• Journal of the Korea Concrete Institute
• /
• v.29 no.1
• /
• pp.23-32
• /
• 2017

The joints between precast PSC slabs of the intermediate road slab in double deck tunnel are inevitably generated in the road traffic vehicle traveling direction. Therefore, it is important to make the behavior of parts on the joint in one piece. The imtermediate road slab system of double deck tunnel in great depth proposed in this study will be constructed with precast PSC slab in order to minimize the construction period. And the joint connection between the precast slab has been developed in two methods: the 'Transverse tendon reinforcement method' and 'High strength bolts connection method'. Also, the experiments were performed for the full scale model in order to evaluate the performance of the intermediate road deck slab with two type joints systems, the structural stability was verified through the F.E.M analsysis. The results of static loading test and F.E.M analysis investigated a very stable behavior of intermediate road deck slab in double deck tunnel applying the joint methods developed in this study, in the cracks and deflections to satisfy the design standards of Highway Roads Bridges (2011), it was determined that there is no problem even servicebility.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.5
• /
• pp.637-646
• /
• 2011

This study is related to the development of a design automation system for the construction design phase of steel structures. The system intended for beam splice friction connections using high-strength bolts. The standard design method and standardization principles that are suggested in the design manual for standard connections using high-strength bolts published by the Korean Society of Steel Construction(KSSC) were reviewed. A structural analysis algorithm was formulated from the review. A design automation system that can automatically calculate the structural design of connections and automatically generate the connection model without separate inputs was developed. To verify the validity of the developed system, its results were compared with the date in the table for the connection design in the Design Manual. The development system was also applied to the sample model. Then the structural design results were compared with the properties of the connection models and drawings created from the results.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.6
• /
• pp.9-17
• /
• 2012

Concrete sewage culvert shows degradation with time since it is always exposed to various harmful ions, and deterioration of concrete culvert propagates to structural safety problems. After reclamation, maintenance for concrete sewage culvert is very difficult so that high durable and structural performance are essential for the sewage concrete culvert. Recently polymer concrete has been used to improve mechanical properties and durability performance. In this paper, engineering properties are evaluated for sewage culvert made with polymer concrete, and leakage and adhesive strength between joints are evaluated with small-scale models. The polymer sewage culvert shows high compressive strength over 100MPa with low water permeability and chloride penetration. Furthermore, high resistances to chemical and biological attack are evaluated. Through tests for leakage and adhesive, unification of joints is verified with evaluation of no leakage and high adhesive strength. Precast polymer sewage culvert in this paper can be actively used for severe conditions like sewage lines.

• Journal of the Korea Institute of Building Construction
• /
• v.21 no.2
• /
• pp.129-139
• /
• 2021

Recent rise in the supply rate of new public apartment houses leads to an increasement in disputes regarding the construction quality of the apartments between the residents and the construction companies. According to the dispute cases filed for claiming the collective defect repair fees, inter-layer concrete joints turned out to be the most frequently disputed item. For this reason, this study selects the inter-layer concrete joints to further analyze the primary causes and details of each dispute case. From the results of this study, three primary causes of the disputes are found, which are 1) the absence of standard specifications for construction quality control and management after construction; 2) the absence of established standards for repair when construction defects are found; and 3) the fact that the court grants generous compensation for disputes concerning the apartment houses. In order to prevent construction defects in inter-layer concrete joints, this study provides three suggestions including 1) the current standard specifications for inter-layer concrete joints should be further specified by the Ministry of Land, Infrastructure and Transport; 2) a construction defect should be judged according to the compliance to the standard specifications; and 3) a clear and institutional protocol needs to be established for defect repair in cases that new public apartment houses have been judged to have defects.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.4
• /
• pp.23-32
• /
• 2023

The seismic performance of buried PE pipes is reported to be favorable due to their exceptional elongation capacity at break. Although a seismic performance evaluation procedure based on the response displacement method has been summarized in Korea for fusion-bonded PE pipes, there is currently no procedure available for mechanically jointed PE pipes. This article aims to present a seismic performance evaluation procedure based on the response displacement method specifically designed for mechanically jointed PE pipes in Korea. When employing the mechanical joining method for PE pipes, it is recommended to adhere to the evaluation procedure established for segment-type pipes. This involves assessing the stress induced by the pipe, the expansion and contraction strain of the joint, and the bending angle of the pipe joint. Furthermore, the coefficient of inhomogeneity of the soil, which is necessary for estimating the axial strain of the ground, is introduced. Additionally, a computation method for determining lateral displacement and reconsolidation settlement in soil susceptible to liquefaction is proposed. As a result of the sensitivity analysis considering the typical soil condition in Korea, the mechanically jointed PE pipe with a certain quality was shown to have good structural seismic safety when soil liquefaction was not considered. This procedure serves as a valuable tool for seismic design and evaluating the seismic performance of mechanically joined buried PE pipes, which are primarily utilized for connecting small-diameter pipes.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.6
• /
• pp.513-523
• /
• 2015

