• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.141-152
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• 2001

This paper presents the evaluation of behavior and the prediction of tensile capacity of anchors that can cause a failure of the concrete on the basis of the design for anchorage. Tests of cast-in-place headed anchors, domestically manufactured and installed in uncracked and unreinforced concrete member are conducted to test the effected of embedment length and edge distance. The failure modes and the load-deformation responses of the anchors are discussed and then the concrete failure data are compared with capacities by the two present methods : the 45 degree cone method of ACI 349, 318 and the concrete capacity design (COD) method. Differences between the results by test and by two prediction methods are analyzed Finite Element Method (FEM).

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.493-501
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• 2011

The $45^{\circ}$cone failure theory has been used for concrete anchor bolt design, but the CCD (concrete capacity design) method was adopted as a new design method in 2000. The method was allowed to be used, however, only for anchors with a diameter of less than 50 mm and an embedment depth of less than 635 mm because it is based on the experiment results from medium-sized to small anchor bolts. Therefore, it is necessary to develop a rational concrete breakout capacity equation for medium-sized to large anchor bolts. In this study, tension tests on an M56 cast-in-place single anchor bolt with an effective embedment depth of 400-450 mm were carried out for the five test specimens. Based on the test results together with the other recent test results, the applicability of the concrete breakout capacity equation in the current design code to the large to medium-sized anchor bolts with an embedment depth of 280-1,200 mm was estimated.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.591-594
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• 2004

Recently, a tendency for development of seismic approach of foreign countries is capacity design development. Capacity design is rational seismic design concept of capacity protection considering not only earthquake magnitude, but also behavior of structure. For that reason, the most bridge seismic design specifications contain capacity protection provisions explicitly or implicitly. The capacity protection is normally related with slenderness effect of the columns, force transfer in connections between columns and adjacent elements, and shear design of columns. It intends to prevent brittle failure of the structural components of bridges, so that the whole bridge system may show ductile behavior and failure during earthquake events. The objectives of this paper are to deduce needed provisions for the moderate seismicity regions such as Korea after studying current seismic design codes and to establish rational criteria provisions of seismic design for future revision of seismic design specifications.

• Steel and Composite Structures
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• v.13 no.3
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• pp.277-293
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• 2012

The interaction between steel tube and concrete core is the key design considerations for concrete-filled steel tube columns. In a concrete-filled steel tube (CFST) column, the steel tube provides confinement to the concrete core which permits the composite action among the steel tube and the concrete. Due to construction faults and plastic shrinkage of concrete, the debonding separation at the steel-concrete interface weakens the confinement effect, and hence affects the behaviour and bearing capacity of the composite member. This study investigates the axial loading behavior of the concrete filled circular steel tube columns with debonding separation. A three-dimensional nonlinear finite element model of CFST composite columns with introduced debonding gap was developed. The results from the finite element analysis captured successfully the experimental behaviours. The calibrated finite element models were then utilized to assess the influence of concrete strength, steel yield stress and the steel-concrete ratio on the debonding behaviour. The findings indicate a likely significant drop in the load carrying capacity with the increase of the size of the debonding gap. A design formula is proposed to reduce the load carrying capacity with the presence of debonding separation.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.295-298
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• 2005

Coupled shear wall(CSW) has been adopted as a lateral force resisting system in building frame structures. New Zealand code recommends the capacity design in designing the CSW. Capacity design based on using moment redistribution of member force may provide the economical benefit to designer. In this study, CSW's are designed by both capacity design and strength -based design. The design results and the seismic performance are compared by using nonlinear static analyses. The amount of reinforcement of shear wall and the section area of steel coupling beams by capacity design appear to be reduced by 19$\%$ and 17$\%$, respectively. Also CSW designed by capacity design shows good seismic performance at the ultimate state.

• Steel and Composite Structures
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• v.35 no.3
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• pp.371-384
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• 2020

The steel-concrete double composite girder in the negative flexural region combines an additional concrete slab to the steel bottom flange to prevent the local steel buckling, however, the additional concrete slab may lower down the neutral axis of the composite section, which is a sensitive factor to the tensile stress restraint on the concrete deck. This is actually of great importance to the structural rationality and durability, but has not been investigated in detail yet. In this case, a series of 5.5 m-long composite girder specimens were tested by negative bending, among which the bottom slab configuration and the longitudinal reinforcement ratio in the concrete deck were the parameters. Furthermore, an analytical study concerning about the influence of bottom concrete slab thickness on the cracking and sectional bending-carrying capacity were carried out. The test results showed that the additional concrete at the bottom improved the composite sectional bending stiffness and bending-carrying capacity, whereas its effect on the concrete crack distribution was not obvious. According to the analytical study, the additional concrete slab at the bottom with an equivalent thickness to the concrete deck slab may provide the best contributions to the improvements of crack initiation bending moment and the sectional bending-carrying capacity. This can be applied for the design practice.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03a
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• pp.65-84
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• 2000

