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Although many studies on the blast-resistant performance of structures have focused mainly on single members such as beams and columns, there is little research on the behavior of joints that are subjected to blast loads. In this study, the structural behavior of a slab–column connection subjected to blast load was investigated using a numerical analysis method. LS-DYNA was used as a finite element analysis program, and in order to improve the accuracy of numerical analysis, mesh size, material model, and simulation method of blast load were determined through preliminary analysis. The effect of different restraints of the joints, depending on the position of the columns in the slab, on the blast resistance performance was investigated. As a result, the highly confined slab-interior column connection showed better behavior than other edge and corner columns. The drop panel installed between the lower column and the slab was effective in improving the blast-resistance performance of the slab–column connection. For a more accurate evaluation of blast resistance performance, it was suggested that various evaluation factors such as ductility ratio, reinforcing stress, and concrete fracture area can be considered along with the support rotation, which is an important evaluation factor suggested by many standards.
Kwang Mo Lim; Taek Hee Han; Joo Ha Lee. Numerical Simulation on Dynamic Behavior of Slab–Column Connections Subjected to Blast Loads. Applied Sciences 2021, 11, 7573 .
AMA StyleKwang Mo Lim, Taek Hee Han, Joo Ha Lee. Numerical Simulation on Dynamic Behavior of Slab–Column Connections Subjected to Blast Loads. Applied Sciences. 2021; 11 (16):7573.
Chicago/Turabian StyleKwang Mo Lim; Taek Hee Han; Joo Ha Lee. 2021. "Numerical Simulation on Dynamic Behavior of Slab–Column Connections Subjected to Blast Loads." Applied Sciences 11, no. 16: 7573.
The behavior of a slab-column joint subjected to blast loads was studied by numerical analysis using a general-purpose finite element analysis program, LS-DYNA. Under the explosive load, the joint region known as the stress disturbed zone was defined as a region with a scaled distance of 0.1 m/kg1/3 or less through comparison with ConWep’s empirical formula. Displacement and support rotation according to Trinitrotoluene (TNT) weight and scaled distance were investigated by dividing in and out of the joint region. In addition, fracture volume was newly proposed as an evaluation factor for blast-resistant performance, and it was confirmed that the degree of damage to a member due to blast loads was well represented by the fracture volume. Finally, a prediction equation for the blast-resistant performance of the slab-column joint was proposed, and the reliability and accuracy of the equation were verified through additional numerical analysis.
Kwang Mo Lim; Do Guen Yoo; Bo Yeon Lee; Joo Ha Lee. Prediction of Damage Level of Slab-Column Joints under Blast Load. Applied Sciences 2020, 10, 5837 .
AMA StyleKwang Mo Lim, Do Guen Yoo, Bo Yeon Lee, Joo Ha Lee. Prediction of Damage Level of Slab-Column Joints under Blast Load. Applied Sciences. 2020; 10 (17):5837.
Chicago/Turabian StyleKwang Mo Lim; Do Guen Yoo; Bo Yeon Lee; Joo Ha Lee. 2020. "Prediction of Damage Level of Slab-Column Joints under Blast Load." Applied Sciences 10, no. 17: 5837.
The accurate measurement of effective absorption capacity is crucial for highly absorptive materials when they are used within cement-based materials. In this study, a method for examining effective absorption capacity using isothermal calorimetry is reviewed and investigated in detail to accommodate different circumstances. Specifically, the effect of different pore structures and water-to-cement ratios in determining effective absorption capacity is experimentally examined using activated carbon fibre and powdered activated carbon. The results suggest that the method may be suitable for porous materials with micropores but not suitable for those with mesopores. Also, the results indicate that the effective absorption capacity value can change with the water-to-cement ratio used. These findings can be used to find the effective absorption capacity of highly absorptive materials more accurately using the isothermal calorimetry method.
Joo-Ha Lee; Do Guen Yoo; Bo Yeon Lee. Effective Absorption Capacity Examined by Isothermal Calorimetry: Effect of Pore Structure and Water-to-Cement Ratio. Advances in Materials Science and Engineering 2020, 2020, 1 -8.
AMA StyleJoo-Ha Lee, Do Guen Yoo, Bo Yeon Lee. Effective Absorption Capacity Examined by Isothermal Calorimetry: Effect of Pore Structure and Water-to-Cement Ratio. Advances in Materials Science and Engineering. 2020; 2020 ():1-8.
