• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.1
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• pp.1-9
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• 2022

Semi-integral abutment bridges are a type of integral abutment bridges. These bridges eliminate expansion joints on the structure and can be used in situations not suitable for full-integral abutment bridge. Moreover, Semi-integral bridges have excellent maintenance and can be economically constructed. This study is about precast wall-type blocks at each end which provide lateral support for PSC girder, as well as acting as retaining walls to resist longitudinal movement of semi-integral abutment bridge. The end-diaphragm connection between ended blocks of PSC girders can be achieved by in-suit nonshrinkage concrete. The results show that 3-point experiment of end-diaphragm beam have an acceptable performance which is so better than results of structural design. Moreover, the effects of backfill soil on semi-integral abutment bridge constructed are analyzed the behavior according to the temperature changes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.485-502
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• 2021

In order to evaluate the impact of ground subsidence and superstructures that are inevitably caused by tunnel excavation, a total of seven major influencing factors of surface subsidence and structural soundness reduction were set, and a Parameter Study using numerical analysis was conducted. Stability analysis was performed using scheme of Boscardin and Cording method and the maximum subsidence amount and the angular displacement, and correlation analysis was performed for each major influencing factor. In addition, it was applied that used the mutual behavior of the ground and the structure by parameter analysis in the site of the 𐩒𐩒𐩒 tunnel located in Hwaseong-si, Gyeonggi-do, and the applicability of the site was analyzed. As a result, the error was found to be 1.0%, and it could be used as a basic material for determining the appropriate tunnel route under various conditions when evaluating the stability of the structure according to tunnel excavating at the design stage.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.287-297
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• 2022

This paper presents experimental and analytical studies on the lateral cyclic behavior of RC columns actively confined with iron-based shape memory alloy (Fe-SMA) strips. Based on the Anexperimental study, we investigated the effectiveness of active confinement through compression testings of concrete cylinders confined by Fe SMA strips and carbon fiber-reinforced polymer (CFRP) sheets. The test results showed that the specimens confined with Fe SMA strips significantly increased the deformation capacity of the concrete, even under lower confining pressures, compared to those specimensconfined with CFRP sheets. The experimental results were used to develop finite-element models of RC columns confined with Fe SMA or CFRP in their plastic-hinge region. After validating the proposed analytical model through comparison with the results from a previous RC column test, a series of lateral cyclic load analyses were carried out for the RC columns confined with Fe SMA and CFRP. The analytical results revealed that the lateral cyclic behavior of the Fe SMA-confined column was greatly enhanced in terms of deformation and energy dissipation capacities compared with tothat of the as-built and CFRP-confined columns.

• Journal of Korean Association for Spatial Structures
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• v.22 no.3
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• pp.33-40
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• 2022

Recently, cultural heritages in South Korea gain many interests of restoration and preservation from the government since many of that have been severely damaged during earthquakes. Many previous studies in both terms of experimental and analytical approaches have been done to examine structural behavior and decide appropriate methods of preservation. Being motivated by such researches, this research aims to investigate a religious stone pagoda dated back to the Goryeo Dynasty in Korea. The structure consists of a granite stone foundation and baked bricks, which resembles the shape of traditional pagodas. In order to examine the structural behavior of the pagoda, an analytical model is implemented using ANSYS, a comprehensive engineering simulation platform. For the time history analysis of the pagoda, several earthquake excitations are chosen and input to simulation modeling. Seismic response of the tower such as time domain, natural frequency, modal shapes and peak acceleration measured at each layer are presented and discussed. In addition, the amplification ratio of the tower is calculated from the accelerations of each layer to determine tower stability in accordance with Korean seismic design guide. The determination and evaluation of status and response of the brick tower by simulation analysis play an important role in the preservation of history as well as valuable architectural heritages in South Korea.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.37-45
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• 2021

This paper is a basic study to evaluate the possibility of earthquake-resistant reinforcement by reinforcing engineered cementitious composite in masonry members. In order to examine the performance according to the fiber mixing rate of the engineered cementitious composite, a test specimen was prepared according to the formulation design, and flow ability, compressive strength, flexural strength, length change rate, and direct tensile strain were measured. In addition, non-reinforced masonry members, masonry members reinforced with engineered cementitious composite, and masonry members in which glass fibers and wire mesh were separately reinforced with engineered cementitious composites were manufactured, and flexural strength and maximum displacement were measured. All specimens reinforced with engineered cementitious composite showed more than 16 times the effect of maximal strength compared to that of no reinforcement, and as a result of examining the crack shape, the energy dissipation ability was excellent, confirming the possibility of seismic reinforcement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.185-192
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• 2021