In steel moment frames constructed of H-shapes, strong-axis moment connections should be used for maximum structural efficiency if possible. And most of cyclic seismic testing, domestic and international, has been conducted for strong-axis moment connections and cyclic test data for weak-axis connections is quite limited. However, when perpendicular moment frames meet, weak-axis moment connections are also needed at the intersecting locations. Especially, both strong- and weak-axis moment connections have been frequently used in domestic practice. In this study, cyclic seismic performance of RBS (reduced beam section) weak-axis welded moment connections was experimentally investigated. Test specimens, designed according to the procedure proposed by Gilton and Uang (2002), performed well and developed an excellent plastic rotation capacity of 0.03 rad or higher, although a simplified sizing procedure for attaching the beam web to the shear plate in the form of C-shaped fillet weld was used. The test results of this study showed that the sharp corner of C-shaped fillet weld tends to be the origin of crack propagation due to stress concentration there and needs to be trimmed for the better weld shape. Different from strong-axis moment connections, due to the presence of weld access hole, a kind of CJP butt joint is formed between the beam flange and the horizontal continuity plate in weak-axis moment connections. When weld access hole is large, this butt joint can experience cyclic local buckling and subsequent low cycle fatigue fracture as observed in this testing program. Thus the size of web access hole at the butt joint should be minimized if possible. The recommended seismic detailing such as stickout, trimming, and thicker continuity plate for construction tolerance should be followed for design and fabrication of weak-axis welded moment connections.

• Composites Research
• /
• v.12 no.2
• /
• pp.26-35
• /
• 1999

This paper presents the vibration damping characteristic of a single lap joint beam with partial dampers analyzed using the model strain energy method and the harmonic response analysis which were based on a finite element model. The two finite element analysis methods exhibited very similar results of the resonant frequency and system loss factor which were comparable to those by the theoretical analysis. Effects of the location of partial dampers and elastic moduli and thickness of their layers on the system loss factor were studied. The damping effects due to changes of modules and loss factor of the viscoelastic layer in lap joint and partial dampers were also studied. Consequently, the geometrical and material conditions at maximizing the system loss factor were suggested.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.4
• /
• pp.136-143
• /
• 2015

Galvanizing is one of the method used to solve the problem of corrosion of reinforcement in concrete structures. There few research reported in the literature regarding the effect of galvanized coating on the behavior of lap splices in concrete beams. The objective of this study was to determine whether galvanized rebar adversely affects lap splice behavior and bond strength. Concrete beams reinforced with black or galvanized rebar were tested in flexure. The test variables included the presence of galvanized rebar steel diameter, and lengths of lap splices. The study concentrated on comparing crack, failure pattern, and bond strength. The ultimate behavior of beams reinforced with galvanized rebar was not significantly different from that of black steel reinforced beams. Therefore, the test results indicated that the use of galvanizing-coated rebar had no adverse effect on behavior in lap splices of rebar compared to the use of black rebar.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.6
• /
• pp.262-269
• /
• 2021

This paper conducts an evaluation of the structural performance of the lap splice detail of SD700 headed bar experiment for developing an RC beam with different depths joint details. The experiment variable is lap splice length, yield strength, and end anchorage of main reinforcements. For all specimens, a headed bar was applied to the main reinforcement of the beam with low depth (B2), and the beam with high depth (B1) was applied to the main reinforcement with two splice methods: straight headed bar and 90° hooked-headed bar. The experimental results were that specimens of applying SD500 and SD600 had the results of flexural fracture at the lap splice location, which maximum load was similar. For specimens of appling SD500, the 90° hooked-headed bar of B1, suppressed horizontal cracks in the lap splice section compared to the straight headed bar. Specimens of applying an SD 700 headed bar had the results of brittle anchorage failure. In addition, maximum load was increased with the lap splice length increasing. For specimens of applying SD700 headed bar, test for test maximum load/theoretical load for test development length/design development length were estimated to be 1.30~1.48 for the ACI 318-19 equation, and 1.14~1.30 for the KDS-2021 equation. Thus, ACI 318-19 equation had conservatively greater safety factors as estimated development lengththened.

• Journal of Broadcast Engineering
• /
• v.23 no.5
• /
• pp.656-668
• /
• 2018

VR (Virtual Reality) is one of the important research topics in the field of multimedia application system. The quality of the visual data composed from multiple pictures depends on the performance of stitching technique. The stitching module consists of feature extraction, mapping of those, warping, seam finding, and blending. In this paper, we proposed a preprocessing scheme to provide the efficient mask for seam finder. Incorporating of the proposed mask removes the distortion, such as ghost and blurring, in the stitched image. The simulation results show that the proposed algorithm outperforms other conventional techniques in the respect of the subjective quality and the computational complexity.