Chicago/Turabian StyleJoo-Ha Lee; Do Guen Yoo; Bo Yeon Lee. 2020. "Effective Absorption Capacity Examined by Isothermal Calorimetry: Effect of Pore Structure and Water-to-Cement Ratio." Advances in Materials Science and Engineering 2020, no. : 1-8.
Water supply facilities such as waterworks systems are facilities that supply residential and industrial water essential for humans to live and it is essential for these facilities to be prepared for earthquake hazards. In the present study, new hydraulic analysis procedures that can complement problems in existing model were proposed for performance quantification under seismic hazards. Detailed procedures for estimating the serviceability of water supply networks using pressure dependent demand (PDD) and pressure dependent leakage (PDL) techniques were proposed. The developed methodologies can simulate many pipe leakage and breakage situations more realistically. The methodologies were applied to representative pipe networks to investigate the models and new performance quantification indicators were additionally presented. The developed models are judged to be usable as a basic tool finding for guidelines because they can simultaneously quantify the amount of leakage calculated from the viewpoint of suppliers as well as the water availability of consumers when an earthquake hazard has occurred.
Do Guen Yoo; Joo Ha Lee; Bo Yeon Lee. Comparative Study of Hydraulic Simulation Techniques for Water Supply Networks under Earthquake Hazard. Water 2019, 11, 333 .
AMA StyleDo Guen Yoo, Joo Ha Lee, Bo Yeon Lee. Comparative Study of Hydraulic Simulation Techniques for Water Supply Networks under Earthquake Hazard. Water. 2019; 11 (2):333.
Chicago/Turabian StyleDo Guen Yoo; Joo Ha Lee; Bo Yeon Lee. 2019. "Comparative Study of Hydraulic Simulation Techniques for Water Supply Networks under Earthquake Hazard." Water 11, no. 2: 333.
This study evaluated the performance of latex-modified fiber-reinforced concrete (RC) segments as a function of the substitution level of microsilica and type of reinforced fiber, to address the problem of corrosion of steel segments and steel-reinforced fiber segments, which are commonly used to shield tunnel-boring machine (TBM) tunnels in urban spaces. Our study compared macro synthetic, steel, and hybrid (macro synthetic fiber + polypropylene fiber) reinforcing fibers. The substitution levels of microsilica used were 0, 2, 4, and 6%. The target strengths were set at 40 and 60 MPa to test compressive strength, flexural strength, chloride ion penetration resistance, and impact resistance. Testing of latex-modified and fiber-reinforced segment concrete showed that the compressive strength, flexural strength, and chloride ion penetration resistance increased with an increasing substitution level of microsilica. These improvements were attributed to the densification of the concrete due to filling micropores with microsilica. Micro synthetic fiber was more effective in terms of improved compressive strength, flexural strength, and chloride ion penetration resistance than steel fiber. These results were due to the higher number of micro synthetic fibers per unit volume compared with steel fiber, which reduced the void volume and suppressed the development of internal cracks. The optimal microsilica content and fiber volume fraction of micro synthetic fiber were 6% and 1%, respectively. To evaluate the effects of the selected mixtures and hybrid fibers simultaneously, other mixing variables were fixed and a hybrid fiber mixture (combination of macro synthetic fibers and polypropylene fibers) was used. The hybrid fiber mixture produced better compressive strength, flexural strength, chloride ion penetration resistance, and impact resistance than the micro synthetic fibers.
Woong Kim; Ri-On Oh; Joo-Ha Lee; Mi-Sol Kim; Sang-Min Jeon; Chan-Gi Park. Mechanical and Durability Characteristics of Latex-Modified Fiber-Reinforced Segment Concrete as a Function of Microsilica Content. Advances in Civil Engineering 2019, 2019, 1 -10.
AMA StyleWoong Kim, Ri-On Oh, Joo-Ha Lee, Mi-Sol Kim, Sang-Min Jeon, Chan-Gi Park. Mechanical and Durability Characteristics of Latex-Modified Fiber-Reinforced Segment Concrete as a Function of Microsilica Content. Advances in Civil Engineering. 2019; 2019 ():1-10.
