{{\upsilon}c}}'$) value at cyclic number five and fine content. Number of cyclic is 30 under the effective vertical stress of 100kPa, 70% of relative density for fine content of 15%. when the cyclic stress ratio at each relative density was compared at cyclic number five, the double amplitude(DA) 1%, 3%, 5%, 7.5% and 10%, and the pore-pressure ratio (${\Delta}u/{\sigma'}_c$) 0.95 value were compared; under the relative density of 70% and the effective confining pressure of 100kPa. The pore-pressure ratio (${\Delta}u/{\sigma'}_c$) 0.95 value showed a similar trend to the double amplitude (DA) 5% line.

• Structural Engineering and Mechanics
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• v.44 no.2
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• pp.163-178
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• 2012

A strut-and-tie model is introduced in this paper to predict the ultimate shear strength of non-seismically detailed columns. The validity and applicability of the proposed strut-and-tie model are evaluated by comparison with available experimental data. The model was developed based on visible crack patterns observed on the test specimens. The concrete contribution is integrated into the strut-and-tie model through a concept of equivalent transverse reinforcement. To further validate the model a full-scale non-seismically detailed reinforced concrete column was tested to investigate its seismic behavior. The specimen was tested under the combination of a constant axial load, $0.30f_c{^{\prime}}A_g$ and quasi-static cyclic loadings simulating earthquake actions. Quasi-static cyclic loadings simulating earthquake actions were applied to the specimen until it could not sustain the applied axial load. The analytical results reveal that the strut-and-tie method is capable of modeling to a satisfactory accuracy the ultimate shear strength of non-seismically detailed columns subjected to reserved cyclic loadings.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.5
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• pp.57-66
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• 2003

In order to verify the applicability of the developed modified parallel IWAN model. two types of cyclic torsional shear tests were performed using Kum-Kang and Toyoura sands. One was a symmetric-limit loading test and the other was an irregular loading test. Model parameters were derived from the symmetric limit loading tests at various relative densities and confining pressures. The modified parallel IWAN model can predict the cyclic hardening behavior of sands very well as increasing loading cycles in the symmetric-limit tests. Irregular loading tests were performed using the loading shape suggested by Pyke(1979). Cyclic behaviors under irregular loading were simulated using model parameters derived from symmetric limit loading test results of similar loading conditions. The predicted cyclic hardening behaviors under irregular loading matched well with experimental results and the applicability of the proposed model was verified.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.53-60
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• 2023

Recently, a novel cast-in specialty insert was developed in Korea as an anchor for lightweight pipe supports, including fire-protection pipes. As these pipe supports and anchors play a critical role in transferring loads of fire-protection pipes to structural members, it is crucial to evaluate their seismic performance before applying the newly developed insert. In this study, the seismic shear performance of the insert anchors was evaluated through cyclic loading tests based on the loading protocols of ACI 355.2 and FEMA 461. Initially, five monotonic loading tests were conducted on the insert anchors in cracked concrete, followed by cyclic loading tests based on the monotonic test results. The findings revealed that the insert anchors exhibited negligible decrease in shear strength even after cyclic loading. Furthermore, a comparison of the maximum load and displacement of the insert anchors obtained under the loading protocols of ACI 355.2 and FEMA 461 was performed to investigate the applicability of the FEMA 461 loading protocol for anchor performance evaluation.

• Journal of Korean Society of Steel Construction
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• v.30 no.1
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• pp.37-48
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• 2018

Cyclic loading tests for shear dominant hybrid steel link beams with circular web openings were performed to evaluate the seismic performance. Four half-scaled specimens with bolted connections were tested. The test parameter is a diameter of the web opening, i.e., shear strength ratio ($V_{pw}/V_p$) of the link beam and presence of top-seat angles. Using test results, adequate design shear strength of link beam was finally suggested. Test results showed that when the shear capacity is less than half of the plastic shear strength, seismic performance was improved due to mitigation of pinching under reversed cyclic inelastic deformations.

• Journal of the Korean GEO-environmental Society
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• v.12 no.11
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• pp.65-70
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• 2011

It is well known all much information for evaluation on possibility of liquefaction and lateral flow for sand over the world. Recently, it is started to be known that liquefaction happens on non-plastic silt, too. But cyclic and post-cyclic characteristics for non-plastic silt is a few familiar to the world. Specially, it is not aware of the estimating method for lateral flow on non-plastic silt. The main purpose in this paper is to propose the evaluation for liquefaction and lateral flow on non-plastic silt. The method used in this research is that possibility for liquefaction on non-plastic silt was evaluated with cyclic direct simple shear test, and then residental strength was estimated with static shear test. Through the test results liquefaction on non-plastic silt is well not happened but strength decreases rapidly with increasing shear stress. With the proposed method it can be evaluated possibility of liquefaction and propose lateral flow.

• Computers and Concrete
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• v.10 no.2
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• pp.173-196
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• 2012

Experimental results of cyclic reversed lateral force test on a two-story reinforced concrete shear wall sub-assemblage are simulated analytically by using the PERFORM-3D program. A comparison of experimental and analytical results leads to the following conclusions: (1) "Shear Wall" and "General Wall" models with "Concrete shear" cannot simulate the pinching phenomena due to shear and show larger amounts of inelastic energy absorption than those in the experiment. (2) Modeling a story-height wall by using two or more "General Wall" elements with "Diagonal shear" in the vertical direction induces the phenomenon of swelling-out at the belly, leading to the erroneous simulation of shear behaviors. In application to tall building structures, it is recommended to use one element of "General Wall" with "Diagonal shear" for the full height of a story. (3) In the plastic hinge area, concrete deformations of analytical models overestimate elongation and underestimate shortening when compared with experimental results.

• Geomechanics and Engineering
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• v.18 no.5
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• pp.503-513
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• 2019

In the present, the liquefaction potential of fiber-reinforced sandy soils was investigated through the energy-based approach by conducting a series of strain-controlled cyclic simple shear tests. In the tests, the effects of the fiber properties, such as the fiber content, fiber length, relative density and effective stress, and the test parameters on sandy soil improvement were investigated. The results indicated that the fiber inclusion yields to higher cumulative liquefaction energy values compared to the unreinforced (plain) ground by increasing the number of cycles and shear strength needed for the liquefaction of the soil. This result reveals that the fiber inclusion increases the resistance of the soil to liquefaction. However, the increase in the fiber content was determined to be more effective on the test results compared to the fiber length. Furthermore, the increase in the relative density of the soil increases the efficiency of the fibers on soil strengthening.