In this study, Full-scale hollow slab Mock-up with VPS(Void Plywood Slab System) was produced. Through Mock-up, the safety of the flat plate hollow slab against short-term sagging and long-term sagging is to be evaluated. The hollow rate of the mock-up specimen to which the hollow core slab was applied was designed to be 24%. When loading through concrete blocks, the most central part of the slab was deflection 8.88mm when loading. However, it shows a safe value compared to the reference value (l_n/240=17.93mm) for short-term deflection. As a result of 3 months of measurement of the mock-up experiment, the deflection at the center of the slab increased by 6.792mm from the initial deflection. In addition, it was found that the reference value by the load used suggested by KBC2016 was satisfied.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.6
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• pp.775-786
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• 2022

In the plant structures including nuclear power plants, penetrations are frequently installed in walls and slabs to reinforce facilities during operation, and reinforcing bars are sometimes cut off during concrete coring. Since these penetrations are not considered at the design or construction stage, cutting of reinforcing bar during opening installation is actually damage to the structure, structural integrity evaluation considering the stress transition range or effective width around the new penetration is necessary. In this study, various nonlinear analyses and static loading experiments are performed to evaluate the effect of reinforcing bar cutting that occurs when a penetration is newly installed in the shear wall of wall-type building of operating nuclear power plant. In addition, the decrease in wall stiffness due to the installed new penetration and cutting of reinforcing bars is evaluated and the stress and strain distributions of rebars around penetration are also measured.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.64-71
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• 2022

In this study, fire and egress simulation was conducted for the egress safety evaluation of the nursing hospitals. A fire simulation was performed with or without the smoke exhaust system using the FDS, and the available safe egress time (ASET) of the nursing hospitals was calculated. In addition, an egress simulation considering the characteristics of occupants and egress delay time was performed using Pathfinder, and the required safe egress time (RSET) was calculated. By comparing the ASET and RSET, the egress safety of the nursing hospital with or without a smoke exhaust system was evaluated according to the number of egress guides and the egress delay time. The simulation results show that the number of casualties increased as the egress delay time increased, and the required safe egress time decreased as the number of egress guides increased. In addition, it was found that if a smoke exhaust system with the capacity specified in the KFPA is secured, the available safe egress time can be greatly increased and the number of casualties can be greatly reduced.

• Structural Engineering and Mechanics
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• v.83 no.4
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• pp.515-535
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• 2022

The strength models for fiber-reinforced polymer (FRP)-confined normal strength concrete (NC) cylinders available in the literature have been suggested based on small databases using limited variables of such structural members portraying less accuracy. The artificial neural network (ANN) is an advanced technique for precisely predicting the response of composite structures by considering a large number of parameters. The main objective of the present investigation is to develop an ANN model for the axial strength of FRP-confined NC cylinders using various parameters to give the highest accuracy of the predictions. To secure this aim, a large experimental database of 313 FRP-confined NC cylinders has been constructed from previous research investigations. An evaluation of 33 different empirical strength models has been performed using various statistical parameters (root mean squared error RMSE, mean absolute error MAE, and coefficient of determination R²) over the developed database. Then, a new ANN model using the Group Method of Data Handling (GMDH) has been proposed based on the experimental database that portrayed the highest performance as compared with the previous models with R²=0.92, RMSE=0.27, and MAE=0.33. Therefore, the suggested ANN model can accurately capture the axial strength of FRP-confined NC cylinders that can be used for the further analysis and design of such members in the construction industry.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.193-203
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• 2022

In this study, in order to compare the seismic performance of steel structure beam-column connection details and non-scallop connection details mainly used in Korea, a full-scale static cyclic loading test and FEM analysis were conducted through the same modeling as the experiment. For quantitative numerical comparison, the strain concentration ratio and moment transfer efficiency used in previous studies were cited. As the welding area of the beam web decreased, the deformation rate of the beam flange increased, and the plastic deformation capacity according to the rotation angle decreased or brittle fracture occurred. Comparing the analysis results with the experimental results, the possibility of brittle fracture tended to increase when the web welding ratio for the total cross-sectional area of H-shaped fell below 60%.