Chicago/Turabian StyleWoong Kim; Ri-On Oh; Joo-Ha Lee; Mi-Sol Kim; Sang-Min Jeon; Chan-Gi Park. 2019. "Mechanical and Durability Characteristics of Latex-Modified Fiber-Reinforced Segment Concrete as a Function of Microsilica Content." Advances in Civil Engineering 2019, no. : 1-10.
Nowadays prestressed concrete (PSC) bridges have become very common, but there are still many difficulties in predicting their long-term behavior. In order to predict the long-term behavior of PSC bridges, it is possible to use very complex formulas developed by various researchers or numerical analysis through computer, but many engineers are having difficulty in using such methods. Moreover, the accuracy of the prediction result is not satisfactory compared to the effort. On the contrary, the PCI Bridge Design Manual proposes a method that can easily predict the long-term behavior using multipliers. However, this method does not take into account various construction schedules and has some assumptions that are inadequate for the current situation in various girder sections and topping thicknesses. Therefore, in this study, new long-time factors were developed by modifying the multipliers of the PCI Bridge Design Manual by a rational manner. This allows prediction of long-term behavior of bridges taking into account various construction schedules and the characteristics of modern girder sections. The prediction results of the long-term camber and deflection of PSC bridges using the proposed multipliers were compared with those using the basic PCI Bridge Design Manual, the improved PCI Bridge Design Manual, KR C-08090 (same as ACI 318-14), and numerical analysis. As a result, the newly proposed method makes possible to predict the long-term behavior at any time after casting, and the accuracy of the prediction is also improved.
Joo-Ha Lee; Kwang-Mo Lim; Chan-Gi Park. Modified PCI Multipliers for Time-Dependent Deformation of PSC Bridges. Advances in Civil Engineering 2018, 2018, 1 -13.
AMA StyleJoo-Ha Lee, Kwang-Mo Lim, Chan-Gi Park. Modified PCI Multipliers for Time-Dependent Deformation of PSC Bridges. Advances in Civil Engineering. 2018; 2018 ():1-13.
Chicago/Turabian StyleJoo-Ha Lee; Kwang-Mo Lim; Chan-Gi Park. 2018. "Modified PCI Multipliers for Time-Dependent Deformation of PSC Bridges." Advances in Civil Engineering 2018, no. : 1-13.
This study assessed the mechanical properties and durability of latex-modified fiber-reinforced segment concrete (polyolefin-based macrosynthetic fibers and hybrid fiber-macrosynthetic fiber and polypropylene fiber) for a tunnel liner application. The tested macrosynthetic fiber-reinforced concrete has a better strength than steel fiber-reinforced concrete. The tested concrete with blast furnace slag has a higher chloride ion penetration resistance (less permeable), but its compressive and flexural strengths can be reduced with blast furnace slag content increase. Also, the hybrid fiber-reinforced concrete has higher compressive strength, flexural strength, chloride ion water permeability resistance, impact resistance, and abrasion resistance than the macrosynthetic fiber-reinforced concrete. The modified fiber improved the performance of concrete, and the hybrid fiber was found to control the formation of micro- and macrocracks more effectively. Therefore, overall performance of the hybrid fiber-reinforced concrete was found superior to the other fiber-reinforced concrete mixes tested for this study. The test results also indicated that macrosynthetic fiber could replace the steel fiber as a concrete reinforcement.
Joo-Ha Lee; Hwang-Hee Kim; Sung-Ki Park; Ri-On Oh; Hae-Do Kim; Chan-Gi Park. Mechanical Properties and Durability of Latex-Modified Fiber-Reinforced Concrete: A Tunnel Liner Application. Advances in Materials Science and Engineering 2018, 2018, 1 -14.
AMA StyleJoo-Ha Lee, Hwang-Hee Kim, Sung-Ki Park, Ri-On Oh, Hae-Do Kim, Chan-Gi Park. Mechanical Properties and Durability of Latex-Modified Fiber-Reinforced Concrete: A Tunnel Liner Application. Advances in Materials Science and Engineering. 2018; 2018 ():1-14.
Chicago/Turabian StyleJoo-Ha Lee; Hwang-Hee Kim; Sung-Ki Park; Ri-On Oh; Hae-Do Kim; Chan-Gi Park. 2018. "Mechanical Properties and Durability of Latex-Modified Fiber-Reinforced Concrete: A Tunnel Liner Application." Advances in Materials Science and Engineering 2018, no. : 1-14.