Europe and US which have more restrictive regulations than Korea about the noise and vibration during construction are using Auger-cast Pile to reduce the problem relating with noise and vibration. However Auger-cast Pile has problems like difficult quality control and low bearing capacity. In Europe, Displacement in-situ concrete Pile has been used to sove that problems since 1990s, and Korea has performed the test construction in 1997 and it has been used as the real structural foundation since 1998. Test and real construction results verified that the allowable capacity of the pile(diameter = 410mm) is between 70 and 100ton. Though De Beer & Van Imps design method utilizing CPT result is used to calculate the bearing capacity of the Displacement in-situ Pile, Korea is dependant upon the SPT as the sounding test, so design method utilizing SPT result is necessary to promote the application of the pile. To find out reasonable design method using SPT result, rearing capacity of the pile constructed in sand and clay in Korea was calculated using Meyerhof, SPT-CPT translation method, Nordlund, Douglas and DM-7 method, and the calculation results were compared to the load test result. Analysis result shows that SPT-CPT translation method is more reliable than others and economical design can be possible because it considers efficiently the friction capacity of Displacement in-situ Pile.

• Advances in concrete construction
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• v.11 no.1
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• pp.33-43
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• 2021

A new type of composite insulated concrete sandwich wall (ICS-wall), which is composed of a triangle truss steel wire network, an insulating layer, and internal and external concrete layers, is proposed. To study the mechanical properties of this new ICS-wall, tensile, compression, and shearing tests were performed on 22 specimens and tensile strength and corrosion resistance tests on 6 triangle truss joints. The variables in these tests mainly include the insulating plate material, the thickness of the insulating plate, the vertical distance of the triangle truss framework, the triangle truss layout, and the connecting mode between the triangle truss and wall and the material of the triangle truss. Moreover, the failure mode, mechanical properties, and bearing capacity of the wall under tensile, shearing, and compression conditions were analyzed. Research results demonstrate that the concrete and insulating layer of the ICS-wall are pulling out, which is the main failure mode under tensile conditions. The ICS-wall, which uses a graphite polystyrene plate as the insulating layer, shows better tensile properties than the wall with an ordinary polystyrene plate. The tensile strength and bearing capacity of the wall can be improved effectively by strengthening the triangle truss connection and shortening the vertical distances of the triangle truss. The compression capacity of the wall is mainly determined by the compression capacity of concrete, and the bonding strength between the wall and the insulating plate is the main influencing factor of the shearing capacity of the wall. According to the tensile strength and corrosion resistance tests of Austenitic stainless steel, the bearing capacity of the triangle truss does not decrease after corrosion, indicating good corrosion resistance.

• Structural Engineering and Mechanics
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• v.57 no.4
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• pp.763-783
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• 2016

A methodology based on Teaching Learning-Based Optimization (TLBO) algorithm is proposed for optimum design of reinforced concrete retaining walls. The objective function is to minimize total material cost including concrete and steel per unit length of the retaining walls. The requirements of the American Concrete Institute (ACI 318-05-Building code requirements for structural concrete) are considered for reinforced concrete (RC) design. During the optimization process, totally twenty-nine design constraints composed from stability, flexural moment capacity, shear strength capacity and RC design requirements such as minimum and maximum reinforcement ratio, development length of reinforcement are checked. Comparing to other nature-inspired algorithm, TLBO is a simple algorithm without parameters entered by users and self-adjusting ranges without intervention of users. In numerical examples, a retaining wall taken from the documented researches is optimized and the several effects (backfill slope angle, internal friction angle of retaining soil and surcharge load) on the optimum results are also investigated in the study. As a conclusion, TLBO based methods are feasible.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.5 s.51
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• pp.85-97
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• 2006

Capacity design is to guarantee ductile failure of whole bridge system by preventing brittle failure of columns and any other structural elements until the columns develope fully enough plastic deformation capacity. This concept has been explicitly regulated in most bridge design specifications of foreign countries except the current Korea Bridge Design Specifications. In the capacity design, the transformed shear force from flexural overstrength of reinforced concrete column is used as the design lateral shear force for shear design of columns and design of footings and piles. Different calculating methods are adopted by the design specifications, since the variability of material strength and construction circumstances of the local regions should be considered. This paper proposed material overstrength factors by investigating 3,407 reinforcing bar data and 5,405 concrete compressive strength data collected in Korean construction sites. It also proposed calculating procedures for flexural overstrength of reinforced concrete columns using the material overstrength. Finally, overstrength factor was proposed as 1.5 by investigating 1,500 column section data from moment-curvature analysis using the material overstrength.