This study evaluated the influence of reinforcement fiber type and microsilica content on the performance of latex-modified fiber-reinforced roller-compacted rapid-hardening cement concrete (LMFRCRSC) for a concrete pavement emergency repair. Experimental variables were the microsilica substitution ratio (1, 2, 3, and 4%), and the reinforcement fiber (jute versus macrosynthetic fiber). In the tests, compressive, flexural, and splitting tensile strength; chloride ion penetration resistance; and abrasion resistance were assessed. From the compressive and flexural strength tests with microsilica substitution, the 4-hour curing strength decreased as the microsilica substitution ratio increased. From the chloride ion penetration test, as the microsilica substitution ratio increased, chloride ion penetration decreased. The abrasion resistances increased with the substitution ratio of microsilica increase. Based on these test results, microsilica at a substitution ratio of 3% or less and macrosynthetic fiber as the reinforcement improved the performance of LMFRCRSC for a concrete pavement emergency repair and satisfied all of the target strength requirements.
Woong Kim; Jong-Chan Jeon; Byung-Hwan An; Joo-Ha Lee; Hae-Do Kim; Chan-Gi Park. Effects of Reinforcing Fiber and Microsilica on the Mechanical and Chloride Ion Penetration Properties of Latex-Modified Fiber-Reinforced Rapid-Set Cement Concrete for Pavement Repair. Advances in Materials Science and Engineering 2018, 2018, 1 -8.
AMA StyleWoong Kim, Jong-Chan Jeon, Byung-Hwan An, Joo-Ha Lee, Hae-Do Kim, Chan-Gi Park. Effects of Reinforcing Fiber and Microsilica on the Mechanical and Chloride Ion Penetration Properties of Latex-Modified Fiber-Reinforced Rapid-Set Cement Concrete for Pavement Repair. Advances in Materials Science and Engineering. 2018; 2018 ():1-8.
Chicago/Turabian StyleWoong Kim; Jong-Chan Jeon; Byung-Hwan An; Joo-Ha Lee; Hae-Do Kim; Chan-Gi Park. 2018. "Effects of Reinforcing Fiber and Microsilica on the Mechanical and Chloride Ion Penetration Properties of Latex-Modified Fiber-Reinforced Rapid-Set Cement Concrete for Pavement Repair." Advances in Materials Science and Engineering 2018, no. : 1-8.
This numerical study investigated the effects of different reinforcing details in beam-column joints on the blast resistance of the joints. Due to increasing manmade and/or natural high rate accidents such as impacts and blasts, the resistance of critical civil and military infrastructure or buildings should be sufficiently obtained under those high rate catastrophic loads. The beam-column joint in buildings is one of critical parts influencing on the resistance of those buildings under extreme events such as earthquakes, impacts and blasts. Thus, the details of reinforcements in the joints should be well designed for enhancing the resistance of the joints under the events. Parameters numerically investigated in this study include diagonal, flexural, and shear reinforcing steel bars. The failure mechanism of the joints could be controlled by the level of tensile stress of reinforcing steel bars. Among various reinforcing details in the joints, diagonal reinforcement in the joints was found to be most effective for enhancing the resistance under blast loads. In addition, shear reinforcements also produced favourable effects on the blast resistance of beam-column joints.
Kwang-Mo Lim; Hyunoh Shin; Dong-Joo Kim; Young-Soo Yoon; Joo-Ha Lee. Numerical Assessment of Reinforcing Details in Beam-Column Joints on Blast Resistance. International Journal of Concrete Structures and Materials 2016, 10, 87 -96.
AMA StyleKwang-Mo Lim, Hyunoh Shin, Dong-Joo Kim, Young-Soo Yoon, Joo-Ha Lee. Numerical Assessment of Reinforcing Details in Beam-Column Joints on Blast Resistance. International Journal of Concrete Structures and Materials. 2016; 10 (S3):87-96.
Chicago/Turabian StyleKwang-Mo Lim; Hyunoh Shin; Dong-Joo Kim; Young-Soo Yoon; Joo-Ha Lee. 2016. "Numerical Assessment of Reinforcing Details in Beam-Column Joints on Blast Resistance." International Journal of Concrete Structures and Materials 10, no. S3: 87-96.